WO2006026592A2 - Oral administration of poorly absorbed drugs, methods and compositions related thereto - Google Patents

Abstract

The invention provides methods and compositions for the delivery of poorly absorbed drugs. In some embodiments, the drug is administered in the form of microparticles or nanoparticles. In other embodiments, the drug is encapsulated with polymer. In certain embodiments, the drug is administered in combination with an absorption enhancer. The invention further relates to dosing schedules to maintain the oral bioavailability of poorly absorbed drugs, such as paclitaxel. In another embodiment, the method involves administering inhibitors of one or more inhibitors of a drug efflux pump in combination with a poorly absorbed drug.

Description

ORAL ADMINISTRATION OF POORLY ABSORBED DRUGS, METHODS AND COMPOSITIONS RELATED THERETO

Related Applications This application claims the benefit of U.S. Provisional Application

Nos. 60/604,990, filed August 27, 2004, 60/604,991, filed August 27, 2004, 60/605,198, filed August 27, 2004, 60/605,199, filed August 27, 2004, 60/605,200, filed August 27, 2004, 60/605,201, filed August 27, 2004, 60/607,905, filed September 8, 2004, 60/635,812, filed December 13, 2004, 60/650,191, filed February 4, 2005, 60/650,375, filed February 4, 2005 and 60/676,383, filed April 29, 2005. This application is also a continuation-in- part of U.S. Application No. 11/009,327, filed December 9, 2004 and a continuation-in-part of U.S. Application No. 11/072,098, filed March 3, 2005. The entire teachings of the above-referenced applications are incorporated herein by reference.

Background of the Invention

Current formulations for oral administration of hydrophobic drugs employ a wide variety of approaches to improve their uptake into the gastrointestinal tract. The selection of polymers and other aspects of dosage forms can influence how the drag is absorbed from certain segments of the gut. Principal routes of absorption include uptake by intestinal cells. Dissolved molecules may be directly absorbed by the plasma membrane or absorbed via transporters. Particles can be absorbed into the cells via pinocytosis and similar mechanisms or via penetration between cells, particularly in regions of loosened intercellular adherence, such as the gastrointestinal associated lymphoid tissue ("GALT") and Peyers Patches. Barriers to absorption include lack of aqueous solubility, lack of transporters, phagocytosis (which leads to degradation of the drug), and direct expulsion of the drug via transmembrane pumps (e.g., by the P-glycoprotein series (PGP)).

Important to the safety and effectiveness of any pharmaceutical formulation is its ability to maintain a target blood level of the active pharmaceutical agent within the agent's therapeutic concentration range. The window of absorption for certain drugs presents a serious challenge to the development of effective modified-release preparations of these compounds. The poor or decreased absorption of these drugs may be attributed to a variety of barriers, which may be biological or physico- chemical in nature, and can be, but are not limited to poor solubility, low permeability, and saturable active absorption or influx mechanisms such as carrier-mediated transport. Poor solubility over a broad pH range is another barrier that inhibits absorption and overall bioavailability for a number of compounds. Furthermore, when solubility is limited at the higher pH's found in the distal gastrointestinal (GI) tract, a limited window of absorption is effectively created.

Such windows of absorption can significantly curtail the bioavailability of a compound and the extent to which Tmax, the time at which the rate of absorption of an active agent into the bloodstream is equal to its rate of elimination from the bloodstream, can be extended using conventional modified release dosage forms known in the art.

Paclitaxel is a natural product that has been shown to possess cytotoxic and antitumor activity. While having an unambiguous reputation of tremendous therapeutic potential, paclitaxel has some patient-related drawbacks as a therapeutic agent. These stem partly from its extremely low aqueous solubility and low permeability (BCS Class IV drug), which makes it difficult to provide in suitable dosage form. Additional difficulties in administration are due to the binding of paclitaxel with P-glycoprotein, which acts as an efflux pump. Because of paclitaxel's poor aqueous solubility, the current approved (U.S. FDA) clinical formulation consists of a 6 mg/ml solution of paclitaxel in 50% polyoxyethylated castor oil (CREMOPHOR EL™) and 50% dehydrated alcohol. Am. J. Hosp. Pharm., 48: 1520-24 (1991). CREMOPHOR EL™ is administered with paclitaxel for its low water solubility. In some instances, severe reactions, including hypersensitivity, are induced by the CREMOPHOR EL™. As a result of the incidence of hypersensitivity reactions to the commercial paclitaxel formulations and the potential for paclitaxel precipitation in the blood, the formulation must be infused over several hours. In addition, patients must be pretreated with steroids and antihistamines prior to the infusion. In humans, the normal intravenous dosing regimen involves administering paclitaxel in a vehicle for 4 to 24 hours of infusion, followed by a two to three week rest period before re-administration of therapy. In part, the interval is dictated by the toxic effects of the clinically-approved vehicle, CREMOPHOR EL™.

The costs of prolonged parenteral administration of poorly absorbed drugs, such as paclitaxel, due in part to the need for hospitalization, are very high. Additionally, patient compliance is low. Therefore, there is a need to decrease the cost of administration and increase patient compliance for poorly absorbed drugs.

Drugs characterized by poor biomembrane permeability are commonly delivered parenterally. Traditional approaches to parenteral delivery include using large volumes of aqueous diluents, solubilizing agents, detergents, non-aqueous solvents, or non-physiological pH solutions. These formulations, however, can increase the systemic toxicity of the drug composition or damage body tissues at the site of administration. There is therefore a need for improved formulations for delivery of poorly absorbed drugs.

Summary of the Invention Described herein are methods and compositions for the oral delivery of poorly absorbed drugs, hi some embodiments, the invention relates to delivery of poorly absorbed drugs that are micronized to nanoparticles. hi other embodiments, the drug in the form of nanoparticles is encapsulated, e.g., with a polymer. Representative drugs include paclitaxel, tacrolimus, and caspofungin. hi some embodiments, the drug formulation comprises absorption enhancers, which may be administered in soluble form with nanoparticles; co-encapsulated in nanoparticles with the drug; or admixed as solids (excipients) in solid oral dosage forms such as tablets or capsules along with nanoparticulate drug. Enteric coatings, diffusion limiting coatings, and/or bioadhesive coatings may be applied to the particles.

In other embodiments, the invention relates to dosing schedules to maintain the oral bioavailability of poorly absorbed drugs, such as paclitaxel, by compensating for poor absorption in the days following an initial oral administration of the drug, hi certain embodiments, the dosing schedule commences with one or more oral administrations, and then delays subsequent oral administrations by a period of time sufficient to achieve a response similar to that of the initial dose or initial dose group (a period referred to herein as the "recovery period"). The recovery period between doses or dose groups is preferably at least one day, more preferably two days, more preferably at least three days, more preferably at least four days, and most preferably at least five days. A preferred recovery period between oral administrations is about three to five days, hi one embodiment, the subsequent dose is greater than the previous dose, hi another embodiment, the method involves administering, along with the poorly absorbed drug, one or more inhibitors of inducible enzymes or protein pumps. This co¬ administration can occur with each administration of the drug or with selective administrations, e.g., with the initial or one or more subsequent administrations. The suitability of the methods and formulations for improving the oral bioavailability of any drug, preferably a poorly absorbed drug, can be readily determined as described herein.

BRIEF DESCRIPTION OF THE DRAWINGS Figure IA is a graph of the induction of paclitaxel resistance in mice, and gradual recovery from it; plotting paclitaxel plasma concentration (ng/ml) over time (h) indicating an increase in paclitaxel plasma levels (Cp vs. time) when two administered oral doses of paclitaxel are separated by increasing amounts of time. Each group received one dose at 0 h and its second dose at one of the following times: 12 h, 24 h, 48 h, 72 h, or 96 h. Figure IB is a graph of the data of Figure IA in terms of "area under the curve" (AUC) (measured herein as ng.h/ml) values.

Figure 2 A is a graph of the plasma levels of paclitaxel in mice resulting from four oral administrations spaced 12 hours apart. Figure 2B is a graph of the AUC and maximum plasma concentration (Cmax) values from the same experiment. Figure 3 A is a graph of the plasma levels of paclitaxel in mice resulting from four oral administrations spaced 24 hours apart. Figure 3B is a graph of the AUC and Cmax values from the same experiment. Figure 4A is a graph of the plasma levels of paclitaxel in mice resulting from four oral administrations spaced 48 hours apart. Figure 4B is a graph of the AUC and Cmax values from the same experiment.

Figure 5 A is a graph of the plasma levels of paclitaxel in mice resulting from four oral administrations spaced 96 hours apart. Figure 5B is a graph of the AUC and Cmax values from the same experiment.

Figure 6 A is a graph of the plasma levels of paclitaxel in mice from five oral administrations spaced 24 hours apart, each in combination with oral ketoconazole. Figure 6B is a graph of the AUC and Cmax values from the same experiment.

Figure 7 A is a graph of the plasma levels of paclitaxel in mice from four oral administrations spaced 24 hours apart, each in combination with oral cyclosporin A. Figure 7B is a graph of the AUC and Cmax values from the same experiment. Figure 8 A is a graph of the plasma levels of paclitaxel resulting from four escalating-dose oral administrations spaced 24 hours apart. Figure 8B is a graph of the AUC and Cmax values from the same experiment.

Figure 9 A is a graph of the plasma levels of paclitaxel resulting from four escalating-dose oral administrations spaced 24 hours apart. Figure 9B is a graph of the AUC and Cmax values from the same experiment.

Figure 1OA is a graph of the plasma levels of paclitaxel resulting from four escalating-dose oral administrations spaced 24 hours apart, where oral cyclosporin A was simultaneously administered only at doses 3 and 4. Figure 1OB is a graph of the AUC and Cmax values from the same experiment.

Figure 1 IA is a graph of the plasma levels of paclitaxel resulting from four escalating-dose oral administrations, each spaced 48 hours apart. Figure 1 IB is a graph of the AUC and Cmax values from the same experiment. Figure 12A is a graph of the plasma levels of paclitaxel following administration of three different oral paclitaxel formulations (using two different dispersants). Figure 12B is a bar graph of the Cmax and calculated AUC values for each formulation from the same experiment. Figure 13 A is a graph of the plasma levels of paclitaxel following oral administration at different dosing intervals within a 12 hr period. Figure 13B is a bar graph of the AUC and Cmax values from the same experiment.

Figure 14A is a graph of the plasma levels of paclitaxel following oral administration at different dosing intervals within a 12 hr period. Figure 14B is a bar graph of the AUC and Cmax values from the same experiment.

Figure 15A is a graph of the plasma levels of paclitaxel following oral administration at different dosing intervals within a 12 hour period. Figure 15B is a bar graph of the AUC and Cmax values from the same experiment.

Figure 16A is a graph of the plasma levels of paclitaxel following oral administration at different dosing intervals within a 12 hour period. Figure 16B is a bar graph of the AUC and Cmax values from the same experiment. Figure 17 is a schematic cross-sectional view of a solid oral dosage form containing nanoparticulate drug and absorption enhancers in a central matrix of hydroxypropylmethyl cellulose (HPMC) and microcrystalline cellulose (MCC). The inner core is surrounded on two sides by bioadhesive polymer (preferably DOPA-derivatized BMA polymer). The final tablet is coated with an enteric coating (Eudragit Ll 00-55) to prevent release of the drug until the tablet has moved to the small intestine or large intestine.

Figure 18 is a longitudinal cross-section of a longitudinally compressed tablet containing a drug and exciepients, and optionally permeation and/or dissolution enhancers, disposed in a single monolithic layer. The tablet is coated peripherally with a bioadhesive polymer coating comprising either Spheromer I (anhydride polymers), Spheromer II (anhydride oligomers blended with pharmaceutical polymers), Spheromer III (catechol grafted anhydride polymers) or any combination of these polymer layers. These polymer coatings can serve as a rate-controlling composition as well as a bioadhesive composition as needed to keep the dosage form at the target absorption site.

Figure 19 is a graph depicting the results of repeat dosing of BioVir™ CR (400mg, ql2 hrs x2) compared to Zovirax® (200 mg q 6 hrs x 4). n=6 dogs per study. DETAILED DESCRIPTION OF THE INVENTION Described herein are methods and compositions related to the oral administration of poorly absorbed drugs. Poorly absorbed drugs are drugs that have low permeability across the intestinal cell layer. The subject invention provides methods and compositions, which enable increased uptake of such drugs across the intestinal epithelium. For example, in preferred embodiments, a low permeability drug is administered with one or more absorption enhancers, which facilitate uptake of the drug across the intestinal cell layer. In some embodiments, bioadhesive polymers are used to encapsulate the drug formulation in order to increase residence time of the drug formulation at the target absorption site, thereby further increasing the likelihood of drug uptake by the intestinal epithelium.

In some instances, the poor permeability of a drug is due to its efflux from a cell via a membrane transporter that acts as a drug efflux pump, such as P-glycoprotein. Therefore, in some embodiments, a poorly absorbed drug is administered with one or more inhibitors of a drug efflux protein pump, such as cyclosporin. hi other embodiments, the bioavailability of a poorly absorbed drug is maintained or enhanced by application of dosing regimens of the invention, which compensate for poor absorption of the drug in the days following an initial oral administration of the drug, hi a preferred embodiment, the invention provides dosing regimens relating to the administration of oral dosage formulations comprising paclitaxel.

The methods and compositions of the invention provide for the administration of low permeability drugs in a wide variety of dosage forms. For example, in some embodiments, a low permeability drug is administered in the form of microparticles or nanoparticles, optionally in combination with one or more dispersants. Preferably, particles have a diameter less than or equal to one micron, even more preferably less than 500 nm. In other embodiments, the low permeability drug is administered in the form of a tablet or capsule, which preferably comprises a bioadhesive polymer. Additionally, the tablet or capsule may further comprise nano- or microparticles of the drug, hi some embodiments, the low permeability drug is administered as a suspension, emulsion, or in liquid form. Suitable Drugs

The methods and compositions described herein are well suited for the administration of poorly absorbed drugs, although any kind of therapeutic, prophylactic, or diagnostic agent can be administered using the methods and compositions of the instant invention, hi preferred embodiments, the agent is a poorly absorbed drug, such as a BCS Class El or Class IV drug. In certain embodiments, the drug has low aqueous solubility, such as a BCS Class II or Class IV drug.

As used herein, a "poorly absorbed drug" is a drug that has low permeability across the intestinal cell layer. For example, a drug substance may be considered to have low permeability when the extent of absorption in humans is determined to be less than 90% of an administered dose. Typically, a poorly absorbed drug will have an oral bioavailability that is between 0.5% and 75% when administered alone. Poorly absorbed drugs include low-permeability drugs such as Class

III and Class IV drugs, which are classified according to the Biopharmaceutical Classification System (BCS). BCS separates pharmaceuticals for oral administration into four classes based on their solubility and their absorbability through the intestinal cell layer. According to the BCS, drug substances are classified as follows:

Class I - High Permeability, High Solubility

Class π - High Permeability, Low Solubility

Class El - Low Permeability, High Solubility

Class IV - Low Permeability, Low Solubility _. The interest in this classification system stems largely from its application in early drug development and in the management of product change through its life-cycle. In the early stages of drug development, knowledge of the class of a particular drug is an important factor influencing the decision to continue or stop its development. The solubility class boundary is based on the highest dose strength of an immediate release (IR) formulation and a pH-solubility profile of the test drug in aqueous media with a pH range of 1 to 7.5. Solubility can be measured by the shake-flask or titration method or analysis by a validated stability-indicating assay. A drug substance is considered highly soluble when the highest dose strength is soluble in 250 ml or less of aqueous media over the pH range of 1-7.5. The volume estimate of 250 ml is derived from typical bioequivalence (BE) study protocols that prescribe administration of a drug product to fasting human volunteers with a glass (about 8 ounces) of water. In the absence of evidence suggesting instability in the gastrointestinal tract, a drug is considered highly soluble when 90% or more of an administered dose, based on a mass determination or in comparison to an intravenous reference dose, is dissolved. Based on BCS, low-solubility compounds are compounds whose highest dose is not soluble (i.e., less than 90% dissolves) in 250 niL or less of aqueous media from pH 1.2 to 7.5 at 37 ⁰C. See Cynthia K. Brown, et al., "Acceptable Analytical Practices for Dissolution Testing of Poorly Soluble Compounds", Pharmaceutical Technology (Dec. 2004).

The permeability class boundary is based directly on measurements of the rate of mass transfer across human intestinal membrane, and, indirectly, on the extent of absorption (fraction of dose absorbed, not necessarily systemic bioavailability) of a drug substance in humans. The extent of absorption in humans can be measured using mass-balance pharmacokinetic studies; absolute bioavailability studies; intestinal permeability methods; in vivo intestinal perfusion studies in humans; and in vivo or in situ intestinal perfusion studies in animals. In vitro permeation experiments can be conducted using excised human or animal intestinal tissue or with epithelial cell monolayers. Alternatively, nonhuman systems capable of predicting the extent of drug absorption in humans can be used (e.g., in vitro epithelial cell culture methods), hi determining the permeability of a drug, reference standards of known permeability can be employed in the absorption assay.

A drug substance is considered highly permeable when the extent of absorption in humans is determined to be greater than 90% of an administered dose. A drag substance is considered to have low permeability when the extent of absorption in humans is determined to be less than 90% of an administered dose. These measurements can be based on mass-balance or in comparison to an intravenous reference dose. An immediate release (IR) drag product is considered rapidly dissolving when no less than 85% of the labeled amount of the drug substance dissolves within 30 minutes, using U.S. Pharmacopeia (USP) Apparatus I at 100 rpm (or Apparatus II at 50 rpm) in a volume of 900 ml or less in each of the following media: (1) 0.1 N HCI or Simulated Gastric Fluid USP without enzymes; (2) a pH 4.5 buffer; and (3) a pH 6.8 buffer or Simulated Intestinal Fluid USP without enzymes.

In a preferred embodiment, the drug employed in the methods and compositions of the invention is paclitaxel, or an analogue or derivative thereof that is a substrate for PGP.

Other suitable drugs include BCS Class III or IV drags that are 'cell- effluxed' drags. Examples of poorly soluble, poorly absorbed drugs include doxorubicin, blymicine, and griseofulvin.

Drags that are PGP substrates, and therefore have low permeability, include adriamycin, aldosterone, amiodarone, amisulpride, amprenavir, atorvastatin, bilirubin, bromocriptine, carvedilol, cimetidine, clotrimazole, clozapine, colchicine, Cortisol, CPT-Il, cyclosporin A, cyclosporine, daunorabicin, desmethyl clozapine, desmethyl perazine, dexamethasone, digoxin, diltiazem, domperidone, doxorubicin, doxorubicin hydrochloride, erythromycin, estradiol- 17B-d-glucuronide, etoposide, fentanyl, fexofenadine, flupentixol, fluphenazine, fluvoxamine, GF120918, gramicidin, haloperidol, indinavir, itraconazole, ivermectin, ketoconazole, levomepromazine, loperamide, LY335979, meperidine, methadone, methylprednisolone, midazolam, mithramycin A, morphine, nelfinavir, olanzapine, paclitaxel, pentazocine, perazine, perphenazine, phenothiazine, progesterone, quetiapine, quinidine, quinine, retinoic acid, rhodamine 123, rhodamine 6G, rifampin, ritonavir, saquinavir, sparfloxocin, St John's wort, tamoxifen, tamoxifen citrate, terfenadine, tetracycline, valspodar (PSC-833), vecuronium, verapamil, and vinblastine. . Biopharmaceutical Class III drags are biologic agents that have good water solubility and poor gastrointestinal (GI) permeability, such as proteins, peptides, polysaccharides, nucleic acids, nucleic acid oligomers and viruses. Examples of Class III drugs that may be used in the instant invention include acyclovir, neomycin B, captopril, atenolol, valproic acid, stavudine, salbutamol, methotrexate, lamivudine, ergometrine, ciprogloxacin, amiloride and caspofungin.

Biopharmaceutical Class IV drugs are lipophilic drugs with poor GI permeability. Examples of Class IV drugs that may be used in the instant invention include nalidixic acid, clorothiazide, tobramycin, cyclosporin, allopurinol, acetazolamide, doxycyclin, dapsone, sulfamethoxazole, tacrolimus, and paclitaxel.

Both Class III and IV drugs are characterized by poor biomembrane permeability. They are often problematic or unsuitable for sustained release or controlled release and are commonly delivered parenterally.

Additional examples of suitable BCS Class III and Class TV drugs include abacavir sulfate, acetylsalicylic acid, amoxicillin, atropine sulfate, azathioprine, benznidazole, chloramphenicol, cimetidine, codein phosphate, colchicine, cyclophosphamide, dapsone, dexamethasone, didanosine, diethylcarbamazine citrate, digoxin, ethambutol hydrochloride, ethosuximide, fluconazole, folic acid, furosemide, griseofulvin, hydralazine hydrochloride, hydrochlorothiazide, isoniazid, methyldopa, methoclopramide hydrochloride, methronidazole, nicotinamide, nifurtimox, nitrofurantoin, nystatin, paracetamol, penicillamine, penicillin V potassium, phenobarbital, primaquine phosphate, propylthiouracil, pyrazinamide, pyridostigmine bromide, pyridoxine hydrochloride, pyrimethamine, sulfate, sulfadiazine, theophylline, trimethoprim, and zidovudine.

Caspofungin is a Class III drug and is an antifungal agent used to treat serious fungal infections. Caspofungin acetate is a semisynthetic lipopeptide (echinocendin) compound synthesized from a fermentation product of Glarea lozoyensis. Caspofungin acetate is a hygroscopic, white to off-white powder, which is freely soluble in water and methanol, and slightly soluble in ethanol. The pH of a saturated aqueous solution of caspofungin acetate is approximately 6.6. Caspofungin acetate has an empirical formula of C₅₂H₈₈N₁ o0₁₅-2C2H₄0₂ and a formula weight of 1213.42. Caspofungin acetate is designated as l-[(4i£, 5»S)-5-[(2-aminoethyl)amino]-N²-(10, 12- dimethyl- 1 -oxotetradecyl)-4-hydroxy-L-ornithine] -5 - [(3 IRI)-3 -hydroxy-L- ornithine] pneumocandin B₀ diacetate (salt). Caspofungin acts as an antifungal agent through inhibition of the cell wall synthesis of fungi such as Aspergillus and Candida. Caspofungin acetate is currently available for intravenous injection at 50 mg/day with an elimination half-life of 9-10 hours and is suitable for once-daily regimens. Casposfungin is slowly metabolized by hydrolysis and N-acetylation and also undergoes spontaneous chemical degradation. The oral bioavailability of Caspofungin is currently 0%.

Tacrolimus is a Class IV drug and is a macrolide immunosuppressant produced by Streptomyces tsukubaensis. Tacrolimus prolongs the survival of the host and transplanted graft in animal transplant models of liver, kidney, heart, bone marrow, small bowel and pancreas, lung and trachea, skin, cornea, and limb. Tacrolimus acts as an immunosuppressant through inhibition of T-lymphocyte activation through a mechanism that is unknown.

Tacrolimus is designated as [3R*[E(IS*, 3S*, 4S*)], AS*, 5R*, SS*, 9E, 12R*, UR*, 15S*, 16R*, ISS*, 19S*, l6aR*}]-

5,6,8,11, 12,13,14,15,16,17,18,19,24,25,26,26a-hexadecahydro-5, 19- dihydroxy-3 - [2-(4-hydroxy-3 -methoxycyclohexyl)- 1 -methylethenyl] - 14, 16- dimethoxy-4,10,12, 18-tetramethyl-8-(2-propenyl)-15, 19-epoxy-3H- pyrido[2, 1 -c] [ 1 ,4] oxaazacyclotricosine- 1 ,7,20,21 (4H,23H)-tetrone, monohydrate. Tacrolimus has an empirical formula of C₄₄H₆₉NO₁₂-H₂O and a formula weight of 822.05. Tacrolimus appears as white crystals or crystalline powder. It is practically insoluble in water, freely soluble in ethanol, and very soluble in methanol and chloroform.

Tacrolimus is commercially available for oral administration as capsules or as a sterile solution for injection. Absorption of tacrolimus from the gastro-intestinal tract after oral administration is incomplete and variable. The absolute bioavailability of tacrolimus is approximately 17% at a 5 mg dose taken twice a day.

Paclitaxel is a chemotherapeutic agent that displays cytotoxic and antitumor activity. Paclitaxel is a natural product obtained via a semi¬ synthetic process from Taxus baccata. Paclitaxel is a white to off-white crystalline powder available in a nonaqueous solution for injection. It is designated as 5β, 20-Ερoxy-l,2α, 4, 7 β, 10 β, 13 a-(2R, 3S)-_V-benzoyl-3- phenylisoserine, has an empirical formula Of C₄₇H₅₁NO₁₄, and a molecular weight of 853.9. Paclitaxel is highly lipophilic and insoluble in water. Dosing Regimens

Sometimes a drug is poorly absorbed in the days following an initial oral administration of the drug. The subject invention provides methods and compositions that are administered with particular timing selected to compensate for this poor absorption in the days following an initial oral administration of the drug. For example, poor absorption in the days following an initial oral administration of a drug is often due to efflux of the drug from a cell by a drug efflux pump, such as P glycoprotein.

Oral bioavailability is typically determined by administering a dose of a therapeutic orally and calculating the AUC for that oral dose and administering a dose of the same therapeutic intravenously (Lv.) and calculating the AUC for that i.v. dose. Assuming a linear relationship exists between dose and AUC, oral bioavailability (F) can be calculated as follows:

F= (Doseiv x AUCorai)/ (Dose_oral x AUQ_V)

This calculation can also be used when the same dose is administered orally multiple times.

The methods and compositions of the instant invention will typically enhance the oral bioavailability of a poorly absorbed drug. For example, in certain embodiments, the oral bioavailability of a drug is ordinarily between 0.5%-75%. hi some embodiments, the oral bioavailability of the drug is between 0.5%-10%, between 10%-25%, between 25%-50%, or between 50%-75%. hi some embodiments, the oral bioavailability is between 20% and 40%. By using a formulation of the instant invention, the oral bioavailability of the drug may be increased, such that its oral bioavailability is greater than 1%, greater than 5%, greater than 10%, greater than 20%, greater than 30%, greater than 40%, greater than 50%, greater than 60%, greater than 70%, greater than 80%, or even greater than 90%. It is expected that formulating a compound as described herein increases bioavailability by at least 5%, 10%, or even by 20% or more over the bioavailability when the compound is administered alone, hi certain embodiments, the invention provides dosing schedules to maintain the oral bioavailability of a poorly absorbed drug by compensating for poor absorption in the days following an initial oral administration of the drug.

As used in the following description, "dose group" refers to multiple oral administrations within 24 hours, preferably within a time period of 10 to 24 hours or less, preferably 12 hours or less, most preferably within 1 to 6 hours.

As used herein, "recovery period" refers to a period of time between doses or dose groups that is sufficient to achieve a response in the second dose or dose group similar to that of the initial dose or initial dose group. "Cmax" refers to the maximum plasma concentration achieved following administration of a dose or dose group. Cmax is determined via pharmacokinetic (PK) studies, typically using an animal model. The dose may be administered to an animal in a fed or fasted stated. After each dosing, blood samples are obtained at set time points (such as 0.33, 0.67, 1, 2, 4, 6, and 8 hours). The blood samples are then analyzed to measure the amount of drug in the plasma, such as by LC-MS-MS.

As used herein, "area-under-the curve" ("AUC") refers to the area under the plasma concentration versus time curve that is plotted during PK studies. The plasma concentration for each time point is plotted and the area is calculated to determine the AUC for a given dose or dose group.

A "similar response" generally refers to an area-under-the curve (AUC) value that is equal to 30-100% of the AUC value for the previous dose or dose group, preferably with an AUC equal to 50% or greater of the AUC for the previous dose or dose group, or a Cmax value that is equal to 30-100% of the Cmax value for the previous dose or dose group, preferably with a Cmax equal to 50% or greater of the Cmax for the previous dose or dose group.

In certain embodiments, a dosing schedule commences with a single oral dose, or dose group, and then delays subsequent oral administrations by a recovery period. The recovery period is at least one day, preferably two days, more preferably at least three days, more preferably at least four days, and most preferably at least five days. Other suitable recovery periods include at least 6 days and at least 7 days. A preferred recovery period is from about three to about five days. In certain embodiments, this dosing schedule is used for the oral administration of paclitaxel.

The recovery period is determined experimentally, by administering a dose or dose group to the species to be treated and periodically obtaining blood samples to measure the amount of drug in the plasma at a given time period following administration. This data is used to determine the Cmax and AUC for a dose or dose group. A second dose or dose group is administered after a set time period, which is at least greater than one day, and blood samples are periodically obtained for each time period. This data is used to determine the Cmax and AUC for the subsequent dose. If the

Cmax and/or AUC for the subsequent dose is greater than or equal to 30% of the Cmax and/or AUC for the first dose, preferably greater than or equal to 50% of the Cmax and/or AUC for the first dose, the time period between the first dose and the subsequent dose is the recovery period. If the Cmax and/or AUC for the subsequent dose is less than 30% of the Cmax and/or AUC for the first dose, the test is repeated, with an increased or decreased time period between the first and second doses or dose groups, until a recovery period is reached.

Studies described in the examples were conducted to determine which recovery periods between oral administrations of paclitaxel ("PTL") are most effective. Initial tests in mice showed that repeat administration of PTL within certain intervals, e.g., 48 hours, as shown in Figures 1-3, leads to markedly lower plasma levels from subsequent doses. Suitable recovery periods between two oral administrations of paclitaxel are greater than 48 hours, 72 hours, 96 hours, 192 hours, and 288 hours. Preferably the recovery period is about 96 hours, e.g., 80-120 hours. Recovery periods in humans are typically about the same, or somewhat longer than those found in mice. The recovery period for drugs and categories of drugs will be species- specific and drug-specific, and can be determined experimentally using routine methods well known in the art. Similarities in recovery periods likely exist across species and can be estimated from known anatomic, physiologic and/or metabolic similarities across species, and/or through analysis of physicochemical properties of the drugs. A dose group may contain multiple oral administrations of drug within a time period of 24 hours, preferably within a time period of 10 to 24 hours or less, preferably 12 hours or less, most preferably within 1 to 6 hours (e.g., within 3 hours). Dose groups may be used during the administration of paclitaxel or other drugs that are substrates for PGP to maximize the amount of drug absorbed prior to the induction and/or overexpression of PGP.

Subsequent doses may be the same as the initial dose, less than, or greater than the previous dose(s). In one embodiment, the instant invention relates to a method to increase the bioavailability of a poorly absorbed drug by administering the drug via an escalating dosage regimen. For example, in one embodiment, subsequent dose(s) are greater than each previous dose so as to provide a reasonably even plasma level of drug during administration. Optionally, recovery periods shorter than about 2 days may be used. For example, in some embodiments, the recovery period is at least 24 hours, 28 hours, 32 hours, 36 hours, 40 hours, 44 hours, or 48 hours. Preferably the dosage is increased when using shorter recovery periods than about 2 days. The dose may be increased at each interval to compensate for the increased efflux, metabolism, enzymatic or other degradation, or conversion of drugs from the circulation. Because the disclosed compositions in many cases utilize very low amounts of excipient, compositions formulated as described herein may require smaller total volumes. For example, in certain embodiments, a drug that by traditional formulations requires multiple pills to achieve a single therapeutic dose may be formulated in a single dosage form when the need for substantial amounts of excipient is eliminated. Thus, in certain embodiments, a poorly absorbed drug that requires a high therapeutic dose, such as nalidixic acid, is administered in a single dosage form. For example, microparticles of a stable, amorphous form of a poorly absorbed drug, such as nalidixic acid, may be administered in a single dosage form. Drug Formulations

The dosage forms of the invention may comprise one or more drugs in various forms, such as amorphous or crystalline. In preferred embodiments, a composition of the invention comprises a drug that is predominantly in an amorphous form. In other embodiments, a composition of the invention comprises crystals or crystalline forms of the drug. Depending on the desired bioavailability, the ratio of amorphous to crystalline forms of the drug can be adjusted. For example, delivery of a drug to the GI tract can be enhanced by administering a drug in a predominantly crystalline form. Alternatively, oral bioavailability can be increased by increasing the ratio of amorphous form of the drug that is administered, thereby enhancing its uptake and distribution throughout the body. In certain embodiments, the ratio of amorphous to crystalline drug is 90:10, 80:20, 70:30, or 60:40. hi other embodiments, the ratio is 50:50. hi yet other embodiments, the crystalline form predominates, and the ratio of amorphous to crystalline drug is 40:60; 30:70; 20:80; or 10:90. Inhibitors

Where the low permeability of a drug is due to its efflux from a cell by a membrane transporter, it is preferable to administer the drug with an inhibitor of a drug efflux pump. Thus, in certain embodiments, the invention provides dosage formulations comprising one or more inhibitors of inducible enzymes or protein pumps in combination with a poorly absorbed drug. This co-administration can occur with each administration of the drug or with selective administrations, e.g., with the initial or one or more subsequent administrations. Enzyme or protein pump families include but are not limited to glycoprotein pumps and cytochrome P450 ("CYP") oxidative enzymes. ATP-dependent pumps for removing small "xenobiotic" and other molecules from mammalian cells are known, hi addition, cytochrome P450 can be present in peripheral tissues as well as in the liver and can be induced. Examples of inhibitors of drug efflux pumps include cyclosporins, ketoconazole and related azole drugs. Suitable inhibitors also include inhibitors of protein synthesis. Optionally, short recovery periods, such as less than two days, are used during the co-administration of a low permeability drug with one or more inhibitors of an inducible enzyme or protein pump. hi one embodiment, one or more inhibitors of a drug efflux pump are administered in combination with paclitaxel. The inhibitor may be cyclosporin, ketoconazole or an inhibitor of a cytochrome P450. In some embodiments, the inhibitor and poorly absorbed drug are administered in the same dosage formulation. The drug and inhibitor can be released at a similar rate or at different rates from the same dosage formulation. In other embodiments, the inhibitor is administered in a different dosage formulation. An inhibitor can be formulated to release at the same rate as the poorly absorbed drug or at a different rate. An inhibitor of an inducible enzyme or protein pump can be administered at the same time as the poorly absorbed drug or at a separate time. If administered at a different time, the inhibitor can be administered before or after administration of the poorly absorbed drug. For example, in certain embodiments, the inhibitor is administered 30 minutes before or 1 hour before the poorly absorbed drug.

Absorption Enhancers

To promote uptake of a poorly absorbed drug by the intestinal epithelium, it is desirable to include one or more absorption enhancers in the dosage formulation. Accordingly, in some embodiments, a drug formulation of the invention comprises one or more absorption enhancers, which may be administered in soluble form with nanoparticles, co-encapsulated in nanoparticles with the drug, or admixed as solids (excipients) in solid oral dosage forms such as tablets or capsules along with nanoparticulate drug.

An absorption enhancer facilitates the uptake of a drug across the gastrointestinal epithelium. Absorption enhancers include compounds that improve the ability of a drug to be solubilized in the aqueous environment in which it is originally released and/or in the lipophilic environment of the mucous layer lining of the intestinal walls. Absorption enhancers further include compounds that increase disorder of the hydrophobic region of the membrane exterior of intestinal cells, promote leaching of membrane proteins that results in increased transcellular transport, or widen the pore radius between cells for increased paracellular transport. Examples of absorption enhancers include sodium caprate, ethylenediamine terra (acetic acid) (EDTA), citric acid, lauroylcarnitine, pahnitoyl carnitine, tartaric acid and other agents known to increase GI permeability. Other suitable absorption enhancers include sodium salicylate, sodium 5-methoxysalicylate, indomethacin, diclofenac, polyoxyethylene ethers, sodium lauryl sulfate, quaternary ammonium compounds, sodium deoxycholate, sodium cholate, octanoic acid, decanoic acid, glyceryl- 1- monooctanoate, glyceryl- 1-monodecanoate, DL-phenylalanine ethylacetoacetate enamine, chloφromazine, D-myristoyl-L-propyl-L-prolyl- glycinate, concanavaline A, DL-α-glycerophosphate, and 3-amino-l- hydroxypropylidene- 1 , 1 -diphosphonate.

Orally-acceptable absorption enhancers include surfactants such as sodium lauryl sulfate, palmitoyl carnitine, Laureth-9, phosphatidylcholine, cyclodextrin and derivatives thereof; bile salts such as sodium deoxycholate, sodium taurocholate, sodium glycocholate, and sodium fusidate; chelating agents including EDTA, citric acid and salicylates; and fatty acids (e.g., oleic acid, lauric acid, acylcarnitines, mono- and diglycerides). Other oral absorption enhancers include Pluronics, lecithin, benzalkonium chloride, benzethonium chloride, CHAPS (3-(3-cholamidopropyl)-dimethylammonio- 1 -propanesulfonate), Big-CH AP S (N, N-bis-(3 -D-gluconamidopropyl)- cholamide), chlorobutanol, octoxynol-9, benzyl alcohol, phenols, cresols, and alkyl alcohols.

Absorption enhancers also include permeation enhancers. Permeation enhancers increase membrane permeability and facilitate drug transport through biological membranes, thereby enhancing the bioavailability of a poorly absorbed drug. Suitable permeation enhancers may be selected from the compounds referenced above and include sodium caprate, sodium caprylate, oleic acid, bile salts, detergents, chelating agents, and weak organic acids. In some embodiments, the formulation comprises greater than 75%, greater than 80%, greater than 85%, greater than 90%, or greater than 95% of a poorly absorbed drug and an absorption enhancer. Absorption enhancers can be present in a concentration in the final dosage form of from about 0.01 % to about 99% by weight. In certain embodiments, the enhancers are present in the final composition at about 0.01% to about 50% by weight. In other embodiments, absorption enhancers are present in the final composition at about 0.1% to about 30% by weight.

In some embodiments, the absorption enhancer and poorly absorbed drug are administered in the same dosage formulation. The drug and absorption enhancer can be released at a similar rate or at different rates from the same dosage formulation, hi other embodiments, the absorption enhancer is administered in a different dosage formulation. An absorption enhancer can be formulated to release at the same rate as the poorly absorbed drug or at a different rate. An absorption enhancer of an inducible enzyme or protein pump can be administered at the same time as the poorly absorbed drug or at a separate time. If administered at a different time, the absorption enhancer can be administered before or after administration of the poorly absorbed drug. In preferred embodiments, the release of the absorption enhancer is substantially coextensive with that of the poorly absorbed drug. For example, the absorption enhancer may be released at a rate similar to the release rate of the poorly absorbed drug. In certain embodiments, the release of the absorption enhancer precedes or at least corresponds with the release of the poorly absorbed drug. If the absorption enhancer is released too early, the poorly absorbed drug may be diluted in the fluids of the alimentary canal, which might reduce the concentration of the drug into values below those required to maintain effective concentration gradients across the intestinal epithelium. To improve absorption, it is desirable that the poorly absorbed drug is accompanied by the absorption enhancer until the drug's absorption has been completed.

Bioadhesive Polymers

Absorption of a poorly absorbed drug may be further improved by the use of bioadhesive polymers in the dosage formulation. In some embodiments, bioadhesive polymers may be included in the formulations of the invention to improve gastrointestinal retention of drug microparticles, nanoparticles, or multiparticulate beads or other solid drug formulations, such as capsules and tablets or minitablets, via adherence of the microparticles, nanoparticles, multiparticulate beads, capsules, tablets, or minitablets to the walls of the GI tract. In general terms, adhesion of polymers to tissues may be achieved by (i) physical or mechanical bonds, (ii) primary or covalent chemical bonds, and/or (iii) secondary chemical bonds (e.g., ionic). Secondary chemical bonds, contributing to bioadhesive properties, include dispersive interactions (e.g., Van der Waals interactions) and stronger specific interactions, which include hydrogen bonds. The hydrophilic functional groups responsible for forming hydrogen bonds are the hydroxyl (--OH) and the carboxylic acid groups (— COOH).

As used herein "bioadhesion" generally refers to the ability of a material to adhere to a biological surface for an extended period of time. Bioadhesion requires contact between a bioadhesive material and a surface (e.g., tissue and/or cells). Thus the amount of bioadhesive force is affected by both the nature of the bioadhesive material, such as a polymer, and the nature of the surrounding medium. A suitable measurement method is set forth in U.S. Patent No. 6,235,313 to Mathiowitz et al. Suitable polymers include polylactic acid (2 kDa MW, types SE and HM), polystyrene, poly(bis carboxy phenoxy propane-co-sebacic anhydride) (20:80) (poly (CCP:SA)), alginate (freshly prepared); and poly(fumaric anhydride-co-sebacic anhydride (20:80) (p(FA:SA)), types A (containing sudan red dye) and B (undyed). Other high-adhesion polymers include p(FA:SA) (50:50) and non- water-soluble polyacrylates and polyacrylamides.

Suitable polymers that are bioadhesive include soluble and insoluble, nonbiodegradable and biodegradable polymers. These can be hydrogels or thermoplastics, homopolymers, copolymers or blends, natural or synthetic. Two classes of polymers that have useful bioadhesive properties are hydrophilic polymers and hydrogels. hi the large class of hydrophilic polymers, those containing carboxylic groups (e.g., poly(acrylic acid)) exhibit the best bioadhesive properties, and therefore polymers with the highest concentrations of carboxylic groups should be the materials of choice for bioadhesion on soft tissues. Among polymers known to provide good results are sodium alginate, carboxymethylcellulose, hydroxymethylcellulose and methylcellulose. Some of these materials are water-soluble, while others are hydrogels.

Rapidly bioerodible polymers such as poly(lactide-co-glycolide), polyanhydrides, and polyorthoesters, having carboxylic groups exposed on the external surface as their smooth surface as they erode, are also excellent bioadhesive polymers.

Representative natural polymers include proteins, such as zein, modified zein, casein, gelatin, gluten, serum albumin, or collagen, and polysaccharides, such as cellulose, dextrans, polyhyaluronic acid, polymers of acrylic and methacrylic esters and alginic acid. Representative synthetic polymers include polyphosphazines, polyvinyl alcohols), polyamides, polycarbonates, polyalkylenes, polyacrylamides, polyalkylene glycols (e.g., polyethylene glycol (PEG)), polyalkylene oxides, polyalkylene terephthalates, polyvinyl ethers, polyvinyl esters, polyvinyl halides, polyvinylpyrrolidone (PVP), polyglycolides, polysiloxanes, polyurethanes and copolymers thereof. Representative synthetically modified natural polymers include alkyl celluloses, hydroxyalkyl celluloses, cellulose ethers, cellulose esters, and nitrocelluloses.

Specific polymers include, but are not limited to, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose (HPMC), hydroxybutyl methyl cellulose, cellulose acetate, cellulose propionate, cellulose acetate butyrate, cellulose acetate phthalate, carboxymethyl cellulose, cellulose triacetate, cellulose sulfate sodium salt, poly(methyl methacrylate), poly(ethyl methacrylate), poly(butyl methacrylate), poly(isobutyl methacrylate), poly(hexyl methacrylate), poly(isodecyl methacrylate), poly(lauryl methacrylate), poly(phenyl methacrylate), poly(methyl acrylate), poly(isopropyl acrylate), poly(isobutyl acrylate), poly(octadecyl acrylate) polyethylene, polypropylene, polyethylene glycol), poly(ethylene oxide), poly (ethylene terephthalate), poly( vinyl acetate), polyvinyl chloride, polystyrene, polyvinyl pyrrolidone, polyvinylphenol, poly(butic acid), poly(valeric acid), poly(lactide-co- caprolactone), poly(lactide-co-glycolide), polyanhydrides, polyorthoesters, blends and copolymers thereof.

These polymers can be obtained from sources such as Sigma Chemical Co., St. Louis, MO., Polysciences, Warrenton, PA, Aldrich, Milwaukee, WI, Fluka, Ronkonkoma, NY, and BioRad, Richmond, CA or synthesized from monomers obtained from these suppliers using standard techniques.

Mucoadhesive polymers may be defined as polymers that have an adherence to living mucosal tissue of at least about 110 N/m of contact area (11 mN/cm²). A suitable measurement method is set forth in U.S. Patent No. 6,235,313 to Mathiowitz et al. Polyanhydrides are a preferred type of mucoadhesive polymer. Suitable polyanhydrides include polyadipic anhydride, polyfumaric anhydride, polysebacic anhydride, polymaleic anhydride, polymalic anhydride, polyphthalic anhydride, polyisophthalic anhydride, polyaspartic anhydride, polyterephthalic anhydride, polyisophthalic anhydride, poly carboxyphenoxypropane anhydride and copolymers with other polyanhydrides at different mole ratios.

Other mucoadhesive polymers include DOPA-maleic anhydride co polymer, isophthalic anhydride polymer, DOPA-methacrylate polymers, DOPA-cellulosic based polymers, and DOPA-acrylic acid polymers.

Mucoadhesive materials include Spheromer™ I (poly(fumaric acid:sebacic acid) or "p(FASA)", as described in U.S. Patent No. 5,955,096 to Mathiowitz et al), Spheromer™ II (anhydride oligomers, such as Fumaric Anhydride Oligomer and Metal oxides, such as CaO, ferric oxide, magnesium oxide, titanium dioxide, as described in U.S. Patent No. 5,985,312 to Jacob et al), and Spheromer™ III (L-DOPA grafted onto butadiene maleic anhydride at 5% to 95% substitution efficiency (L-DOP A- BMA)) (see e.g., U.S. Application No. 11/009,327, filed December 9, 2004, and WO 2005/056708). Spheromer™ II may be blended with methylmethacrylates, celluloses and substituted celluloses, polyvinylpyrrolidones, PEGs, Polyvinyl alcohols). Alternatively Spheromer II may be blended with other bioadhesive polymers including p(FA:SA), p(AA), and L-DOPA-BMA.

In certain embodiments, mucoadhesive polymers are typically hydrophobic enough to be non-water-soluble, but contain a sufficient amount of exposed surface carboxyl groups to promote adhesiveness. These include, for example, non-water-soluble polyacrylates and polymethacrylates; polymers of hydroxy acids, such as polylactide, polyglycolide, and polylactide-co-glycolide; polyanhydrides; polyorthoesters; blends comprising these polymers; and copolymers comprising the monomers of these polymers. Blending or copolymerization sufficient to provide a certain amount of hydrophilic character in the polymer matrix can be useful to improve wettability of the materials. For example, about 5% to about 20% of monomers may be hydrophilic monomers. Hydrophilic polymers such as hydroxypropylcellulose (HPC), hydroxpropylmethylcellulose (HPMC), carboxymethylcellulose (CMC) are commonly used for this purpose. Also suitable are hydrophobic polymers such as polyesters and polyimides. It is known to those skilled in the art that these polymers may be blended with polyanhydrides to achieve compositions with different drug release profiles and mechanical strengths. Preferably, the polymers are bioerodable, with preferred molecular weights ranging from 1000 to 15,000 kDa, and most preferably 2000 to 5000 Da.

Cellulosic polymers such as ethylcellulose, cellulose acetate, cellulose acetate phthalate; methacrylate polymers such as EUDRAGIT RS 100, RL 100, ElOO PO, L100-55, LlOO, SlOO (distributed by Rohm America) or other polymers commonly used for encapsulation of pharmaceuticals may also be used in embodiments where the oral dosage formulation comprises a drug that is encapsulated. In designing bioadhesive polymeric formulations based on polylactides, polymers that have high concentrations of carboxylic acid are preferred. This can be accomplished by using low molecular weight polymers (Mw 2000), since low molecular weight polymers contain high concentration of carboxylic acids at the end groups. hi addition, polymers that contain a catechol functionality are also bioadhesive. As used herein "catechol moiety" refers to a moiety with the following generic structure:

These aromatic groups can be substituted for monomers on the backbone of a suitable polymer. The degree of substitution will vary based on the desired adhesive strength. It may be as low as 10%, 25%, 50%, or up to 100% substitution. On average, at least 50% of the monomers in a suitable polymeric backbone are substituted with at least one aromatic group. See e.g., U.S. Application No. 11/009,327, filed December 9, 2004, and WO 2005/056708. Excipients may also be added to improve bioadhesion. Suitable excipients include FeO/Fe₂O₃, fumaric anhydride pre-polymer (FAPP), L- DOPA-L-DOPA dimer, and adipic anhydride pre-polymer (AAP). Additional suitable excipients are described below. Drug release rates

Drug release rates may be controlled by varying the proportion of drug to hydrophobic polymer in the solution used to prepare the particles. For example, in some formulations, a drug-polyanhydride system can release drug rapidly, with at least 40% of the drug load in 30 minutes and at least 70% in 60 minutes (in vitro). Drugs are incorporated into the polymer matrix at loadings of 1 to 50% w/w and most preferably in the range of 20- 30% w/w.

The time period for release can be extended by increasing the drug to polymer ratio, with release drawn out to 80% in 90 minutes (in vitro). Increased relative drug concentration is believed to have the effect of increasing the effective drug domain size within the polymer matrix; and increased drug domain size results in slower drug dissolution, hi the case of a polymer matrix containing certain types of hydrophobic polymers, the polymer will act as a mucoadhesive material and increase the retention time of the drug product in the gastrointestinal tract. Excipients and Additives

The formulations of the invention can include at least one excipient. Suitable excipients include solvents, co-solvents, emulsifiers, plasticizers, surfactants, thickeners, pH modifiers, emollients, antioxidants, and chelating agents, wetting agents, water absorbing agents, cleansing agents, and nail conditioners. Excipients can be added to inhibit aggregation of dry particles comprising the drug to be delivered. An oral drug formulation of the invention may comprise 0.5-50% of one or more excipients. Preferably, the percent of excipients is 50% or less. In other embodiments, the oral drug formulation comprises up to 60%, up to 75%, or up to 90% of one or more excipients. In some embodiments, a formulation may also include one or more additives, for example, dyes, colored pigments, pearlescent agents, deodorizers, and odor maskers.

Formulations may be prepared using a pharmaceutically acceptable carrier composed of materials that are considered safe and effective and may be administered to an individual without causing undesirable biological side effects or unwanted interactions. The term "pharmaceutically acceptable" refers to a non-toxic material that does not interfere with the effectiveness of the biological activity of the active ingredients. The term "pharmaceutically- acceptable carrier" refers to one or more compatible solid or liquid fillers, diluents, or encapsulating substances which are suitable for administration to a human or other vertebrate animal. A carrier is all components present in a pharmaceutical formulation other than the active ingredient or ingredients. As generally used herein, "carrier" embraces, but is not limited to, diluents, binders, lubricants, disintegrants, stabilizers, surfactants, colorants, and fillers.

Diluents, also referred to herein as "fillers", are typically necessary to increase the bulk of a solid dosage form so that a practical size is provided for compression of tablets or formation of beads and granules. Suitable diluents include, but are not limited to, dicalcium phosphate dihydrate, calcium sulfate, lactose, sucrose, mannitol, sorbitol, cellulose, microcrystalline cellulose, kaolin, sodium chloride, dry starch, hydrolyzed starches, pregelatinized starch, silicone dioxide, titanium oxide, magnesium aluminum silicate and powdered sugar. Dispersants include water, phosphate-buffered saline (PBS), saline, glucose, sodium lauryl sulfate (SLS), polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), and hydroxypropylmethylcellulose (HPMC), cyclodextrin, hydroxypropylcellulose, hydroxyethylcellulose, and Pluronic.

In some embodiments, the formulation comprises greater than 75%, greater than 80%, greater than 85%, greater than 90%, or greater than 95% of a poorly absorbed drug and a dispersant. Li certain embodiments, the drug is paclitaxel.

Binders can be used to impart cohesive qualities to a solid dosage formulation, and thus ensure that a tablet or bead or granule remains intact after the formation of the dosage forms. Suitable binder materials include, but are not limited to, starch, pregelatinized starch, gelatin, sugars (including sucrose, glucose, dextrose, lactose and sorbitol), polyethylene glycol, waxes, natural and synthetic gums such as acacia, tragacanth, sodium alginate, cellulose, including hydroxypropylmethylcellulose, hydroxypropylcellulose, ethylcellulose, and veegum, and synthetic polymers such as acrylic acid and methacrylic acid copolymers, methacrylic acid copolymers, methyl methacrylate copolymers, aminoalkyl methacrylate copolymers, polyacrylic acid/polymethacrylic acid and polyvinylpyrrolidone. Lubricants can be used to facilitate tablet manufacture. Examples of suitable lubricants include, but are not limited to, magnesium stearate, calcium stearate, stearic acid, glycerol behenate, polyethylene glycol, talc, and mineral oil.

Disintegrants can be used to facilitate dosage form disintegration or "breakup" after administration, and generally include, but are not limited to, starch, sodium starch glycolate, sodium carboxymethyl starch, sodium carboxymethylcellulose, hydroxypropyl cellulose, pregelatinized starch, clays, cellulose, alginine, gums or cross linked polymers, such as cross- linked PVP (Polyplasdone XL from GAF Chemical Corp). Stabilizers can be used to inhibit or retard drug decomposition reactions which include, by way of example, oxidative reactions.

Surfactants may be anionic, cationic, amphoteric or nonionic surface active agents. Suitable anionic surfactants include, but are not limited to, those containing carboxylate, sulfonate and sulfate ions. Examples of anionic surfactants include sodium, potassium, ammonium salts of long chain alkyl sulfonates and alkyl aryl sulfonates such as sodium dodecylbenzene sulfonate; alkyl aryl sulfonates, such as sodium dodecylbenzene sulfonate; dialkyl sodium sulfosuccinates, such as sodium bis-(2-ethylthioxyl)- sulfosuccinate; and alkyl sulfates such as sodium lauryl sulfate. Cationic surfactants include, but are not limited to, quaternary ammonium compounds such as benzalkonium chloride, benzethonium chloride, cetrimoniurn bromide, stearyl dimethylbenzyl ammonium chloride, polyoxyethylene and coconut amine. Examples of nonionic surfactants include ethylene glycol monostearate, propylene glycol myristate, glyceryl monostearate, glyceryl stearate, ρolyglyceryl-4-oleate, sorbitan acylate, sucrose acylate, PEG-150 laurate, PEG-400 monolaurate, polyoxyethylene monolaurate, polysorbates, polyoxyethylene-octylphenylether, PEG-1000 cetyl ether, polyoxyethylene tridecyl ether, polypropylene glycol butyl ether, Poloxamer® 401, stearoyl monoisopropanolamide, and polyoxyethylene hydrogenated tallow amide. Examples of amphoteric surfactants include sodium N-dodecyl-β -alanine, sodium N-lauryl-β-iminodipropionate, myristoamphoacetate, lauryl betaine and lauryl sulfobetaine.

If desired, the formulation may also contain minor amounts of nontoxic auxiliary substances such as wetting or emulsifying agents, dyes, pH buffering agents, or preservatives.

In a preferred embodiment, the formulation contains paclitaxel and a dispersant containing polyethylene glycol, hydroxypropylmethylcellulose, polyvinyl alcohol, methacrylic acid copolymer (preferably EUDRAGIT^® Ll 00-55), sodium lauryl sulfate, and polyvinylpyrrolidone in phosphate- buffered saline (PBS). Preferred dispersants include polyvinylpyrrolidone and/or EUDRAGIT^®. Other preferred dispersants include cyclodextrin, hydroxypropylcellulose, hydroxyethylcellulose, and Pluronic. Oral formulations containing paclitaxel nanoparticles (e.g., average diameter of about 300 nm) in a dispersant containing polyethylene glycol (PEG, 0.5% w/v), hydroxypropylmethylcellulose (HPMC, 0.5% w/v), polyvinyl alcohol (PVA, 2.5% w/v), methacrylic acid copolymer (EUDRAGIT^® Ll 00-55, 2.5% w/v), sodium lauryl sulfate (SLS, 0.5% w/v), and polyvinylpyrrolidone (PVP, 0.5% w/v) in phosphate-buffered saline (PBS) has been tested and shown to yield bioavailabilities in the 20-40% range, hi contrast, if the typically i.v. paclitaxel formulation (e.g., paclitaxel in 50% polyoxyethylated castor oil (CREMOPHOR EL™) and 50% dehydrated alcohol) is administered orally, the formulation has a very low bioavailability of about 5%. Other drugs that can be used in the preferred dispersants include drugs with low aqueous solubility, such as BCS Class II and Class IV drugs. These drugs will typically have a solubility of less than 1 mg/mL. Methods of Making Drug Formulations The oral dosage formulations of the instant invention may be administered in any number of forms, such as micro- or nanoparticles or tablets.

Methods of Making Micro- or Nanoparticles In some embodiments, oral dosage formulations of the invention comprise nanoparticles or microparticles of a drug alone in that the drug is formed as microparticles without any polymers. In other embodiments, the nano- or microparticles may contain polymers. In some embodiments, the agent to be delivered is not encapsulated. The term "microparticles" is art-recognized, and includes microspheres and microcapsules, as well as structures that may not be readily placed into either of the above two categories, all with dimensions on average of less than about 1000 microns. The term "microspheres" is art- recognized, and includes substantially spherical colloidal structures having a size ranging from about one or greater up to about 1000 microns. In general, "microcapsules", also an art-recognized term, may be distinguished from microspheres, because microcapsules are generally covered by a substance of some type, such as a polymeric formulation, e.g., a bioadhesive coating or rate-controlling polymer layer. If the structures are less than about one micron in diameter, then the corresponding art-recognized terms

"nanoparticle," "nanosphere," and "nanocapsule" may be utilized. In certain embodiments, the nanospheres, nancapsules and nanoparticles have an average diameter of about 500, 200, 100, 50 or 10 nm. hi certain embodiments, one or more drugs (e.g., paclitaxel), and one or more excipients, optionally including polymers, are dissolved in a first organic solvent in which these components are soluble, such as dichloromethane, acetone, chloroform, or ethyl acetate, or another hydrophobic solvent with some polarity. Alternatively, the solvent can be water-miscible, such as ethanol, methanol or acetone. The solution is passed through a filter, such as a 0.1 μm or 0.2 μm poly(tetrafluoroethylene) PTFE filter, to eliminate undissolved material. Optionally, if insoluble materials, such as inorganic metal salts or oxides, are included in the formulation, the non-soluble materials are added and mixed with the solution to form a suspension. Then, the solution or suspension is poured into a vessel containing a non-solvent for the drug, such as pentane, hexane, heptane, or petroleum ether. If a water miscible solvent is used, the non-solvent can be hydrophilic and/or contain water. Preferably, the non-solvent is present at a volume of 5-100 times the volume of the solvent. The solution or suspension self-disperses, or can be agitated if necessary, forming nano or micro droplets or particles of the solution/suspension. Free-drug (drug that is essentially free of any polymer e.g., drug that comprises less than 5% of any polymer) or drug-encapsulated nanoparticles or microparticles typically form quickly and spontaneously as the solvent leaves the droplets and enters the non-solvent. The particles can be removed by filtration and vacuum dried to remove residual solvent and/or non-solvent. For example, particles can be removed by filtering using N₂- gas (10 psi) through a paper filter (e.g., 2.5 μm-pore size) on which the particles will be retained. Upon completion of the filtration step, the particles are dried (e.g., 10 minutes by N₂-gas stream). The particles may then be collected (e.g., in a glass vial) and dried further under vacuum to remove residual solvents. For free-drug particles such as paclitaxel nanoparticles described herein, this process will typically produce paclitaxel nanoparticles about 300 nm in diameter. Suitable methods for making the micro- or nanoparticles include spray-drying, other spray-type manufacturing processes, and solvent removal, as described above. One method of making the formulation is described in more detail in WO 2004/098570. Other methods are described in U.S. Patent No. 6,143,211 to Mathiowitz et al. The collected and dried nanoparticles or microparticles can be administered in any convenient form. Optionally, the nanoparticles or microparticles are further processed into dosage forms, such as beads, granules, compressed soft slugs, tablets and capsules. For example, the drug nanoparticles or microparticles can be further processed by granulation, fluid bed spheronization, or other methods.

In certain embodiments, an oral paclitaxel formulation is prepared by forming paclitaxel nanoparticles or microparticles and then suspending the nanoparticles or microparticles in a suitable dispersant, such as the preferred dispersant described above, thereby providing a formulation with the desired concentration.

Methods of Making Self-Dispersing Drug Formulations In certain embodiments, the drug formulations of the instant invention comprise formulations with free-flowing characteristics and that readily disperse when hydrated. By "readily disperse" is meant that the drug formulation fully disperses in water e.g., within 5 minutes, preferably with 2 minutes. In embodiments where the drug formulation is administered by injection, the drug formulation does not clog the needle, hi certain embodiments, the drag is micronized and is a Class IV drag, such as paclitaxel. In embodiments where the drag is in a dry powder form and is resuspended in a liquid vehicle, preferably the drug does not aggregate and does not require sonication in order to be dispersed. In certain embodiments, the drug is a Class II or Class IV drag that is administered in the form of a solid, fast-disintegrating pill or in an oral suspension. hi certain embodiments, micronized drug (e.g., micronized paclitaxel) is mixed with encapsulating polymer in combination with one or more absorption enhancers (e.g., PEG 3350, Pluronic F-127) and/or surfactants in a solvent. In preferred embodiments, the drug is a hydrophobic drag, such as a low solubility drag (e.g., a BCS Class II or Class IV drug), hi the solvent, everything but the drug is dissolved. The suspension is then added to an anti-solvent (e.g., pentane), which contains surfactant (e.g., Span 80). The drag is coated with polymer, and the coated drug particles precipitate in the surfactant matrix, hi certain embodiments, a combination of low concentration of coating polymer and a high concentration of plasticizer

(e.g., PEG 3350 or Pluronic F-127) are employed to yield small particle sizes (e.g., 300-400 nm). For example, ratios between 1:4 and 1:6 of polymer to plasticizer, such as PEG 3350 or Pluronic F-127, can be used to produce 300-400 nm particles that self-disperse. In other embodiments, particle sizes are in the range of 600-3000 nm.

Methods of Encapsulating Drags

In certain embodiments, an oral dosage formulation of the invention is encapsulated. For example, low permeability drags of the invention may be encapsulated in nano- or microparticles for delivery. Methods used to encapsulate drugs and absorption enhancers include phase inversion nanoencapsulation (PIN), solvent evaporation encapsulation, spray-drying, solvent-removal encapsulation, interfacial polycondensation and other methods known to those skilled in the art. Methods used to produce nanoparticulate drug include milling, precipitation, PIN, spray-drying, coacervation, super critical fluid drying. The nanoparticulate drug thus produced is suitable for administration, for example, by injection or inhalation.

Interfacial polycondensation can be used to microencapsulate a core material in the following manner. One monomer is dissolved in a first solvent, and the core material is dissolved or suspended in the first solvent. A second monomer is dissolved in a second solvent (typically aqueous) which is immiscible with the first. An emulsion is formed by suspending the first solution through stirring in the second solution. Once the emulsion is stabilized, an initiator is added to the aqueous phase, causing interfacial polymerization at the interface of each droplet of emulsion.

Spray drying is typically a process for preparing 1 to 10 μm-sized microspheres in which the core material to be encapsulated is dispersed or dissolved in a polymer solution (typically aqueous), the solution or dispersion is pumped through a micronizing nozzle driven by a flow of compressed gas, and the resulting aerosol is suspended in a heated cyclone of air, allowing the solvent to evaporate from the microdroplets. The solidified particles pass into a second chamber and are collected.

Hot melt microencapsulation is a method in which a core material is added to molten polymer. This mixture is suspended as molten droplets in a nonsolvent for the polymer (often oil-based) which has been heated approximately 10 °C above the melting point of the polymer. The emulsion is maintained through vigorous stirring while the nonsolvent bath is quickly cooled below the glass transition of the polymer, causing the molten droplets to solidify and entrap the core material. Microspheres produced by this technique typically range in size from 50 μm to 2 mm in diameter. This process generally requires the use of polymers with fairly low melting temperatures (e.g., less than about 150° C, to prevent biomolecule denaturation; preferably less than about 80° C for most proteins and some nucleic acids), and with glass transition temperatures above room temperature, and core materials which are thermo-stable.

In solvent evaporation microencapsulation, the polymer is typically dissolved in a water-immiscible organic solvent and the material to be encapsulated is added to the polymer solution as a suspension or solution in organic solvent. An emulsion is formed by adding this suspension or solution to vigorously stirred or agitated water (often containing a surface active agent to stabilize the emulsion). The organic solvent is evaporated while continuing to stir. Evaporation results in precipitation of the polymer, forming solid microcapsules containing core material.

Phase separation microencapsulation is typically performed by dispersing the material to be encapsulated in a polymer solution by stirring. While continuing to uniformly suspend the material through stirring, a nonsolvent for the polymer is slowly added to the solution to decrease the polymer's solubility. The polymer either precipitates or phase separates into a polymer-rich and a polymer-poor phase, depending on the solubility of the polymer in the solvent and nonsolvent. Under proper conditions, the polymer in the polymer-rich phase will migrate to the interface with the continuous phase, encapsulating the core material in a droplet with an outer polymer shell.

One embodiment of the process is described in U.S. Patent No. 5,407,609 to Tice, et al., which discloses a phase separation microencapsulation process which reportedly proceeds very rapidly. In the method, a polymer is dissolved in a solvent, and then an agent to be encapsulated is dissolved or dispersed in that solvent. Then the mixture is combined with an excess of nonsolvent and is emulsified and stabilized, whereby the polymer solvent no longer is the continuous phase. Aggressive emulsification conditions are applied to produce microdroplets of the polymer solvent. The stable emulsion then is introduced into a large volume of nonsolvent to extract the polymer solvent and form microparticles. The size of the microparticles is determined by the size of the microdroplets of polymer solvent.

"Phase inversion nanoencapsulation" or "PIN" is a nanoencapsulation technique which takes advantage of the immiscibility of dilute polymer solutions in select "non-solvents" in which the polymer solvent has good miscibility. The result is spontaneous formation of nanospheres (less than 1 μm) and microspheres (1-10 μm) within a narrow size range, depending on the concentration of the initial polymer solution, the molecular weight of the polymer, selection of the appropriate solvent-non-solvent pair and the ratio of solvent to non-solvent. Encapsulation efficiencies are typically 75-90% and recoveries are 70-90% and bioactivity is generally well-maintained for sensitive bioagents.

"Phase inversion" of polymer solutions under certain conditions can bring about the spontaneous formation of discrete microparticles. Phase inversion nanoencapsulation differs from existing methods of encapsulation in that it is essentially a one-step process, is nearly instantaneous, and does not require emulsification of the solvent. Under proper conditions, low viscosity polymer solutions can be forced to phase invert into fragmented spherical polymer particles when added to appropriate nonsolvents.

Phase inversion phenomenon has been applied to produce macro- and micro-porous polymer membranes and hollow fibers, the formation of which depends upon the mechanism of microphase separation. A prevalent theory of microphase separation is based upon the belief that "primary" particles of about 50 nm diameter, form as the initial precipitation event resulting from solvent removal. As the process continues, primary particles are believed to collide and coalesce, forming "secondary" particles with dimensions of approximately 200 nm, which eventually join with other particles to form the polymer matrix. An alternative theory, "nucleation and growth", is based upon the notion that a polymer precipitates around a core micellar structure (in contrast to coalescence of primary particles).

The process results in a very uniform size distribution of small particles forming at lower polymer concentrations without coalescing supports the nucleation and growth theory, while not excluding coalescence at higher polymer concentrations (e.g., greater than 10% weight per volume) where larger particles and even aggregates can be formed. (Solvent would be extracted more slowly from larger particles, so that random collisions of the partially-solvated spheres would result in coalescence and, ultimately, formation of fibrous networks.) By adjusting polymer concentration, polymer molecular weight, viscosity, miscibility and solventnonsolvent volume ratios, the interfibrillar interconnections characteristic of membranes using phase inversion are avoided, with the result being that microparticles are spontaneously formed. These parameters are interrelated and the adjustment of one will influence the absolute value permitted for another.

In a preferred processing method, a mixture is formed of the agent to be encapsulated, a polymer and a solvent for the polymer. The agent to be encapsulated may be in liquid or solid form. It may be dissolved in the solvent or dispersed in the solvent. The agent thus may be contained in microdroplets dispersed in the solvent or may be dispersed as solid microparticles in the solvent. The phase inversion process thus can be used to encapsulate a wide variety of agents by including them in either micronized solid form or else emulsified liquid form in the polymer solution.

The loading range for the agent within the microparticles is between 0.01-80% (agent weight/polymer weight). When working with nanospheres, an optimal range is 0.1-5% (weight/weight).

The working molecular weight range for the polymer is on the order of 1 kDa- 150,000 kDa, although the optimal range is 2 kDa-50 kDa. The working range of polymer concentration is 0.01-50% (weight/volume), depending primarily upon the molecular weight of the polymer and the resulting viscosity of the polymer solution, hi general, the low molecular weight polymers permit usage of a higher concentration of polymer. The preferred concentration range will be on the order of 0.1%- 10% (weight/volume), while the optimal polymer concentration typically will be below 5%. It has been found that polymer concentrations on the order of 1- 5% are particularly useful.

The viscosity of the polymer solution preferably is less than 3.5 cP and more preferably less than 2 cP, although higher viscosities such as 4 or even 6 cP are possible depending upon adjustment of other parameters such as molecular weight. It will be appreciated by those of ordinary skill in the art that polymer concentration, polymer molecular weight and viscosity are interrelated, and that varying one will likely affect the others.

The nonsolvent, or extraction medium, is selected based upon its miscibility in the solvent. Thus, the solvent and nonsolvent are thought of as "pairs". The solubility parameter (δ (cal/cm³)¹⁷² is a useful indicator of the suitability of the solvent/nonsolvent pairs. The solubility parameter is an effective protector of the miscibility of two solvents and, generally, higher values indicate a more hydrophilic liquid while lower values represent a more hydrophobic liquid (e.g., δi water = 23.4(cal/cm³)^1/2 whereas δl hexane = 7.3 (cal/cm³)¹⁷². Solvent/nonsolvent pairs are useful wherein the absolute value of the difference between the δ of the solvent and the δ of the nonsolvent is less than about 6 (cal/cm³)¹⁷². Although not wishing to be bound by any theory, an interpretation of this finding is that miscibility of the solvent and the nonsolvent is important for formation of precipitation nuclei which ultimately serve as foci for particle growth. If the polymer solution is totally immiscible in the nonsolvent, then solvent extraction does not occur and nanoparticles are not formed. An intermediate case would involve a solvent/nonsolvent pair with slight miscibility, in which the rate of solvent removal would not be rapid enough to form discrete microparticles, resulting in aggregation of coalescence of the particles.

Nanoparticles generated using "hydrophilic" solvent/nonsolvent pairs (e.g., a polymer dissolved in methylene chloride with ethanol as the nonsolvent) tend to yield particles in the size range of 100-500 nm compared to the larger particles measuring 400-2000 nm produced when "hydrophobic" solvent/nonsolvent pairs were used (e.g., the same polymer dissolved in methylene chloride with hexane as the nonsolvent).

Similarly, the solventnonsolvent volume ratio can be important in determining whether microparticles form without particle aggregation or coalescence. A suitable working range for solventnonsolvent volume ratio is believed to be 1 :40-l : 1,000,000. An optimal working range for the volume ratios for solventnonsolvent is believed to be 1:50-1:200 (volume per volume). Ratios of less than approximately 1:40 typically result in particle coalescence, presumably due to incomplete solvent extraction or else a slower rate of solvent diffusion into the bulk nonsolvent phase.

It will be understood by those of ordinary skill in the art that the ranges given above are not absolute, but instead are interrelated. For example, although it is believed that the solventnonsolvent minimum volume ratio is on the order of 1 :40, it is possible that microparticles still might be formed at lower ratios such as 1:30 if the polymer concentration is extremely low, the viscosity of the polymer solution is extremely low and the miscibility of the solvent and nonsolvent is high. Thus, the polymer is dissolved in an effective amount of solvent, and the mixture of biomolecule, polymer and polymer solvent is introduced into an effective amount of a nonsolvent, to produce polymer concentrations, viscosities and solventnonsolvent volume ratios that cause the spontaneous and virtually instantaneous formation of microparticles. A variety of polymers may be used, including polyesters such as poly(lactic acid), poly(lactide-co-glycolide) in molar ratios of 50:50 and 75:25; polycaprolactone; polyanhydrides such as poly(fumaric-co-sebacic) acid or P(FA:SA) in molar ratios of 20:80 and 50:50; poly(carboxyphenoxypropane-co-sebacic) acid or P(CPP:SA) in molar ratio of 20:80; and polystyrenes (PS). Poly(ortho)esters, blends and copolymers of these polymers can also be used, as well as other biodegradable polymers and non-biodegradable polymers such as ethylenevinyl acetate and polyacrylamides.

Nanospheres and microspheres in the range of 10 nm to 10 μm have been produced by these methods. Using initial polymer concentrations in the range of 1-2% (weight/volume) and solution viscosities of 1-2 cP, with a "good" solvent, such as methylene chloride and a strong non-solvent, such as petroleum ether or hexane, in an optimal 1 : 100 volume ratio, generates particles with sizes ranging from 100-500 nm. Under similar conditions, initial polymer concentrations of 2-5% (weight/volume) and solution viscosities of 2-3 cP typically produce particles with sizes of 500-3,000 nm. Using very low molecular weight polymers (less than 5 kDa), the viscosity of the initial solution may be low enough to enable the use of higher than 10% (weight/volume) initial polymer concentrations which generally result in microspheres with sizes ranging from 1-10 μm. Li general, it is likely that with concentrations of 15% (weight/volume) and solution viscosities greater than about 3.5 cP, discrete microspheres will not form but, instead, will irreversibly coalesce into intricate, interconnecting fibrilar networks with micron thickness dimensions. These encapsulation methods can result in product yields greater than 80% and encapsulation efficiencies as high as 100%, of nano- to micro-sized particles.

Supercritical fluids can be used to process bioadhesive polymers, especially polyanhydrides or graft polyanhydrides, as described below.

Production of flowable pharmaceutical powders can be achieved by atomization of SCF solubilized polymers through a nozzle using rapid expansion of supercritical solutions (RESS) and gas antisolvent precipitation (GAS), precipitation with compressed antisolvent process (PCA), solution enhanced-dispersion by supercritical fluids (SEDS), supercritical antisolvent (SAS) process, and aerosol supercritical extraction system (ASES).

Extraction with supercritical fluids can be used in the purification of bioadhesive polymers, especially polyanhydrides and grafted polyanhydrides. Supercritical fluids can be used to micronize and impregnate carrier particles with drugs, such as encapsulation of drugs and biologies with bioadhesive polymers, especially polyanhydrides and grafted polyanhydrides.

Supercritical fluids can also be used to deliver coatings of pharmaceutical dosage formulations, either nanoparticles, microparticles or solid oral dosage formulations with bioadhesive polymers, especially polyanhydrides and grafted polyanhydrides.

The methods described herein also can be used to produce microparticles characterized by a homogeneous size distribution. The methods described herein can produce, for example, nanometer sized particles that are relatively monodisperse in size. By producing a microparticle that has a well defined and less variable size, the properties of the microparticle, such as when it is used for release of a biomolecule, can be better controlled. The methods are also useful for controlling the size of the microspheres. This is particularly useful when the material to be encapsulated must first be dispersed in the solvent and when it would be undesirable to sonicate the material to be encapsulated. The mixture of the material to be encapsulated and the solvent (with dissolved polymer) can be frozen in liquid nitrogen and then lyophilized to disperse the material to be encapsulated in the polymer. The resulting mixture then can be redissolved in the solvent and then dispersed by adding the mixture to the nonsolvent. This methodology was employed in connection with dispersing DNA (see WO 01/501082 to Brown University Research Foundation, incorporated herein by reference).

In many cases, the encapsulation methods described above can be carried out in less than five minutes. Preparation time may take anywhere from one minute to several hours, depending on the solubility of the polymer and the chosen solvent, whether the agent will be dissolved or dispersed in the solvent and so on. Nonetheless, the actual encapsulation time typically is less than thirty seconds.

After formation of the microcapsules, they can be collected by centrifugation, filtration, or other standard techniques. Filtering and drying may take several minutes to an hour depending on the quantity of material encapsulated and the methods used for drying the nonsolvent. The process in its entirety may be a discontinuous or a continuous process. Dosage Forms

In one embodiment, the solid oral dosage form comprises a multilayer tablet containing nanoparticulate drug and absorption enhancers in a central matrix of hydroxypropylrnethyl cellulose (HPMC) and microcrystalline cellulose (MCC). The inner core is surrounded on two sides by bioadhesive polymer (preferably DOPA-derivatized BMA polymer). The final tablet is coated with an enteric coating (Eudragit Ll 00-55) to prevent release of drugs until the tablet has moved to the small intestine. See Figure 17. hi a preferred embodiment, illustrated in Figure 18, the solid oral dosage form is a longitudinally compressed tablet 10 containing a single drug (e.g., paclitaxel) or more than one drug, excipients, and optionally permeation and/or dissolution enhancers, combined in a single monolithic layer 11. The tablet is sealed peripherally with a layer of bioadhesive composition 12 leaving the upper and lower sides 13A and 13B of the tablet available for drug release. First-order and, more advantageously, zero-order release profiles are achievable with this tablet design. It is feasible to create different drag release rates by changing the composition of the core matrix. The size range of nanoparticulate drugs and nanoparticles required for transmucosal GI absorption is typically in the range of 0.05 to 2 microns. Drug-loaded nanoparticles may be delivered using conventional solid oral dosage forms including tablets, minitab or spheroidal particles containing drugs and bioadhesive polymers. Minitabs or spheroidal particles may optionally be delivered in a capsule and optionally coated with enteric polymers to release drug in the small intestine. The inclusion of bioadhesives in the solid oral dosage form will bring the dosage form into close proximity with the target epithelium and facilitate diffusion of drugs (and absorption enhancers) into intestinal tissue.

Dosage forms for oral administration may comprise microspheres. In some embodiments, the microspheres are stabilized against aggregation by a hydrophobic polymer and are therefore amenable to any of the usual dosage forms. A preferred form is encapsulation of the microsphere in a coating that will dissolve in the stomach and/or the intestine. Other forms include tablets, slurries or dispersions for oral administration, preferably made up at the time of use, and filled tablets. In a preferred embodiment, the particles are coated with a bioadhesive polymer, such as a polyanhydride, to improve their uptake from the intestine.

Additionally, protein particles and other biomolecule particles formed in this manner can be used as aggregates in larger capsules. Small particles with a suitable coating offer improved delivery across the intestine, leading to clinically useful bioavailabilities. Additionally, these small biomolecule particles can be used for immunization, optionally in admixture with immune system stimulants and adjuvants. This can involve "Peyer's patches" and similar organs, in the intestine and in other mucosae. Nucleic acid particles can be used to transform cells and to engage in other intracellular uses of nucleic acids, of which a large variety have been proposed in the art, e.g., plasmids and RNA silencing, hi general, the particles of biomolecules are advantageous for use in the known therapeutic uses for the particular biomolecule. In the preferred embodiment the particles are suitable for oral administration.

Other suitable solid oral dosage forms include tablets. Types of tablets include multilayer tablets, such as a trilayer tablet having an inner core that includes one or more drugs in an appropriate matrix of excipients and optionally absorption enhancers that is surrounded on two sides by a bioadhesive polymeric coating. In another example, a tablet is a longitudinally compressed tablet containing precompressed inserts of the poorly absorbed drug, excipients, and optionally an absorption enhancer. Preferably, the compressed tablet comprises a bioadhesive polymeric coating on at least part of its surface. In some embodiments, drug is only released at the edge of this tablet, which can result in zero-order kinetics. Administration of Dosage Forms

Often, biomolecule particles will be delivered to a patient for the treatment of a disease or disorder. In one embodiment, the particles are suitable for delivery to mucosal surfaces, such as oral, intranasal, pulmonary, or vaginal. In another embodiment, the particles are suitable for parenteral administration.

Micronized or nanoparticle drug particles may be administered to patients using a full range of routes of administration. For example, micronized drug particles may be blended with direct compression or wet compression tableting excipients using standard formulation methods. The resulting granulated masses may then be compressed in molds or dies to form tablets and subsequently administered via the oral route of administration. Alternately micronized drug granulates may be extruded, spheronized and administered orally as the contents of capsules and caplets. Tablets, capsules and caplets may be film coated to alter dissolution of the delivery system or target delivery of the microspheres or nanospheres to different regions of the gastrointestinal tract (e.g., an enteric coating). Additionally, micronized drug may be orally administered as suspensions in aqueous fluids or sugar solutions (syrups) or hydroalcoholic solutions (elixirs) or oils. Micronized drug may be co-mixed with gums and viscous fluids and applied topically for purposes of buccal, rectal or vaginal administration. Micronized drug may also be co-mixed with gels and ointments for purposes of topical administration to epidermis for transdermal delivery. Micronized or nanoparticle drug particles may also be suspended in non- viscous fluids and nebulized or atomized for administration of the dosage form to nasal membranes. Micronized drug may also be delivered parenterally by either intravenous, subcutaneous, intramuscular, intrathecal, intravitreal or intradermal routes as sterile suspensions in isotonic fluids. Finally, micronized or nanoparticle drug particles may be nebulized and delivered as dry powders in metered-dose inhalers for purposes of inhalation delivery. For administration by inhalation, the compounds for use according to the present invention may be conveniently delivered in the form of an aerosol spray presentation from pressurized packs or a nebulizer, with the use of a suitable propellant, e.g., air, carbon dioxide or other suitable gas. In the case of a pressurized aerosol the dosage unit may be determined by providing a valve to deliver a metered amount. Capsules and cartridges of for use in an inhaler or insufflator may be formulated containing the microparticle and optionally a suitable base such as lactose or starch. Those of skill in the art can readily determine the various parameters and conditions for producing aerosols without resort to undue experimentation. Several types of metered dose inhalers are regularly used for administration by inhalation. These types of devices include metered dose inhalers (MDI), breath-actuated MDI, dry powder inhaler (DPI), spacer/holding chambers in combination with MDI, and nebulizers. Techniques for preparing aerosol delivery systems are well known to those of skill in the art. Generally, such systems should utilize components which will not significantly impair the biological properties of the agent in the microparticle (see, for example, Sciarra and Cutie, "Aerosols," in Remington's Pharmaceutical Sciences, 18th ed., p. 1694-1712 (1990)).

Micronized drug particles, when it is desirable to deliver them systemically, may be formulated for parenteral administration by injection, e.g., by bolus injection or continuous infusion. Formulations for injection may be presented in unit dosage form, e.g., in ampoules or in multi-dose containers, with an added preservative. The compositions may take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilizing and/or dispersing agents. For drugs requiring absorption in buccal and sublingual regions of the

GI tract, bioadhesive tablets and particularly bioadhesive multiparticulates and nanoparticles are desirable. Drugs absorbed in these sites avoid first- pass metabolism by liver and degradation by GI tract enzymes and harsh pH conditions typically present in the stomach and small intestine. Drugs absorbed in the buccal and sublingual compartments benefit from rapid onset of absorption, typically within minutes of dosing. Particularly suitable are bioadhesive particulates in fast-dissolving dosage forms, e.g., OraSolv (Cima Labs) that disintegrate within 30 sec after dosing and release the bioadhesive particles. Target release profiles include immediate release (IR) and combinations of zero-order controlled release (CR) kinetics and first-order CR kinetics. Preferably, pharmaceutical formulations targeting the buccal and sublingual regions are constructed such that the formulation disintegrates before passing into the esophagus.

For drugs requiring absorption in the stomach and upper small intestine and/or topical delivery to these sites, particularly drugs with narrow absorption windows, bioadhesive, gastroretentive drug delivery systems are the option of choice. Bioadhesive tablets and multiparticulates are formulated to reside for durations greater than 3 hours and optimally greater than 6 hours in the fed state. Drug release profiles from these systems are tailored to match the gastric residence times, so that greater than 85% of an encapsulated drug is released during the gastric residence time. Target release profiles include zero-order CR kinetics, first-order CR kinetics and combinations of IR and CR kinetics.

For drugs requiring absorption or topical delivery only in the small intestine, enteric-coated, bioadhesive drug delivery systems are a preferred method. Such systems are particularly well suited for topical delivery of therapeutics to Crohn's disease patients. Enteric-coated, bioadhesive tablets and multiparticulates are formulated to reside in the stomach for durations less than 3 hrs in the fed state and less than 1 hr in the fasted state, during which time less than 10% of an encapsulated drug is released, due to the enteric coating. Following gastric emptying, the enteric coating is "triggered" to dissipate, revealing the underlying bioadhesive coating. Suitable triggers include pH and time duration. Typical of enteric polymers utilizing pH as a trigger are Eudragit polymers manufactured by Rohm America: Eudragit L100-55 dissolves at pH values than 5.5, typically found in duodenum; Eudragit LlOO dissolves at pH values exceeding 6.0, typically found in jejunum; Eudragit SlOO dissolves at pH values exceeding 7.0, typically found in ileum and the ileocecal junction. Time may be used as a trigger to unmask the bioadhesive coating.

Coatings that dissolve after 3 hrs when the dosage form is administered in the fed state and after 1-2 hrs when the dosage form is administered in the fasted state are suitable for bioadhesive delivery systems to the small intestine. Erosion of soluble polymer layers is one means to achieve a time- triggered, enteric dissolution. Polymers such as HPMC, HPC, PVP, PVA or combinations of the above maybe used as time-delayed, enteric coatings and timing of the dissolution of the coating can be increased by applying thicker coating weights.

Alternately, non-permeable coatings of insoluble polymers, e.g., cellulose acetate, ethylcellulose, can be used as enteric coatings for delayed/modified release (DR/MR) by inclusion of soluble pore formers in the coating, e.g., PEG, PVA, sugars, salts, detergents, triethyl citrate, triacetin, etc., at levels ranging from 0.5 to 50% w/w of the coating and most preferably from 5 to 25% w/w of the coating. Also suitable are rupturable coating systems, e.g., Pulsincap, that use osmotic forces of swelling from hydrophilic polymers to rupture enteric membranes to reveal underlying bioadhesive coatings.

Target release profiles for the small intestine include: no more than 10% drug release during the first 3 hours post-dosing followed by either IR kinetics, zero-order CR kinetics, first-order CR kinetics and combinations of IR and CR kinetics. Kits

Dosage formulations of the invention can be packaged for individual dosing or provided in a kit with instructions and individually labeled packaging to ensure that the correct dosage is given at the desired intervals to maximize bioavailability. The kit may contain constant or escalating doses of the formulation. The time periods for each oral administration may be included in the kit. Exemplification

The application now being generally described, it will be more readily understood by reference to the following examples, which are included merely for purposes of illustration of certain aspects and embodiments of the present invention, and are not intended to limit the invention. Examples

Paclitaxel Nanoparticles for all Examples Paclitaxel nanoparticles were formed as follows: 1.2 grams of paclitaxel is dissolved in 40 ml of dichloromethane to form a 3% (w/v) paclitaxel solution and passed through a 0.1 μm poly(tetrafluoroethylene)(PTFE) syringe filter. The filtered solution was then poured rapidly into 4000 ml of pentane (1:100 solventnon-solvent) creating an very fine dispersion of paclitaxel/dichloromethane solution droplets. The dichloromethane spontaneously diffused from the droplets into the pentane leaving behind solid paclitaxel nanoparticles. The entire suspension of paclitaxel nanoparticles in dichloromethane/pentane was pressured filtered using N₂-gas (10 psi) through a paper filter (2.5 μm-pore size), on which the paclitaxel nanoparticles were retained. Upon completion of the filtration step, the nanoparticles were dried in place for 10 minutes by the N₂-gas stream. The nanoparticles were collected in a glass vial and dried further under vacuum for at least 2 days to remove residual solvents. This process generally produced paclitaxel nanoparticles about 300 nm in diameter.

In Vivo Test Conditions for all Examples Paclitaxel formulations were prepared as described in each example.

The formulations were tested in vivo. 20-30 g mice received the administration(s) via an oro-gastric feeding needle, at the paclitaxel dosing level specified in each example. All mice were fasted for ±2 hours around each dosing, receiving only water for the duration of the fasting period. After each dosing, blood samples were obtained from one cohort at time points of 0.33, 0.67, 1, 2, 4, 6, and 8 hours (5 mice per timepoint). All blood samples were drawn into heparinized tubes at the specified time points, centrifuged immediately, and the plasma aliquotted and stored frozen until analysis for paclitaxel content by LC-MS-MS.

Example 1 : Oral Administration of Paclitaxel to Mice with second dose at 12, 24, 48, 72, or 96 hours after the first dose, for two constant doses Paclitaxel Formulation for Examples 1-5 and 8-11 The paclitaxel formulation was prepared for oral administration by suspending the paclitaxel nanoparticles in a dispersant (PBS containing 0.5% (w/v) sodium lauryl sulfate and 0.5% (w/v) polyvinylpyrrolidone), at a concentration of 5.6 mg/ml, and bath sonicating for 4 minutes.

The paclitaxel formulation was administered twice, via oral gavage, to each of several cohorts of mice at a dosing level of 48 mg/kg. A total of 35 mice per cohort were used in this study. Each mouse received a first dose at 0 hours, followed by a second dose after only one of the following intervals: 12, 24, 48, 72, or 96 hours. After the second oral dose blood samples, from 5 mice per time-point, were taken at 0.33, 0.67, 1, 2, 4, 6, and 8 hours. A control cohort (cohort 1) received a single dose and blood samples at 0.33, 0.67, 1, 2, 4, 6, and 8 hours were obtained immediately following the dosing. Cohort 2 received doses at 0 hours and 12 hours, and blood samples were obtained at 0.33, 0.67, 1, 2, A, 6, and 8 hours following the second dose. This was repeated in cohorts 3, 4, 5, and 6 but with separations between the two doses of 24, 48, 72 and 96 hours, respectively. After each second dosing blood samples were obtained at 0.33, 0.67, 1, 2, 4, 6, and 8 hours.

Plasma paclitaxel concentration profiles are plotted at respective time points, and shown in Figure IA. Figure IB summarizes the obtained AUC ("area under the curve", a surrogate for total amount of exposure) values of the initial dose and each of the second doses at the different "2nd-dose" time points.

As shown in Figure IA, no paclitaxel was detected in the blood plasma of the mice prior to paclitaxel administration (at the 0-hour time point) As shown in Figures IA and IB, the AUC and Cmax of the dose administered to Cohort 1, which received only a single dose at 0 hours, is approximately 8100 ng^»h/ml and 3500 ng/ml, respectively. The AUC and Cmax of the second dose administered to Cohort 2, which received equal doses at 0 and 12 hours, is approximately 1000 ng^»h/ml and 500 ng/ml, respectively. The AUC and Cmax of the second dose administered to Cohort 3, which received equal doses at 0 and 24 hours, is approximately 1400 ng^»h/ml and 750 ng/ml, respectively. The AUC and Cmax of the second dose administered to Cohort 4, which received equal doses at 0 and 48 hours, is approximately 3700 ng^#h/ml and 1600 ng/ml, respectively. The AUC and Cmax of the second dose administered to Cohort 5, which received equal doses at 0 and 72 hours, is approximately 3200 ng^»h/ml and 1800 ng/ml, respectively. The AUC and Cmax of the second dose administered to Cohort 6, which received equal doses at 0 and 96 hours, is approximately 7000 ng»h/ml and 3100 ng/ml, respectively. The increase in AUC and Cmax that occurred with most of the increases in inter-dose interval, indicates improved net absorption following the second dose of paclitaxel.

These results indicate that oral paclitaxel is initially well-absorbed, having a bioavailability in the range of about 10-15% or more. It appears from the results that some biological function is subsequently induced that prevents the absorption of later dose(s) of paclitaxel, i.e., causes paclitaxel resistance, and that this resistance then diminishes with time over the following three days. It is expected that similar phenomena will be seen in humans, but the details of the time required for induction of resistance, and the decay of drug resistance, may differ.

Example 2: Oral Administration of Paclitaxel to Mice, Every 12 Hours for 4 Constant Doses

The paclitaxel formulation was administered via oral gavage to each of four cohorts of 35 mice at a paclitaxel dosing level of 48 mg/kg. Cohorts 1, 2, 3, and 4 were dosed at 0 hours; Cohorts 2, 3, and 4 were dosed again at 12 hours; Cohorts 3 and 4 were dosed again at 24 hours; and Cohort 4 was dosed again at 36 hours.

Plasma paclitaxel concentrations profiles (ng/ml) are plotted at respective time points (hours) in Figure 2 A. Figure 2B is a graph of AUC and maximum paclitaxel plasma concentration (Cmax) values for each dose. As seen in Figures 2A and 2B the AUC and Cmax of the dose administered to Cohort 1, which received only a single dose at 0 hours, are approximately 7900 ng»h/ml and 2800 ng/ml, respectively. The AUC and Cmax of the second dose administered to Cohort 2, which received equal doses at 0 and 12 hours, are approximately 8000 ng^»h/ml and 3500 ng/ml, respectively. The AUC and Cmax of the third dose administered to Cohort 3, which received equal doses at 0, 12, and 24 hours, are approximately 1050 ng^»h/ml and 400 ng/ml, respectively. The AUC and Cmax of the fourth dose administered to Cohort 4, which received equal doses at 0, 12, 24, and 36 hours, are approximately 1100 ng^«h/ml and 750 ng/ml, respectively. As shown in Figures 2A and 2B, "induced resistance" to paclitaxel is evident only after the second dose, at a time between the 12-hour and 24-hour doses. Some variability in the time to inducement of paclitaxel resistance likely exists since the data in Figures IA and IB show increased resistance at the 12-hour dose (AUC was reduced from 8000 to 1000 ngh/ml and Cmax was reduced from 35000 to 500 ng/ml when 12 hours recovery time were used.) The increased resistance to oral paclitaxel is evident at the 24-hour dose, but the resistance decreases at the 48-hour dose (see Figures IA and IB). Example 3: Oral Administration of Paclitaxel to Mice Every 24 Hours for 4 Constant Doses

The paclitaxel formulation was administered via oral gavage to each of four cohorts of 35 mice at a paclitaxel dosing level of 48 mg/kg. Cohorts 1, 2, 3, and 4 were dosed at 0 hours; cohorts 2, 3, and 4 were dosed again at 24 hours; cohorts 3 and 4 were dosed again at 48 hours; and cohort 4 was dosed again at 72 hours.

Plasma paclitaxel concentrations are plotted at respective time points, and shown in Figure 3Aa. Figure 3B is a graph of AUC and Cmax values for each dose. As seen in Figures 3 A and 3B the AUC and Cmax of the dose administered to Cohort 1, which received only a single dose at 0 hours, are approximately 5200 ng^#h/ml and 1800 ng/ml, respectively. The AUC and Cmax of the second dose administered to Cohort 2, which received equal doses at 0 and 24 hours, are approximately 2500 ng^#h/ml and 1200 ng/ml, respectively. The AUC and Cmax of the third dose administered to Cohort 3, which received equal doses at 0, 24, and 48 hours, are approximately 1900 ng^»h/ml and 700 ng/ml, respectively. The AUC and Cmax of the fourth dose administered to Cohort 4, which received equal doses at 0, 24, 48, and 72 hours, are approximately 1750 ng^#h/ml and 600 ng/ml, respectively. As graphically depicted in Figures 3 A and 3B, the "induced resistance" to paclitaxel is evident in each subsequent dose. The AUC and Cmax values decrease with each dose, demonstrating increasing resistance when a recovery period of 24 hours was used. Example 4: Oral Administration of Paclitaxel to Mice Every 48 Hours for 4 Constant Doses

The paclitaxel formulation was administered via oral gavage to each of four cohorts of 35 mice at a paclitaxel dosing level of 48 mg/kg. Cohorts 1, 2, 3, and 4 were dosed at 0 hours; cohorts 2, 3, and 4 were dosed again at 48 hours; cohorts 3 and 4 were dosed again at 96 hours; and cohort 4 was dosed again at 144 hours.

Plasma paclitaxel concentrations are plotted at respective time points, and shown in Figure 4 A. Figure 4B is a graph of AUC and Cmax values for each dose. As seen in Figures 4A and 4B, the AUC and Cmax of the dose administered to Cohort 1, which received only a single dose at 0 hours, are approximately 12700 ng»h/ml and 3600 ng/ml, respectively. The AUC and Cmax of the second dose administered to Cohort 2, which received equal doses at 0 and 48 hours, are approximately 4400 ng^#h/ml and 1600 ng/ml, respectively. The AUC and Cmax of the third dose administered to Cohort 3, which received equal doses at 0, 48, and 96 hours, are approximately 5700 ng^»h/ml and 1400 ng/ml, respectively. The AUC and Cmax of the fourth dose administered to Cohort 4, which received equal doses at 0, 48, 96, and 144 hours, are approximately 5600 ng»h/ml and 3200 ng/ml, respectively. As graphically depicted in Figures 4A and 4B, the "induced resistance" to paclitaxel is evident at the 48-hour dose. The AUC value increases slightly at the 96-hour dose and remains constant at the 144-hour dose. However, both the AUC and Cmax for the recovery period of 48-hours was greater than 30% of the AUC and Cmax for the initial dose (e.g. the AUC and Cmax for the 48-hour dose were approximately 35% of the AUC for the initial dose and approximately 44% of the Cmax for the initial dose; the AUC and Cmax for the 96-hour dose were approximately 45% of the AUC for the initial dose and approximately 39% of the Cmax for the initial dose; and the AUC and Cmax for the 144-hour dose were approximately 44% of the AUC for the initial dose and approximately 89% of the Cmax for the initial dose). Thus, 48 hours is a suitable recovery period for this formulation.

Example 5: Oral Administration of Paclitaxel to Mice Every 96 Hours for 4 Constant Doses

The paclitaxel formulation was administered via oral gavage to each of four cohorts of 35 mice at a paclitaxel dosing level of 48 mg/kg. Cohorts 1, 2, 3, and 4 were dosed at 0 hours; cohorts 2, 3, and 4 were dosed again at 96 hours; cohorts 3 and 4 were dosed again at 192 hours; and cohort 4 was dosed again at 288 hours.

Plasma paclitaxel concentrations are plotted at respective time points, and shown in Figure 5 A. Figure 5B is a graph of AUC and Cmax values for each dose. As seen in Figures 5 A and 5B, the AUC and Cmax of the dose administered to Cohort 1, which received only a single dose at 0 hours, are approximately 12,100 ng*h/ml and 5000 ng/ml, respectively. The AUC and Cmax of the second dose administered to Cohort 2, which received equal doses at 0 and 96 hours, are approximately 8800 ng^»h/ml and 2400 ng/ml, respectively. The AUC and Cmax of the third dose administered to Cohort 3, which received equal doses at 0, 96, and 192 hours, are approximately 7500 ng*h/ml and 3400 ng/ml, respectively. The AUC and Cmax of the fourth dose administered to Cohort 4, which received equal doses at 0, 96, 192, and 288 hours, are approximately 17000 ng^»h/ml and 4300 ng/ml, respectively. As graphically depicted in Figures 5A and 5B, the "induced resistance" to paclitaxel is evident at the 96-hour dose. The AUC value continues to decrease at the 192-hour dose, and increases drastically at the 288-hour dose. However, both the AUC and Cmax for the recovery period of 96-hours was greater than 45% of the AUC and Cmax for the initial dose (e.g. the AUC and Cmax for the 96-hour dose were approximately 73% of the AUC for the initial dose and approximately 48% of the Cmax for the initial dose; the AUC and Cmax for the 192-hour dose were approximately 62% of the AUC for the initial dose and approximately 68% of the Cmax for the initial dose; and the AUC and Cmax for the 288-hour dose were approximately 140% of the AUC for the initial dose and approximately 86% of the Cmax for the initial dose). Thus 96 hours is a suitable recovery period for this paclitaxel formulation.

Example 6: Oral Administration of Paclitaxel and Ketoconazole to Mice Every 24 Hours for 5 Constant Doses Paclitaxel/Ketoconazole Formulation

Formulations for oral administration were prepared by suspending the paclitaxel nanoparticles in a dispersant (PBS containing 0.5% (w/v) sodium lauryl sulfate, 0.5% (w/v) polyvinylpyrrolidone, and 0.117% (w/v) ketoconazole), at a concentration of 5.6 mg/ml, and bath sonicating for 4 minutes.

The paclitaxel/ketoconazole formulation was administered via oral gavage to each of five cohorts of 35 mice at a paclitaxel dosing level of 48 mg/kg and a ketoconazole dose of 10 mg/kg. Cohorts 1, 2, 3, 4, and 5 were dosed at 0 hours; cohorts 2, 3, 4, and 5 were dosed again at 24 hours; cohorts 3, 4, and 5 were dosed again at 48 hours; cohorts 4 and 5 were dosed again at 72 hours; and cohort 5 was dosed again at 96 hours.

Plasma paclitaxel concentrations are plotted at respective time points, and shown in Figure 6 A. Figure 6B is a graph of AUC and Cmax values for each dose. As seen in Figures 6 A and 6B, the AUC and Cmax of the sole dose administered to Cohort 1, which received only a single dose at 0 hours, are approximately 16000 ng^»h/nil and 8300 ng/ml, respectively. The AUC and Cmax of the second dose administered to Cohort 2, which received equal doses at 0 and 24 hours, are approximately 2700 ng^»h/ml and 2000 ng/ml, respectively. The AUC and Cmax of the third dose administered to Cohort 3, which received equal doses at 0, 24, and 48 hours, are approximately 3150 ng^»h/ml and 2000 ng/ml, respectively. The AUC and Cmax of the fourth dose administered to Cohort 4, which received equal doses at 0, 24, 48, and 72 hours, are approximately 1600 ng^»h/ml and 1500 ng/ml, respectively. The AUC and Cmax of the fifth dose administered to Cohort 5, which received equal doses at 0, 24, 48, 72, and 96 hours, are approximately 1050 ng^#h/ml and 750 ng/ml, respectively. As graphically depicted in Figures 6A and 6 B, the paclitaxel AUC and Cmax values were increased following most administrations when compared to administration of the paclitaxel formulation alone as described in Example 3, although the trend of decreasing values over time remained.

Example 7: Oral Administration of Paclitaxel and Cyclosporin A to Mice Every 24 Hours for 4 Constant Doses Paclitaxel/Cvclosporin A Formulation

Formulations for oral administration were prepared by suspending the paclitaxel nanoparticles in a dispersant (PBS containing 0.5% (w/v) sodium lauryl sulfate, 0.5% (w/v) polyvinylpyrrolidone, and 0.176% (w/v) cyclosporin A), at a concentration of 5.6 mg/ml, and bath sonicating for 4 minutes.

The paclitaxel/cyclosporin A formulation was administered via oral gavage to each of four cohorts of 35 mice at a paclitaxel dosing level of 48 mg/kg and a cyclosporine A dose of 15 mg/kg. Cohorts 1, 2, 3, and 4 were dosed at 0 hours; cohorts 2, 3, and 4 were dosed again at 24 hours; cohorts 3 and 4 were dosed again at 48 hours; and cohort 4 was dosed again at 72 hours.

Plasma paclitaxel concentrations are plotted at respective time points, and shown in Figure 7 A. Figure 7B is a graph of AUC and Cmax values for each dose. As seen in Figures 7 A and 7B the AUC and Cmax of the sole dose administered to Cohort 1, which received only a single dose at 0 hours, are approximately 24800 ng^»h/ml and 6900 ng/ml, respectively. The AUC and Cmax of the second dose administered to Cohort 2, which received equal doses at 0 and 24 hours, are approximately 9100 ng^»h/ml and 4400 ng/ml, respectively. The AUC and Cmax of the third dose administered to Cohort 3, which received equal doses at 0, 24, and 48 hours, are approximately 5700 ng^»h/ml and 3200 ng/ml, respectively. The AUC and Cmax of the fourth dose administered to Cohort 4, which received equal doses at 0, 24, 48, and 72 hours, are approximately 2700 ng*h/ml and 1300 ng/ml, respectively. As graphically depicted in Figures 7A and 7B, the paclitaxel AUC and Cmax values were increased following most administrations when compared to administration of the paclitaxel formulation alone as described in Example 3. The effect appears to be greater than that of ketoconazole, although the trend of decreasing values over time remained. Example 8: Oral Administration of Paclitaxel to Mice Every 24 Hours for 4 Escalating Doses

The paclitaxel formulation was administered via oral gavage to each of four cohorts of 35 mice. Cohorts 1, 2, 3 and 4 were dosed at 0 hours at 12 mg/kg; cohorts 2, 3, and 4 were dosed again at 24 hours though at an increase dose of 24 mg/kg; cohorts 3 and 4 were dosed again at 48 hours, at an increased dose of 48 mg/kg; and cohort 4 was dosed again at 72 hours at an increased dose of 96 mg/kg.

Plasma paclitaxel concentrations are plotted at respective time points, and shown in Figure 8 A. Figure 8B is a graph of AUC and Cmax values for each dose. As seen in Figures 8 A and 8B, the AUC and Cmax of the dose administered to Cohort 1, which received only a single dose of 12 mg/kg at 0 hours, are approximately 1200 ng»h/ml and 400 ng/ml, respectively. The AUC and Cmax of the second dose administered to Cohort 2, which received a 12 mg/kg dose at 0 hours and an 24 mg/kg dose at 24 hours, are approximately 2350 ng^#h/ml and 1250 ng/ml, respectively. The AUC and Cmax of the third dose administered to Cohort 3, which received a 12 mg/kg dose at 0 hours, a 24 mg/kg dose at 24 hours, and a 48 mg/kg dose at 48 hours, are approximately 13000 ng^#h/ml and 5200 ng/ml, respectively. The AUC and Cmax of the fourth dose administered to Cohort 4, which received a 12 mg/kg doses at 0 hours, a 24 mg/kg dose at 24 hours, a 48 mg/kg dose at 48 hours, and a 96 mg/kg dose at 72 hours, are approximately 12200 ng*h/ml and 5850 ng/ml, respectively. As graphically depicted in Figures 8A and 8B, increasing dosages generally resulted in increased plasma paclitaxel concentrations.

Example 9: Oral Administration of Paclitaxel to Mice Every 24 Hours for 4 Escalating Doses

The paclitaxel formulation was administered via oral gavage to each of four cohorts of 35 mice. Cohorts 1, 2, 3, and 4 were dosed at 0 hours at 24 mg/kg; cohorts 2, 3, and 4 were dosed again at 24 hours at an increased dose of 36 mg/kg; cohorts 3 and 4were dosed again at 48 hours at an increased dose of 48 mg/kg; and cohort 4 was dosed again at 72 hours at an increased dose of 60 mg/kg. Plasma paclitaxel concentrations are plotted at respective time points, and shown in Figure 9 A. Figure 9B is a graph of AUC and Cmax values for each dose. As seen in Figures 9 A and 9B the AUC and Cmax of the sole dose administered to Cohort 1, which received only a single dose of 24 mg/kg at 0 hours, are approximately 2100 ng^»h/ml and 780 ng/ml, respectively. The AUC and Cmax of the second dose administered to Cohort 2, which received a 24 mg/kg dose at 0 hours and an 36 mg/kg dose at 24 hours, are approximately 1600 ng»h/ml and 800 ng/ml, respectively. The AUC and Cmax of the third dose administered to Cohort 3, which received a 24 mg/kg dose at 0 hours, a 36 mg/kg dose at 24 hours, and a 48 mg/kg dose at 48 hours, are approximately 3300 ng^«h/ml and 2000 ng/ml, respectively. The AUC and Cmax of the fourth dose administered to Cohort 4, which received a 24 mg/kg doses at 0 hours, a 36 mg/kg dose at 24 hours, a 48 mg/kg dose at 48 hours, and a 60 mg/kg dose at 72 hours, are approximately 4300 ng^»h/ml and 1980 ng/ml, respectively. As graphically depicted, increasing dosages generally resulted in increased plasma paclitaxel concentrations.

Example 10: Oral Administration of Paclitaxel to Mice Every 24 Hours for 4 Escalating Doses with Simultaneous Oral Administration of Cyclosporin A at Doses 3 and 4

The paclitaxel formulation was administered via oral gavage to each of four cohorts of 35 mice. Cohorts 1, 2, 3, and 4 were dosed at 0 hours at 12 mg/kg; cohorts 2, 3, and 4 were dosed again at 24 hours at an increased dose of 24 mg/kg; cohorts 3 and 4 were dosed again at 48 hours at 24 mg/kg and also with cyclosporin A at 15 mg/kg; and cohort 4 was dosed again at 72 hours at an increased dose of 48 mg/kg and also with cyclosporin A at 15 mg/kg. For doses 3 and 4 only, Cyclosporin A was added to the dispersant used to produce the formulation at a concentration such that cyclosporin A was administered at 15 mg/kg. Plasma paclitaxel concentrations are plotted at respective time points, and shown in Figure 1OA. Figure 1OB is a graph of AUC and Cmax values for each dose. As seen in Figures 1OA and 1OB the AUC and Cmax of the sole dose administered to Cohort 1, which received only a single dose of 12 mg/kg at 0 hours, are approximately 1200 ng^»h/ml and 500 ng/ml, respectively. The AUC and Cmax of the second dose administered to Cohort 2, which received a 12 mg/kg dose at 0 hours and an 24 mg/kg dose at 24 hours, are approximately 2200 ng'h/ml and 1450 ng/ml, respectively. The AUC and Cmax of the third dose administered to Cohort 3, which received a 12 mg/kg dose at 0 hours, a 24 mg/kg dose at 24 hours, and a 24 mg/kg dose at 48 hours along with a 15 mg/kg dose a cyclosporin A, are approximately 7550 ng«h/ml and 3000 ng/ml, respectively. The AUC and Cmax of the fourth dose administered to Cohort 4, which received a 12 mg/kg doses at 0 hours, a 24 mg/kg dose at 24 hours, a 24 mg/kg dose at 48 hours along with a 15 mg/kg dose of cyclosporin A, and a 48 mg/kg dose at 72 hours along with a 15 mg/kg dose of cyclosporin A, are approximately 8100 ng*h/ml and 2300 ng/ml, respectively. As graphically depicted, increasing dosages generally resulted in increased plasma paclitaxel concentrations and cyclosporin A appeared to increase the paclitaxel AUC and Cmax values following its administration.

Example 11: Oral Administration of Paclitaxel to Mice Every 48 Hours for 4 Escalating Doses

The paclitaxel formulation was administered via oral gavage to each of four cohorts of 35 mice. Cohorts 1, 2, 3, and 4 were dosed at 0 hours at 12 mg/kg; cohorts 2, 3, and 4 were dosed at 48 hours at an increased dose of 24 mg/kg; cohorts 3 and 4 were dosed at 96 hours at an increased dose of 48 mg/kg; and cohort 4 was dosed at 144 hours at an increased dose of 96 mg/kg.

Plasma paclitaxel concentrations are plotted at respective time points, and shown in Figurel IA. Figurel IB is a graph of AUC and Cmax values for each dose. As seen in Figures 1 IA and 1 IB the AUC and Cmax of the sole dose administered to Cohort 1, which received only a single dose of 12 mg/kg at 0 hours, are approximately 1300 ng*h/ml and 400 ng/ml, respectively. The AUC and Cmax of the second dose administered to Cohort 2, which received a 12 mg/kg dose at 0 hours and an 24 mg/kg dose at 48 hours, are approximately 1300 ng^#h/ml and 750 ng/ml, respectively. The AUC and Cmax of the third dose administered to Cohort 3, which received a 12 mg/kg dose at 0 hours, a 24 mg/kg dose at 48 hours, and a 48 mg/kg dose at 96 hours, are approximately 9000 ng^»h/ml and 4100 ng/ml, respectively. The AUC and Cmax of the fourth dose administered to Cohort 4, which received a 12 mg/kg doses at 0 hours, a 24 mg/kg dose at 48 hours, a 48 mg/kg dose at 96 hours, and a 96 mg/kg dose at 144 hours, are approximately 20000 ng^»h/ml and 6800 ng/ml, respectively. As graphically depicted, increasing dosages generally resulted in increased plasma paclitaxel concentrations.

Example 12: Oral Administration of Paclitaxel Formulation containing HPMC, PVA, Eudragit L100-55, SLS, and PVP in Dispersant to Mice Every 48 Hours for 4 Doses Paclitaxel Formulation

The paclitaxel nanoparticles were made as described in Examples 1- 11. The dispersant for the in vivo studies contained polyethylene glycol (PEG, 0.5% w/v), hydroxypropylmethylcellulose (HPMC, 0.5% w/v), polyvinyl alcohol (PVA, 2.5% w/v), methacrylic acid copolymer (EUDRAGIT^® L1OO-55, 2.5% w/v), sodium lauryl sulfate (SLS, 0.5% w/v), and polyvinylpyrrolidone (PVP, 0.5% w/v) in phosphate-buffered saline (PBS).

The oral formulation (herein referred to as DOE "T") was prepared for administration as follows: 16.9 mg of the paclitaxel nanoparticles were weighed into each of several 7 ml glass scintillation vials. To each vial was added 3.0 ml of the dispersant, producing a 0.56% (w/v) suspension. Each vial was then bath- sonicated for 4 minutes, resulting in a fine particle dispersion.

Dosing This formulation was administered to four cohorts of mice during three studies. Each cohort received a single dose of 48 mg/kg and blood samples were obtained for 8 hours immediately following the dosing. After each dosing, blood samples were obtained from one cohort at time points of 0.33, 0.67, 1, 2, 4, 6, and 8 hours (5 mice per timepoint). AU blood samples were drawn into heparinized tubes and centrifuged. The plasma was removed and analyzed for paclitaxel content by LC-MS-MS.

The plasma paclitaxel concentrations (four cohorts averaged) are plotted at respective time points, and shown in Figure 12 A, along with data from administrations of two other types of oral paclitaxel formulations, including paclitaxel in a 0.5% w/v SLS/0.5% w/v PVP/PBS dispersant ("P3"), and "P3" administered simultaneously with 15 mg/kg oral cyclosporin A. Figure 12B provides the calculated AUC values for each administration. Data for each of these formulations was obtained in a similar manner (same paclitaxel dosing amount, same time points, same number of mice). The "P3" formulation was prepared in the same way as the DOE-T, except that the "P3" dispersant was used instead. The same applies to the Cyclosporin A study, except that 15 mg Cyclosporin A was added to the vial just prior to sanitation. These results indicate that paclitaxel, when formulated in this manner and administered orally, is absorbed well and can result in an AUC greater than that of an equal paclitaxel dose orally administered along with cyclosporin A.

Example 13: Oral Administration of Paclitaxel Formulation Containing HPMC, PVA, Eudragit Ll 00-55, SLS, and PVP in Dispersant to Mice at Different Dosing Intervals Within a 12 hr Period

Paclitaxel Formulation

The paclitaxel nanoparticles were made as described in Examples 1- 11. The dispersant for the in vivo studies contained polyethylene glycol (PEG, 0.5% w/v), hydroxypropylmethylcellulose (HPMC, 0.5% w/v), polyvinyl alcohol (PVA, 2.5% w/v), methacrylic acid copolymer (EUDRAGIT^® L100-55, 2.5% w/v), sodium lauryl sulfate (SLS, 0.5% w/v), and polyvinylpyrrolidone (PVP, 0.5% w/v) in phosphate-buffered saline (PBS).

The oral formulation (herein referred to as DOE "T") was prepared for administration as follows: 101.4 mg of the paclitaxel nanoparticles were weighed into each of 24, 25ml glass lyophilization vials. To each vial was added 18.0 ml of the dispersant, producing a 0.56% (w/v) suspension. Each vial was then bath-sonicated for 4 minutes, resulting in a fine particle dispersion. The dispersion was frozen and lyophilized for 72.5 hrs in a Virtis Advantage shelf lyophilizer.

Just prior to use, 18 ml of deionized water was added to each vial and the solids were reconstituted by repeated inversion for 1 min. Dosing

This formulation was freshly reconstituted and administered by gavage to cohorts of fasted mice during six studies. The following dosing regimens were evaluated: 32 mg/kg, every 3 hr x 1; 32 mg/kg, every 3 hr x 2; 32 mg/kg, every 3 hr x 3; 48 mg/kg, every 3 hr x 1 ; 48 mg/kg, every 3 hr x 2; 96 mg/kg, x 1. Total dose in a 12 hr period did not exceed 96 mg/kg. After each dosing, blood samples were obtained from one cohort at time points of 0.33, 0.67, 1, 2, 4, 6, and 8 hours (5 mice per timepoint). AU blood samples were drawn into heparinized tubes and centrifuged. The plasma was removed and analyzed for paclitaxel content by LC-MS-MS .

Results are shown in Figures 13 A, 13B, 14A, and 14B. The results indicate that it is possible to repeatedly dose paclitaxel nanoparticles within a 12 hr period and not observe a significant reduction in either AUC (bioavailability) or Cmax at dose levels of 32 and 48 mg/kg. Composite AUCs were greater from the 48 mg/kg x2 dose level than from the 32 mg/kg x 3 dose level, even though the total dose over 12 hrs was the same at 96 mg/kg, and nearly matched the single dose AUC of 96 mg/kg. This may be because the P-gp and CYP3A4 are not induced within a 12 hr time interval, facilitating dosing without concomitant reduction in AUC or Cmax.

Example 14: Oral Administration of Paclitaxel Formulation Containing HPMC, PVA, Eudragit L100-55, SLS, and PVP in Dispersant to Mice at Different Dosing Intervals Within a 12 hr Period

The experiments described in Example 13 were repeated and the results are depicted in Figures 15 A, 15B, 16A, and 16B. As in Example 13, the results indicate that it is possible to repeatedly dose paclitaxel nanoparticles within a 12 hr period and not observe a significant reduction in either AUC (bioavailability) or Cmax at dose levels of 32 and 48 mg/kg. Composite AUCs were greater from the 48 mg/kg x2 dose level than from the 32 mg/kg x 3 dose level, even though the total dose over 12 hrs was the same at 96 mg/kg, and nearly matched the single dose AUC of 96 mg/kg. This may be because the P-gp and CYP3A4 are not induced within a 12 hr time interval, facilitating dosing without concomitant reduction in AUC or Cmax. Example 15: Comparative Performance of Bioadhesive Acyclovir Formulation (BioVir™) and Zovirax® Tablets in Repeat Dose Trial

Acyclovir is categorized as a Class III drug according to the Biopharmaceutical Classification System because of its moderate water solubility and low bioavailability (10-20%). The drug is soluble only at acidic pH (pKa 2.27), thereby limiting absorption in the GI tract to the duodenum and the jejunum. There is no effect of food on drug absorption. Peak plasma levels are reached 3 to 4 hours following an oral dose. Bioavailability decreases with increasing drug dose. Elimination from plasma has a terminal half-life of 2.5 to 3.3 hours. Zovirax® is normally dosed at either 200 mg every 4 hrs, or 400 mg every 12 hrs depending on the antiviral indication.

The Spherics trilayer tablet controlled release (CR) formulation (BioVir™) comprises 400 mg of acyclovir blended with glutamic acid, functioning as an acidulant, and Ethocel to formulate an inner-core blend with controlled-release properties. The outer bioadhesive coating comprises of Spheromer™ III, a nonerodable, catechol-grafted bioadhesive in combination with excipients. The inner core blend is sandwiched between outer bioadhesive layer blends and direct compressed to create a bioadhesive, trilayer tablet.

The BioVir™ formulation is designed to reside in the stomach for greater than 6 hrs in the fed state and release acyclovir downstream, in a controlled manner, to duodenum and upper jejunum, the main absorptive sites. Cohorts of six, female beagle dogs (10-12 kg) were dosed with either

Zovirax® or BioVir™ CR, 30 min after a standard meal. 200 mg capsules of Zovirax® were dosed four times, every 6 hrs and compared to BioVir™ CR, containing 400 mg of acyclovir, dosed twice, every 12 hrs. The total drug dose level in both cases was 800 mg given over 24 hrs. 1 ml blood samples were collected at appropriate intervals extending to 48 hours. Plasma was collected after centrifugation for 10 min at 3,000 rpm at 4⁰C. Samples were stored frozen at -2O⁰C until analyzed.

Serum acyclovir was determined by LC/MS/MS. Turbulent flow chromatography using a 2300 HTLCTM system (Cohesive Technologies, Franklin, MA) was coupled to tandem-mass spectrometry (MS/MS) performed on a triple stage quadropole from Perkin Elmer SCIEX API 365 (Sciex, Concord, Ontario, Canada) with an atmospheric pressure ionization (API) chamber. The limit of detection of acyclovir in dog plasma was 10 ng/ml.

For each dog the following pharmacokinetic parameters were calculated for the parent drug, acyclovir: maximum observed concentration (Cmax), time at which Cmax was observed (tmax), and area under the plasma concentration versus time curve (AUC) carried out to 48 hrs (AUCO- t).

The effect of repeat dosing on plasma drug levels is shown in Figure 18. The AUCs of the immediate release Zovirax® capsules and CR tablet formulations were nearly identical (167 ug/ml*hr for Zovirax® compared to 164 ug/ml*hr for BioVir™ CR, n=6 dogs/study). As described above, a bioadhesive, gastroretentive dosage form was able to reduce dosing requirements from four doses per day to two doses per day.

INCORPORATION BY REFERENCE AU publications and patents mentioned herein are hereby incorporated by reference in their entirety as if each individual publication or patent was specifically and individually indicated to be incorporated by reference. In case of conflict, the present application, including any definitions herein, will control.

EQUIVALENTS

While specific embodiments of the subject invention have been discussed, the above specification is illustrative and not restrictive. Many variations of the invention will become apparent to those skilled in the art upon review of this specification and the claims below. The full scope of the invention should be determined by reference to the claims, along with their full scope of equivalents, and the specification, along with such variations.

Claims

We claim:

1. A method of delivering a poorly absorbed drug to a patient, comprising: a) administering a first oral dose of the drug at a first time; and b) administering a second oral dose of the drug at a second time after a recovery period, wherein the recovery period is a period of time between doses resulting in an area-under-the curve (AUC) value for the second dose that is greater than or equal to 30% of the AUC value for the first dose.

2. The method of claim 1 , wherein the recovery period is a period of time between doses resulting in an area-under-the curve (AUC) value for the second dose that is greater than or equal to 50% of the AUC value for the first dose.

3. A method of delivering a poorly absorbed drug to a patient, comprising: a) administering a first oral dose of the drug at a first time; and b) administering a second oral dose of the drug at a second time after a recovery period, wherein the recovery period is a period of time between doses resulting in a Cmax value that is greater than or equal to 30% of the Cmax value for the first dose.

4. The method of claim 3, wherein the recovery period is a period of time between doses resulting in a Cmax value that is greater than or equal to 50% of the Cmax value for the first dose.

5. The method of claim 1 or claim 3, wherein the recovery period is between at least one day and at least seven days.

6. The method of claim 1 or claim 3, wherein the drug is paclitaxel or an analogue or derivative thereof that is a substrate for P-glycoprotein (PGP).

7. The method of claim 1 or claim 3, wherein the second dose is administered at least 3 days after the first dose.

8. The method of claim 1 or claim 3, wherein the second dose is administered at least 4 days after the first dose.

9. The method of claim any of claims 1 to 8, wherein the second dose is followed by at least one subsequent dose administered about the same recovery period after the previous dose.

10. The method of claim 6, further comprising administering at least one inhibitor of a drug efflux pump to the patient.

11. The method of claim 10, wherein the inhibitor is a cyclosporin.

12. The method of claim 6, further comprising administering one or more inhibitors of cytochrome P450 to the patient.

13. The method of claim 12, wherein the inhibitor is ketoconazole.

14. The method of claim 6, wherein the second dose of paclitaxel is greater than the first dose of paclitaxel.

15. A kit comprising two or more doses of an oral formulation, wherein the formulation comprises a poorly absorbed drug, and a label specifying the time to allow between administration of the doses, wherein administration of the doses separated by the specified time results in an area-under-the curve (AUC) value for a second dose that is greater than or equal to 30% of the AUC value for the first dose.

16. A kit comprising two or more doses of an oral formulation, wherein the formulation comprises a poorly absorbed drug, and a label specifying the time to allow between administration of the doses, wherein administration of the doses separated by the specified time results in a Cmax value for a second dose that is greater than or equal to 30% of the Cmax value for the first dose.

17. The kit of claim 15 or claim 16, wherein the oral formulation further comprises one or more absorption enhancers.

18. A paclitaxel formulation, comprising paclitaxel in the form of nanoparticles or microparticles and a dispersant.

19. The paclitaxel formulation of claim 18, wherein the paclitaxel formulation is formulated for oral delivery.

20. The paclitaxel formulation of claim 19, wherein the formulation has an oral bioavailability of 5% to 50%.

21. The paclitaxel formulation of claim 18, wherein the dry particles have a size in the range of 0.05 to 2 microns.

22. The formulation of claim 18, wherein the formulation consists essentially of paclitaxel in the form of nanoparticles or microparticles and a dispersant.

23. The formulation of claim 18, wherein the formulation comprises greater than 90% paclitaxel in the form of nanoparticles or microparticles and a dispersant.

24. The paclitaxel formulation of claim 18, wherein the dispersant comprises at least one excipient selected from methacrylic acid copolymers and polyvinylpyrrolidone.

25. The paclitaxel formulation of claim 24, wherein the dispersant comprises one or more of polyethylene glycol, hydroxypropyhnethylcellulose, polyvinyl alcohol, a methacrylic acid copolymer, sodium lauryl sulfate, polyvinylpyrrolidone, cyclodextrin, hydroxypropylcellulose, hydroxyethylcellulose, and Pluronic.

26. The formulation of claim 25, wherein the dispersant comprises polyethylene glycol (PEG, 0.5% w/v), hydroxypropylmethylcellulose (HPMC, 0.5% w/v), polyvinyl alcohol (PVA, 2.5% w/v), methacrylic acid copolymer (EUDRAGIT^® L100-55, 2.5% w/v), sodium lauryl sulfate (SLS, 0.5% w/v), and polyvinylpyrrolidone (PVP, 0.5% w/v).

27. A formulation comprising nanoparticles or microparticles of a poorly absorbed drug in combination with an absorption enhancer.

28. The formulation of claim 27, wherein the formulation consists essentially of nanoparticles or microparticles of a poorly absorbed drug in combination with an absorption enhancer.

29. The formulation of claim 27, wherein the drug is selected from Neomycin B, Captopril, Atenolol, Caspofungin, Clorothiazide, Tobramycin, Cyclosporin, Tacrolimus, and Paclitaxel.

30. The formulation of claim 27, wherein the dry particles have a size in the range of 0.05 to 2 microns.

31. The formulation of claim 27, wherein the absorption enhancer is selected from sodium caprate, ethylenediamine tetra-(acetic acid) (EDTA), citric acid, lauroylcarnitine, palmitoylcarnitine, tartaric acid and other agents that increase GI permeability.

32. The formulation of claim 27, wherein the formulation is a solid oral dosage form selected from tablets, capsules, minitabs, spheroidal particles, granules, and powder.

33. The formulation of claim 32, wherein the formulation further comprises a bioadhesive polymer.

34. The formulation of claim 32, wherein the formulation readily disperses upon gentle mixing in a liquid vehicle suitable for administration of the drug.

35. The method of claim 1 or claim 3, wherein the drug is in an amorphous form.

36. The formulation of claim 18, wherein the particles comprise an amorphous form of paclitaxel.

37. The formulation of claim 27, wherein the particles comprise an amorphous form of the drug.

38. A method of delivering a poorly absorbed drug to a patient, comprising: a) administering a first oral dose of the drug at a first time; and b) administering a second oral dose of the drug at a second time, wherein the second dose is greater than the first dose and results in an area- under-the curve (AUC) value for the second dose that is greater than or equal to the AUC value for the first dose.

39. The method of claim 38, wherein the second dose results in an area- under-the curve (AUC) value for the second dose that is greater than or equal to 75% of the AUC value for the first dose.

40. The method of claim 38, wherein the second dose is administered after a recovery period, wherein the recovery period is a period of time between doses resulting in an area-under-the curve (AUC) value for the second dose that is greater than or equal to the AUC value for the first dose.

41. A method of delivering a poorly absorbed drug to a patient, comprising: a) administering a first oral dose of the drug at a first time; and b) administering a second oral dose of the drug at a second time, wherein the second dose is greater than the first dose and results in Cmax value for the second dose that is greater than or equal to the Cmax value for the first dose.

42. The method of claim 41, wherein the second dose results in a Cmax value for the second dose that is greater than or equal to 75% of the Cmax value for the first dose.

43. The method of claim 41 , wherein the second dose is administered after a recovery period, wherein the recovery period is a period of time between doses resulting in a Cmax value for the second dose that is greater than or equal to the Cmax value for the first dose.

44. The method of claim 38 or claim 41, wherein the recovery period is between at least one day and at least seven days.

45. The method of claim 38 or claim 41, wherein the second dose is administered at least 3 days after the first dose.

46. The method of claim 38 or claim 41, wherein the second dose is administered at least 4 days after the first dose.

47. The method of claim any of claims 38 to 43, wherein the second dose is followed by at least one subsequent dose that is greater than the dose immediately preceding.

48. The method of claim 47, wherein each subsequent dose is greater than the dose immediately preceding and results in a Cmax value for the subsequent dose that is greater than or equal to the Cmax value for the immediately preceding dose.

49. The method of claim 47, wherein each subsequent dose is greater than the dose immediately preceding and results in an area-under-the curve (AUC) value for the subsequent dose that is greater than or equal to the AUC value for the immediately preceding dose.

50. The formulation of claim 33, wherein the bioadhesive polymer is disposed around a core.

51. The formulation of claim 50, wherein the bioadhesive polymer coats the individual drug particles.