WO1998006444A1

WO1998006444A1 - Collagen-based blood coagulating foams, method and devices for their delivery

Info

Publication number: WO1998006444A1
Application number: PCT/US1997/014263
Authority: WO
Inventors: Eugene Bell; Tracy M. Sioussat
Original assignee: Tissue Engineering, Inc.
Priority date: 1996-08-13
Filing date: 1997-08-13
Publication date: 1998-02-19
Also published as: AU4065297A

Abstract

The invention pertains to collagen-based blood coagulating compositions, devices for administering the compositions to a subject, and methods for coagulating blood in a subject using the compositions and devices described herein. Preferred collagen-based compositions which can be used in the invention include compositions which include fetal and adult collagen and a pharmaceutically acceptable carrier, compositions which include collagen type I, collagen type II, and collagen type III and a pharmaceutically acceptable carrier, and compositions which include fetal collagen and a pharmaceutically acceptable carrier. These compositions can be administered to a site of unwanted bleeding, e.g., a wound site, in the form of a blood coagulating foam dispensed from the devices of the invention.

Description

COLLAGEN-BASED BLOOD COAGULATING FOAMS, METHOD AND DEVICES FOR THEIR DELIVERY

Background of the Invention

Internal or external traumatic injuries, whether incurred in military action or in civilian life, often result in uncontrolled hemorrhaging which in turn can lead to hypovolemia and ultimately death. For example, hypovolemia, secondary to hemorrhage, is the main cause of death among soldiers who are not killed outright by injuries. In addition, internal bleeding due to, for example, traumatic injuries or internal bleeding occurring postoperatively, can also lead to extensive and dangerous blood loss. A variety of materials are now used to counteract hemorrhaging. These materials include simple cotton gauze dressings used principally for external bleeding. Such dressings have the disadvantage of being passive dressings which are unable to initiate or accelerate blood clotting. Another material, available for use in Europe but not in the United States, is fibrin glue, which forms upon the combination of fibrinogen and thrombin solutions. However, as a hemostatic agent, fibrin glue has the major drawback of carrying with its use a risk of transmitting serological disease from donated human blood, the source of the proteins. In addition, the requirement that the two components, fibrinogen and thrombin, be combined at the moment of use can be time-consuming. Thrombin alone, as a powder or in solution, produced by Parke-Davis under the tradename Thrombostat® is another hemostatic product. The thrombin solution, which includes calcium chloride, sodium chloride and glycine, must be constituted at the moment of its use. This requirement is inconvenient and time-consuming. In addition, Thrombostat® has not been approved by the United States Food and Drug Administration for use in humans. Recently, other hemostatic agents, such as collagen-based hemostatic agents have been developed. Collagen is the protein to which platelets normally attach when they escape from the vascular system. The vessels comprising the vascular system are surrounded by networks of collagen fibrils which are also present throughout the tissues of the body. Ohtani (1988) Arch. Histol. Cytol. 51 :473-488. Escaping platelets attach to collagen in the extracellular matrix of tissues around an injury. Upon contact with the collagen, the normally disc-shaped platelets become spherical, extend filopodia, and release ADP, calcium, 5-hydroxytryptamine, serotonin, prostaglandins, thromboxane A2 and initiate the blood clotting cascade of the intrinsic pathway through activation of factor XII. The foregoing chemicals released by attached platelets initiate binding of other platelets to those already adhering to the collagen. The result is platelet aggregation and triggering of platelet activation leading to formation of a tightly fused mass incorporating fibrin (Hatsuoka, M. et al. (1986) Thromb. Res. 42:407-412) thought to be crosslinked to collagen by factor Xlla.

There are a number of fibrillar collagen products now on the market primarily in the form of powders or webs which are used for the control of surgical bleeding under hospital operating room conditions. One example of such a product is Avitene

(available from MedChem) which is microfibrillar collagen in the form of a powder derived from animal, mainly bovine, sources.

Two recently issued United States patents disclose the use of collagen, in a paniculate form, for use in wound treatment. See e.g., U.S. Patent Nos. 5,196,185 and 5,356,614. In U.S. Patent Nos. 5,196,185 and 5,356,614, a collagen preparation which includes microparticulate collagen within a selected particle size range is disclosed for use in wound treatment. The particulate collagen, which is produced by milling in an appropriate Ball Mill, can then be delivered to the wound site in the form of an aerosol.

Summary of the Invention

The present invention pertains to collagen-based blood coagulating compositions and foams, devices for administering or delivering these compositions and foams to a subject, and methods for coagulating blood in a subject using the compositions, foams, and devices described herein. Accordingly, in one embodiment, the collagen-based composition is suitable for packaging in a pressurized aerosol container and for dispensing as a blood coagulating foam and includes fetal and adult collagen and a pharmaceutically acceptable carrier. The fetal and adult collagen can be obtained from animals, e.g., mammals, such as pigs, and marine animals, e.g., marine mammals. A preferred source of collagen is a pig. In one embodiment, the fetal collagen is obtained from a near term pig fetus. In a preferred embodiment, the composition is in the form of a blood coagulating foam which includes a gas, e.g., an aerosol propellant gas, e.g., a hydrofluorocarbon gas. Examples of hydrofluorocarbon gases which can be used in the invention include those in which collagen is soluble. A preferred hydrofluorocarbon gas is 1,1,1,2-tetrafluoroethane (dymel-l,3,4A-P). The fetal and adult collagen can further include a neutralizing solution, e.g., a buffer with a pH greater than 5.0. The fetal collagen can include one type of collagen or can include a mixture of two or more of the types of collagen, e.g., collagen types I, II, III, IV, or V. Similarly, the adult collagen can include one type of collagen or can include a mixture of two or more of the known types of collagen. In a preferred embodiment, the fetal collagen includes collagen type I, collagen type III, and collagen type IV. In a preferred embodiment, the adult collagen includes collagen type I and collagen type III. Typically, the collagen is at a concentration in the composition of about 1 mg/ml to about 10 mg/ml. In a preferred embodiment, the collagen in the composition is at a concentration of about 5 mg/ml. In another embodiment, the collagen is fibrillar collagen. Preferred pharmaceutically acceptable carriers include aqueous solutions.

In another embodiment, the collagen-based composition is suitable for packaging in a pressurized aerosol container and for dispensing as a blood coagulating foam and includes collagen type I, collagen type III, and collagen type IV and a pharmaceutically acceptable carrier. As described herein, the collagen can also include a neutralizing solution, e.g., a buffer with a pH greater than 5.0, and is preferably obtained from a mammal such as a pig or a marine mammal. A preferred source of collagen is a pig, e.g., fetal pig. In a preferred embodiment, the composition is in the form of a blood coagulating foam which includes a gas, e.g., an aerosol propellant gas, e.g., a hydrofluorocarbon gas. Examples of hydrofluorocarbon gases are described herein. In yet another embodiment, the collagen-based composition is suitable for packaging in a pressurized aerosol container and for dispensing as a blood coagulating foam and includes fetal collagen and a pharmaceutically acceptable carrier. The fetal collagen can be obtained from a animal, e.g., a mammal, e.g., pig, or marine animal, e.g., marine mammal. Fetal porcine collagen is preferred. The fetal collagen can further include a neutralizing solution, e.g., a buffer with a pH greater than 5.0. As described herein, the composition can be in the form of a blood coagulating foam which includes a gas described herein. The compositions described herein can also be contained within containers, e.g., within containers which include means for dispensing the compositions from the containers in the form of a blood coagulating foam. The invention also pertains to devices for delivering a blood coagulating foam to a subject, e.g., to a site of bleeding on or in a subject. The devices include a container, e.g., a canister, e.g., a glass canister with means for dispensing the compositions from the containers in the form of blood coagulating foams, e.g., a glass canister with appropriate valves and actuators, which has at least one aperture through which contents of the container are dispensed and which holds a composition comprising a collagen- based solution described herein and a compound, e.g., a gas, in which the collagen-based composition is soluble and which exerts a level of pressure sufficient to propel the composition from the container in the form of a blood coagulating foam. Preferred compounds which can exert a level of pressure sufficient to propel the composition from the container in the preferred form include gases which are typically used as aerosol propellants, e.g., hydrofluorocarbon gases. An example of a hydrofluorocarbon gas which can be used in the invention is 1 , 1 , 1 ,2-tetrafluoroethane. The composition in the device is typically maintained at a pH of about 4.0 to about 6.0, preferably at a pH of about 5.0 to about 6.0, to prevent gelling of the collagen in the container. The devices of the invention can further include an extendible arm having an axial bore therethrough, e.g., extendible hollow arm, e.g., an extendible tube, through which the composition can be delivered to a selected location and which is coaxial with at least one aperture of the container. This arm enables delivery of the composition to areas which are difficult to reach, e.g., body cavities, to coagulate blood, e.g., to reduce or prevent hemorrhaging, e.g., internal hemorrhaging. The devices of the invention can also include a separate compartment in which a neutralizing solution is stored. The neutralizing solution can be released from the same nozzle as the collagen-based solution to accelerate gelling of the collagen-based solution as it exits the device.

The invention further pertains to methods for coagulating blood at a site of bleeding in a subject. These methods include administering to the subject the compositions or foams described herein. The compositions or foams can be dispensed from the devices of the invention.

Brief Description of the Drawings

Other objects, features and advantages of the invention will be described in, or be apparent from, the following descriptions of preferred embodiments of the invention, including the drawings thereof, in which

Fig. 1 is a schematic representation of a first container embodying one form of the invention; and

Fig. 2 is a schematic representation of a second container embodying another form of the invention.

Detailed Description of the Invention

The invention pertains to compositions and foams which are capable of coagulating blood in a subject. These compositions can be inserted into the devices of the invention for administration to a subject. In one embodiment, the composition of the invention is a composition which is suitable for packaging in a pressurized aerosol container and for dispensing as a blood coagulating foam and which comprises fetal and adult collagen and a pharmaceutically acceptable carrier. The term "coagulate" as used herein has its art recognized meaning and refers to a solidification or change from a fluid state to a semisolid mass. When referring to blood, the term "coagulate" means the formation of blood clot. The formation of blood clots upon administration of the compositions and foams of the invention to a site of bleeding results in a decrease in bleeding at the site of application or administration of the composition as compared to the bleeding at the site in the absence of application or administration of the composition. These compositions can be used, therefore, to prevent and/or reduce bleeding at selected locations in and on a subject.

The phrase "fetal collagen" as used herein refers to collagen obtained from an animal, e.g., a mammal, during gestation of the animal. Preferably the fetal collagen is obtained from a mammal. Examples of mammals from which the fetal collagen can be obtained include pigs and marine animals, e.g., marine mammals. The collagen can be isolated according to the methods set forth in WO 96/15818, published on May 30, 1996, the contents of which are incorporated herein by reference. In a preferred embodiment, the fetal collagen is obtained from a pig. Preferred gestational ages of a pig for harvesting collagen include gestational days near term, e.g., near birth, e.g., about day 100 to about day 1 14 or 115. In a preferred embodiment, the fetal collagen includes a mixture of collagen type I, collagen type III, and collagen type IV. The phrase "adult collagen" as used herein refers to collagen obtained from an animal, e.g., a mammal, after birth. In a preferred embodiment, the adult collagen includes a mixture of collagen type I and collagen type III. Typically, the collagen is at a concentration in the composition of about 1 mg/ml to about 10 mg/ml. In a preferred embodiment, the collagen in the composition is at a concentration of about 5 mg/ml.

The collagen used in the compositions and foams of the invention can be in the form of collagen microfibrils. The language "collagen microfibril" as used herein refers to collagen in the form described in Williams, B.R. et al. (1978) J. Biol. Chem. 253 (18):6578-6585, the contents of which are incoporated herein by reference. In a preferred embodiment, the collagen microfibrils are prepared as a semisolid (viscous) pellet of collagen microfibrils resulting from centrifugation of a neutralized solution of collagen. For example, the collagen can be neutralized by liquid 0.01-1.0 N NaOH, 0.1- 10% ammonium hydroxide, or other known neutralizing solutions, before spinning in a centrifuge to yield a microfibrillar collagen pellet mass. The liquid content of the microfibrillar collagen pellet mass can be manipulated by the relative centrifugal force employed. For example, the stronger the centrifugal force, the less liquid and the higher the resulting concentration of microfibrillar collagen (e.g., from about 10 to about 100 mg/ml). The resultant semisolid pellet of neutralized microfibrillar collagen can be manipulated like a fluid such that it can be propelled from, for example, a device of the present invention, onto or into a site of bleeding. Since the microfibrillar collagen is already neutral, no gelling is required. However, the density of this form of collagen allows it to remain in place at the desired site of bleeding. The structure of the microfibrillar collagen provides the surface to initiate the clotting cascade at the site of bleeding.

Methods for purifying collagen in the microfibrillar form typically include the steps of extracting proteins from, for example, the skin of an animal, e.g., chicken, mammal, e.g., a marine mammal, a cow, goat, sheep, or, preferably, a pig, e.g., a fetal or newborn pig. This extraction step involves the use of organic acid such as formic or acetic acid. The collagen is then precipitated from the extract by salt (e.g., sodium chloride up to 3.0M or ammonium sulfate up to 50%) and collected by centrifugation. The collagen is then redissolved in organic acid and concentrated. The collagen can then be used or subjected to as many rounds, e.g., two rounds, of salt precipitation and centrifugation as desired before concentrating and using in the present invention. A preferred collagen concentration used to make microfibrillar collagen is 4.0 to 10.0 mg/ml. An alternative method for purifying collagen in the microfibrillar form includes a method in which pepsin is included in the extraction acid solution, with all other steps the same as described above, with the additional updated steps described below.

For further details on the methods for purifying collagen in the microfibrillar form, see U.S. Patent No. 5,562,946 (hereinafter the "'946 patent"), the corresponding PGT application of which was published on 17 May 1996 and assigned International Publication No. WO 96/14452, the contents of both of which are incoporated herein by reference. This purification method is described at columns 6-8 of the '946 patent has been updated as follows: at lines 57-61, of column 7, rather than dialysis bags for dialysis, hollow fiber membranes are used with a 0.1 μm cutoff (100,000 MW). Thus, the centrifugation step at lines 62-64 of column 7, occurs before the dialysis step and the concentration step described at 66-67 of column 7 and lines 1-4 of column 8 occurs at the same time as the dialysis in the same hollow fiber.

Neutralizing solutions used in the present invention include solutions which can raise the pH of the collagen-based compositions and foams of the invention such that the collagen in these compositions and foams gels at an accelerated pace compared to the collagen in compositions and foams in the absence of the neutralizing solutions. For example, while it is desirable to maintain the collagen of the compositions and foams in the form of a solution within the devices described herein, once the collagen compositions and foams are released from the devices, it is desirable to convert the collagen to a gel, which is the preferred blood-coagulating form of the collagen. Thus, the devices described herein can also include a compartment, preferably a compartment which is separate from the collagen-containing compartment, which includes the neutralizing solution. This neutralizing solution can then be released from the device through an independent aperture in the same nozzle as the collagen. The separate compartment and aperture ensure that the collagen remains at an acidic pH, e.g., pH 5.0, and retains fluidity in the device. The coincident spraying allows for mixing of the collagen and neutralizing solution before and upon contact with the site of bleeding, where gelling and clotting of the collagen, due to the presence of the neutralizing solution, is more rapid than gelling and clotting of the collagen in the absence of the neutralizing solution. Non-limiting examples of neutralizing solutions which can be used in the present invention include solutions with a pH which is greater than 5.0. For example, neutralizing solutions used in the present invention have a pH of between about 8.0 and 11.0 or greater. Examples of neutralizing solutions include buffers such as Good's buffers at the relevant pHs. Good's buffers at pH's between about 5.0 and 8.0 include MES, ADA, PIPES, ACES, BES, MOPS, TES, and HEPES. Good's buffers at pHs between 8.0 and 11.0 include EPPS, Tricine, Bicine, CHES and CAPS. See, e.g., page 125 of D. Freifelder "Physical Biochemistry Applications to Biochemistry and Molecular Biology", 2nd ed. (W.H. Freeman and Company, New York, NY, 1982). These Good's buffers as well as additional Good's buffers (e.g., TAPS) which can be used in the present invention are commercially available from Sigma Chemical Company, St. Louis, Missouri. Examples of other neutralizing solutions which can be used in the present invention include phosphate buffers such as dibasic sodium phosphate {see, e.g., page 123 of D. Freifelder "Physical Biochemistry Applications to Biochemistry and Molecular Biology", 2nd ed. (W.H. Freeman and Company, New York, NY, 1982)), and other buffers such as boric acid, CAPSO and CHES at concentrations ranging from about 0.01 to about 0.5 M at, for example, a pH of 9.5, sodium bicarbonate (e.g., 0.1 to l.OM), and glycine (0.01 to 0.5M at, for example, a pH of 9.5).

As used herein the phrase "pharmaceutically acceptable carrier" is intended to include any and all solutions, solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like, compatible with pharmaceutical administration. The use of such media and agents for pharmaceutically active substances is well known in the art. Preferred pharmaceutically acceptable carriers include sterile saline and aqueous buffer solutions. In a preferred embodiment, the pharmaceutically acceptable carriers include sterile aqueous solutions with very low conductivity, e.g., sterile aqueous solutions free of dissolved electrolytes such as salts and acids, e.g., Milli-Q™ water. The use of such carriers is well known in the art. In another embodiment, the composition which is suitable for packaging in a pressurized aerosol container and for dispensing as a blood coagulating foam includes collagen type I, collagen type III, and collagen type IV and a pharmaceutically acceptable carrier. Preferably, the collagen is obtained from an animal, e.g., a mammal. Examples of mammals from which the collagen can be obtained includes fetal or adult pigs, and marine mammals. In a preferred embodiment, the collagen is fetal collagen obtained from a pig. The different types of collagen can be mixed together in various ratios to obtain a composition which is capable of coagulating blood, e.g., decreasing clotting time, upon contact with a site at which unwanted bleeding is occurring. The composition can be in the form of a foam as described herein. Typically, the collagen is at a concentration in the composition of about 1 mg/ml to about 10 mg/ml. In a preferred embodiment, the collagen in the composition is at a concentration of about 5 mg/ml.

In yet another embodiment, the composition which is suitable for packaging in a pressurized aerosol container and for dispensing as a blood coagulating foam includes fetal collagen and a pharmaceutically acceptable carrier. The fetal collagen can be obtained from a mammal, e.g., any of the mammals described herein. Preferably, the fetal collagen is obtained from a fetal pig at the selected gestational ages described herein. The fetal collagen can include one type of collagen or a mixture of two or more types of collagen described herein. Typically, the collagen is at a concentration in the composition of about 1 mg/ml to about 10 mg/ml. In a preferred embodiment, the collagen in the composition is at a concentration of about 5 mg/ml. The composition can be in the form of a blood coagulating foam as described herein. The compositions can also be contained within containers, e.g., containers with means for dispensing the composition from the container as a blood coagulating foam. Such means are described in more detail herein.

In another aspect, the invention pertains to a device for delivering a blood coagulating composition or foam. The device typically includes a container which holds a blood coagulating composition described herein. The composition, the first component, is in the container together with a second component. The second component is a compound in which the composition is soluble and which exerts a level of pressure sufficient to propel the composition from the container (i.e., the composition can be dispensed from the container) in the form of a blood coagulating foam. Typically the compound in which the collagen is soluble and which exerts a level of pressure sufficient to propel the composition from the container in the form of a foam is a gas, e.g., a gas which can be used as a aerosol propeliant. Preferred gases for use within the device are hydrofluorocarbon gases. Examples of hydrofluorocarbon gases, which are commercially available, e.g., from DuPont, Wilmington, Delaware, and which can be used according to the invention include 1,1,1,2-tetrafluoroethane, hydrofluorocarbon (HFC)-l 52A, and HFC-2273A. Other gases which can be used according to the invention include dimethyl ether, isobutane, propane, n-butane, nitrous oxide, suva, and mixtures thereof. For example, A-46, an industry designation for a mixture of n-butane, isobutane, and propane in proportions chosen such that the blend has a vapor pressure of 46 psig at 70°F, can also be used in the present invention. The gases are typically at a concentration within the device of at least about 5 to about 30%, preferably at least about 10 to about 20%, more preferably at least about 15% by weight, e.g., by weight of the entire composition, and a pressure, e.g., vapor pressure, from about 30 to about 70 psig at room temperature, e.g., 70°F. Within the devices described herein, the collagen compositions are preferably in the form of a solution, e.g., a liquid containing dissolved substance, e.g., an aqueous carrier containing dissolved collagen. As they are being released from the devices, the collagen compositions form a blood coagulating foam. As used herein, the term "foam" refers to a mass of gas bubbles, e.g., hydrofluorocarbon gas bubbles, in a liquid-film matrix, e.g., a liquid- protein film matrix, e.g., an aqueous-collagen film matrix. The foam can then be easily delivered to the selected site through an aperture, e.g., a small diameter aperture, in the device. To maintain the compositions in the form of a solution within the devices described herein, the following parameters can be manipulated: (1) pH of the composition; (2) concentration of collagen in the composition; (3) the type of pharmaceutically acceptable carrier in which the collagen is in solution; and (4) the amount and temperature of the gas within the device. For example, it is preferable that the pH of the composition be as close to neutrality, i.e., pH 7.0, as possible. As the pH of the composition within the device approaches neutrality, the composition will tend to form a gel. Formation of a gel within the device is typically undesirable as the gels are difficult to release or dispense from the device. Thus, the pH of the composition within the device is generally maintained at a pH as close to neutrality as possible but which will not initiate the formation of a gel. A preferred pH range is from about 4.0 to about 6.0, preferably from about 5.0 to 6.0. In addition, if the concentration of collagen in the composition is increased, the composition will begin to form a gel at a lower, i.e., more acidic, pH. For example, if the collagen is at a concentration in the composition of about 5 mg/ml, the composition will begin to form a gel as the pH approaches 6.0. If the concentration of the collagen in the composition is greater than 5 mg/ml, the composition will begin to form a gel at a pH of about 5.0. The type of pharmaceutically acceptable carrier which can be used according to the invention depends upon, for example, the ability of the carrier to maintain the collagen in solution and the compatibility of the carrier with pharmaceutical administration in a subject, e.g., a human. Various carriers having these preferred characteristics can be used in the invention and are described herein. In addition, the amount and temperature of the gas within the device can be regulated to maintain the compositions in the form of a solution.

As shown in Fig. 1, the device 10 includes a container 12 with the appropriate valves 14 and actuators 16 to facilitate release of the composition 18 of the invention through nozzle 19. The container 12 can be any container which can hold the composition 18 without detrimentally affecting the form or activity of the composition. For example, preferred containers 12 include containers, e.g., bottles or canisters, which are composed of glass. In a preferred embodiment, the container 12 is composed of glass and coated with plastic to prevent shattering upon release of the collagen composition. In addition, it is preferable that the container 12 be resistant to temperatures up to at least 80 or 90°F. The device can also be fitted with desired extensions, e.g., delivery tubes, through which the composition can be delivered to locations which are difficult to reach, e.g., body cavities (to reduce internal bleeding). As shown in Fig. 2, in a second embodiment, the device 10 is fitted with an extendible arm, e.g., tube 20, with a lumen 22 through which the composition can be delivered to a selected location. The elements of aerosol delivery devices such as those described in Figs. 1 and 2 for delivering proteins to desired locations are known in the art. For examples of aerosol delivery devices for delivering proteins to desired locations see U.S. Patent Nos. 5, 399,347, 5,356,614 and 5,196,185. In yet another aspect, the invention pertains to methods for coagulating blood at a site of bleeding in or on a subject. These methods include administering to the subject, e.g., at a site of bleeding, a composition or foam of the invention. As used herein the term "administering" refers to the delivery of the compositions or foams described herein to a subject by a method or route which allows the composition to perform its intended function of coagulating blood. Examples of routes of administration which can be used in this method include percutaneous, e.g., topical, administration, parenteral, e.g., subcutaneous, administration, and intraperitoneal administration. A preferred method of administering a composition or foam of the present invention is percutaneous, e.g., topical, administration. In a preferred embodiment, the composition or foam is administered to the subject by spraying the composition or foam directly onto (or into, e.g., into the peritoneal cavity, in the case of internal bleeding) a wound site or a site where hemorrhaging is occurring. This can be accomplished by inserting the composition into a device described herein and dispensing the composition in the form of a blood coagulating foam from the device.

Subjects who can be treated according to the methods of the invention include mammals, particularly humans, susceptible to a disorder or injury which can result in unwanted bleeding. For example, subjects who can be treated according to the method of the invention include mammals, e.g., humans, suffering from injuries, e.g., traumatic injuries, resulting in internal or external hemorrhaging. Non-limiting examples of such persons include military personnel with combat injuries, persons with injuries received as a result of accidents, and persons suffering from hemorrhaging associated with surgical procedures.

This invention is further illustrated by the following example which in no way should be construed as being further limiting. The contents of all cited references (including literature references, issued patents, published patent applications, and co- pending patent applications) cited throughout this application are hereby expressly incorporated by reference.

EXAMPLE

Laparotomies were performed on six mice to expose the liver in each mouse. A one-half square centimeter of liver tissue was removed to initiate bleeding and the resultant bleeding was timed. Using a glass aerosol can which contained 5 mg/ml of acid extracted fetal porcine collagen including collagen types I, III, and IV and 15% by weight of 1,1,1,2-tetrafluoroethane (dymel-l,3,4A-P) at a pressure of 70 psig, the collagen solution was sprayed onto the bleeding sites of the mouse livers. A clot formed within about 2.5 minutes upon administration of the collagen and loss of blood was curtailed. The clot was formed on the livers of the test mice in a time period which was significantly shorter than the clot formation on the livers of control mice.

Equivalents Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents of the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.

Claims

What is claimed is:

I . A blood coagulating foam comprising fetal and adult collagen.

2. The foam of claim 1 , further comprising a hydrofluorocarbon gas.

3. The foam of claim 1 or 2, further comprising a neutralizing solution.

4. The foam of claim 2, wherein the hydrofluorocarbon gas comprises 1,1,1,2-tetrafluoroethane.

5. The foam of claim 1 , wherein the fetal collagen comprises collagen type I, collagen type III, and collagen type IV.

6. The foam of claim 1, wherein the adult collagen comprises collagen type

I and collagen type III.

7. A composition which is suitable for packaging in a pressurized aerosol container and for dispensing as a blood coagulating foam, the composition comprising a solution of fetal and adult collagen and a pharmaceutically acceptable carrier.

8. A blood coagulating foam comprising collagen type I, collagen type III, collagen type IV and a pharmaceutically acceptable carrier.

9. The foam of claim 8, further comprising a hydrofluorocarbon gas.

10. The foam of claim 8 or 9, further comprising a neutralizing solution.

I I . The foam of claim 9, wherein the hydrofluorocarbon gas comprises 1,1,1,2-tetrafluoroethane.

12. A composition which is suitable for packaging in a pressurized aerosol container and for dispensing as a blood coagulating foam, the composition comprising collagen type I, collagen type III, collagen type IV and a pharmaceutically acceptable carrier.

13. A blood coagulating foam comprising fetal collagen and a pharmaceutically acceptable carrier.

14. The foam of claim 13, wherein the fetal collagen comprises fetal porcine collagen.

15. The foam of claim 13, further comprising a hydrofluorocarbon gas.

16. The foam of claim 13 or 15, further comprising a neutralizing solution.

17. The foam of claim 16, wherein the hydrofluorocarbon gas comprises 1,1,1 ,2-tetrafluoroethane.

18. A composition which is suitable for packaging in a pressurized aerosol container and for dispensing as a blood coagulating foam, the composition comprising a solution of fetal collagen and a pharmaceutically acceptable carrier.

19. A device for delivering a blood coagulating foam, the device comprising a container which has at least one aperture through which contents of the container are dispensed and which holds: a composition comprising a solution of fetal collagen, adult collagen, and a pharmaceutically acceptable carrier; and a gas in which the composition is soluble and which exerts a level of pressure sufficient to propel the composition from the container in the form of a blood coagulating foam.

20. The device of claim 19, wherein the composition has a pH from about 4.0 to about 6.0.

21. The device of claim 19, wherein the gas is at a weight percent in the composition of at least about 15 weight percent.

22. The device of claim 19, wherein the gas comprises a hydrofluorocarbon gas.

23. The device of claim 22, wherein the hydrofluorocarbon gas comprises 1,1,1 ,2-tetrafluoroethane.

24. The device of claim 19, further comprising an extendible arm having an axial bore extending therethrough through which the composition can be delivered to a selected site, the bore being coaxial with the at least one aperture of the container.

25. A device for delivering a blood coagulating foam, the device comprising a container which has at least one aperture through which contents of the container are dispensed and which holds: a composition comprising a solution of collagen type I, collagen type III, and collagen type IV, and a pharmaceutically acceptable carrier; and a gas in which the composition is soluble and which exerts a level of pressure sufficient to propel the composition from the container in the form of a blood coagulating foam.

26. A device for delivering a blood coagulating foam, the device comprising a container which has at least one aperture through which contents of the container are dispensed and which holds: a composition comprising a solution of fetal porcine collagen type I, collagen type HI, and collagen type IV, and a pharmaceutically acceptable carrier; and a hydrofluorocarbon gas in which the composition is soluble and which exerts a level of pressure sufficient to propel the composition from the container in the form of a blood coagulating foam.

27. A device for delivering a blood coagulating foam, the device comprising a container which has at least one aperture through which contents o the container are dispensed and which holds: a composition comprising a solution of fetal collagen, and a pharmaceutically acceptable carrier; and a gas in which the composition is soluble and which exerts a level of pressure sufficient to propel the composition from the container in the form of a blood coagulating foam.

28. A device for delivering a blood coagulating foam, the device comprising a container which has at least one aperture through which contents of the container are dispensed and which holds: a composition comprising a solution of fetal porcine collagen, and a pharmaceutically acceptable carrier; and a hydrocarbon gas in which the composition is soluble and which exerts a level of pressure sufficient to propel the composition from the container in the form of a blood coagulating foam.

29. The device of claim 19, 25, 26, 27, or 28 further holding a neutralizing solution.

30. A method for coagulating blood at a site of bleeding in a subject, comprising administering the foam of claim 1, 8, or 13 to the site of bleeding in the subject.