WO2006072887A1

WO2006072887A1 - Ocular iontophoresis device for delivering sirna and aptamers

Info

Publication number: WO2006072887A1
Application number: PCT/IB2006/000277
Authority: WO
Inventors: Pierre Roy
Original assignee: Eyegate Pharma Sa
Priority date: 2005-01-05
Filing date: 2006-01-03
Publication date: 2006-07-13

Abstract

The invention relates to a device of ocular iontophoresis for delivering active substances, comprising: a reservoir capable of receiving at least one medium containing active substances chosen among interfering RNA (siRNA) and aptamers, the reservoir extending along a surface intended to cover a part of an eyeball; an active electrode associated with the reservoir so as to, when polarized, supply an electric field through the medium to the eye; wherein the area and the shape of the surface of the reservoir are chosen for maximising the distribution of the active substances on an ocular area determinate by the limits of accessibility of the reservoir and the nature of the intraocular tissue to be treated.

Description

Ocular iontophoresis device for delivering siRNA and aptamers

TECHNICAL FIELD

The invention relates to the delivery of large nucleotide-based pharmaceutical agents to ocular tissues, especially the delivery of interfering ribonucleic acid (siRNA) or aptamers capable of inhibiting or modulating Vascular Endothelial Growth Factor (VEGF) protein production.

Ocular Neovascularization and VEGF

During embryogenesis, endothelial cells differentiate from mesodermal blood islands and proliferate rapidly to form new blood vessels. The vascular system develops through the mechanisms of vasculogenesis and angiogenesis. In vasculogenesis, blood vessels develop de novo from differentiating endothelial cells in situ, whereas in angiogenesis, capillaries originate from preexisting vessels. Vasculogenesis ceases after development, and endothelial cell proliferation nearly ceases in adults.

However, highly regulated angiogenesis does occur normally in adults and is responsible for physiologic functions, such as wound healing, ovulation, and placental maturation.

When unregulated, endothelial cells can cycle and divide abnormally to cause and contribute to pathologic states, such as tumor growth and eye disease.

In the eye this process is referred to as ocular neovascularization. Neovascularization in the developed eye almost always impairs function and may ultimately lead to blindness. These new vessels may grow into nearly all mature ocular tissue and affect the cornea, iris, retina, and optic disk.

In Cornea for example, contact lens wear, alkali or other chemical burns and trachoma can lead to corneal neovascularization.

In Iris, Retinoblastoma, Central retinal vein occlusion and a part of Diabete Mellitus with its long-term vascular complications lead to neovascularization of the Iris. In Retina, diseases associated with retinal neovascularization are

Proliferative diabetic retinopathy, Retinopathy of prematurity and sickle cell retinopathy.

In Choroid, neovascularization is a consequence of age related macular degeneration.

Although no one factor can explain all causes of ocular neovascularization, multiple contributing factors have been implicated, such as inflammation and its molecular mediators, tumor angiogenic factors, and a hypoxic retinal diffusible factor. The new vessels that form are structurally weak, both leaking fluid and lacking structural integrity. The resultant haemorrhage, exudates, and accompanying fibrosis often cause blindness.

Neovascularization is a cascade of events, and numerous clinical and experimental observations have indicated that hypoxia (or ischemia) is the driving force for retinal neovascularization, where a diffusible factor that can stimulate angiogenesis is released by the ischemic retina in many retinal diseases.

Hypoxia causes upregulation of growth factors most of which then stimulate endothelial cell proliferation. Growth factors can also cause increased expression of integrins and proteinases both of which are important for cell migration. Both endothelial cell proliferation and migration are important key steps in angiogenesis. The switch to the angiogenic steps depends on a balance between angiogenic factors and endogenous angiogenesis inhibitors. Among the growth factors involved in angiogenesis, Vascular

Endothelial Growth Factor (VEGF) is thought to be the major mediator as increased levels of VEGF were identified in the retina and vitreous of patients and laboratory animals with ischemic retinopathies.

VEGF is a 46 kDa homodimer glycoprotein with both vasopermeability and angiogenic activity. VEGF comprise four isoforms, including VEGF-121 ,

VEGF-165, VEGF-189, and VEGF-206, which are believed to be the result of alternative splicing of mRNA. VEGF-165 is the most abundant, amounting to approximately 90% of the total VEGF. VEGF family binds to two related high affinity cell surface tyrosine kinase receptors — VEGFR-1 (Flt-1) and VEGFR-2 (kinase domain region, KDR or Flk-1). A large number of high affinity VEGF receptors is identifed on retinal microvascular endothelial cells compared to other endothelial cell types.

Aptamers

Several strategies for inhibiting neovascularization are currently being tested or evaluated in the field of ophthalmology that: -(1) interfere with pro-angiogenic growth factors, their receptors or the downstream signalling

-(2) upregulate endogenous inhibitors or administer exogenous inhibitors

-(3) directly target neovasculature. Among these strategies, there is the use of nucleotide-based pharmaceutical agents such as aptamers which are able to, when bounded to a VEGF, inactivate the VEGF by rendering it incapable of binding to its receptor in the vascular tissue. Then the undesirable or abnormal growth of blood vessels is slowed or stopped. For example, Carol BELL et al « oligonucleotide NX1838 inhibits VEGFi₆S - mediated cellular responses in vitro » (In Vitro Cellular & Developmental Biology ; Oct. 1999 ; 35, 9 ; Health & Medical Complete, p. 533) shows that an aptamer can inhibit a VEGF.

RNA interference

Another strategy in development is the use of nucleic acid technology to develop RNA interference therapeutics.

Inside the cell, a process of protein production, and in particular of

VEGF protein production, involves a number of steps, beginning with the reading of the gene in the nucleus by a process called transcription. This process generates a messenger RNA (mRNA), which is then translated into protein in the cytoplasm. RNAi-based therapeutics specifically target and degrade mRNA using a naturally occurring cellular mechanism that regulates the expression of genes. The natural cellular mechanism, called RNA interference (RNAi), is the fact that the presence of double stranded RNA (dsRNA) in a cell results in the destruction of mRNA whose sequences share homology to the dsRNA.

Degrading a mRNA that is to be translated into a specific protein results in a profound reduction in the level of that protein without directly altering the original genetic material (DNA). RNAi is a highly promising therapeutic approach for those diseases where aberrant protein production is a problem.

One advantage of this approach is that a typical mRNA produces approximately 5,000 copies of a protein. Consequently, targeting mRNA rather than the protein itself is potentially a much more efficient approach to block protein function.

In RNAi-based therapy, a double-stranded short interfering RNA (siRNA) molecule, typically of 21 and 22 nucleotides in length is engineered to precisely match the protein-encoding nucleotide sequence of the target mRNA to be silenced. Following administration, the siRNA molecule associates with a group of proteins termed the RNA-induced silencing complex (RISC), and directs the RISC to the target mRNA. The siRNA-associated RISC binds to the target mRNA through a base-pairing interaction and degrades it. The RISC is then capable of degrading additional copies of the targeted mRNA. Therefore, by altering the function, the mRNA can be used to modulate the cell's machinery and particularly the mRNA transferring the information leading to VEGF protein production, then slowing or stopping the undesirable, abnormal growth of blood vessels.

One of the first documents having described RNA interference mechanism is EP 1 ,144,623. The following other documents are more specific to VEGF inhibition: US 2004/0018176, WO 03/070910, US 2004/0142895, US 2004/0138163, US 2004/ 0198682 and US 2004/0209832.

These documents describe various nucleic acid constructions, formulations and uses that are useful, among other things, in the treatment of proliferating diseases due to VEGF overexpression. These various nucleic acids have then to be introduced in the eye.

TECHNICAL BACKGROUND

Like the brain, the eye is protected from the central venous system by biological barriers (hemo-ocular, hemo-aqueous, hemo-retinal) making it very difficult to administer active substances at sufficient concentration, in various intraocular tissues affected by neovascularization like cornea, iris and specifically to the posterior segment of the eye, in particular to the retina and choroid.

The systemic path (oral or intravenous) can thus administer only a very small fraction (a few %) of the initial quantity into the internal tissue of the eyes, and thus rapidly becomes insufficient.

That is why techniques of locally administering active substances to the eye have been and are being developed, including direct injections around the eye (peribulbar, retrobulbar) or into the eye (intraocular), topical applications of drops, photodynamic therapy, inserts in the form of reservoirs of active substances placed on the surface of the eye (in noninvasive manner) such as lenses or preferably in the conjunctival sac and serving to deliver active substances in continuous or in a programmed manner, intraocular implants for programmed release of active substances are put into place surgically in the vitreous humor.

Ocular iontophoresis is another technique for local administration of active substances into the eye, and it enables most of the drawbacks that have the other techniques previously listed. In particular, it makes it possible in non-invasive manner to obtain concentrations and residence times in the eye that are equal to or greater than prior techniques. Ocular iontophoresis devices are typically constituted by a direct current (DC) electric field source coupled to two electrodes referred to respectively as "active" and "passive" electrodes. The active electrode acts on an electrolyte containing active principle(s), while the passive electrode serves as a return electrode and enables the electric circuit to be looped through the patient's body.

US 3,122,137 describes an applicator applied on the orbit and not on the eye's surface and incorporating the current source. It does not propose means for keeping the eye's open and it is believed a large part of the product is also delivered into systemic circulation, due to a lack of precision in the placement of the device.

Devices in US 5,522,864 and US 6,101 ,411 should suffer from the same drawbacks.

US 4,564,016 discloses a device having a small application surface (diameter 1 mm), applied on sclera and allowing very high current densities

(between 50 and 2000mA/cm2) for "focal iontophoresis". These values should be toxic for concerned tissues, as confirmed in Maurice article in

Ophthalmology (January 1986, vol 93, number 1) entitled « Iontophoresis of fluorescing into the posterior segment of the rabbit eye ». Last, US 6,154,671 , discloses the principle of a device for delivering all kinds of active substances with safety and accuracy by iontophoresis, and answers then to most of the problematic of iontophoresis for ophthalmology.

More recently, US 6,319,240 proposes an improvement of previous methods with a sealed reservoir applied on sclera (with a semi-permeable membrane on application face) under the eyelid. The semi-permeable membrane of this device is supposed to limit arcing effect between the electrode and the eye's surface that could occur due to the limited thickness and small surface of the device.

US 6,442,423 describes a device where the product is cast in a gel and applied on cornea. This known prior art devices do not take account of the specificity of the delivery of nucleotide-based drugs such as aptamers or siRNA which can bring some associated problems.

Indeed siRNA or aptamers are very heavy molecules (greater than 5,000 Da) . A difficulty is then to homogeneously penetrate the ocular tissue to be treated with such large molecules.

Moreover, these active substances need to be administered very precisely.

Finally, these active substances are very expensive, and a delivery with a minimum of product losses would be desirable.

US 2004 / 0142895, US 2004 / 0138163, US 2004 / 0198682 and US 2004 / 0209832 suggest the use of iontophoresis among a list of several siRNA delivering techniques, without any other precisions relative to the method or the device to be employed for performing such a iontophoresis. US 2003/017130 and US 2004/0167091 suggest the use of iontophoresis among a list of aptamers delivering techniques, without any other precisions relative to the method or the device to be employed for performing such a iontophoresis.

US 6,579,276 and US 2002/0115959 propose a method for delivering aptamers by iontophoresis by adjusting chemical parameters and/or by associating them to other substances in the reservoir of the device.

US 2002/0099321 proposes a method for delivering aptamers by iontophoresis by adjusting chemical parameters and/or by associating them to other substances in the reservoir of the device and/or by providing a malleable and non-abrasive medium placed in the reservoir.

A first object of the invention is to provide an ocular iontophoresis device that is dedicated to the delivery of siRNA or aptamers in the intraocular tissue.

Another object of the invention is to reach the first object by providing a device which maximises the distribution of the active substances on the eyeball, for rendering the penetration area as large as possible and for homogenising the penetration rate, for then treating intraocular tissues.

Another object of the invention is to reach the first object by providing a device which limits the losses of active substances during iontophoresis. Another object of the invention is to reach the first object by providing a device which allows a precise control of the number of active substances which are delivering to the intraocular tissues

BRIEF DESCRIPTION OF THE INVENTION

The present invention attempts to reach these purposes by proposing, according to a first aspect, a device of ocular iontophoresis for delivering active substances, comprising:

- a reservoir capable of receiving at least a medium containing active substances chosen among interfering RNA (siRNA) and aptamers, the reservoir extending along a surface intended to cover a part of an eyeball; - an active electrode associated with the reservoir so as to, when polarized, supply an electric field through the medium to the eye; wherein the area and the shape of the surface of the reservoir are chosen for maximising the distribution of the active substances on an ocular area determined by the limits of accessibility of the reservoir and the nature of the intraocular tissue to be treated.

Other characteristics of this first device are listed below: The fact that siRNA or aptamers are chosen for inhibiting or modulating respectively VEGF production or VEGF itself.

Active substances are preferably present in a concentration between approximately 0.1 mg and approximately 10 mg per ml of medium, and the medium has a pH ranging between approximately 6.5 and approximately 8.5.

The device may include means for guiding the electric field from the active electrode to the ocular surface in a direction substantially perpendicular to this surface, the active electrode being placed in the device so as to be closely electrically connected to the guiding means and so as to be sufficiently distant from the ocular surface for obtaining a global electric flux substantially constant along the guiding means. The active electrode may then be distant from the ocular surface about or greater than 3 times the longest linear dimension of the surface of reservoir intended to cover ocular surface.

The distance between the active electrode and the ocular surface is chosen so as to prevent any damage of the ocular tissue due to the electric field.

The reservoir can be divided in several sub-reservoirs, each provided with an own active electrode.

The reservoir can further comprise a barrier to current leaking out from the reservoir and/or against intrusion of external contaminants into the reservoir.

The reservoir may comprise a first container for receiving the medium containing active substances and a second container for receiving an electrical conductive medium containing electrical conductive elements, the first and second containers being separated by a semi-permeable membrane which is permeable to electrical conductive elements and non- permeable to the active substances. Optionally, the active substances and the electrical conductive elements are in solution, and the device is provided with means for filling the first and/or the second container(s) with active substances in solution, or for circulating the active substances in solution in the first and/or the second container(s).

The reservoir may also comprise flexible side wall sufficiently flexible to adapt oneself to the ocular surface when the device is positioned thereon so as to maintain the distance between the surface of the electrode and the ocular surface substantially constant, and wherein the reservoir has a reinforced or rigid rear portion suitable for sufficiently withstanding to pressures exerted by eyelids. Optionally, the flexible side walls form a barrier to current leaking out the reservoir and/or against intrusion of external contaminants into the reservoir. The active electrode may include a through opening, and the reservoir may comprise an outer side wall and an inner side wall so that the active electrode extends between them, the end wall of the reservoir being the active electrode or a transverse wall connecting one end of the outer side wall to one end of the inner side wall. The reservoir comprises optionally rigid side walls extending from flexible side walls to the active electrode.

According to a second aspect, the invention proposes a device of ocular iontophoresis for delivering active substances, comprising:

- a reservoir capable of receiving at least one medium containing active substances chosen among interfering RNA (siRNA);

— an active electrode associated with the reservoir so as to, when polarized, supply an electric field through the medium to the surface of the reservoir into contact with the eye; wherein the reservoir comprises a first container for receiving the medium containing active substances and a second container for receiving an electrical conductive medium containing electrical conductive elements, the first and second containers being separated by a semi-permeable membrane which is permeable to electrical conductive elements and non- permeable to active substances. Optionally, the active substances is in solution and the electrical conductive medium is a solution, and the device is provided with means for filling the first and/or the second container(s) with their respective solutions, or for circulating their respective solutions in the first and/or the second container(s).

Other characteristics of this latter device are the following: The conductive medium included in the second container forms means for guiding the electric field from the active electrode to the ocular surface in a direction substantially perpendicular to this surface, the active electrode being placed in the device so as to be closely electrically connected to the conductive medium and so as to be sufficiently distant from the ocular surface for obtaining a global electric flux substantially constant along the section of the second container. The length of the second container can be chosen about or greater than 3 times the longest linear dimension of the surface of the reservoir intended to cover ocular surface. The reservoir can also be divided in several sub-reservoirs, each having its own active electrode and its own semi-permeable membrane. According to a third aspect, the invention proposes a device of ocular iontophoresis for delivering active substances, comprising:

- a reservoir capable of receiving at least one medium containing active substances chosen among interfering RNA (siRNA) and aptamers;

- an active electrode associated with the reservoir so as to, when polarized, supply an electric field through the mediums to the surface of the reservoir into contact with the eye; wherein the device comprises means for guiding the electric field from the active electrode to the ocular surface in a direction substantially perpendicular to this surface, wherein the active electrode is placed in the device so as to be closely electrically connected to the guiding means and so as to be sufficiently distant from the ocular surface for obtaining a global electric flux substantially constant along the guiding means. The active electrode is then optionally distant from the reservoir surface covering the ocular tissue of about or greater than 3 times the longest linear dimension of the said reservoir surface.

BRIEF DESCRIPTION OF THE FIGURES

Other characteristics, objects, and advantages of the invention appear better on reading the description below, which is illustrated by the following figures: Figure 1 is a longitudinal cross section of an ocular iontophoresis system in operation on an eye.

Figure 2A to 2E show various shapes and areas of surfaces of reservoirs of devices according to the invention.

Figure 3 shows a first device according to the invention. Figure 4 shows a particular device in the case of it is provided with a large reservoir surface area. Figure 5 shows a second device according to the invention. Figure 6 shows a variant of the second device according to the invention.

Figure 7 shows a third device according to the invention. Figure 8A to 8C show different shapes for the flexible portion of the reservoir of an ocular iontophoresis device according the invention.

DETAILED DESCRIPTION OF THE INVENTION With reference to Figure 1 , an ocular iontophoresis system comprises an iontophoresis device 1 including an active electrode 10, a reservoir 20 (defined in this device 1 as a cavity in a housing 23), and at least one active substances 30 stored in the reservoir 20, a passive electrode 40 enabling the electric circuit to be looped, and an electrical power supply 300 delivering DC to the electrodes 10 and 40.

The power supply 300 for generating an electrical potential difference may be housed within the ocular iontophoretic device 1 , or alternatively, may be remotely associated with the ocular iontophoretic device 1 via conventional electrical conduit 60. Energy source preferably supplies low voltage constant direct current not exceeding 10 mA/cm² (depending on the device's surface) for generating an electrical potential difference. The active electrode 10 is disposed in the reservoir 20 either by being fitted thereto or by being formed therein directly (e.g. by electro-plating).

The reservoir 20 is made of an electrically insulating material, such as plastics material, silicone material, polymer, or any other equivalent material. Active substances 30 are present in a medium 35 placed in the reservoir.

These active substances are selected among: - siRNA preferably for inhibiting or modulating neovascularization production, and especially VEGF production; or among - aptamers preferably for inhibiting or modulating neovascularization, and especially VEGF. Molecular weight of such molecules, associated or not to agents, is typically greater than 5,000 Da, and no more than 50,000 Da. For example aptamers can be about 8,000 Da and siRNA about 15,000 Da (without associated agents). The medium 35 housed in the reservoir 20 extends from eyeball's surface 500 and is preferably manufactured from a material capable of temporarily retaining siRNA or aptamers. Medium 35 may comprise, for example, a natural or synthetic gel member, a natural or synthetic foam that is geometrically and compositionally compatible for ocular applications for receiving the active substances 30 in solution, or a single solution. Electrical conductive medium, like water or hydrogel, can also be placed in the reservoir 20 in order to guide and conduct the electric field through the reservoir 20 to the surface of the eyeball 500.

Active substances 30 are preferably present in a concentration between approximately 0.1 mg and approximately 10 mg per ml of medium 35, and the medium 35 has a pH ranging between approximately 6.5 and approximately 8.5.

The medium 35 may also contain supplemental agents, such as electrolytes, stability additives, medicament preserving additives, pH regulating buffers, PEGylating agents, and any other agent that, when associated, shall increase its half-life or bioavailability intraocularly.

The active substances 30 are ionisable by themselves or are in a form that facilitates their ionization. Thus, It is possible to bond active substances to additives presenting terminating ions, such as polymer, dendrimer, polymer nanoparticle or microsphere, or liposome (the active substance is then contained in the aqueous core and not in the wall of the liposome). Various other examples of techniques for improving active substances ionization should also be found in "Progress in retinal and eye research" from Le Bourlais et al. (VoI 17, No 1 , p 33-58, 1998; Ophthalmic drug delivery systems - recent advances"), in "Recent developments in ophthalmic drug delivery" from Ding (PSTT Vol. 1 , No. 8 November 1998) and in "European Journal of Pharmaceutics and Biopharmaceutics" from Lallemand et al. (2003, « Cyclosporine A delivery to the eye: A pharmaceutical challenge").

The passive electrode 40 may be placed on a portion of the body (in order to "loop" current through the body), for example on an ear, the forehead, or a cheek. As with active electrode 10, passive electrode 40 may comprise an anode or a cathode depending upon whether the active substances 30 are cationic or anionic.

The device 1 is placed on the eyeball 500, optionally at least partly inserted under eyelid.

The reservoir 20 extends along a surface intended to cover an ocular area on the surface of the eyeball 500.

The ocular area to be covered by the reservoir 20 is determinate by the limits of accessibility of the reservoir and the nature of the internal ocular tissue to be treated. Thus, it is chosen the largest ocular area for delivering the active substances to internal ocular tissue, in order to maximise the distribution of the active substances 30 on a part of the eyeball 500 that can be useful for the delivery of active substances 30.

Intraocular tissues to be targeted are especially new vessels that grow into nearly all mature ocular tissue and may affect the cornea, iris, retina, and/or optic disk, as previously discussed.

For example, if the affected tissues are located in Cornea or in Iris, the chosen ocular area on the surface of the eyeball 500 intended to receive the active substances 30 from the reservoir 20 can be the whole Cornea 501 , eventually extended to the periphery of the sclera 502 in order to administer active substances 30 to the ciliary body that may be an additional path for reaching Iris.

Eventually, a removal of the anterior corneal epithelium can be previously operated for making the remained corneal tissues (i.e. stroma and posterior corneal epithelium) more permeable to the active substances 30. In another example, if the affected tissues are located in Retina or in

Choroid, the chosen ocular area on the surface of the eyeball 500 intended to receive the active substances 30 from the reservoir 20 can be the whole part of the sclera 502 that is accessible to active substances 30, eventually extended to the part of the sclera located under eyelids.

Then, the dimensioning and the shape of the reservoir 20 are arranged in such a manner that the large and heavy molecules to be delivered are distributed in a homogeneous manner and on the large ocular area so as to minimize their action per area unit, and thus to preserve the superficial ocular tissues from too much stresses, and also to deliver the product precisely in targeted intraocular tissues with avoiding systemic absorption. Moreover, a larger surface area allows a lower electric field residence time on the eyeball 500 and limit the current density on it.

Thus, knowing the ocular surface area intended to receive active substances 30, the surface of the reservoir 20 will be chosen for covering all this area or an area larger than this area. It is thus not only the area but also the shape of the reservoir 20 that can be adapted for reaching the purpose of maximising a homogeneous distribution of active substances 30. Thus shapes as shown in figures 2A to 2E can be chosen Furthermore, the device 1 according to the invention takes account of the size and the cost of siRNA and aptamers molecules to deliver, by limiting active product losses and by improving the delivery efficiency.

The reservoir 20 of the device 1 may thus be adapted to administer the active substances 30 via: • at least a part of the cornea 501 alone; or

• at least a part of the sclera 502 and at least a part of the cornea 501 ; or

• at least a part of the sclera 502 alone.

The cornea 501 constitutes about 5% of the total area of the eye and joins the sclera 502 at the limbus 503. In the human being, the diameter of limbus 503 is about 11.7 mm. In a preferred embodiment of the invention, the device 1 is arranged so as to dispense the active substances 30 through at least a part of the sclera 502 if only this part is necessary for reaching the targeted tissues, it being understood that it presents characteristics that encourage iontophoresis (greater permeability, greater surface area for administration, more favourable to the application of high currents) and that the cornea 501 is a portion of the eye that is much more critical than the sclera 502.

Especially, sclera 502 is much more permeable to large particles such as siRNA and aptamers than cornea 501. Figures 2A to 2E show particular shapes which may be given to a surface of the reservoir 20 covering the eyeball 500, such as an entire ring (Figure 2A), a disk shape (Figure 2B), a shape constituting a portion of a ring (Figure 2C), an ellipse shape (Figure 2D), or an eye-shape (Figure 2E). Other shapes can be chosen depending on the ocular area chosen for receiving the active substances 30. These different shapes should be close to or greater than the shape and the area of the ocular surface to be treated. In a particular case, these shapes reproduce the ocular surface to be treated.

Referring to Figures 2A to 2E, the active electrode 10 provided for such surfaces and shapes of reservoir 20, can be arranged for matching the inner surface of the reservoir 20 illustrated on these figures. Thus, active electrode 10 in a ring-shape (figure 2A), in a disk-shape (figure 2B), in a shape of a part of a ring or in an arc-shape (figure 2C), in an ellipse-shape (figure 2D), in an eye-shape (figure 2E) can be provided for being included inside the respective reservoir 20.

The active electrode 20 can be constituted of a wire (like a loop wire in a short circuit), of a grid or array patterned for supplying a homogeneous field, or of a surface (i.e. a film or a plate).

The active electrode 10 is placed in the device 1 for being in a tight electrical relation with the content of the reservoir 20. The active electrode 10 can then be situated at the bottom of the reservoir 20 (see figure 1), or can be separated from the content of the reservoir 20 by a layer of protection formed on the electrode 10 as described in FR 04/04673, or by an end wall provided between the active electrode 10 and the reservoir 20.

Optionally, the electrode 10 has a predefined concave shape complementary to the eyeball's convex surface (as shown for example in figure 4) for keeping a substantially constant distance "L" between the active electrode 10 and the surface of the eyeball 500.

The active electrode 10 is advantageously arranged, in operation, to present current density of about 10 mA/cm² or less, and to be polarized for about 10 minutes or less.

The active electrode 10 may be placed against the end wall of the reservoir 20 (as shown in figure 1).

The active electrode 10 may be formed directly on the end wall of the reservoir 20. For this purpose, it is possible to use one of the following techniques:

• electroplating to form the conductive layer with a conductive material to form for example a metallic film;

• depositing an ink filled with an electrically conductive material in order to form the conductive layer; • depositing a solid film, of acetate for example, filled with an electrically conductive material to form the conductive layer; and

• overmolding polymers filled respectively with an electrically conductive material to form conductive layers.

A protective layer is optionally formed on the active electrode 10 so as to protect it or to protect the active substances 30 from metallic contaminants, as described in FR 04/04673.

The device 1 is advantageously arranged in such a manner that the distance between the active electrode 10 and the ocular surface is chosen so as to prevent any damage of the ocular tissue due to the electric field. Thus, this distance can be chosen about or greater than 4 mm from the ocular surface, the current of the active electrode 10 of the invention advantageously not exceeding 10 mA/cm², and the application time preferably not exceeding 10 minutes to preserve lacrymal film function.

Referring to figure 3, a first device 1 according to the invention comprises a reservoir 20 (preferably designed as previously described) comprising an electrical conductive medium 37 capable of conducting the electric field E supplied by the active electrode 10, further to the active substances 30 (not shown). This electrical conductive medium 37 can be for example an aqueous solution or a hydrogel. The length "L" of the reservoir

20 is designed so that its content guides the electric field E from the electrode 10 through the medium 37 to the surface 29 of the reservoir 20 covering ocular tissue in a direction substantially perpendicular to this surface 29, and thus obtaining an electric field E globally straight with a flux substantially constant along the section of the reservoir 20 with few or no leaking current, particularly at the contact point between the reservoir wall 23 and ocular surface.

Thus, the reservoir 20 can be arranged so that active electrode 10 is distant from the surface 29 of the reservoir 20 facing the eyeball 500 of about or greater than 3 times the longest linear dimension of the said reservoir surface 29. Indeed the Applicant noticed that, with such a distance value, the electric field E is sufficiently guided inside the reservoir 20 for significantly not decreasing in the main section of the reservoir 20 so that the field deviation becomes no harmful, and precision, deepness of penetration and distribution of the large molecules 30 through the surface of the eyeball 500 are significantly improved. In this device 1 , the said distance of the active electrode 10 from the surface 29 is adjusted by adjusting the length "L" of the reservoir 20, and the said longest linear dimension of the said reservoir surface 29 can be the width "W" of a circular reservoir 20.

When the reservoir 20 has a large surface, it can be divided into a group of sub-reservoirs to keep that ratio "L/W" to a minimum with, inside each sub-reservoir, a sub-electrode whose dimension and shape match the dimension and shape of the sub-reservoir (not shown). Optionally, the reservoir 20 further comprises barrier(s) to current leaking out from the reservoir 20 and/or against intrusion of external contaminants into the reservoir 20 for further improving the homogeneous penetration of the large molecules, as nextly explained by reference to figures 8A to 8C.

Such a design of the reservoir 20 so improves the delivery of siRNA and aptamers by iontophoresis.

Referring to figure 4, the active electrode 10 is here designed to be concave with a degree of concavity substantially identical to the degree of concavity of the surface of the eyeball 500 on which the device 1 is intended to be applied. Thus, a distance "L" is kept substantially constant between the surface of the active electrode 10 and the surface of the eyeball 500 on which the device 1 is applied. This is a variant all the more interesting than the surface area of the eyeball 500 on which the device 1 has to be applied is large. Device 1 comprises advantageously rigid means for conserving the concavity of the active electrode 10.

Referring to figure 5, a second device 1 according to the invention has a reservoir 20 (whose surface is preferably designed as previously described referring to figures 1, 2A to 2E) comprising a first container 21 for receiving the medium 35 containing the said active substances 30 and a second container 22 for receiving an electrical conductive medium 37 containing electrical conductive elements. This electrical conductive medium 37 may be for example an aqueous solution or a hydrogel. The first and second containers 21-22 are separated by a semi-permeable membrane 70 which is permeable to electrical conductive elements (for example water molecules) and non-permeable to the active substances 30, electrical conductive element like water ions being smaller than active substances ions.

The medium 35 can then be limited in thickness to reduce the active substances 30 volume to the minimal, and to permit a precise dosage of its content, improving the control upon the iontophoresis and the cost of it. The size of the second container 22 is optionally arranged so that the conductive medium 37 guides the electric field from the electrode 10 through the mediums 37 and 35 to the surface 29 of the reservoir 20 intended to cover a part of the eyeball 500 in a direction substantially perpendicular to this surface 29, and thus obtaining a global electric flux substantially constant along the section of the reservoir 20. Optionally, the active electrode 10 is distant from the reservoir surface 29 facing the ocular area of about or greater than 3 times the longest linear dimension of the said reservoir surface, as previously described referring to figure 3. Optionally, the reservoir 20 further comprises barrier(s) to current leaking out from the reservoir 20 and/or against intrusion of external contaminants into the reservoir 20 for further improving the homogeneous penetration of the large molecules, as nextly explained by reference to figures 8A to 8C. Referring to figure 6, the active substances are in solution in the first container 21 , and the device 1 is provided with means 80 for filling the first container 21 with these active substances 30 in solution. Such filling means 80 can be formed of a canal 80 in the moulded external wall 23 of the reservoir 20, and connected to apparatus arranged for filling it. Such apparatus (not shown) is arranged and the solution is dosed so that the quantity of active substances 30 is delivered in the first container 21 very precisely. Of course, the same tube 80 can be used for pumping out the active substances 30 in solution. Optionally, another tube 80 is provided in the external wall 23 of the device 1 for circulating the active substances 30 in solution in the first container 21 , a first tube 80 for pumping in the active substances 30, and the other tube 80 for pumping out the active substances 30 (not shown).

Still referring to figure 6, the electrical conductive medium 37 is an electrical conductive solution, and the device 1 is provided with means 90 for filling the second container 22 with this electrical conductive solution, and/or means for circulating this electrical conductive solution in the second container 22. The principle is similar to that exposed for the filling up and/or the circulation in the first container 21.

With reference to Figure 7, a third ocular iontophoresis device 1 according to the invention comprises an active electrode 10 with a through opening so as to provide an annular structure, and is placed at the end of the reservoir 20, which is also annular in section.

As previously explained, the reservoir 20 extends along a surface intended to cover an ocular area of the eyeball 500 that is chosen for maximising the distribution of the active substances on the ocular tissue to be treated. The ocular area intended to receive active substances 30 from the device 1 is at least a part of the sclera 502, as described here-below.

The reservoir 20 is divided in two parts:

- a first container 21 placed at the front part of the reservoir 20 (the front part being the closest part from the eyeball 500) delimited by an outer side wall 23a and an inner side wall 23b;

- a second container 22 placed at the bottom part of the reservoir 20 delimited by an outer side wall 24a and an inner side wall 24b extending substantially perpendicularly from the surface of the active electrode 10.

The first container 21 is intended to receive the medium 35 containing the active substances 30, and the second container 22 is intended to receive an electrically conductive medium 37 like an aqueous solution or a hydrogel. The first and second containers 21-22 are separated by a semi-permeable membrane 70 permeable to electrical conductive elements contained in the medium 37 and non-permeable to active substances 30 of the first container 21.

Preferably, the inner wall 24a and outer wall 24b extend from the surface of the electrode 10 so as to define between them the second container 22 in a cylinder-shape with a cross-section of a ring-shape. The cylinder is preferably chosen sufficiently long so that the electrical conductive medium 37 provided herein guides the electric field from the active electrode 10 to the surface of the reservoir covering the ocular surface in a direction substantially perpendicular to this surface. Leaking current can then be at least partly removed,

As previously explained, the length of this cylinder can be chosen to be close to or greater than 3 times the longest linear dimension of the said reservoir surface.

A rigid material can be chosen for manufacturing these inner and outer walls 24a-24b for hardening such a long structure of device 1.

The inner side wall 24b of the second container 22 optionally presents a mean inside diameter di such that 0.9D < dj < 1.2D, D being the diameter of a cornea 501.

In such case, iontophoresis principally takes place through the sclera 502.

The outer side wall 24a of the second container 22 optionally presents a mean outside diameter d_e where 1.3D < d_e < 2D. One end of the outer side wall 24a may be connected to one end of the inner side wall 24b by a transverse wall for forming an end wall of the second container 22 (not shown). The active electrode 10 is then positioned or formed on said end wall.

In a variant, the active electrode 10 is positioned or formed for closing the side walls 24a and 24b of the second container 22 in such a manner as to constitute the end wall of the reservoir (as shown in figure 7).

The active electrode 10 optionally includes an offset portion 15 enabling the connection 50 with a wire link 60 that supplies electricity to be offset out from the reservoir 20 when connected to a suitable electrical power supply (not shown), one end of the offset part 15 being electrically connected to the electrode layer 10, while the other end of the offset part receives the wire link 60. Thereby harmful effects that might arise from the electrical connection can be avoided (local heating by Joule effect, local leakage currents, ...). In addition, the device 1 has a rear portion 25 that is sufficiently reinforced or rigid for holding the whole device 1 when placed on the eyeball 500 without significantly deforming the reservoir 20, and for maintaining the geometry of the active electrode 10.

Eventually, the active electrode 10 is concave as shown in figure 4.

In this case, the active electrode 10 is interposed between the rear portion 25 and the reservoir 20, resting against the rigid rear portion 25.

Thus, when the reservoir 20 is in position, the distance between the surface of the active electrode 10 and the surface of the eyeball 500 can be maintained more or less constant in spite of the mechanical stresses exerted by the eyelids and by the hand of the user. The ring formed by the active electrode 10 can keep its shape under the pressure exerted by the eyelids and by the user, thereby maintaining the application area and also the distance between the active electrode 10 and the ocular surface greater than a limit distance, in order to prevent any damage of the ocular tissue due to the electric field. Thus, this limit distance can be chosen about 4 mm from the ocular surface, (as previously described), since otherwise there would be a danger of a short-circuit by favourable lines of current being established between the active electrode 10 and the ocular tissues.

Outer side wall 23a and inner side wall 23b define the volume of the first container 21 wherein the medium 35 containing the active substances 30 to be delivered is intended to be placed. These outer and inner side walls 23a-23b globally extend in continuity to the outer and inner side walls 24a- 24b defining the second container 22 so that first container 21 and second container 22 define a single reservoir 20 in which a semi-permeable membrane 70 is provided between the said containers.

Outer and inner side walls 23a-23b have at least the end of their structure made of a flexible material for acting as a barrier against external contaminants and lacrymal liquid that might disturb the operation of the device 1 (arc effect). The free end of the inner side wall 23b is optionally slightly offset relative to the free end of the outer side wall 23a such that the opening of the reservoir 20 (between these free ends) thus defines a concave curved surface that is substantially complementary in shape to the convex curved shape of the surface of the eyeball 500.

The flexible part of the side walls 23a and 23b may be made of silicone of the polydimethyl siloxane type (PDMS), a material that is highly suitable for making contact with the eyeball 500.

However its flexibility certainly does not enable it to keep its shape in geometrically accurate manner.

That is why it is appropriate for the rigid or reinforced rear portion 24a, 24b, 25 (and eventually a rear part of the side walls 23a and 23b) to make them in a material such as, for example, polymethyl methacrylate

(PMMA), or any rigid polymer material with a specific resistance (elastic modulus/weight ratio) appropriate to maintain its initial shape under mechanical constraint. PMMA is a rigid material suitable for keeping the active electrode 10 in shape. However it is unsuitable for making the flexible portion of side walls 23a and 23b intended to be brought into contact with the eyeball 500

(it is a material that is too traumatic for the delicate mucus membrane of the eye). These two materials in combination thus provide a device 1 structure that is entirely suitable for ocular iontophoresis.

The rigid portion 25 and the inner and outer walls 24a-24b of the reservoir 20 can be made, for example, by machining, moulding, vacuum casting, or any other method suitable for working polymer materials of rigid or semi-rigid kind such as polystyrene (PS), acrylonitrile-butadiene-styrene

(ABS), polyethylene (PE), polypropylene (PP)₁ polyamide (PA), polycarbonate (PC), PMMA, polyurethane (PUR).

During fabrication of the part, provision can be made to mould means for filling the reservoir 20 with active substances 30 and/or means for circulating the active substances 30 in the reservoir 20. For example, tubes for feeding of active substances 30, and optionally outlet tubes may be provided (not shown).

The active electrode 10 can then be deposited on the surface of the part forming the end wall of the active substances reservoir, using for example one of the methods mentioned above.

Finally, the flexible side walls 23a-23b can be made of a polymer material such as, for example, an elastomer polymer of the PUR type, polyether block amide (PEBA), silicone (Sl), or styrene-ethylene-butadiene- styrene (SEBS), and it may be fitted to the assembly using any suitable method, for example adhesive, heat sealing (e.g. by ultrasound, or by rotation, or by mirror), or by overmolding.

The flexible portion 23a-23b of the reservoir 20 may also be made by successively adding sections of material of progressively-varying hardness, from the thickest to the thinnest and from the stiffest to the most flexible, so as to make a reservoir of stiffness that increases progressively going away from the surface to be treated (see below).

The inside walls of the reservoir 20 are optionally provided so as to define compartments, the active electrode 10 then being subdivided into active electrode portions, each active electrode portion being suitable for being placed in its own compartment. Specific treatments can then be performed using different active substances 30, each occupying a different compartment, and administered simultaneously or in deferred manner (in which case each electrode portion has its own current control). Advantageously, filling and/or circulation means for medication 30 are provided in each compartment.

In a particular aspect of the invention, the flexible side walls 23a and 23b of the reservoir 20 are progressively more rigid on going progressively further away from the application surface of the device 1 in operation (i.e. going away from the opening of the reservoir 20). With reference to Figures 8A to 8C, several examples are shown of such side walls 23 of increasing rigidity, each of section that becomes progressively larger and larger on going away from the opening of the reservoir 20.

With reference to Figure 8A, the side wall 23 thus forms a ramp sloping progressively away from the opening of the reservoir 20 until having the thickness of the rigid rear side wall 24.

With reference to Figure 8B, the side wall 23 thus formed is a lip of section that increases going away from the opening of the reservoir 20, and of sides that are concave.

With reference to Figure 8C, the side wall 21 is thus constituted by successive layers of ever increasing section (on going away from the opening of the reservoir 20). These various layers may optionally be of ever increasing hardness.

Claims

1. Device of ocular iontophoresis for delivering active substances, comprising:

- a reservoir capable of receiving at least one medium containing active substances chosen among interfering RNA (siRNA) and aptamers, the reservoir extending along a surface intended to cover a part of an eyeball;

- an active electrode associated with the reservoir so as to, when polarized, supply an electric field through the medium to the eye; wherein the area and the shape of the surface of the reservoir are chosen for maximising the distribution of the active substances on an ocular area determinate by the limits of accessibility of the reservoir and the nature of the intraocular tissue to be treated.

2. Device according to claim 1 , wherein siRNA or aptamers are chosen for inhibiting or modulating respectively VEGF production or VEGF itself.

3. Device according to claim 1 , wherein or aptamers chosen have molecular weight greater than 5,000 Da.

4. Device according to claim 1 , wherein the medium containing the active substances is a solution containing the active substances, or a foam containing the active substances in solution, or a gel containing the active substances.

5. Device according to claim 1 , wherein the active substances are associated with an agent capable of increasing the intraocularly half-life or bioavailability of the active substances.

6. Device according to any of claims 1 to 5, wherein active substances are present in a concentration between approximately 0.1 mg and approximately 10 mg per ml of medium, wherein the medium has a pH ranging between approximately 6.5 and approximately 8.5.

7. Device according to claim 1, wherein the said surface area and shape of the reservoir are chosen so that surface covers at least a portion of a cornea.

8. Device according to claim 1, wherein the said surface area and shape of the reservoir are chosen so that surface covers at least a portion of the cornea and at least a portion of a sclera.

9. Device according to claim 1 , wherein the said surface area and shape of the reservoir are chosen so that surface covers at least a portion of a sclera.

10. Device according to claim 1 , wherein the active electrode is arranged, in operation, to present current density of about 10 mA/cm or less and to be polarized for about 10 minutes or less.

11. Device according to claim 1 , wherein the distance between the active electrode and the ocular surface is chosen so as to prevent any damage of the ocular tissue due to the electric field.

12. Device according to claim 11 , wherein the active electrode is distant of about or greater than 4 mm from the ocular surface.

13. Device according to claim 1, wherein the device is arranged for being, in operation, covered at least partly by an eyelid.

14. Device according to claim 1 , wherein the device is arranged for being not, in operation, covered by an eyelid.

15. Device according to claim 1 , wherein the device includes means for guiding the electric field from the active electrode to the ocular surface in a direction substantially perpendicular to this surface, wherein the active electrode is placed in the device so as to be closely electrically connected with the guiding means and so as to be sufficiently distant from the ocular surface for obtaining a global electric flux substantially constant along the guiding means.

16. Device according to claim 15, wherein the active electrode is distant from the ocular surface about or greater than 3 times the longest linear dimension of the surface of reservoir intended to cover ocular surface.

17. Device according to one of claims 15 and 16, wherein the reservoir is divided in several sub-reservoirs, each provided with an own active electrode.

18. Device according to claim 15 or 16, wherein the reservoir further comprises a barrier to current leaking out from the reservoir and/or against intrusion of external contaminants into the reservoir.

19. Device according to claim 1 , wherein the reservoir comprises a first container for receiving the medium containing active substances and a second container for receiving an electrical conductive medium containing electrical conductive elements, the first and second containers being separated by a semi-permeable membrane which is permeable to electrical conductive elements and non-permeable to the active substances.

20. Device according to claims 15 and 19, wherein the said guiding means are constituted by the electrical conductive medium contained in the second container.

21. Device according to claim 19, wherein the active substances are in solution, and wherein the device is provided with means for filling the first container with active substances in solution, or for circulating the active substances in solution in the first container.

22. Device according to claim 19 or 21 , wherein the electrical conductive medium is an electrical conductive solution, and wherein the device is provided with means for filling the second container with this electrical conductive solution, or for circulating this electrical conductive solution in the second container. .

23. Device according to claim 19, wherein the medium containing the electrical conductive elements is an aqueous solution or a hydrogel.

24. Device according to claim 1 , wherein the reservoir comprises flexible side wall sufficiently flexible to adapt oneself to the surface of the eye when the device is positioned thereon so as to maintain the distance between the surface of the electrode and the ocular surface substantially constant, and wherein the reservoir has a reinforced or rigid rear portion suitable for sufficiently withstanding to pressures exerted by eyelids.

25. Device according to claim 24, wherein the flexible side walls of the reservoir are progressively more rigid on going progressively further away from the surface of the reservoir that is applied to the ocular surface.

26. Device according to claim 25, wherein the side walls are arranged for being progressively thicker on going progressively further away from the ocular surface thereby achieving said progressively-varying rigidity.

27. Device according to any of claims 24 to 26, wherein the flexible side walls form a barrier to current leaking out from the reservoir and/or against intrusion of external contaminants into the reservoir.

28. Device according to claim 24, wherein the active electrode is placed between the reinforced or rigid portion and the reservoir.

29. Device according to claim 28, wherein the active electrode is concave so as to keep a substantially constant distance between the surface of the active electrode and the convex ocular surface on which the device is intended to be applied.

30. Device according to claim 24, wherein the active electrode includes a through opening, and wherein the reservoir comprises an outer side wall and an inner side wall so that the active electrode extends between them, the end wall of the reservoir being the active electrode or a transverse wall connecting one end of the outer side wall to one end of the inner side wall.

31. Device according to claim 30, wherein the reservoir also comprises rigid side walls extending from flexible side walls to the active electrode.

32. Device according to claim 1 , wherein the reservoir contains internal walls so as to define compartments, and wherein the active electrode is subdivided into active electrode portions, each active electrode portion being suitable for being placed in a respective compartment.

33. Device of ocular iontophoresis for delivering active substances, comprising: - a reservoir capable of receiving at least one medium containing active substances chosen among interfering RNA (siRNA);

- an active electrode associated with the reservoir so as to, when polarized, supply an electric field through the medium to the surface of the reservoir into contact with the eye; wherein the reservoir comprises a first container for receiving the medium containing active substances and a second container for receiving an electrical conductive medium containing electrical conductive elements, the first and second containers being separated by a semi-permeable membrane which is permeable to electrical conductive elements and non- permeable to active substances.

34. Device according to claim 33, wherein siRNA or aptamers are chosen for inhibiting or modulating respectively VEGF production or VEGF itself.

35. Device according to claim 33, wherein siRNA or aptamers have molecular weight more than about 5,000 Da.

36. Device according to claim 33, wherein the active substances are in solution and wherein the device is provided with means for filling the first container with active substances in solution, or for circulating the active substances in solution in the first container.

37. Device according to claim 33 or 36, wherein the electrical conductive medium is an electrical conductive solution and wherein the device is provided with means for filling the second container with active substances in solution, or for circulating the active substances in solution in the second container.

38. Device according to claim 33, wherein the medium containing the active substances is a solution containing the active substances, or a foam containing the active substances in solution, or a gel containing the active substances.

39. Device according to claim 33, wherein the electrical conductive medium is an aqueous solution or a hydrogel.

40. Device according to claim 33, wherein the conductive medium included in the second container forms means for guiding the electric field from the active electrode to the ocular surface in a direction substantially perpendicular to this surface, wherein the active electrode is placed in the device so as to be closely electrically connected to the conductive medium and so as to be sufficiently distant from the ocular surface for obtaining a global electric flux substantially constant along the section of the second container.

41. Device according to claim 40, wherein the length of the second container is about or greater than 3 times the longest linear dimension of the surface of the reservoir intended to cover ocular surface.

42. Device according to one of claims 40 and 41, wherein the reservoir is divided in several sub-reservoirs, each having its own active electrode and its own semi-permeable membrane.

43. Device according to claims 40, wherein the said guiding means are constituted by the electrical conductive medium contained in the second container.

44. Device of ocular iontophoresis for delivering active substances, comprising: - a reservoir capable of receiving at least one medium containing active substances chosen among interfering RNA (siRNA) and aptamers;

— an active electrode associated with the reservoir so as to, when polarized, supply an electric field through the mediums to the surface of the reservoir into contact with the eye; wherein the device comprises means for guiding the electric field from the active electrode to the ocular surface in a direction substantially perpendicular to this surface, wherein the active electrode is placed in the device so as to be closely electrically connected to the guiding means and so as to be sufficiently distant from the ocular surface for obtaining a global electric flux substantially constant along the guiding means.

45. Device according to claim 44, wherein the active electrode is distant from the ocular surface about or greater than 3 times the longest linear dimension of the surface of reservoir intended to cover ocular surface.

46. Device according to one of claims 44 and 45, wherein the reservoir is divided in several sub-reservoirs, each having its own active electrode.

47. Device according to claim 44, wherein siRNA or aptamers are chosen for inhibiting or modulating respectively VEGF production or VEGF itself.

48. Device according to claim 44, wherein siRNA or aptamers have molecular weight more than about 5,000 Da.

49. Device according to one of claims 44 to 48, wherein the reservoir comprises a barrier to current leaking out from the reservoir and/or against intrusion of external contaminants into the reservoir.