EP0734254A1

EP0734254A1 - Adhesive patch for transdermal drug delivery

Info

Publication number: EP0734254A1
Application number: EP95901575A
Authority: EP
Inventors: Ary Saaman; Michael Graetzel; Patrick Poscio
Original assignee: Westonbridge International Ltd
Current assignee: Westonbridge International Ltd
Priority date: 1993-12-17
Filing date: 1994-12-13
Publication date: 1996-10-02
Also published as: JPH09510431A; KR960706332A; CH686928A5; US5750138A; WO1995016439A1; CA2179178A1; AU1075795A; AU688823B2

Abstract

An adhesive patch for delayed onset transdermal drug delivery, comprising a reservoir or matrix containing the drug. An imprevious membrane is arranged on said reservoir or matrix and designed to become pervious after a given delay period by receiving an external stimulus that alters its physical/chemical structure.

Description

Adhesive dressing for transdermal drug administration

The present invention relates to an adhesive bandage for deferred transdermal administration of a medicament, more commonly known as a patch, which generally comprises a reservoir or a matrix containing said medicament, as well as a strip of removable protection, this protection being intended to be removed just before applying the adhesive bandage to the patient's skin.

Such a patch is well known and already used for the transdermal administration of various types of drugs such as nitroglycerin, entofenamate, estradiol, scopolamine, isorbide dinitrate, clonidine, fentanyl, nicotine, etc. from the article by Richard W. Baker in "Controlled release of biologically active agents", J. Wiley & Sons, New York (1987), p.239-45. There are various types of such patches, also as disclosed by the aforementioned document, which also highlights the advantages and disadvantages of this route of administration. In summary, they can be divided into two main categories: (a) those which have a chamber serving as a reservoir for the medicament, the latter being released after removal of the protective strip before sticking the patch to the skin, either directly or through a microporous membrane, and (b) those which comprise a porous matrix, for example made of silicone rubber or of a cellulose ester, containing the medicament which will diffuse in the skin from this support once the patch in service position. Of course, other variants of these patches are possible, for example by combining the two main types above.

With the currently known patches, the administration of the medicament begins immediately after the protective strip has been removed and the patch stuck on the skin, the speed of administration being of course a function in particular of the structure and nature of the porous membrane and / or the support, as well as the drug to be administered.

However, this feature turns out to be a drawback when it is desired that this administration be deferred after the patch has been put in place. This is for example the case of the treatment of angina pectoris by means of ni¬ troglycerin. Indeed, an important element of this treatment is to be able to administer the nitroglycerin just before waking the patient to prevent the effects of angina pectoris. It is therefore desirable in practice to have a patch, the effect of which is delayed for example from 6 to 8 hours after its application.

Thus, the object of the present invention is to provide an adhesive dressing of the aforementioned type or patch, the administration of the medicament contained in this patch being deferred over time, for example from a few minutes or hours to several days.

The adhesive dressing for the transder¬ mic administration of a medicament, object of this invention and aiming to achieve the above-mentioned aim, comprises a reservoir or a matrix containing said medicament, and is characterized in that it comprises an impermeable membranous device in permanent contact or not with said reservoir or matrix, this device being produced in such a way that it becomes permeable in a delayed manner by modification of its physico-chemical structure under the effect of an external stimulus.

The waterproof membrane device can be formed directly from a membrane made of a compound which is itself sensitive to an external stimulus, or else can comprise a membrane made of a neutral, inert and porous material which contains a compound sensitive to a stimulus. outside; it may, for example, be an "off-on" type membrane which can then also be combined with a late layer, for example in the form of a gel.

On the other hand, according to a variant of the invention, the permeable membrane device can constitute a separate, independent element, which is intended to be brought into contact with the reservoir or the matrix in the service position, this reservoir or this matrix being able to be for example a patch of known type and commercially available.

With regard to the material sensitive to an external stimulus, here is meant any compound or mixture of compounds of which at least one physical or chemical property can be modified under the effect of an external stimulus to partially or completely destroy or modify its structure, for example whose physicochemical structure is sensitive to pH, redox equilibrium, ionic strength, etc.

As for the external stimulus, it may be visible or UV light, heat, an electric field. or magnetic, of an electrical impulse, of an oxidizing or reducing gas or liquid, of the contacting of two substances, of direct contact with the skin (secreting sebaceous acid), etc.

By way of examples, a few principles which can be used to carry out the present invention will be mentioned below, more particularly for modifying the permeability or the state of aggregation of the membrane, as well as practical applications of the invention.

(1) pH modification and autocataly ic process

In the case of a pH variation, the principle consists in emitting protons in order to be able to destroy the membrane. This membrane must therefore consist of a structure sensitive to pH.

A polymer having contraction / extension properties can be used for the production of the membrane thanks to its ionizable functional groups. A polymer consisting, for example, of carboxylic groups has an extended structure at basic pH, due to the repulsion of the ionized groups. If we lower the pH, it will curl up because the groups are protonated. The pores of the support, previously blocked by the ionized polymer, then become accessible and the medicament can be delivered. The membrane can also consist of a miscellar / vesicular layer. By changing the pH, the nature of the charge of the head group of the surfactant is varied. This then causes a change in electrostatic forces, and the vesicles are destroyed, making the membrane permeable. The leading groups of surfactants used can be carboxylic, amino, pyridinium or sulfonic groups. Finally, the use of hydrogels containing ionizable groups is also possible. The presence of charged monomers greatly increases the swelling power of these hydrogels. When the ionizable groups are in the neutral form, the hydrogels cannot swell and are impermeable. By changing the pH, the groups ionize and the hydro¬ gels swell due to repulsive forces. The membrane then becomes permeable to the medicinal substance.

(1A) Photo-induced pH change

The principle consists in the use of a photo-induced proton emitter intended to create a significant modification of the pH in order to destroy the membrane of the administration system and allow delayed release of the drug that it contains. Such a system must therefore include a photo-induced proton emitter, and a structure sensitive to pH.

For example, an aryl functional group typically exhibits a ground state pKa = 7-9, while the excited state falls to 0-2; thus, under ideal conditions, a jump in pH to 7 can be induced. Other functional groups such as carboxylic acids or amines exhibit similar effects in different pH ranges. The wavelength of the light serving as a stimulus must correspond to the energy difference between the ground state and the excited state of the photosensitive compound, that is to say that the light stimulus must include at least one wavelength at which the photo-induced proton donor absorbs. For example, aryl alcohols involve a UV light range close to 330 to 450 nm and compounds of the coumarin class from 350 to 500 nm (blue light). Most of these photoinduced proton donors contain -OH groups, such as pyranine (Λ = 400 nm), 7-hydroxycoumarin (X = 400nm) and green bromocresol (A = 630nm), and inject as such protons; similar compounds with -NH2 or -Cθ2 ^{~ groups} can be used, which are proton acceptors.

As for the structure sensitive to a change in pH, it can be in micellar or vesicular form. For example, if we consider a surfactant molecule with a head functional group whose pKa falls in the pH range available for the photoinduced pH jump, the nature of the charge on the head group will change. This change in the electrostatic charge is normally sufficient to destroy the micelles, and thus make the membrane permeable. Surfactants having ionic carboxylic, amino, pyridine, sulfonic or phosphate head groups fall into this category. Another class of usable surfactants are betaines. It is also possible to use polymers which are only stable at neutral pH, the reduction in pH producing hydrolysis of the polymer and making the structure of the latter permeable.

In practice, for the production of the active membrane, it is possible, for example, to use a support layer of an inorganic or organic polymer in contact with a photoinduced proton donor layer. The pH-sensitive layer must therefore contain chemical groups which can be protonated or deprotonated by the photoinduced change in pH, in order to produce the desired modification of the permeability of the layer.

The combination of these two superimposed layers can be obtained by well known techniques. For example, a solution in a volatile solvent of the photoinduced proton donor product can be deposited on the support layer, to form a layer thereof after evaporation of the solvent. The number of layers will depend on the desired goal, that is to say on the desired delay time, thus of course on the concentration of the solution. The thickness of a monomolecular layer will typically be from 20 to 40 Å depending on the dimensions of the functional groups, for example of the aryl chain.

According to another variant, the photo¬ induced proton donor is integrated into the support membrane, for example by reacting this donor with functional groups in or on the surface of a support sensitive to the preexisting pH; alternatively, this pH-sensitive support can be formed simultaneously with the addition of the photoinduced proton donor. For example, a mixture of a polymeric monomer and proton-donating compounds containing polymerizable groups (such as acetylene or arylate groups) is co-polymerized by a conventional technique.

In general, the higher the density of the photoinduced proton donor integrated in the limb, the faster the change in photinduced permeability: this therefore constitutes a possibility of adjusting the duration of the delay effect.

As already mentioned, the pH-sensitive layer should preferably contain an ionizable group such as - NI-2 or -Cθ2 ^~ - After protonization, the hydrophobicity is modified, which tends to "tear" the layer, and its permeability to hydrophilic molecules increases to allow the release of the active principle. Examples of pH-sensitive surfactants are stearic acid (-C0- 2), alkyl sulfates (-0-S020-) such as dodecyl sodium sulfate (SDS), bile salts such as cho- lates (-C02-) or primary, secondary or tertiary amines. Such compounds could for example be incorporated into an inert matrix of polyvinyl chloride. Of course, when the matrix is porous, this matrix must not itself absorb light at the same wavelength as the photoin¬ duxed proton donor compound that it contains.

(1B) Autocatalytic process.

The kinetics of the autocatalytic reactions lends itself particularly well to the initiation of the opening of the membrane with delay effect: after a period of induction, the duration of which is adjustable by a judicious choice of the starting conditions, the rate of formation of the sti¬ mulus grows exponentially to reach its maximum after a well-defined period of time.

Advantageously, the combination of an "off-on" mem¬ brane is used, the pH permeability of which and a retard layer in contact therewith, for example in the form of a hydrogel, the opening of the membrane taking place under the effect of acidification by an autocatalytic process of this retarded layer.

For example, the "off-on" membrane can be formed by a cellulose support on which is grafted an acrylic acid polymer; depending on the pH value, the polymer changes structure and either closes the pores of the support or not.

As for the delay layer, it can be constituted by a hydrolysable ester, preferably in the form of a gel, for example a polyacrylamide gel. The hydrolyzable ester can be a lactone of propionic or gluconic acid. The delay effect is therefore obtained by the hydrolysis of this ester, which tends to acidify the "off-on" membrane in a controlled manner. This process is autocatalytic, since it itself produces the protons necessary for said hydrolysis. As for the primitive source of protons necessary to trigger the process, it results from external stimuli, for example from contact with the reservoir or the matrix containing the drug to be administered.

(2) Modification of the redox balance

Any redox system can be used, including a modification induced for example by chemical or electrochemical means leads to a change in the permeability or the state of aggregation. One can for example choose a molecule comprising a redox head nucleus to which is linked a hydrophobic group ("tail") which allows the formation of micelles or aggregates. As the redox nucleus, it is possible to use, for example, a quinone, a ferrocene, a 4,4'-bipyridine (viologene) or also an organometallic complex such as the complexes of 2,2'-bipyridine and of metals of group VIII. As for the hydrophobic group, it can consist of a long branched or unbranched alkyl chain, of a compound with an aromatic nucleus, or of any other suitable group.

By way of example, mention may be made of FUTMAB (ferrocenylundecyltetramethylammonium bromide). In the reduced form (Fe (II)), the critical micellar concentration (CMC) is 5.10 ^~ 5 M ^~ ^; thus, above this concentration, it is possible to form micelles or a self-associated mono¬ layer on a solid support. The CMC of the oxidized form (Fe (III)) is 6.10 ^-3 M ^-1 , that is to say su¬ higher than that of the reduced form. If the concentration of FUTMAB is higher than the CMC of the reduced form, but lower than that of the oxidized form, then an oxidation induced by an external stimulus will produce the rupture of the micellar or aggregated structure, and thus destroy the impermeable barrier. It is also possible to make a structure permeable by rupture of the disulfide bond which it comprises.

The external stimulus for producing the desired redox modification can be constituted by an electrical contact of the sensitive redox molecule with an electrode, or by a redox-electrochemical reaction for example with a liquid oxidizing agent (for example H2O2) or dissolved in a solvent, or by means of an oxidizing gas, such as oxygen in the air. Finally, as regards more particularly the construction of the membrane, it is preferable for it to be entirely produced with a compound sensitive to the redox equilibrium. This sensitive film or layer can be deposed by any known technique, or else formed by polymerization or chemical fixation in situ, etc.

The duration of the desired delay effect can easily be adjusted as a function of the number of layers or of the thickness thereof. It is also possible to use a microporous support (for example made of polycarbonate or based on cellulose, etc.), the pores of which are filled with a compound sensitive to the redox equilibrium, so that a modification of this balance causes the destruction of this compound and the opening of the pores; in this case, the duration of the delay effect will also depend on the porosity of the support.

(3) Practical applications

The present invention can be applied, for example, to a patch intended to treat angina pectoris and therefore containing as active ingredient nitroglycerin, this basic patch being able to be similar to those already marketed. According to the invention, it will also be provided with an impermeable membrane, and for its use, the patch must be subjected to an external stimulus as described above, before or simultaneously with its placement on the patient's skin, in its position of active service. This stimulus will thus trigger a reaction which will preferably lead in 6 to 8 hours to the destruction of the sensitive membrane, or to the opening of the pores thereof, so the drug in the patch can be released and administered transdermally to the patient. The duration of the delay effect which can be regulated in particular by the number of layers, the thickness of these, or the porosity of the support, will thus allow the patient to apply the patch in the evening before going to sleep, so that its action can start just before waking up the next morning.

In practice, and by way of example, a delay device has been produced according to the invention, in a separated form in the out-of-service position of the reservoir or of the matrix containing the drug to be administered transdermally, here nitroglycerin or trinitrine. One could possibly use as a trinitrine matrix a patch commercially available, for example under the brand "DIA-FUSOR"; such a transdermal device consists of an adhesive diffusion matrix (acrylic polymer, thickener, crosslinking agent) which contains tri¬ nitrine in its mass and of a flexible film support intended for the bonding of the adhesive (material thermoplastic coextruded polyethylene-polyvinylidene), the matrix being protected in the out-of-storage position by a polyvinyl silicone film. This device is designed to transdermally release an average dose of 5 mg, respectively 10 mg, per 24 hours, and has an adhesive surface of 10 cm ^, respectively 20 cm ^, the matrix containing 40 mg, respectively. 80 mg trinitrine.

The delay device according to the invention consists for example of an “off-on” type membrane formed of a cellulose support on which a polymer is grafted acrylic, whose structure is sensitive to pH, this membrane being placed between a delay effect layer and an adhesive layer, these two layers being advantageously in the form of gels and protected in the storage out-of-service position each by a protective film appropriate type known.

The adhesive layer intended to come into contact in service position with the patient's skin, is produced for example in an aqueous acrylic emulsion, such as that known under the brand "GELVA" (Multipolymer Emulsion RA-3011) from the company Monsanto (USA).

As for the delay layer, it can be formed from a polyacrylic gel containing in its mass a hydrolysable ester, such as a lactone of gluconic acid.

Thus, in the case of application to the treatment of angina pectoris, the patient will use, before bedtime, a trinitrin patch, such as those currently marketed or of another type, from which he will remove the film. protective and that it will have on the delay layer of the device according to the invention also previously rid of its protective film; the trinitrin patch-delay device assembly then sticks to the patient's skin after removing the protection from the adhesive layer of the delay device.

Bringing the patch matrix containing the trinitrin into contact with the delay layer of the device according to the invention will then constitute the external stimulus necessary for triggering the process; indeed, the matrix formed of a gel contains approximately 5% of water, and will thus constitute a primary source of protons, the aqueous solution of trinitrine being indeed acidic (approx. pH 4). These protons will trigger the hydrolysis reaction of the lactone present in the delay layer, this reaction being then autocatalytic. The delay layer will then gradually become acidified, and after approximately 6 to 8 hours, reach a pH of less than approximately 4.5, leading to the destruction of the structure of the acrylic polymer grafted on the mem¬ brane "off -on "and open the pores thereof, thus leaving the passage to trinitrin which will have diffused through the retard layer and will reach the patient's skin after passage of the adhesive layer. From this moment, the transdermal administration of the drug is carried out normally, that is to say in the same manner as with a known patch. On the other hand, the start of this administration could be postponed voluntarily by 4 to 8 hours, preferably 6-8 hours, so that the effect of trinitrine can begin before the patient awakens.

Still by way of examples of practical applications, mention may also be made of the use of an adhesive bandage according to the invention for transdermal administration with a delayed effect, for example from 4 to 6 or 8 hours, d '' a sleeping pill, which could be useful for people who must avoid orally absorbing too high a dose of sleeping pill or for those who have a certain addiction to said sleeping pill whose effect is then insufficient over time, or an anti-inflammatory agent, for example for the treatment of polyarthritis.

Of course, the person skilled in the art will have to make sure, in the production of the membrane, to choose the latter so that it does not interfere with the active principle to ad- ministrer or its support, nor presents toxic effects for the patient by contact with the skin or diffusion in it.

Claims

1. Adhesive dressing for the transdermal administration of a medicament comprising a reservoir or a matrix containing said medicament, characterized in that it comprises an impermeable membranous device in permanent contact or not with said reservoir or matrix, this positive being produced in such a way that it becomes permeable in a delayed manner by modification of its physico-chemical structure under the effect of an external stimulus.

2. Dressing according to claim 1, characterized in that said device is a membrane formed by a material sensitive to said external stimulus, so that in the inactive position in the absence of this external stimulus this membrane is waterproof and that in an active position under the effect of the external stimulus its structure is partially or completely destroyed or made permeable.

3. Dressing according to claim 1, characterized in that said device comprises a membrane formed by an inert porous support, the pores of which are blocked in the inactive position by a material sensitive to said external stimulus, so that the structure of this material either destroyed or modified and the pores of the support open in the active position, under the effect of said stimulus.

4. Dressing according to one of claims 1 to 3, charac¬ terized in that said membranous device is ré¬ made of a material or contains a material whose physicochemical structure is sensitive to pH, redox equilibrium or ionic strength, and by the fact that a modification of said pH, of said redox equilibrium or of said ionic strength is triggered by exposure to light, or by the action of an electric current or an oxidizing or reducing agent, to destroy said membrane or make it permeable.

5. A dressing according to claim 4, characterized in that said material comprises a photoinduced proton donor compound capable of emitting protons under the effect of light, and a pH-sensitive compound.

6. Dressing according to claim 5, characterized in that the photoinduced proton donor compound contains hydroxyl groups, such as, for example, pyranines, coumarins and green bromocresol, and that the pH-sensitive compound contains ionizable groups, such as -NH2 or -C02- as for example surfactants, such as alkyl sulfates, stearic acid, bile salts and amines, or betaines.

7. The dressing as claimed in claim 4, characterized by the fact that said material comprises a redox-sensitive head group such as a quinone, a ferrocene, a viologen, or an organometallic complex, linked to a "tail" formed a hydrophobic group, such as an alkyl chain or an aromatic compound.

8. Dressing according to claim 7, characterized in that the redox balance of said head group is liable to be modified under the effect of electrical contact with an electrode, or of an oxidizing agent under liquid form such as H2O2 or gaseous form such as oxygen in the air.

9. Dressing according to one of claims 1 to 3, charac¬ terized in that said membranous device is formed by miscellar or vesicular layers sensitive to said external stimulus.

10. Dressing according to one of claims 1 to 9, charac¬ terized in that said membranous device com¬ carries an "off-on" type membrane combined with a delay effect layer.

11. A dressing according to claim 10, characterized in that said "off-on" membrane is a porous cellulose support on which is grafted a polymer sensitive to pH, and that said delay layer consists of a hydrolysable ester in the form of gel.

12. A dressing according to claim 11, characterized in that it comprises a source of protons intended to be brought into contact in the service position with said retard layer, so as to serve as an external stimulus to trigger the autocatalytic hydrolysis process. of said ester.

13. Dressing according to one of claims 1 to 12, ca¬ characterized by the fact that said membranous device constitutes a separate element intended to be brought into contact with said reservoir, in the service position, this device having on one side of the membrane an adhesive layer intended to come into contact with the skin in the service position.

14. A dressing according to claim 13, characterized in that said separate element also comprises a delay effect layer in permanent contact with said membrane on its face opposite to that comprising the adhesive layer.

15. Dressing according to one of claims 1, 13 or 14, for the delayed administration of nitroglycerin, characterized by the fact that said membrane is produced in such a way that the passage from its impermeable structure to its permeable structure lasts for example 4 to 8 hours from the application of the external stimulus.

16. A dressing according to claim 1 for the delayed administration of a sleeping pill, characterized in that the said membrane is produced so that the passage from its impermeable structure to its permeable structure lasts for example 4 to 6 hours at count from the application of the external stimulus.

17. A dressing according to claim 1 for the delayed administration of an anti-inflammatory agent, characterized in that the said membrane is produced so that the transition from its impermeable structure to its permeable structure lasts for example 4 to 8 hours from the application of the external stimulus.

18. Delay device intended to cooperate in the service position with an adhesive dressing for the transdermal administration of a medicament comprising a reservoir or a support containing said medicament, characterized in that this device comprises an impermeable membrane, this membrane being produced so that it de- comes permeable in a delayed manner by modification of its physicochemical structure under the effect of an external stimulus.

19. Delay device according to claim 18, caracté¬ ized in that it comprises on one of the faces of said membrane an adhesive layer intended to come into contact with the skin in the service position.

20. Delay device according to claim 19, caracté¬ ized in that it also comprises a delay effect layer in permanent contact with said membrane on its face opposite to that comprising the adhesive layer.