JPH0772131B2 - External patch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention increases the ability to absorb a drug that has excellent adhesion to the skin and is transdermally absorbed into the body from the skin.
The present invention relates to an external patch for treating diseases.

(B) Conventional Technology In recent years, many attempts have been made to administer a drug transdermally in vivo using a sheet-shaped patch for external use and thereby treat a disease regardless of whether it is systemic or local. Has been done.

However, most of these patches are those in which a pressure-sensitive adhesive containing a drug is applied to one side of a substrate, and generally 12 to 24 hours are applied, but 70% or more after application. The drug remains in the tape.

Therefore, it is extremely uneconomical because the drug must be contained in many times the amount actually required for treatment.

Therefore, in order to solve this problem, the following proposals have been made.

The first proposal is to use occlusive bandage therapy (so-called ODT therapy) to treat the disease.

That is, an external drug such as an ointment is applied to the skin, and this is covered with a non-breathable film to effectively percutaneously absorb the drug.

As a second proposal, a pressure-sensitive adhesive containing a drug is provided on one surface of a substrate film via a pressure-sensitive adhesive layer containing no drug, and the total amount of these two adhesive layers is 20
˜100 μm (Japanese Patent Publication No. 60-5569).

The third proposal is 5 to 20% in the longitudinal direction and 50 to 150 in the weft direction.
%, And a thickness of polyurethane elastic layer on one side of the woven fabric which is specified in the range of 0.05 to 0.5 mm before stretching.
It is made by applying a plaster on a stretchable base cloth having a thickness of 0.01 to 0.1 mm (Japanese Utility Model Publication No. 47-19479).

(C) Problems to be Solved by the Invention However, in the above-mentioned first proposal, not only is the procedure such as attachment to the affected area cumbersome but also bulky or easily peeled off, and the area of the affected area is large or the affected area is large. When the shape is complicated or the affected part expands and contracts, there is a problem that it is difficult to adhere to the affected part.

In the above second proposal, the concentration of the drug on the adhesive surface side to the skin in the adhesive layer is high compared to the method of containing the drug in the entire adhesive layer in a uniform concentration, and as a result, the external patch is The absorption rate from the skin is increased due to the large concentration gradient between the drug concentration on the surface and the skin surface, but there are the following problems.

That is, for a drug having a high diffusion rate in the adhesive layer, the drug diffuses and moves between the time after the external patch is manufactured and the time it is used. The drug concentrations on the surface side and the base material film side are substantially the same, and eventually there is no point in forming two layers. by the way,
This problem can be prevented to some extent by a drug having a low diffusion rate, but if the diffusion rate of the drug is low, there is a problem that the drug efficacy is not sustained.

Therefore, in order to solve these problems all at once, as a drug-free pressure-sensitive adhesive that is interposed between the base material and the drug-containing pressure-sensitive adhesive layer, the drug distribution rate is low and diffusion of the drug occurs. Although it is necessary to select a difficult one, selection of such an adhesive is actually quite difficult and lacks in practicality.

The third proposal is one in which a polyurethane elastic body layer having a thickness of 0.01 to 0.1 mm is provided on one side of a stretchable woven fabric,
Moreover, this polyurethane elastic layer is not formed of a foam, but is formed by a melting method or by applying a liquid dissolved in a solvent.

That is, in the third proposal, not the foam, but the elastic polyurethane layer is interposed to follow the stretchability of the stretchable woven fabric, and the stretchable woven fabric is stretched in the surface direction according to the movement of the skin surface. However, since this polyurethane elastic layer is not a foam, the cushioning property in the thickness direction is insufficient,
As a result that the function as a buffer cannot be fully exhibited, it is necessary to increase the thickness of the plaster.

However, if the plaster is thickened in this way, the drug inside the plaster will not be effectively used, so it is necessary to add many times the drug in advance to the amount required for actual treatment, which is extremely unfavorable. There are problems such as the economy.

(D) Means for Solving the Problems The inventors of the present invention have diligently studied to improve these drawbacks, and as a result, interpose a foam between the base material and the drug-containing pressure-sensitive adhesive layer. As a result, it was found that even if the pressure-sensitive adhesive layer containing a drug is thinned, an external patch having excellent adhesion to the skin and a high drug utilization rate can be obtained. Has been completed.

That is, the present invention is a patch wherein a pressure-sensitive adhesive layer is provided on one surface of a substrate via a foam made of a soft synthetic resin mainly composed of closed cells or open cells, Foam made of soft synthetic resin has a compression hardness of 0.005-1 kg / cm ² (JI
(Measured by the method according to SK 6767) and having a thickness of 3 mm or less, and moreover, the adhesive layer contains a transdermally absorbable drug.

Hereinafter, the present invention will be described in detail.

The substrate used in the present invention can be used without particular limitation as long as it is a film or sheet formed of a material having flexibility, and a preferable specific example thereof will be shown.
Polyethylene, polypropylene and other polyolefins, polyester, ethylene-vinyl acetate copolymer, soft polyvinyl chloride, polyurethane, polyvinyl alcohol, polyamide and other films and sheets, rubber and / or synthetic resin foam sheets / films, non-woven fabrics, woven fabrics , Paper, metal foil, laminated films or sheets of these, and the like.

The foam used in the present invention includes polyolefins such as polyethylene and polypropylene, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyurethane, polystyrene, silicon rubber, ethylene propylene terpolymer, chloroprene rubber, nitrile rubber, polybutadiene. A flexible synthetic resin foam mainly composed of other closed cells or open cells and having flexibility is used.

This foam is appropriately selected and used according to the application site, but it is necessary that the compression hardness is in the range of 0.005 to 1 kg / cm ² (measured by the method according to JIS K6767).
Particularly, the range of 0.01 to 0.7 kg / cm ² is desirable.

When the compressive strength is 1 kg / cm ² or more, the cushion elasticity is poor,
The thickness of the pressure-sensitive adhesive layer cannot be reduced, so that not only the utilization rate of the drug cannot be improved but also it is impossible to follow the expansion and contraction of the skin during exercise after application. . On the other hand, if it is less than 0.005 kg / cm ² , it is not practical because it is difficult to process and it is difficult to obtain commercially.

That is, the present inventor has provided a drug-containing pressure-sensitive adhesive layer containing a transdermal drug on one surface of a substrate via a soft synthetic resin foam mainly composed of closed cells or open cells. When repeated experiments were carried out, the soft synthetic resin foam had a compression hardness measured by a method according to JIS K 6767,
0.005~1kg / cm ^2, especially in the range required to be in the range of 0.01~0.7kg / cm ^2, it was confirmed that there is no practical except in this range.

Also, if the thickness is 3 mm or more, it tends to peel off due to friction with clothes when applied to the skin, and it is necessary to increase the thickness of the drug-containing pressure-sensitive adhesive layer in order to obtain skin adhesion that overcomes the frictional force of clothes etc. Which is contrary to the object of the present invention.

Therefore, a particularly preferred thickness of the foam is in the range 0.1-1.5 mm.

The pressure-sensitive adhesive pressure-sensitive adhesive layer used in the present invention is not particularly limited as long as it has pressure-sensitive adhesiveness at room temperature, but in consideration of stability and release of the contained drug. It is desirable to select it.

Specific examples of the pressure sensitive adhesive pressure-sensitive adhesive layer include the following.

First, a layer formed of an acrylic pressure-sensitive adhesive having a pressure-sensitive adhesive property.

Examples of the acrylic pressure-sensitive adhesive adhesive include (meth) acrylic acid butyl ester, (meth) acrylic acid pentyl ester, (meth) acrylic acid hexyl ester, (meth) acrylic acid hepsil ester, (meth)
Acrylic octyl ester, (meth) acrylic acid nonyl ester, (meth) acrylic acid decyl ester, (meth) acrylic acid undecyl ester, (meth) acrylic acid dodecyl ester, (meth) acrylic acid tridecyl ester, (meth) Homopolymers of (meth) acrylic acid alkyl ester such as acrylic acid tetradecyl ester,
Alternatively, a copolymer with another monomer copolymerizable with the ester may be used.

Examples of the other copolymerizable monomer include (meth)
Carboxyl group-containing monomers such as acrylic acid, itaconic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, styrene sulfonic acid, allyl sulfonic acid, sulfopropyl acrylate, (meth) acryloyloxynaphthalene sulfonic acid, acrylamidomethyl Sulfoxyl group-containing monomers such as propane sulfonic acid and acryloyloxybenzene sulfonic acid, hydroxyl group-containing monomers such as (meth) acrylic acid hydroxyethyl ester and (meth) acrylic acid hydroxypropyl ester,
Amide group-containing acrylic monomers such as (meth) acrylamide, dimethyl (meth) acrylic acid amide, N-butylacrylamide, tetramethylbutylacrylamide, N-methylol (meth) acrylamide, (meth) acrylic acid aminoethyl ester, (Meth) acrylic acid dimethylaminoethyl ester, (meth) acrylic acid diethylaminoethyl ester, (meth) acrylic acid tert-
Alkylaminoalkyl group-containing acrylic monomer such as butyl ester, (meth) acrylic acid methoxyethyl ester, (meth) acrylic acid ethoxyethyl ester,
(Meth) acrylic acid butoxyethyl ester, (meth)
Acrylic acid tetrahydrofurfuryl ester, (meth)
Amount containing alkoxy group (or ether bond in side chain) such as acrylic acid methoxyethylene glycol ester, (meth) acrylic acid methoxydiethylene glycol ester, (meth) acrylic acid methoxypolyethylene glycol ester, (meth) acrylic acid methoxypropylene glycol ester Body, vinyl-based monomers such as N- (meth) acryloylamino acid, functional monomers such as acrylic monomers such as urethane of acrylic acid, urea and isocyanate ester, and (meth) acrylonitrile, vinyl acetate, Vinyl propionate, vinylpyrrolidone, vinylpyridine, vinylpyrazine, vinylpiperazine, vinylpiperidone, vinylpyrimidine, vinylpyrrole,
Examples thereof include vinyl-based monomers such as vinylimidazole, vinylcaprolactam, vinyloxazole, vinylthiazole, vinylmorpholine, styrene, α-methylstyrene, and bis (N, N′-dimethylaminoethyl) maleate.

In the present invention, the above-mentioned (meth) acrylic acid alkyl ester and other monomers copolymerizable therewith are various linear and branched isomers having an alkyl moiety, and various isomers having different substituent positions. And derivatives are also included.

As other pressure-sensitive adhesive pressure-sensitive adhesive used in the present invention,
For example, silicone rubber, polyisoprene rubber, polyisobutylene rubber, polybutadiene, styrene-butadiene (or isoprene) -styrene block copolymer rubber,
Acrylic rubber, rubber-based materials such as natural rubber, polyvinyl alkyl ether, polyvinyl acetate, partially saponified polyvinyl acetate, polyvinyl alcohol, vinyl-based polymeric materials such as polyvinylpyrrolidone, methyl cellulose,
Cellulose derivatives such as carboxymethyl cellulose and hydroxypropyl cellulose, pullulan, dextrin, polysaccharides such as agar, polyurethane elastic bodies, polyester elastic bodies, polyacrylic acid (or salts thereof),
Water-containing gel-like mixture of polymethacrylic acid (or a salt thereof), water-soluble acrylic polymer such as carboxyvinyl polymer, polyhydric alcohol such as glycerin, crosslinking agent such as triglycidyl isocyanate, and water Can also be used.

Also, when using the above composition, if there is a possibility that adhesive residue phenomenon may occur on the applied skin surface to cause contamination of the skin surface after sticking to the skin due to lack of cohesive force, do not impair the skin adhesiveness It is preferable to subject the composition to moderately appropriate chemical crosslinking or physical crosslinking treatment.

Examples of such chemical crosslinking treatment include divinylbenzene, ethylene glycol di (meth) acrylate,
Trimethylolpropane tri (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, glycidyl (meth) acrylate vinyl group, acryloyl group, or glycidyl group A treatment method of copolymerizing a monomer having two or more reactive groups in the molecule, an organic peroxide such as benzoyl peroxide, an isocyanate crosslinking agent,
Examples of the treatment method include the addition of an external crosslinking agent such as a melamine-based crosslinking agent, an epoxy-based crosslinking agent, and a metal compound.

Further, the physical crosslinking treatment includes, for example, electron beam, β ray, γ
Examples of the method include irradiation with ionizing radiation such as X-rays and X-rays, irradiation with ultraviolet rays after addition of an ultraviolet absorber.

Further, the transdermal drug used in the present invention is a drug which may be percutaneously absorbed into the living body to exert a pharmacological effect when the external patch is applied to the outer skin. If present, either local or systemic drugs are used.

Examples of such drugs include those listed below, and two or more of these drugs may be used in combination as necessary.

B) Corticosteroids: for example, hydrocortisone, prednisolone, beclomethasone propionate,
Flumethasone, triamcinolone, triamcinolone acetonide, fluocinolone, fluocinolone acetonide, fluocinolone acetonide acetate, clobetasol propionate, etc., b) analgesic anti-inflammatory agents: eg acetaminophen, mefenamic acid, flufenamic acid, indomethacin, diclofenac, diclofenac. Sodium, alclofenac, oxyphenbutazone, phenylbutazone, ibuprofen, flurbiprofen, salicylic acid, methyl salicylate, 1-menthol, camphor, sulindac, tolmetin sodium, naproxen, fenbufen, etc. Barbital, amobarbital, cyclobarbital, triazolam, nitrazepam, lorazepam, haloperidol. , D) tranquilizers: for example fluphenazine, Teoritajin, diazepam, full diazepam, flunitrazepam,
Haloperidol, chlorpromazine, etc. e) antihypertensive agents: eg clonidine, clonidine hydrochloride,
Pindolol, propranolol, propranolol hydrochloride, bufuranolol, indenolol, nivadipine, nimodipine, lofedixin, nitrendipine, nipradilol, bucumolol, nifedipine, etc.)) antihypertensive diuretics: eg hydrothiazide, bendroflumesiazide, cyclopentiazide, to) antibiotics Substances: eg penicillin, tetracycline,
Oxytetracycline, fradiomycin sulfate, erythromycin, chloramphenicol, etc.) Anesthetics: eg lidocaine, dibucaine hydrochloride, benzocaine, ethyl aminobenzoate, etc.)) Antibacterial substances: eg benzalkonium hydrochloride, nitrofurazone, nice titanium , Acetosulfamine, clotrimazole, etc.)) antifungal substances: eg pentamycin, amphotericin B, pyrrolenitrin, clotrimazole, etc.) vitamin agents: eg vitamin A, ergocalciferol, cholecalciferol, octothiacin, Riboflavin butyrate, etc. w) Antiepileptic agents: eg nitrazepam, meprobamate, clonazepam, etc. w) Coronary vasodilators: eg nitroglycerin, nitroglycol, isosorbidodina Trait, erythritol tetranitrate, pentaerythritol tetranitrate, such as prop-chill nitrate, f) antihistamines: e.g. diphenhydramine hydrochloride,
Chlorpheniramine, diphenylimidazole, etc. yo) Antitussives: For example, dextromethorphan hydrobromide, terbutason sulfate, ephedrine, ephedrine hydrochloride, salbutamol sulfate, isoproterenol hydrochloride, isoproterenol sulfate, etc. Ta) sex hormones: for example progesterone , Estradiol, etc.) Anti-depressants: eg doxepinso) Cerebral circulation improvers: eg hydergine, ifenprodil, etc.) Anti-emetics, anti-ulcer agents: eg metoclopramide, crevopride, domperidone, scopolamine, scopolamine hydrobromide etc. , Ne) Biomedical: Polypeptides (derivatives of TRH and LHRH), prostaglandins, etc. Na) Others: For example, fentanyl, digoxin, desmopressin, dihydroergotamine methanesulfone ,
Dihydroergotamine tartaric acid, 5-fluorouracil,
Examples include mercaptopurine.

If desired, these drugs can be used in a mixed system with a compounding agent such as a dissolving agent. Examples of the solubilizer include benzyl alcohol, butyl benzoate, isopropyl myristate, octanol, 1,3-butanediol, propylene glycol, crotamiton, polypropylene glycol, ethylene glycol and glycerin.

The mixing ratio of the pressure-sensitive adhesive and the drug is different depending on the type and amount of the pressure-sensitive adhesive and the drug to be used, but usually the ratio of the drug in the mixture of both is in the range of 0.1 to 30% by weight. It is preferable to adjust so that

The most important feature of the present invention is that a drug-containing pressure-sensitive adhesive layer is formed on one surface of the above-mentioned base material via the above-mentioned foam, whereby the intended purpose can be achieved.

As a method for providing the drug-containing pressure-sensitive adhesive layer on the above-mentioned base material via a foam, the foam is adhered to the base material by a method such as heat adhesion in advance, and the drug-containing pressure-sensitive adhesive is directly attached to the foam side. A conventional method such as a method in which a release agent formed by coating an adhesive layer containing a drug on a release paper is superposed on a bonded body of a base material and a foam instead of applying the agent Means can be appropriately selected and adopted.

If the surface of the foam is rough or the applied drug-containing adhesive is likely to be absorbed inside, it may be flexed between the foam and the drug-containing adhesive layer if necessary. It is preferable to interpose a transparent film or the like.

The thickness of this drug-containing pressure-sensitive adhesive layer is designed in consideration of the types of drugs and pressure-sensitive adhesives to be combined, the solubility of the drug, etc., but it is possible to reduce the thickness by the cushioning effect of the foam.
Therefore, the thickness is sufficient to be about 1 to 30 μm, and 1 to 20 μm is preferable for a drug having a relatively low diffusion rate in the pressure-sensitive adhesive layer.

(E) Action Generally, the external patch varies depending on the application site, the type of the adhesive or base material used, but in order to obtain sufficient adhesiveness when applied to the stretchable or flexed site of the skin, the thickness of the adhesive layer In many cases, 40 μm or more is required. However, considering from the mechanism of adhesion to the skin, it is the part having a thickness of up to about 5 μm from the surface that actually acts as an adhesion function, and the inside from that is the above surface layer (thickness about 5 μm)
Is believed to act as a buffer to help adhere well to the adherend. Therefore, by substituting the thickness of the portion functioning as the buffer body from the pressure-sensitive adhesive with the foam, it has the effect of exerting the function as a patch without impairing the adhesiveness as a whole.

Further, by interposing a foam between the base material and the drug-containing pressure-sensitive adhesive layer, the drug-containing pressure-sensitive adhesive layer can be made thin, and as a result, the drug in the drug-containing pressure-sensitive adhesive layer can be reduced. It also has the effect of increasing the concentration and improving the transdermal absorbability of the drug and the utilization rate of the drug.

In the present invention, in particular, as a soft synthetic resin foam mainly composed of closed cells or open cells, JIS K
The compression hardness is 0.005-1kg / c as measured by the method according to 6767.
Since it has a m ² range, it has excellent cushion elasticity, which makes it possible to reduce the thickness of the adhesive layer and improve the drug utilization rate, as well as to expand and contract the skin during exercise after application. It can be followed, is easy to process, and has a practical effect.

(F) Examples Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited thereto.

In the examples, all parts or% mean parts by weight or% by weight.

Example 1 95 parts of 2-ethylhexyl acrylate and 5 parts of acrylic acid were charged into a flask under an inert gas atmosphere, 0.3 part of azobisisobutyronitrile was added as a polymerization initiator,
Polymerization was carried out in ethyl acetate while maintaining the temperature at about 60 ° C. to obtain an acrylic pressure-sensitive adhesive solution (solid content concentration 25%).

1 part of corticosteroid fluocinolone acetonide was added to and mixed with 99 parts of the solid content of the obtained acrylic pressure-sensitive adhesive solution, and coated on release paper so that the coating thickness after drying was 10 μm. Dried.

The content of fluocinolone acetonide, which is a corticosteroid, in the acrylic pressure-sensitive adhesive layer thus obtained was 10 μg / cm ² .

Next, a 30 μm thick ethylene vinyl alcohol (vinyl alcohol content 19%) film was used as the base material.
On this one side, density 0.2g / cm ³ (measured by the method according to JIS K 6767, the same below), compression hardness 0.6kg / cm ² (measured by JIS K 6767, the same below), tensile strength 4kg / cm ² (JIS K According to the method of the present invention, a polybutadiene foam having a thickness of 400 μm was thermally laminated, and the drug-containing pressure-sensitive adhesive layer formed on the release paper was transferred to the surface of the foam. To obtain a patch for external use.

Example 2 Acrylic acid-2- was placed in a flask under an inert gas atmosphere.
Ethylhexyl 60 parts, 2-methylethyl acrylate 15
And 25 parts of vinyl acetate were added, 0.3 part of benzoyl peroxide was added as a polymerization initiator, and the temperature was adjusted to about 6 in ethyl acetate.
Polymerization was carried out while maintaining the temperature at 0 ° C to obtain a solution of an acrylic pressure-sensitive adhesive (solid content concentration 30%).

To 80 parts of the solid content of this solution, 20 parts of diclofenac, which is an analgesic and anti-inflammatory agent, was added and mixed, and the coating thickness after drying was 20μ.
It was coated on a release paper so as to be m and dried. The content of diclofenac, an analgesic and anti-inflammatory agent, is 400 μg / cm ² .

Next, using a net-shaped rayon non-woven fabric of 30 g / m ² as a base material, a density of 0.024 g / cm ^{3 on} one side, a compression hardness of 0.03 kg / cm ² ,
A soft polyurethane foam having a tensile strength of 1.1 kg / cm ² and a thickness of 1 mm is heat-bonded, and the drug-containing pressure-sensitive adhesive layer formed on the release paper is transferred to the surface on the foam side, and the external patch of the present invention Got

Example 3 100 parts of styrene-isoprene-styrene block copolymer (Califlex TR-1107, manufactured by Shell Chemical), 80 parts of liquid paraffin, 80 parts of petroleum-based resin (Alcon P = 100, manufactured by Arakawa Chemical Co., Ltd.) and polyisobutylene. (Polybutene HV-30
(0, made by Nisseki) 20 parts by melting and mixing, and 10 parts of methyl salicylate, which is an analgesic and anti-inflammatory agent, is added and mixed with 100 parts of this adhesive, and the coated thickness after cooling is 20 μm. Was applied to. The content of methyl salicylate in this adhesive layer is
It is 200 μg / cm ² .

Next, using polyester and nylon blend nonwoven (40g / m ²⁾ as a substrate, density of 0.03 g / cm ³ on one surface thereof, a compression hardness 0.12 kg / cm ^2, tensile strength 1.0 kg / cm ^2, thickness 2mm Polyethylene foam of 30 μm thick urethane film (5
% Modulus 40 g / cm) were sequentially laminated, and the drug-containing pressure-sensitive adhesive layer formed on the release paper was transferred to the polyurethane film surface side to obtain the external patch of the present invention.

Comparative Examples In Examples 1 to 3, those having a structure in which the foam was removed from the external patch were obtained as Comparative Examples 1 to 3, respectively.

Reference Example In Comparative Examples 1 to 3, reference examples were those in which the amount of drug per unit area was not changed, that is, the concentration was lowered to make the thickness of the adhesive layer 50 μm.

Table 1 shows the evaluation results of the patches of the above Examples, Comparative Examples and Reference Examples.

Evaluation method 1. Sticking property Each sample piece (4 x 4 cm) was stuck on the back of a human body, and after 4 hours, the state of adhesion to the skin was visually evaluated according to the following criteria.

The numerical values in Table 1 are average values of 10 samples.

5 points ... Complete adhesion 4 points ... 80% or more adhesion 3 points ... 60% or more adhesion 2 points ... 60% or less adhesion 1 point ... Drop or less than 20% adhesion 2. Water release Each sample piece (2 cm x 2 cm) Is immersed in 400 ml of distilled water at 30 ° C, stirred, and 5m of the liquid is added at each of 1, 5, 10, and 24 hours after immersion.
l was sampled, the drug concentration was measured, and the release rate was calculated assuming that the initial drug content was 100%.

3. Skin transfer rate and residual rate When the test piece attached in the patch test is collected and the amount of the drug remaining in the collected test piece is quantified by gas chromatography, the content in the unattached sample is set to 100%. The ratio of is the residual rate. Further, the reduced amount was defined as the skin transfer rate.

From Table 1, each example is comparable to each comparative example and each reference example, and the skin migration rate is about 2 to 7 of the reference example.
It was confirmed that the transfer rate to the skin was extremely high.

(G) Effect of the Invention The patch for external use of the present invention has the above-mentioned constitution, and since the foam acts as a buffer against the stretchable portion and the bent portion of the skin, the pressure-sensitive adhesive layer should be thickened. As a result, even if the pressure-sensitive adhesive layer is thinned, the external patch applied to the outer skin does not peel off during exercise, etc. It is possible to improve the transdermal absorbability by increasing the concentration of the drug in the drug layer, and because the adhesive layer can be made thin, the drug with poor diffusion properties has a high migration rate to the skin, which is extremely excellent. It has a pharmacological effect.

And in the present invention, in particular, as a soft synthetic resin foam mainly composed of closed cells or open cells, JIS
The compression hardness is 0.005-1kg as measured by the method according to K 6767.
Since the material used is in the range of / cm ² , the cushion elasticity is excellent, and the adhesive layer can be thinned to improve the drug utilization rate. Since it has excellent cushion elasticity and the thickness of the adhesive layer is thin, it can easily follow the expansion and contraction of the skin during exercise after application, so there is no discomfort such as a feeling of tension during use, and it is excellent in usability. In addition, it is easy to process and practical, and is extremely excellent as an external patch.

Claims (2)

[Claims] 1. A patch comprising a pressure-sensitive adhesive layer provided on one surface of a base material through a foam made of a soft synthetic resin mainly composed of closed cells or open cells, which is a soft material. The synthetic resin foam has a compression hardness of 0.005 to 1 kg / cm ² (JIS
K 6767) and a thickness of 3 mm or less, and the adhesive layer contains a transdermally absorbable drug. 2. The pressure-sensitive adhesive pressure-sensitive adhesive layer has a thickness of 1 to 30.
The patch for external use according to claim 1, which has a thickness of μm.