Adhesive polymer and medical adhesive patch

A medical patch comprising an adhesive composition comprising at least one salt of a basic drug and an adhesive,

• wherein the adhesive is a star-shaped acrylic block polymer having a star-shaped structure in which at least three chain polymer portions radiate from a polyvalent mercaptan residue situated at the center, wherein (meth)acrylic acid alkyl ester structural units having 7-17 carbon atoms account for 30-99.9% by mass of whole structural units of the star-shaped acrylic block polymer, and at least one of the chain polymer portions has a structural unit having a copolymer structure of polymerizable monomers comprising at least one (meth)acrylic acid alkyl ester having 7-17 carbon atoms and at least one weakly basic monomer selected from the group consisting of dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate quaternary ammonium salt, dimethylaminopropyl acrylamide, diethylaminopropyl acrylamide, (meth)acrylamide, N-methyl(meth)acrylamide and N-propyl(meth)acrylamide;
• wherein the at least one salt of the basic drug is at least one selected from the group consisting of fentanyl citrate, morphine sulfate, oxycodone hydrochloride, buprenorphine hydrochloride, oxybutynin hydrochloride, tamsulosin hydrochloride, tolterodine tartrate, rasagiline mesylate, pergolide mesylate, amantadine hydrochloride, trihexyphenidyl hydrochloride, ropinirole hydrochloride, lidocaine hydrochloride, procaine hydrochloride, donepezil hydrochloride, memantine hydrochloride, tandospirone citrate, methylphenidate hydrochloride, lurasidone hydrochloride, chlorpromazine hydrochloride, imipramine hydrochloride, asenapine maleate, salbutamol sulfate, clenbuterol hydrochloride, tulobuterol hydrochloride, procaterol hydrochloride, butorphanol tartrate, perisoxal citrate, enalapril maleate, propranolol hydrochloride, bisoprolol hydrochloride, clonidine hydrochloride, diltiazem hydrochloride, verapamil hydrochloride, isosorbide dinitrate, ketotifen fumarate, chlorpheniramine maleate, azelastine hydrochloride, diphenhydramine hydrochloride, granisetron hydrochloride, ramosetron hydrochloride, palonosetron hydrochloride and ondansetron hydrochloride;
• and
• wherein the adhesive composition does not comprise an additive used for converting the at least one salt of the basic drug into a free base.