Preparation of plaster

PURPOSE:A plaster having improved releasing properties of a drug to the surface of the body obtained by spraying or coating thinly the surface of a pressure-sensitive adhesive layer formed on a substrate with a drug-containing polymerizable solution, followed by irradiating it with inonizing radiation or ultraviolet rays. CONSTITUTION:A pressure-sensitive adhesive layer is formed on a substrate, e.g., plastic film, etc. by a well-known method, to give the surface of the pressure-sensitive adhesive layer, which is sprayed or coated thinly with a polymerizable monomer solution comprising a drug to be transferred or absorbed into the surface of the body and optinally an auxiliary to release the drug. The prepared layers are irradiated with ionizing radiation or ultraviolet rays to form discontinuously or partially drug-containing thin films on the surface of the pressure-sensitive adhesive layer which is chemically strongly integrated with the thin films. The plaster thus obtained has no problem in handling caused by falling off, etc. and has good releasing properties of drug to the surface of the body, it is useful for administrating the medicine to the affected part of the body and the circulatory system.