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Abstract

A base polymer for transdermal absorption preparation, which is a solid at ordinary temperatures, which becomes a liquid having a low viscosity near the skin temperature of human, which has heat-sensitive and water-sensitive properties as it has a hydrophilic segment, which is capable of stably storing the drug which conventionally has not been easily formulated into a transdermal absorption preparation, and which is capable of effecting transdermal absorption of the drug at a high releasing ratio and yet in a slow-releasing manner with less skin irritation. The base polymer comprises a heat-sensitive segment polyurethane which is represented by the following general formula: R--A--(U)--C--(U)--B--R' wherein A and B each represents a polymer of ethylene oxide, propylene oxide, tetramethylene oxide or 1,2-butylene oxide, or a random or block copolymer thereof, R and R' each represents a terminal H, CH.sub.3, C.sub.2 H.sub.5, C.sub.3 H.sub.7 or C.sub.4 H.sub.9 thereof, and A=B or A.noteq.B, R=R' or R.noteq.R', C represents a constituting structure which is a moiety of a diisocyanate compound excluding two diisocyanate groups, (U) represents a urethane bond, and at least one of A and B is hydrophilic and at the same time at least one of A and B is characterized in that it melts near the temperature of the human skin.

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First Claim