A pharmaceutic composition includes a pharmaceutically acceptable carrier, comprising a reverse thermally viscosifying polymer. The polymer includes a linear block copolymer, wherein at least one block comprises a poloxamer; and at least one block comprises a biocompatible polymer or oligomer, in an aqueous medium. The composition also includes an active agent which imparts a pharmaceutic or cosmetic effect. The composition viscosifies in response to an environmental stimulus. The composition is suitable for administration of the pharmaceutical agent across dermal, otic, rectal, vaginal, ophthalmic, esophageal and nasal mucosal membranes.