Linear poly(acryloyl-L-proline methyl ester, A-ProOMe), obtained by radiation-induced polymerization of its monomer in ethanol, exhibits a lower critical solution temperature (LCST) of 14°C. A minor amount of 2-hydroxypropyl methacrylate (HPMA) was copolymerized with A-ProOMe to obtain an intelligent biomedical gel for application in drug delivery systems. This gel is characterized by an initial shrinkage at the surface in the deswollen state, that results in formation of a rigid membrane barrier devoid of micropores, namely, a surface regulated matrix. Testosterone (T) was incorporated into this gel and, as a result, it was found that the daily dose of T released in vivo from this formulation remained constant at approximately 30 μg/day throughout an experimental period of 54 weeks.