Controlled release systems and low dose androgens

A pharmaceutical composition comprising a pharmaceutically acceptable diluent or carrier and a plurality of sustained release microspheres having an average size between 5 .mu.m and 40 .mu.m including an active agent dispersed within a sustained-release binder which is biocompatible with human tissues and which undergoes biodegradation in the body into biocompatible metabolic products, wherein said microspheres are capable, under standard conditions, of releasing said active agent during, and as a result of, said biodegradation, of said binder, over a period of at least 28 days, wherein said microspheres have no more than 0.1 percent (by weight relative to total weight of microspheres) of an organic solvent.

A pharmaceutical composition comprising from 10 to 70 percent controlled-release microspheres (by weight relative to total weight of said composition), and further comprising a pharmaceutically acceptable diluent or carrier, wherein said microspheres comprise an androgenic steroid selected from the group consisting of medroxyprogesterone acetate and megestrol acetate, wherein said androgenic steroid is dispersed within a polymeric controlled-release material having hydrolysable ester linkages, the ratio of said androgenic steroid to said controlled release material being between 3:2 and 3:7, wherein said controlled release material is biocompatible with human tissue and capable of undergoing biodegradation in the body into biocompatible metabolic products, wherein said microspheres are capable, under standard conditions, of releasing said androgenic steroid, during and as a result of said biodegradation, at a rate and duration which maintains circulating serum levels of said androgenic steroid between 1.0 and 50.0 nanomoles per liter during a time period beginning 48 hours after administration and ending at least 28 days after administration.