Abstract: Nontoxic sustained release pharmaceutical compositions containing one or more nonionic, lipophilic drugs in a cured low temperature vulcanizable (LTV) silicone elastomer excipient are prepared substantially free of toxic vulcanizing agents or drug-reactive by-products in the elastomeric material by curing an admixture of the drug or drug containing core, LTV-methylvinylsiloxane units containing linear dimethylpolysiloxane and a dimethylpolysiloxane crosslinking composition containing silicon linked H atoms using a noble metal-based catalyst. The resultant compositions are characterized by good physical properties and a constant rate of drug release in the body over long periods of time.