Sublingual buprenorphine, a partial opiate agonist, is a promising new treatment for opiate dependence. A sustained release buprenorphine (SRB) being developed by DrugAbuse Sciences, a pharmaceutical company dedicated exclusively to development of pharmaceuticals for treatment of drug addiction, would have significant advantages over the sublingual tablet for some patients, e.g., better compliance, less potential for diversion, and more likely to be administered in physician office based practice. The objective of the proposed study is to evaluate the safety and pharmacokinetics profile in humans of four SRB formulations. The results will be used to select a formulation of SRB for opiate maintenance. In the proposed phase I study, subjects will first receive a single intmmuscular injection of Buprenex to determine their tolerability of buprenorphine. Sixteen subjects who tolerate buprenorphine will be randomly assigned to receive a single intramuscular injection of 1 of the 4 formulations of sustained release buprenorphine. Blood samples will be collected over 60 days for determination of buprenorphine plasma levels and computation of the pharmacokinetic parameters e.g., Cmax, AUCs for various time intervals of the 4 formulations. The maintenance formulation should provide sustained release of buprenorphine over 15 to 30 days. PROPOSED COMMERCIAL APPLICATION: Buprenorphine, a partial opiate agonist, is not currently approved in the U.S. for managing heroin detoxification and methadone discontinuation. A sustained-release buprenorphine dosage form (SRB) can become a potential alternative to methadone as substitution therapy for opiate dependence. Buprel(TM) is a sustained-release formulation of buprenorphine.