The present invention provides compositions, methods, and kits for administration of nalmefene for treatment of alcoholism, nicotine dependence, or another condition for which treatment with nalmefene is therapeutically beneficial. The invention provides a biocompatible nonerodible polymeric device which releases nalmefene continuously with generally linear release kinetics for extended periods of time. Nalmefene is released through pores that open to the surface of the polymeric matrix in which it is encapsulated. The device may be administered subcutaneously to an individual in need of continuous treatment with nalmefene.