A composition for injection into a host is provided according to the embodiments of the present application. The composition consists of microparticles consisting essentially of an opioid antagonist and a polymeric binder selected from the group consisting of poly(glycolic acid), poly-d,l-lactic acid, poly-l-lactic acid, copolymers of the foregoing, poly(aliphatic carboxylic acids), copolyoxalates, polycaprolactone, polydioxanone, poly(ortho carbonates), poly(acetals), poly(lactic acid-caprolactone), polyorthoesters, poly(glycolic acid-caprolactone), polyanhydrides, and polyphosphazines； an injection vehicle, wherein said injection vehicle consists of water, a viscosity enhancing agent, a wetting agent, and a tonicity adjusting agent； and a steroidal anti-inflammatory agent.
