The present invention relates to a risperidone sustained release delivery systemfor treatment of medical conditions relating delusional psychosis, schizophrenia,bipolar disorder, psychotic depression, obsessive-compulsion disorder,Tourette syndrome, and autistic spectrum disorders. The sustained releasedelivery system includes a flowable composition containing risperidone, ametabolite, or a prodrug thereof and an implant containing risperidone, a metabolite,or a prodrug thereof. The flowable composition may be injected into tissue whereuponit coagulates to become the solid or gel, monolithic implant. The flowable compositionincludes a biodegradable, thermoplastic polymer, an organic liquid, and risperidone,a metabolite, or a prodrug thereof.
