Letter to the Editor July 15, 2005

Allergic Reaction to Depot Risperidone but Not to Oral Risperidone

Roy R. Reeves, DO, PhD; James E. Mack, PhD

J Clin Psychiatry 2005;66(7):949-949

Article Abstract

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Sir: Oral risperidone is an effective and well-tolerated atypicalantipsychotic1 that has been in widespread clinical usage forover 10 years. In recent years, a long-acting injectable form ofdepot risperidone with a delivery system different from otherdepot antipsychotics became available in the United Statesfollowing several years of marketing in other countries. Thisformulation consists of risperidone microencapsulated in 7525polylactide-co-glycolide (PLG) at a concentration of 381 mgof risperidone per gram of microspheres2; the PLG slowly hydrolyzesto release risperidone, allowing administration every2 weeks.