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Comparison of the Effects of Different Routes of Antipsychotic Administration on Pharmacokinetics and Pharmacodynamics

Larry Ereshefsky, Pharm.D., B.C.P.P., F.C.C.P., and Cynthia A. Mascarenas, Pharm.D., M.S.

Clinicians face a dilemma when choosing between short-acting atypical antipsychotics and longacting conventional antipsychotics. Atypical antipsychotics offer better safety and efficacy, while depot formulations of conventional antipsychotics provide more reliable drug delivery, reduced differences in peak and trough plasma levels of drug, and greater dosing precision. Risperidone was recently approved by the U.S. Food and Drug Administration as the first atypical long-acting antipsychotic medication, given as biweekly gluteal injections. This long-acting formulation is synthesized using a microsphere encapsulation process, and gradual hydrolysis of the copolymer encapsulating the drug provides a steady release of medication. Consistent with other long-acting medications, plasma drug level fluctuation is reduced more with long-acting than with oral risperidone. Analyses are currently underway to further examine safety outcomes with long-acting risperidone.

(J Clin Psychiatry 2003;64[suppl 16]:18–23)

From the Departments of Pharmacology and Psychiatry, University of Texas Health Science Center at San Antonio (Dr. Ereshefsky); the Clinical Research Unit, San Antonio State Hospital (Drs. Ereshefsky and Mascarenas); and the College of Pharmacy, University of Texas, Austin (Dr. Mascarenas); California Clinical Trials, Los Angeles (Dr. Ereshefsky).

This article is derived from the teleconference "Partial Compliance: The Need for Long-Acting Atypical Antipsychotics," which was held March 27, 2002, and supported by an unrestricted educational grant from Janssen Pharmaceutica, L.P.

Corresponding author and reprints: Larry Ereshefsky, Pharm.D., University of Texas Health Science Center, 7703 Floyd Curl Dr., MSC6220, San Antonio, TX 78229 (e-mail: