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

Clinicians face a dilemma when choosing between short-acting atypical antipsychotics and longactingconventional antipsychotics. Atypical antipsychotics offer better safety and efficacy, whiledepot formulations of conventional antipsychotics provide more reliable drug delivery, reduced differencesin peak and trough plasma levels of drug, and greater dosing precision. Risperidone was recentlyapproved by the U.S. Food and Drug Administration as the first atypical long-acting antipsychoticmedication, given as biweekly gluteal injections. This long-acting formulation is synthesizedusing a microsphere encapsulation process, and gradual hydrolysis of the copolymer encapsulatingthe 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. Analysesare currently underway to further examine safety outcomes with long-acting risperidone.