SIMPLIFIED HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC METHOD FOR DETERMINATION OF RISPERIDONE AND 9-HYDROXYRISPERIDONE IN SERUM FROM PATIENTS COMEDICATED WITH OTHER PSYCHOTROPIC-DRUGS

A HPLC method was developed for determination of risperidone and its t herapeutically active main metabolite 9-hydroxyrisperidone in serum. A fter a single-step liquid-liquid extraction the analytes were separate d on a C-18 column and measured by UV detection at 280 nm. Inter-day c oefficient of variation was <7% for both compounds at serum levels occ urring in patients treated with ordinary doses. Studies of analytical interference showed that the most commonly coadministered antidepressa nts and benzodiazepines did not interfere. Some conventional low dose neuroleptics and clozapine did interfere, but this is of minor importa nce, because risperidone is intended as an alternative to these drugs. (C) 1997 Elsevier Science B.V.