Correlation between scores on Continuous Performance Test and plasma concentration for schizophrenic patients on risperidone.

The purpose of the present paper was to evaluate the relationship between plasma antipsychotics concentration and cognitive task performance. This may provide valuable information for rational dosage titration. Literature on the relationship between plasma risperidone (RIS) concentration and performance on the Continuous Performance Test (CPT) remains scarce. Ten patients (four male, six female) were given RIS for more than 1 year. Steady-state plasma concentrations of the parent drug RIS and its active metabolite, 9-hydroxy-risperidone (9-OH-RIS), were measured using specific liquid chromatography-tandem mass spectrometry assay. Psychopathology, side-effects of extrapyramidal symptoms (EPS) and CPT were also assessed. A negative correlation was found between CPT performance and the plasma RIS, 9-OH-RIS and its active moiety (RIS + 9-OH-RIS) concentrations. Both RIS and 9-OH-RIS have an impact on the CPT performance of schizophrenic patients. Optimal active moiety plasma concentration for best cognitive performance needs further study.