Effect of risperidone on plasma free 3-methoxy-4-hydroxyphenylglycol (pMHPG) levels in schizophrenic patients: relationship among plasma concentrations of risperidone and 9-hydroxyrisperidone, pMHPG levels, and clinical improvement

Abstract

We examined the relationships among the clinical efficacies of risperidone, plasma concentrations of risperidone and its active metabolite, 9-hydroxyrisperidone, and changes in plasma free MHPG (pMHPG) in 14 schizophrenic patients. Clinical improvement in negative symptoms of schizophrenia treated with risperidone has been associated with increased pMHPG and, in the present study, there were positive correlations between plasma 9-hydroxyrisperidone concentrations and increased pMHPG levels. These results suggest that risperidone might improve negative symptoms in schizophrenia by influencing noradrenergic neurons.