A survey of antipsychotic polypharmacy in outpatients at Nagoya University Hospital

Abstract

Purpose: Antipsychotic polypharmacy has been utilized frequently in the clinical setting despite lack of evidence for its safety or efficacy. In an effort to promote the optimal use of antipsychotic medication, we examined the current state of antipsychotic polypharmacy and the use of excessive doses in outpatients with schizophrenia. Method: The subjects of this study were schizophrenia patients who received oral antipsychotic medications from 1997 to 2007. The patient characteristics and prescription profiles, as well as the dosages, for all medications were obtained from the patients' medical charts. Psychotropic medications were classified into five categories: antipsychotics, antiparkinsonian agents, anxiolytics/sedative hypnotics, antidepressants, and mood stabilizers. The frequency of use and the equivalent doses of each psychotropic drug were summarized and used for correlation analysis. This study was approved by the Ethics Committee of the Nagoya University Graduate School of Medicine. Results: Sixty-four percent of patients on antipsychotic pharmacotherapy received a single antipsychotic drug, and 36% received two or more. Among the 527 patients on monotherapy, 53.5% were prescribed first-generation antipsychotics (FGAs) and 46.5% were prescribed second-generation antipsychotics (SGAs) in the period from 1997 through 2007. Positive correlations between antipsychotics and antiparkinsonian agents were obtained both for the number of drugs (p < 0.01) and the equivalent dosage (p < 0.01); the prescribing rate for antiparkinsonian agents, however, fell significantly from 1997 to 2007 (p < 0.0001). Discussion: These results suggest that the frequency with which antiparkinsonian agents are combined has also decreased due to the increase in the rate at which SGAs are prescribed. Greater awareness among psychiatrists at Nagoya University Hospital of the proper use of antipsychotics has resulted in a reduced prevalence of antipsychotic polypharmacy and less frequent use of excessive dosages.