Antipsychotic polypharmacy: a survey of discharge prescriptions from a tertiary care psychiatric institution.

OBJECTIVE: To perform a retrospective survey of discharge medications at a tertiary care psychiatric facility and to assess the incidence of antipsychotic polypharmacy.
METHOD: This is a retrospective survey that used the Department of Pharmacy's computer database to obtain relevant discharge information on all nongeriatric patients with schizophrenia discharged from Riverview Hospital between November 1, 1996 and October 31, 1998. From a total of 492 eligible patients, 229 met the inclusion criteria and formed the database for the survey.
RESULTS: The main finding of the survey was that 27.5% of our discharged patients diagnosed with schizophrenia left our facility on an antipsychotic polypharmacy regimen. Compared with patients discharged on a single antipsychotic, the pooled data revealed a significantly greater use of anticholinergic agents in those patients prescribed an antipsychotic polypharmacy regimen. Further, of the atypical agents, only risperidone showed a statistically significant reduction in dosage when coprescribed with a second antipsychotic.
CONCLUSION: Although antipsychotic polypharmacy persists today, as it has over the past 30 years, evidence-based data to support this controversial treatment strategy is lacking. As a result clinicians are relying on their clinical experience, and perhaps intuition, to design antipsychotic polypharmacy treatment protocols. Efforts should be made to replace subjective clinical impression with a more rational approach to antipsychotic polypharmacy--one that is based on pharmacodynamic and pharmacokinetic understanding of drug action.