clinicaltrials.gov Identifier: NCT01421342.

Objective This randomized trial addressed risks and benefits of staying on antipsychotic polypharmacy versus switching to monotherapy. Method Adult outpatients with schizophrenia taking two antipsychotics (127 participants across 19 sites) were randomly assigned to Stay on Polypharmacy or Switch to Monotherapy by discontinuing one antipsychotic. The trial lasted for 6 months, with a 6-month naturalistic follow-up. Kaplan-Meier and Cox regression analyses examined time to discontinuation of assigned antipsychotic treatment, and random regression models examined additional outcomes through time. Results Individuals assigned to Switch to Monotherapy had shorter times to all-cause treatment discontinuation than those assigned to Stay (p <.05). By month 6, 86% (n=48) of those assigned to Stay on Polypharmacy were still taking both medications whereas 69% (n=40) of those assigned to Switch to Monotherapy were still taking that monotherapy. Most monotherapy discontinuations entailed returning to the original polypharmacy. Groups did not differ with respect to psychiatric symptomatology or hospitalizations. The monotherapy group lost weight whereas the polypharmacy group gained weight. Conclusions Discontinuing one of two antipsychotics was followed by treatment discontinuation more often and more quickly than when both antipsychotics were continued. However, two thirds of participants successfully switched, groups did not differ with respect to symptom control, and switching to monotherapy resulted in weight loss. This supports the reasonableness of prescribing guidelines encouraging trials of antipsychotic monotherapy for individuals receiving antipsychotic polypharmacy, with the caveat that individuals should be free to return to polypharmacy if an adequate trial on antipsychotic monotherapy proves unsatisfactory.

The results of this study support previous reports of the frequent use of combination antipsychotic therapy in clinical practice. Prospective controlled trials are needed to substantiate perceptions that combination antipsychotic therapy is clinically beneficial and to provide guidelines on when and for whom antipsychotic polypharmacy should be considered.

Concomitant use of psychotropic medications to treat people with schizophrenia is common. Empirical data demonstrating the effectiveness of many of these agents for this population are lacking.