A randomized, double-blind, comparison of the efficacy and safety of low-dose olanzapine plus low-dose trifluoperazine versus full-dose olanzapine in the acute treatment of schizophrenia

Abstract

ObjectiveAntipsychotic polypharmacy is common in clinical practice, but not recommended in guidelines for treating schizophrenia patients. This study aimed to compare the efficacy and safety of low-dose olanzapine plus low-dose trifluoperazine (a first-generation antipsychotic [FGA]) to full-dose olanzapine (a second-generation antipsychotic [SGA]) in the treatment of acute schizophrenia. MethodIn this 6-week, double-blind, fixed-dose study, patients were randomized to receive 5mg/day of olanzapine plus 5mg/day of trifluoperazine or 10mg/day of olanzapine for 6weeks. Efficacy measures, including the Positive and Negative Syndrome Scale (PANSS) and other scales, safety measures, side effect measures, and quality of life were assessed regularly. Response was defined as at least a 30% reduction in the PANSS total score. ResultsBoth groups were similar in: 1) baseline characteristics, 2) score changes in all efficacy measures, safety measures, side effect measures, and quality of life, and 3) response rates at each visit. The polypharmacy group with low-dose olanzapine did not have less weight gain and lower lipid levels than the monotherapy group with full-dose olanzapine. ConclusionPolypharmacy is as efficacious and safe as, but cheaper than, monotherapy in the acute treatment of schizophrenia. Whether our findings can be generalized to other combinations of an appropriate ratio of one FGA to another SGA dosage, which can achieve favorable clinical responses and side effect profiles, needs further investigation.