Risperidone Treatment of Outpatients with Schizophrenia: No Evidence of Sex Differences in Treatment Response

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Abstract
Objective: Given the renewed interest in the role of sex differences in schizophrenia, we undertook a post hoc analysis to determine whether sex differences in treatment response were present among outpatients with schizophrenia who received risperidone in an 8-week, open-label, Phase IV clinical study. Method: We evaluated 330 adult patients (232 men, 98 women) with a DSM-III-R diagnosis of schizophrenia for safety and 292 (206 men, 86 women) for efficacy. Antipsychotic and antiparkinsonian medications were discontinued at study entry. Treatment with risperidone was initiated at a dosage of 2 mg daily, increased to the target dosage of 6 mg daily by day 3, and maintained at 6 mg daily until day 14. The dosage was then maintained at 6 mg daily, increased or decreased by 2 mg daily each week, based on the patient's response. Risperidone treatment was given for 8 weeks; the permitted dosage range was 4 mg to 10 mg daily. Results: Both male and female participants responded well to risperidone treatment; by the final assessment day, they had experienced decreases from baseline in their total Positive and Negative Syndrome Scale (PANSS) scores of 41.0% and 36.5%, respectively. Most male (77%) and female (78%) participants were considered to be PANSS responders: risperidone was effective against both the positive and negative symptoms of schizophrenia. Both sexes showed improvements over baseline in the incidence and severity of parkinsonism, dystonia, and dyskinesia. No significant (P > 0.05) sex differences in treatment response were observed for any of the efficacy outcomes or in the incidence and severity of extrapyramidal symptoms (EPS). Conclusions: In this population of outpatients with chronic schizophrenia, both men and women responded well to flexible doses of risperidone. No significant sex differences were evident either in treatment response or in neurological side effects. The absence of sex differences in response to risperidone treatment may obviate the need for a sex-based differential dosing in schizophrenia management.