Risperidone

Abstract

Since the introduction in 1993 of the novel serotonin-dopamine antagonist antipsychotic risperidone, over 12 million patient-months of exposure to the drug have been accumulated. Further studies have confirmed the efficacy of risperidone across a broad range of patients with schizophrenia who were not represented in the two pivotal clinical trials. Two studies confirm the efficacy of risperidone in first-episode schizophrenia and subanalyses of these studies suggest that the dose in these patients should be lower than in patients with chronic schizophrenia. In addition, a prospective comparison with risperidone and clozapine and a subanalysis of the North American Trial of risperidone show that risperidone is effective in treatment-resistant schizophrenia. The efficacy of risperidone against negative symptoms has been confirmed by a meta-analysis of seven clinical trials comparing risperidone with active control medication, and by further analyses of the North American Trial (analysis of covariance and path analysis). A long-term open study of risperidone has shown that the benefits of the drug extend well beyond the 8 weeks of the double-blind trials, and the low liability of risperidone for extrapyramidal side effects suggests that patients will be more likely to be compliant with risperidone treatment than with conventional neuroleptic treatment. Relapse rates can therefore be expected to be lower. Evidence from over 1100 patients, 503 of whom had taken risperidone for at least 1 year, suggests that the annual incidence of tardive dyskinesia in patients taking risperidone (7.6-9.4 mg/day) is 0.3%, compared to an annual incidence in patients taking conventional neuroleptics of 5-10%. Studies also suggest that risperidone reduces the number of days that patients with chronic schizophrenia spend as inpatients. It is concluded that mental health-care workers will need to raise their expectations about the treatment outcome of schizophrenia as a result of the introduction of risperidone.