Newer atypical antipsychotic medication in comparison to clozapine: a systematic review of randomized trials.

The aim of this study was to evaluate the effectiveness of newer atypical antipsychotic drugs in comparison to clozapine for schizophrenia. Publications in all languages were searched from all relevant databases and all randomized controlled trials comparing clozapine with newer atypical drugs were included. The review and meta-analysis includes eight studies, most of them short in duration. Newer atypical drugs were broadly similar to clozapine when improvement was measured using a psychosis symptom rating scale or a global index. There was a trend for clozapine to be more effective than the others for positive symptoms, and less effective for the negative symptoms. The adverse effect profile of clozapine and newer atypical drugs was dissimilar: while clozapine produced more fatigue, hypersalivation, and orthostatic dizziness, new atypical drugs, with the exception of olanzapine, produced more extrapyramidal symptoms. As these results were obtained from few studies and a relatively small amount of patients, the equal effectiveness and tolerability of new atypical drugs in comparison with clozapine is not yet demonstrated. More trials of sufficient power, with longer duration, and measuring clinically important outcomes are urgently needed.