Background: Perazine is an old phenothiazine derivative used for the treatment of people with schizophrenia which has a reputed low level of extrapyramidal side-effects. However, its use is restricted in the sense that - to the best knowledge of the reviewers - it is only marketed in Germany, Poland, Yugoslavia and the Netherlands.
Objectives: To examine the effects of perazine for those with schizophrenia, and schizophrenia-like psychoses.
Search strategy: Electronic searches of the Cochrane Schizophrenia Group's register which includes relevant randomised controlled trials from the bibliographic databases Biological Abstracts, CINAHL, The Cochrane Library, EMBASE, MEDLINE, PsycLIT, LILACS, PSYNDEX, Sociological Abstracts and Sociofile were undertaken. References of all included studies were searched for further trials. Pharmaceutical companies and authors of trials were contacted.
Selection criteria: All randomised controlled trials that compared perazine with other treatments for people with schizophrenia and/or schizophrenia-like psychoses.
Data collection and analysis: Citations and, where possible, abstracts were independently inspected by two reviewers, papers ordered, re-inspected and quality assessed. Data were independently extracted. Data were excluded if loss to follow up was greater than 50%. For homogeneous dichotomous data the Relative Risk (RR), 95% confidence interval (CI) and, where appropriate, the number needed to treat (NNT) were calculated on an intention-to-treat basis. For continuous data, weighted mean differences were calculated (WMD). All data were inspected for heterogeneity.
Main results: Six trials with a total of 288 participants are included. According to only one trial with 95 participants perazine appeared superior to active placebo (trimipramine) at five weeks for the outcome of 'no important global improvement' (n=95, RR 0.6, CI 0.3-0.9, NNT 4, CI 2-17), but there was no difference in various measures of mental state. The side-effect risk of perazine compared to placebo could not be estimated because they were not reported. Five small trials including only 193 participants which compared perazine with other antipsychotics were incompletely reported and the outcomes were presented in various ways so that meta-analysis was not possible in most occasions. A similar number of participants receiving perazine or comparator antipsychotics left the studies early (n=193, RR 0.9, CI 0.5-1.4). The results on efficacy were controversial and need further assessment by randomised controlled trials. No obvious differences in adverse events between perazine and other antipsychotics could be derived from these limited data. Two haloperidol comparisons did not present extrapyramidal side-effects in a way usable for meta-analysis, but three small comparisons with the atypical antipsychotics zotepine and amisulpride showed no higher risk of akathisia (n=111, RR 0.3, CI 0.1-1.1), dyskinesia (n=111, RR 0.5, CI 0.1-3.5), parkinsonism (n=81, RR 1.2, CI 0.5-2.8) or tremor (n=40, RR 0.8, CI 0.3-2.3) with perazine.
Reviewer's conclusions: The number, size and reporting of randomised controlled perazine trials is insufficient to present firm conclusions about the properties of this antipsychotic. It is possible that perazine is associated with a similar risk of extrapyramidal side-effects as some atypical antipsychotics, and this should be clarified in larger, well-designed trials.