Schizophrenia can be a long-term, chronic illness with a worldwide lifetime prevalence of about one per cent. The most common treatment of this condition is using antipsychotics. In the developed world there is a large choice of antipsychotics including some that are quite expensive, whereas in the developing world the older and cheaper drugs such as haloperidol and chlorpromazine are still used for the majority of the people. In addition, most new medications are tested for their effectiveness against haloperidol or chlorpromazine. This review looks at clinical trials comparing people with schizophrenia who have been treated with either chlorpromazine or haloperidol, in tablet form or as injection into muscle but not by long acting injection. There were 14 trials identified containing a total of 794 people. The trials varied in length from ‘several hours’ to 36 weeks but only two were six months or longer. The most recent trial was published in 1994, and the earliest 1962. As diagnosis of schizophrenia has changed over the years, some people in the early trials may have diagnoses other than schizophrenia by today’s criteria.
Overall the mental health and general functioning of people taking chlorpromazine or haloperidol improved. Compared to nowadays fewer people in both arms of the trial left the study early but those taking chlorpromazine were statistically more likely to do so. This was also the case when the oral medications were analysed on their own, but not in the case of the injected form. There was a suggestion that people may leave the study because of either adverse events or because the treatment did not work well. Haloperidol had statistically more movement side effects while chlorpromazine was statistically more likely to cause low blood pressure (hypotension). Although these trials show both haloperidol and chlorpromazine to be effective drugs for schizophrenia, a lot of data were not able to be used because some measures were not reported. Therefore the area would benefit from a new trial with a large number of people and lasting at least a year.
(Plain language summary prepared for this review by Janey Antoniou of RETHINK, UK www.rethink.org).