Zuclopenthixol decanoate for schizophrenia and other serious mental illnesses

There is a clear link between stopping antipsychotic medications and a relapse of psychotic symptoms. A series of long-acting intra-muscular preparations has been developed since the 1960s in the hope of reducing the frequency of relapse and, hence, overall disability. These depot preparations, active for weeks at a time, are frequently used for those who find taking oral medication on a regular basis difficult or unacceptable. It has, however, been a consistent concern that any reduction in relapse rate afforded by depot preparations may be offset by an increase in adverse effects such as drug-induced movement disorders.

To compare zuclopenthixol decanoate to oral zuclopenthixol and other antipsychotic preparations for the treatment of schizophrenia and similar serious mental illness.

Electronic searches of Biological Abstracts (1982-1998), CINAHL (1982-1998), The Cochrane Library (Issue 2, 1998), The Cochrane Schizophrenia Group's Register (April 1998), EMBASE (1980-1998), MEDLINE (1966-1998), and PsycLIT (1974-1998) were searched. References of all eligible studies were searched for further trials. The manufacturer of zuclopenthixol was contacted.

Inclusion criteria were that the clinical study should be randomised, focus on people with schizophrenia or other serious mental illness with psychotic symptoms, and compare the use of zuclopenthixol decanoate to oral zuclopenthixol or other antipsychotic preparations.

Data was extracted independently by two reviewers (EC, MF). Authors of trials were contacted for additional and missing data. Odds ratios (ORs) and 95% confidence intervals (CIs) of homogenous dichotomous data were calculated with the Peto method. Where possible the number needed to treat (NNT) and its 95% confidence interval was also calculated.

Four studies relating to zuclopenthixol decanoate were included. All compared zuclopenthixol decanoate with other depot preparations. Zuclopenthixol decanoate prevented or postponed relapses when compared to other depots (NNT 8, CI 5-53). However, zuclopenthixol decanoate may induce more adverse effects (NNH 5, CI 3-31) although it decreases need for anticholinergic medication when compared to a group of other depot preparations (NNT 9, CI 5-38). For the risk of leaving the study early, there was also a trend for benefit to those allocated to zuclopenthixol decanoate. None of the studies reported outcomes on service utilisation, costs, or quality of life.

Choice of which depot to use must always take into account clinical judgement and the preferences of the recipients of care and their carers. Limited trial data suggests, however, that there are real differences between zuclopenthixol decanoate and other depots and these differences largely favour the former. This review highlights the need for good controlled clinical trials to fully address the effects of zuclopenthixol decanoate for those with schizophrenia. Future studies should report service utilisation data, as well as satisfaction with care and economic outcomes. Duration of such trials should be of a longer duration than the included studies (12 months or more).