Depot haloperidol decanoate for schizophrenia

Synopsis pending.

Authors' conclusions: 

Haloperidol decanoate may have a substantial effect in improving the symptoms and behaviour associated with schizophrenia in comparison to placebo, but data are remarkably sparse.

There are no discernible differences between the depot form of haloperidol and its oral equivalent. For those needing and willing to take the drug, the means of administration is then a matter of individual choice and clinical judgement. As there are no clear differences between haloperidol decanoate and other depots, the choice of depot medication could also be individually tailored and patient preference exercised.

Well-conducted and reported randomised trials are needed comparing haloperidol decanoate with other depots but the comparison of haloperidol decanoate to oral antipsychotics is a priority.

Read the full abstract...

The mainstay of treatment for schizophrenia is the antipsychotic group of drugs. These are usually given orally but compliance with medication given by this route may be difficult to quantify. Problems with treatment adherence are common. The development of depot injections in the 1960s gave rise to their extensive use as a means of long-term maintenance treatment. Haloperidol decanoate is one depot drug available in clinical practice .


To assess the effects of haloperidol decanoate versus oral anti-psychotics and other depot antipsychotic preparations for people with schizophrenia in terms of clinical, social and economic outcomes.

Search strategy: 

Relevant trials were identified by searching Biological Abstracts (1982-1998), Cochrane Library (Issue 2, 1998), Cochrane Schizophrenia Group's Register (June 1998), EMBASE (1980-1998), MEDLINE (1966-1998) and PsycLIT (1974-1998). References of all identified trials were also inspected for more studies.

Selection criteria: 

All relevant randomised trials focusing on people with schizophrenia where haloperidol decanoate, oral anti-psychotics or other depot preparations were compared. Outcomes such as death, clinically significant change in global function, mental state, relapse, hospital admission, adverse effects and acceptability of treatment were sought.

Data collection and analysis: 

Studies were reliably selected, quality rated and data extracted. For dichotomous data Mantel-Haenszel odds ratios (OR) with the 95% confidence intervals (CI) were estimated. Where possible, the number needed to treat statistic (NNT) was calculated. Analysis was by intention-to-treat. Normal continuous data were summated using the weighted mean difference (WMD). Scale data were presented only for those tools that had attained pre-specified levels of quality.

Main results: 

In a haloperidol decanoate versus placebo comparison, two small studies reported that significantly fewer people on depot left early (OR 0.09 CI 0.03-0.21, NNT 2 CI 1-3) or experienced no important improvement in mental state (OR 0.04 CI 0.01-0.15). Zississ (1982) suggested that those taking haloperidol decanoate would need less additional antipsychotic medication (OR 0.14 Cl 0.04-0.55, NNT 2 CI 1-5).

Haloperidol decanoate was compared to oral haloperidol in a single trial that showed no differences in global impression, mental state or side effects (Zuardi 1983, n=22). Compliance with medication was not reported in this study. Eight trials compared haloperidol decanoate to other depot neuroleptics and again no differences were found for the outcomes of death, global impression, mental state, behaviour, or side effects.