A Cochrane review [Abstract] 1 included 11 studies with a total of 770 subjects. Target conditions were very diverse including migraine, mixed or tension headache (3 studies), myocardial infarction, acute rheumatic pain, postherpetic neuralgia, cancer pain, postoperative pain, trigeminal neuralgia, post-lumbar puncture headache and somatoform pain disorder. All included antipsychotics were older typical antipsychotics. Data from five included randomised double-blind studies showed beneficial effects of antipsychotics in the treatment of acute and chronic pain. Quantitative analysis of these studies showed a significant reduction of mean pain intensity after administration of the antipsychotic compared to placebo or another active compound: Weighted Mean Difference (WMD) -1.78 (95% CI -2.71 to -0.85) for the continuous data and Relative Risk (RR) 0.43 (95% CI 0.25 to 0.73), number-needed-to-treat-to-benefit (NNT) 2.6 for the dichotomous data. The most frequently reported adverse effects were extrapyramidal (i.e. involuntary movements, parkinsonism and akathisia) and sedating effects.
Comment: The quality of evidence is downgraded by inconsistency (heterogeneity in interventions and outcomes) and by imprecise results (limited study size for each comparison).
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