Do the second-generation "atypical neuroleptics" have analgesic properties? A structured evidence-based review

This is a structured, evidence-based review of all available studies on the potential effectiveness of the atypical neuroleptics for the treatment of pain (analgesia). To determine what evidence, if any, exists for, or against, the effectiveness of the atypical neuroleptics for analgesia.

There has been significant controversy over whether the conventional neuroleptics (non-atypicals) have analgesic properties. A recent review (Patt et al. 1994) did conclude that the evidence for effectiveness was sparse, except for methotrimeprazine. However, that review did not include a new class of neuroleptics: the atypicals such as olazapine, risperidone, quetiapine, etc.

A computer and manual search for studies relating to the atypicals and their analgesic effectiveness produced 10 studies/reports. These were reviewed in detail, and information relating to the above problem was abstracted and placed into tabular form. Each report was also categorized by the type of study it represented according to the guidelines developed by the Agency for Health Care Policy and Research (AHCPR). The strength and consistency of the evidence represented by the 10 studies were then categorized according to the AHCPR guidelines. Conclusions of this review were based on these results.

Of the 10 studies/reports, four were characterized by AHCPR guidelines as Type II (experimental), two were Type III (quasiexperimental), two were Type IV (nonexperimental), and two were Type V (case reports). Of these studies/reports, 90% indicated that the atypicals did have an analgesic effect. The overall strength and consistency of this evidence using the AHCPR guidelines was, therefore, categorized as B (generally consistent from Type II, Type III, and Type IV studies).

Based on the above results, it was concluded that the reviewed data were generally consistent, suggesting that some of the atypicals may have an analgesic effect. There were, however, few double-blind, placebo-controlled studies, and many of the reports/studies had less than 50 patients. As such, this question requires further research.