2c The antidepressant-induced analgesic effect

Since 1960 clinicians and researchers have been claiming that there is evidence for an antidepressant-induced analgesic effect. The effect could be accomplished (1) as a secondary effect of a reduction in depression, (2) as a secondary effect of general sedation, or (3) by a biochemical mechanism that is independent of changes in mood or sedation but which is probably related to serotonin reuptake inhibition. Our meta-analysis summarized the results of the available double-blind, placebo-controlled trials for several chronic pain syndromes up to 1990 and found support for an independent biochemical mechanism but not for the crucial role of serotonin reuptake inhibition. Seventeen more recent (since 1990) double-blind, placebo-controlled trials have substantiated the meta-analytical results. Furthermore, recent animal and laboratory studies have confirmed that the antidepressant-induced analgesic effect is not a clinical chimaera and have made important progress with respect to possible sites and mechanisms of action.