Central analgesic effects of desipramine, fluvoxamine, and moclobemide after single oral dosing: a study in healthy volunteers.

The antinociceptive effect of three antidepressants with different postulated modes of action, 75 mg desipramine, 225 mg fluvoxamine, and 450 mg moclobemide, was evaluated after single oral dosing in a randomized, double-blind, placebo-controlled crossover study in 10 healthy volunteers. Experimental pain thresholds (polysynaptic R-III reflex and subjective pain rating) were monitored over 23 hours. Compared with placebo, all drugs induced significant subjective pain threshold increases (maximal increase: desipramine, +20%; fluvoxamine, +17%; moclobemide, +13%). However, only desipramine (maximal increase, +25%) and moclobemide (maximal increase, +14%) displayed a significative effect on R-III threshold. Antidepressants thus exert an antinociceptive effect after a single oral dose. The level of their action apparently relies on the postulated mode of action.