Single doses of the serotonin agonists buspirone and m-chlorophenylpiperazine do not relieve neuropathic pain

Abstract

A large body of evidence links serotonin with analgesia in animal models, but the lack of serotonin agonists suitable for clinical use has delayed study of serotonin's relevance to pain relief in humans. In a randomized, double-blind crossover study, we compared single doses of two 5-HT1 agonists, buspirone and m-chlorophenylpiperazine, to placebo in 20 patients with post-herpetic neuralgia or painful neuropathy. No analgesia was observed after either drug, at doses high enough to produce frequent central nervous system side effects. These results suggest that acute stimulation of 5-HT1 receptors is not sufficient to produce analgesia in patients with these neuropathic pain syndromes.