How do drugs relieve neurogenic pain?

Neurogenic pain is experienced by about 1% of the population. The efficacy of drug treatment for this condition has been poorly evaluated, and only recently have certain treatments been shown to have significant analgesic effects. Monotherapy with topical agents such as capsaicin is not usually sufficient. Oral agents that have proven effective in treating neurogenic pain states include tricyclic antidepressants, selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors and anticonvulsants. Local anaesthetics, administered intravenously, have been reported to relieve pain in selected patients, but data from controlled trials are sparse. Multiple mechanisms contribute to the generation of neurogenic pain. In the future, drug treatment for neurogenic pain is likely to target these mechanisms. Recent studies have shown that N-methyl-D-aspartate (NMDA) receptor antagonists, adenosine receptor agonists and nitric oxide synthase inhibitors may become useful in the treatment of neurogenic pain.