Revista de la Sociedad Española del Dolor
versión impresa ISSN 1134-8046
VIDAL, M. A. et al. Topical capsaicin for the management of neuropathic pain. Rev. Soc. Esp. Dolor [online]. 2004, vol.11, n.5, pp.306-318. ISSN 1134-8046.
Neuropathic pain is one of the most complex painful syndromes and one of the most difficult to treat. It is a symptom resulting from neurological damage (peripheral, central or both) affecting the pain nervous transmission system. Several drugs have been used, but none of them has resulted effective enough and their side effects frequently deter the continuation of the treatment. It can show up in different situations, all of which are more frequent in aged patients. A powerful analgesic with as little number ofside effects as possible is needed. This paper is a bibliographic review performed through the Medline data base of the treatment with topical capsaicin in different cases of neuropathic pain: postherpetic neuralgia, diabetic neuropathy, neuropathic pain associated to AIDS, trigeminal neuralgia, post-mastectomy painful syndromes and regional complex pain. The topical administration of capsaicin 0.075%, has shown to be effective for the management of dysesthesic pain and hence it is a therapeutic alternative for this type of pain. Its mechanism of action appears to be based on the selective stimulation of the neurons of amyelinic fibers C, causing the release of substance P and perhaps of other neurotransmitters; and finally, a depletion of substance P, which would disturb pain transmission to central systems, causing a desensitization phenomenon. While some studies have shown a greater effectiveness of capsaicin versus placebo, few patients have reported a significant response when it is used as monotherapy for neuropathic pain. Sometimes double-blind studies cannot be conducted due to the burning sensation referred to above. Its lacks significant systemic side effects, but during the first week of therapy an itching or burning sensation can appear in the application area that tends to disappear after the first week. This burning sensation is, together with the limited clinical effectiveness, the major limitation of the topical administration of capsaicin. The main indication of topical capsaicin is as co-adjuvant of antidepressants and anticonvulsants for the management of several neuropathic pain conditions, since as monotherapy it seems to be insufficient. It is an option that has to be considered in aged patients with neuropathic pain, since it presents a lower incidence of systemic side effects and drug interactions.
Palabras clave : Capsaicin; Neuropathic pain; Neuropathy; Substance P.