The use of a topical capsaicin 8% may be effective on neuropathic pain associated with postherpetic neuralgia or resulting from trauma or surgery, according to a study published in Pharmacology.
Investigators retrospectively analyzed pain outcomes in patients with postherpetic neuralgia (n=15) and post-traumatic or postsurgical neuropathic pain (n=28). Study participants were treated 3 times with a capsaicin 8% patch for 30 or 60 minutes (for feet and other body areas, respectively).
Pain intensity was assessed with the numeric rating scale at baseline, and 7 and 14 days after each treatment. In addition, a brush was used to produce mechanical allodynia on the skin in order to assess the pain treatment area.
A total of 35 patients (81%) reported reduced numeric rating scale scores after the first treatment (median percentage reduction, −33.3%; 95% CI, −42.7 to −25.0; P <.001). Of these patients, 5 had their pain resolved, and 24 (55.8%) experienced >30% pain relief, compared with baseline. Both numeric rating scale scores (median percentage reduction, −40.0%; 95% CI, −50.0 to −33.3; P <.001) and pain treatment area (median percentage reduction, −35.1%; 95% CI, −50.9 to 3.4; P =.0013) improved after the last treatment compared with baseline.
Study limitations include a lack of a control group and a small sample size.
“This analysis suggests that topical capsaicin 8% not only reduces localized neuropathic pain intensity, but also, treatment pain area in both postherpetic and post-traumatic/postsurgical neuropathic pain, in all oral medication subgroups of patients,” concluded the study authors.
Tenreiro Pinto J, Pereira FC, Loureiro MC, Gama R, Fernandes HL. Efficacy analysis of capsaicin 8% patch in neuropathic peripheral pain treatment. Pharmacology. 2018;101(5-6):290-297.