Topical capsaicin in painful diabetic neuropathy. Controlled study with long-term follow-up.

Abstract

We conducted an 8-wk controlled study with topical 0.075% capsaicin in subjects with chronic severe painful diabetic neuropathy who were unresponsive or intolerant to conventional therapy. Capsaicin is an alkaloid found in capsicum peppers and produces desensitization to noxious thermal, chemical, and mechanical stimuli when applied topically. In 22 randomly assigned subjects, either capsaicin or vehicle cream was applied to painful areas 4 times/day. Pain measurements were recorded at baseline and at 2-wk intervals for 8 wk. Capsaicin treatment was more beneficial than vehicle treatment in the overall clinical improvement of pain status, as measured by physician's global evaluation (P = 0.038) and by a categorical pain severity scale (P = 0.057). Decrease in mean pain intensity by a visual analogue scale was 16% in capsaicin-treated and 4.1% in vehicle-treated subjects. Mean pain relief on visual analogue scale was 44.6 and 23.2%, respectively. In a follow-up open-label study, approximately 50% of subjects reported improved pain control or were cured, and 25% each were unchanged or worse. A burning sensation at the application site was noted by some subjects but both its magnitude and duration decreased with time. Results from this preliminary study suggest that topical 0.075% capsaicin may be of value in subjects with diabetic neuropathy and intractable pain.