title: 0.025% capsaicin gel for the treatment of painful diabetic neuropathy: a randomized, double-blind, crossover, placebo-controlled trial.
abstract: BACKGROUND
  Topical therapy may provide additional benefit in patients with painful diabetic neuropathy (PDN). This study was conducted to study the safety and efficacy of 0.025% capsaicin gel in this condition.
  
  
  METHODS
  A 20-week, double-blind, crossover, randomized, single-center study enrolled subjects with PDN. They received 0.025% capsaicin gel or placebo for 8 weeks, with a washout period of 4 weeks between the two treatments. Primary efficacy end point was percent change in visual analog scale (0-100 mm) of pain severity. Secondary outcomes were score change in Neuropathic Pain Scale (NPS), short-form McGill Pain Questionnaires (SF-MPQ), proportion of patients who had pain score reductions of 30% and 50%, and adverse event.
  
  
  RESULTS
  Of the 35 subjects screened, 33 were enrolled and 33 completed at least an 8-week treatment period. Intention-to-treat analysis showed no significant improvement in pain with capsaicin gel, compared with placebo with visual analog scale (VAS) score 28.8 mm vs. 34.6 mm (P = 0.53). No significant difference between the groups was found in SF-MPQ (7.4 vs. 7.71, P = 0.95), NPS (29.4 vs. 31.3, P = 0.81), and proportion of patients who had 30% or 50% pain relief. Capsaicin gel was well tolerated with minor skin reaction.
  
  
  CONCLUSIONS
  0.025% capsaicin gel is safe and well tolerated, but does not provide significant pain relief in patients with PDN.
authors.affiliation: Division of Neurology, Department of Internal Medicine, Thammasat University, Pathumthani, Thailand. kkulkantrakorn@hotmail.com
authors.forename: Kongkiat
authors.initials: K
authors.lastname: Kulkantrakorn
authors.forename: Chakraphong
authors.initials: C
authors.lastname: Lorsuwansiri
authors.forename: Pongsatorn
authors.initials: P
authors.lastname: Meesawatsom
mesh_terms: D000287:Administration, Topical; D000328:Adult; D000368:Aged; D002211:Capsaicin / Q000008:administration & dosage* / Q000009:adverse effects; D018592:Cross-Over Studies; D003929:Diabetic Neuropathies / Q000175:diagnosis / Q000188:drug therapy* / Q000453:epidemiology*; D004311:Double-Blind Method; D005076:Exanthema / Q000139:chemically induced / Q000175:diagnosis; D005260:Female; D005500:Follow-Up Studies; D005782:Gels; D006801:Humans; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome
chemical_list: D005782:Gels; D002211:Capsaicin