Effect of Topical Capsaicin on Painful Sensory Peripheral Neuropathy in Patients with Type 2 Diabetes: A Double-Blind Placebo-Controlled Randomised Clinical Trial

Objective The aim of this study was to evaluate the efficacy of capsaicin in inducing significant pain relief in a population of sub-Saharan African type 2 diabetic patients with painful peripheral neuropathy. Design This was a prospective double-blind placebo-controlled randomised clinical trial. Setting A single tertiary-level hospital diabetes center in Yaounde, Cameroon. Participants Twenty-two participants with type 2 diabetes mellitus, presenting with painful diabetic neuropathy, aged 18 years and above. Intervention Participants were equally randomised to capsaicin or placebo. Each drug was to be applied on the lower limbs thrice daily. Follow-up was done every two weeks for eight weeks. Main outcome measure Reduction in the median pain score from baseline, as assessed by the Visual Analogue Scale. Results Twenty-two participants aged 57.5 (50-60) years with a median pain intensity of 6.8 units in the capsaicin group and 5.8 units in the placebo group were included; at inclusion, there was no significant difference in the two groups (p=0.29). After two weeks, the value of pain intensity was 3.3 [2.5-4.0] vs 5.0 [4.0-7.4] (p=0.003); at week four, 3.0 [2.5-3.3] vs 5.0 [4.2-5.5] (p=0,02); at week six, 3.3 [2.5-4.0] vs 4.8 [4.0-6.0] (p=0.03); and at week eight, 6.6 [6.0-7.0] vs 5.2 [5.0-6.0] (p=0.54) for capsaicin and placebo respectively. Conclusion This study, carried out due to a paucity of information on the effect of capsaicin and painful diabetic neuropathy in sub-Saharan African diabetes patients, shows that capsaicin significantly reduces neuropathic pain with worsening after eight weeks of use. Trial registration number Pan Africa Trial Registry: PACTR202003714748946.