A randomized clinical trial of efficacy and safety of the topical clonidine and capsaicin in the treatment of painful diabetic neuropathy

Background: Incomplete efficiency of oral medications restricts their therapeutic success in pain control of the painful form of the diabetic peripheral neuropathy (DPN). Use of topical medications because of less systemic side effects is more acceptable. This study aimed to compare the effect of clonidine gel and capsaicin cream in relieving pain associated with DPN. Materials and Methods: This 12-week, randomized, double-blind and parallel-group trial was conducted to compare the efficacy and safety of topical clonidine and capsaicin. Totally, 139 patients with type 2 diabetes with a pain score of at least 4 as assessed by visual analog scale (VAS), were treated for up to 3 months. The endpoint of the study was the reduction in the median pain score from baseline, as assessed by the VAS at the 4 weekly follow-up visits. Results: The intention-to-treat population for the efficacy analysis consists of 69 patients receiving clonidine and 70 patients receiving capsaicin. Both drugs significantly relieved pain at 12 weeks (P < 0.001 for both) but no significant difference in the efficacy between the two treatments was observed (P = 0.931). Dermatologic complications were more common in capsaicin group (P = 0.001). Conclusion: The results of this study showed the comparable efficacy of clonidine gel in comparison with capsaicin cream in the treatment of pain due to DPN with less adverse events. More studies are required to better evaluate the efficacy and safety of this topical compound for relieving pain in DPN.