Objective To evaluate the safety and efficacy of venlafaxine and carbamazepine on painful peripheral diabetic neuropathy. Methods This was a randomized, parallel-group, double-blind, double-dummy clinical trial. 132 patients a venlafaxine group (n=66) and a carbamazepine group (n=66) with painful peripheral diabetic neuropathy were recruited from 3 clinical centers. The venlafaxine group took venlafaxine 25 mg plus one dummy carbamazepine tablet twice a day and the carbamazepine group took carbamazepine 0.1 g plus one dummy venlafaxine tablet twice a day both for 2 weeks. The primary efficacy measurement consisted of a numeric pain intensity scale and the secondary measurement assessed quality of life. Results One hundred and nineteen patients completed the trial. Venlafaxine was superior to carbamazepine in improving mean pain intensity scores at 5,7,10 and 14 days by per-protocol analysis (P=0.02, P=0.03, P=0.003 and P=0.001 respectively). The effects of venlafaxine on the improvement in the total quality of life scores were better than those of carbamazepine at 10 and 14 days (P=0.02 and P=0.01 respectively). Sleep interference and mood were improved by both venlafaxine and carbamazepine, but the efficacy of venlafaxine was superior to that of carbamazepine. The common adverse events of venlafaxine included mild gastrointestinal discomfort, dizziness and somnolence. The frequency of adverse events in the venlafaxine group was about 43.9% (4 patients withdrew because of adverse events) and in the carbamazepine group about 25.76% (2 patients withdrew because of adverse events) (P =0.06). Conclusions Venlafaxine and carbamazepine are effective in the treatment of painful diabetic neuropathy, venlafaxine is superior to carbamazepine in improving pain and quality of life. Both drugs may be safe and well tolerated.
