Oxcarbazepine in painful diabetic neuropathy: results of a dose-ranging study

OBJECTIVES: To evaluate the efficacy and safety of oxcarbazepine in patients with diabetic neuropathy in a multicenter, double-blind, placebo-controlled, dose-ranging 16-week study. METHODS: A total of 347 patients were randomized to oxcarbazepine 600 mg/day (n = 83), 1,200 mg/day (n = 87), 1,800 mg/day (n = 88), or placebo (n = 89). The primary efficacy variable was change in mean visual analog scale (VAS) score from baseline to the last week of the study. RESULTS: No difference between any oxcarbazepine group and the placebo group was noted for the primary efficacy variable. Both the 1,200- and 1,800-mg/day groups showed a trend toward statistical significance (P = 0.101, P = 0.096, respectively). Statistically significant differences were found between the oxcarbazepine 1,200-mg/day (P = 0.038) and 1,800-mg/day (P = 0.005) groups and placebo in the overall mean weekly VAS scores for the entire double-blind treatment phase. CONCLUSIONS: Although the primary efficacy variable did not reach statistical significance, patients taking oxcarbazepine 1,200 and 1,800 mg/day showed improvements in VAS scores compared with placebo. Oxcarbazepine may provide clinically meaningful pain relief in patients with painful diabetic neuropathy.