The effect of venlafaxine HCl on painful peripheral diabetic neuropathy in patients with type 2 diabetes mellitus

Objective: The objective of this study was to evaluate the efficacy of venlafaxine HCl in the symptomatic treatment of painful peripheral diabetic neuropathy (PPDN) among patients with type 2 diabetes mellitus (DM). Design: This study was designed as a prospective, randomized, and controlled trial. Setting: This study was conducted at the Dicle University Medical Faculty (Diyarbakir, Turkey). Patients: Sixty type 2 DM outpatients (47 females and 13 males) with PPDN who had a minimum visual analog scale (VAS) score of 40 mm were enrolled in this study. Interventions: Patients randomized to the treatment group (n=30) received venlafaxine HCl, whereas those randomized to the control group (n=30) received a combination of vitamins B-1 and B-6 tablets. Measures: Severity of pain was measured by VAS, Short-Form McGill Pain Questionnaire, and numerical analog scale scores at admission and at the second, fourth, and eighth weeks of the study. Polyneuropathy was supported by electromyelography. Outcome: In the treatment group, severity of pain was measured as 70.0+/-13.0 in the VAS, as 24.9+/-6.2 in the Short-Form McGill Pain Questionnaire, and as 7.2+/-1.1 in the numerical analog scale. In the control group, it was measured as 73.0+/-8.0 in the VAS, as 26.8+/-6.2 in the Short-Form McGill Pain Questionnaire, and as 7.4+/-0.8 in the numerical analog scale (P>.05). Results: The most common form of PPDN was distal symmetrical sensorimotor polyneuropathy in both groups (46.8% vs. 50.0%). At the end of the study, there was a significant difference in severity of pain between the groups. In the treatment group, scores were 8.5+/-5.2 and 3.1+/-1.6 in the Short-Form McGill Pain Questionnaire and numerical analog scale, respectively; in the control group, these were 20.5+/-7.0 and 5.5+/-1.6, respectively (P<.001). Conclusions: Venlafaxine HCl is a safe and well-tolerable analgesic drug in the symptomatic treatment of PPDN; however, it has minimal adverse effects. It showed its efficacy markedly in the second week of therapy. (C) 2008 Elsevier Inc. All rights reserved.