Sodium valproate for painful diabetic neuropathy: a randomized double-blind placebo-controlled study.

BACKGROUND Various drugs are effective in the management of painful diabetic neuropathy, but none is completely satisfactory. We previously found sodium valproate to be effective and safe in a short-term study. AIM To test the effectiveness and safety of sodium valproate in the management of painful diabetic neuropathy over 3 months. DESIGN Randomized double-blind placebo-controlled study. METHODS Consecutive attending patients with type 2 diabetes mellitus with painful neuropathy were asked to participate in the trial: 48 agreed. Five were excluded: three with HbA(1c) > 11, one with too low a pain level and one who withdrew consent. The remaining 43 were given either drug (group A) or placebo (group B). Each patient was assessed clinically. Quantitative assessment of pain was done by McGill Pain Questionnaire, Visual Analogue Score and Present Pain Intensity, at the beginning of the study, after 1 month and after 3 months. Motor and sensory nerve conduction velocities were measured initially and after 3 months. Liver function tests and other adverse drug-related effects were assessed periodically. RESULTS Of the 43 patients, four dropped out: one in group A and three in group B. There was significant improvement in pain score in group A, compared to group B, at 3 months (p < 0.001). Changes in electrophysiological data were not significant. The drug was well-tolerated by all patients, except one, who had raised serum AST and ALT levels after 1 month of treatment, and whose treatment was discontinued. DISCUSSION Sodium valproate is well-tolerated, and provides significant subjective improvement in painful diabetic neuropathy.