The Pharmaceutical Journal
Vol 272 No 7305 p796
26 June 2004

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Valproate may be effective for painful diabetic neuropathy

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Clinical question Does the anticonvulsant sodium valproate reduce symptoms of painful diabetic neuropathy?

Bottom line This small study provides preliminary evidence that sodium valproate reduces the pain of diabetic neuropathy in a dose of 500mg given twice daily. Larger and longer studies are needed to confirm this finding, and to compare sodium valproate with other therapies. Valproic acid (Depakote) is also available, and is dosed in a 1:1 ratio with sodium valproate.

Synopsis For painful diabetic neuropathy, previous studies have shown that carbamazepine and gabapentin (Neurontin) are potentially useful. However, the former is limited by toxicity and the latter by cost. In this study, the authors randomised (allocation concealment uncertain) 43 patients with diabetic neuropathy, a glycated haemoglobin level of less than 11 per cent and a pain score of more than four on a 10-point visual scale, to sodium valproate 500mg given once daily or placebo. Analysis appears to have been per protocol rather than intention to treat, but this is a minor point since only one patient withdrew from the three-month study. After one week, if they had no nystagmus (involuntary eyeball movement) or ataxia, and normal hepatic transaminases, the dose was increased to 500mg twice daily. The primary outcome measures were the McGill Pain Questionnaire (MPQ), a visual analog scale (VAS) from 0 to 10 and a pain intensity score (PS). At the end of the three months, the MPQ fell from 19.5 to 9.7, the VAS from 6.0 to 3.0 and the PS from 2.7 to 1.3 (all P<0.001). The authors do not give exact numbers, but show graphically that the scores did not change significantly in the placebo group. One patient was withdrawn from the study because of elevated hepatic transaminases, and two patients complained of some nausea.

Level of evidence 1b- (individual randomised controlled trial with a single result with wide confidence interval).

Reference Kochar DK, Rawat N, Agrawal RP, et al. Sodium valproate for painful diabetic neuropathy: a randomised double-blind placebo-controlled study. Quarterly Journal of Medicine 2004;97:33-88

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