[Mexiletine in treatment of painful diabetic neuropathy]

The objective of this double-blind placebo controlled multicenter study was to prove the efficacy of mexiletine in painful diabetic neuropathy. Treatment was provided for in three dosages. For pain measurements a visual analogue scale (VAS) and McGill's verbal rating scale were chosen. 95 patients were included. A global assessment of the VAS showed no differences in treatment. The total evaluation (PRIT = Pain Rating Index Total) of the McGill scale just failed the level of significance. More specific exploratory evaluation of subclasses of the McGill scale, representing different qualities of pain, gave remarkable differences between mexiletine and placebo. According to types of complaints an evaluation showed substantial advantages of the mexiletine treatment with both the VAS and the McGill scale. There is strong evidence that particularly patients with stabbing or burning pain, heat sensations or formication will benefit most by mexiletine therapy. Concerning the dosage, a medium regimen of 450 mg per day seems to be appropriate in this indication. With an increase in dosage the efficacy does not rise proportionally. Mexiletine proved a very safe therapy with negligible side effects at the medium dose range, even less than placebo. There were no cardiovascular side effects. Further investigations should pay more attention to the variety of the complaints and include the quality of life.