Effects of an aldose reductase inhibitor, epalrestat, on diabetic neuropathy. Clinical benefit and indication for the drug assessed from the results of a placebo-controlled double-blind study.

The clinical efficacy of epalrestat (150 mg/day, 50 mg tid, po; A group), an aldose reductase inhibitor, was evaluated in 196 patients with diabetic neuropathy by a double-blind study using placebo (9 mg/day, 3 mg tid, po; P group) as a control for 12 weeks. The disappearance rates of upper limb spontaneous pain were 42.9% and 12.0% in the A and P groups, respectively, and those of lower limb spontaneous pain 48.6% and 22.6%, thus being significantly higher in the A group (p < 0.05, logrank-test). The motor nerve conduction velocity of the peroneal nerve significantly increased only in the A group (delta 1.6 +/- 0.6 m/sec, p < 0.01, paired t-test), and the extent of increase in that of the median nerve was significantly greater in the A group than in the P group (p < 0.05). Thresholds of vibratory sensation and autonomic nerve function were also significantly improved in the A group (p < 0.05). The data were reanalyzed by dividing patients into two groups according to their HbA1c values. The improvement ratings of subjective symptoms and of nerve function tests for cases with HbA1c > or = 7.5% were both significantly different between the A and P groups, with the improvement rate being higher in the A group, and also higher as compared to the analysis for cases with HbA1c < 7.5%.(ABSTRACT TRUNCATED AT 250 WORDS)