Diabetic neuropathy – fidarestat
Neuropathy is a weakness and numbness of the muscles. It is a common complication of diabetes, where nerve fibres become damaged, and the danger of complications from a poor blood supply to the extremities are increased.
It results from poor control of blood sugar levels, and great care in keeping the levels under control is an essential part of its prevention. One of the possible causes is believed to be the accumulation of sorbitol, and the developmental drug fidarestat, an aldose reductase inhibitor formerly known as SNK-860, has been shown to inhibit this. In a clinical trial in 58 patients with Type II diabetes, subjects were given 1mg fidarestat or 150mg epalrestat for four weeks. Those given epalrestat showed no significant change in erythrocyte sorbitol content, and those who received fidarestat saw the level drop to normal. Neither drug had any effect on plasma glucose levels.1
A further multi-centre double blind placebo controlled trial in 279 patients with Type I and Type II diabetes and peripheral neuropathy was carried out over a period of a year to establish the effect of fidarestat on nerve function and the symptoms of neuropathy.
It gave significant improvements in nerve conduction velocity, and also in a variety of subjective symptoms, with similar adverse events being experienced in those receiving the active and the placebo.2
The drug is being developed by NK Curex with Sanwa Kagaku. It has been submitted for regulatory review in Japan, and is currently undergoing clinical trials in the US. Aldose reductase has been shown to play an important role in retinal oxidative stress and vascular endothelial growth factor production in diabetic patients, and so it could also have potential as a treatment for another important diabetes complication, diabetic retinopathy.