Epalrestat
Epalrestat is a carboxylic acid derivative and a noncompetitive and reversible aldose reductase inhibitor used for the treatment of diabetic neuropathy, which is one of the most common long-term complications in patients with diabetes mellitus. It reduces the accumulation of intracellular sorbitol which is believed to be the cause of diabetic neuropathy, retinopathy and nephropathy  It is well tolerated, with the most commonly reported adverse effects being gastrointestinal issues such as nausea and vomiting, as well as increases in certain liver enzymes. Chemically, epalrestat is unusual in that it is a drug that contains a rhodanine group. Aldose reductase is the key enzyme in the polyol pathway whose enhanced activity is the basis of diabetic neuropathy. Aldose reductase inhibitors (ARI) target this enzyme. Out of the many ARIs developed, ranirestat and fidarestat are in the trial stage. Others have been discarded due to unacceptable adverse effects or weak efficacy. Epalrestat is the only ARI commercially available. It is easily absorbed into the neural tissue and inhibits the enzyme with minimum side effects. Evidence 
It has been demonstrated in animal experiments that there is an improvement in sorbitol levels and Na+/K+ ATPase activity leading to improved nerve conduction velocity. Diabetic rats treated with epalrestat showed improvement in morphological abnormalities of nerves. In a placebo controlled double blind trial of 196 patients, it was shown that Epalrestat in a dose of 150 mg/day improved the effects of diabetic neuropathy like upper limb spontaneous pain, motor nerve conduction velocity, thresholds of vibratory sensation and autonomic nerve function as compared to a placebo. These effects were significantly better in those with poorer control of diabetes. A systematic review and metaanalysis showed that based on the results of 10 articles, it can be concluded that Epalrestat has some benefit in the control of diabetic cardiovascular autonomic neuropathy but only in the early or mild cases. It also doesn't influence glycaemic control. Brand names 
 Aldonil (Zydus Medica), India
 Aldorin, Bangladesh
 Alrista (marketed and not manufactured by Macleods), India
 Epalrica-M (Ordain Global), India
 Eparel 50 (Microlabs Ltd), India
 Epimeth (Zaiva Lifesciences), India
 Eplistat 150 SR (Schem), India
 Letostat-SR (Amor Pharmaceuticals), India
 Listap-50 (Vivid Biotek), India
 Tanglin (Yangtze River Pharmaceutical Group), China

References

External links
 Epalrestat at chemblink.com

Aldose reductase inhibitors
Alkene derivatives
Thiazolidines