ranirestat ranirestat ranirestat (also known as as-3201) is an aldose reductase inhibitor being developed for the treatment of diabetic neuropathy by dainippon sumitomo pharma and pharmakyorin. it has been granted orphan drug status. the drug is to be used orally. ranirestat names preferred iupac name (3r)-2′--1′h-spiropyrazine]-1′,2,3′,5(2′h)-tetrone identifiers cas number 147254-64-6 y 3d model (jsmol) interactive image chemspider 135685 n pubchem cid 153948 unii z26p56gftv y comptox dashboard (epa) dtxsid80163642 inchi inchi=1s/c17h11brfn3o4/c18-10-4-3-9(11(19)6-10)8-21-14(24)12-2-1-5-22(12)17(16(21)26)7-13(23)20-15(17)25/h1-6h,7-8h2,(h,20,23,25)/t17-/m1/s1 nkey: qcvnmnyrnimdkv-qgzvfwflsa-n ninchi=1/c17h11brfn3o4/c18-10-4-3-9(11(19)6-10)8-21-14(24)12-2-1-5-22(12)17(16(21)26)7-13(23)20-15(17)25/h1-6h,7-8h2,(h,20,23,25)/t17-/m1/s1key: qcvnmnyrnimdkv-qgzvfwflbs smiles c1cc2n(c1)3(cc(=o)nc3=o)c(=o)n(c2=o)cc4ccc(cc4f)br properties chemical formula c17h11brfn3o4 molar mass 420.189 g/mol except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). n verify (what is yn ?) infobox references trials a canadian phase iii clinical trial has been completed. phase iii trials in europe and the us started in june 2009 and are expected to complete in april 2013. mechanism of action ranirestat is aldose reductase inhibitor that acts by reducing sorbitol accumulation in cells. aldose reductase is an enzyme that catalyzes one of the steps in sorbitol (polyol) pathway which is responsible for formation of fructose from glucose. aldose reductase activity is increased, parallel to glucose blood levels, in tissues that are not insulin sensitive, including lenses, peripheral nerves and renal glomeruli. sorbitol does not diffuse through cell membranes easily and therefore accumulates in these tissues, causing osmotic damage, leading to retinopathy and neuropathy. efficacy results from a canadian double-blind, placebo-controlled biopsy phase iii clinical trial, involving total of 549 patients with diabetic sensorimotor polyneuropathy (dsp) randomly assigned to treatment with placebo or 10, 20, or 40 mg/day ranirestat for 52 weeks, showed that ranirestat appears to have effect on motor nerve function in mild to moderate dsp, but failed to show statistically significant difference in sensory nerve function. efficacy of ranirestat was evaluated by nerve conduction studies, the modified toronto clinical neuropathy score (mtcns), and quantitative sensory tests (qsts).