Pharmacokinetics and Safety of Ranirestat in Patients With Hepatic Impairment

In vitro evaluation of the reductive carbonyl idarubicin metabolism to evaluate inhibitors of the formation of cardiotoxic idarubicinol via carbonyl and aldo-keto reductases

The most important dose-limiting factor of the anthracycline idarubicin is the high risk of cardiotoxicity, in which the secondary alcohol metabolite idarubicinol plays an important role. It is not yet clear which enzymes are most important for the formation of idarubicinol and which inhibitors might be suitable to suppress this metabolic step and thus would be promising concomitant drugs to reduce idarubicin-associated cardiotoxicity. We, therefore, established and validated a mass spectrometry method for intracellular quantification of idarubicin and idarubicinol and investigated idarubicinol formation in different cell lines and its inhibition by known inhibitors of the aldo-keto reductases AKR1A1, AKR1B1, and AKR1C3 and the carbonyl reductases CBR1/3. The enzyme expression pattern differed among the cell lines with dominant expression of CBR1/3 in HEK293 and MCF-7 and very high expression of AKR1C3 in HepG2 cells. In HEK293 and MCF-7 cells, menadione was the most potent inhibitor (IC50 = 1.6 and 9.8 µM), while in HepG2 cells, ranirestat was most potent (IC50 = 0.4 µM), suggesting that ranirestat is not a selective AKR1B1 inhibitor, but also an AKR1C3 inhibitor. Over-expression of AKR1C3 verified the importance of AKR1C3 for idarubicinol formation and showed that ranirestat is also a potent inhibitor of this enzyme. Taken together, our study underlines the importance of AKR1C3 and CBR1 for the reduction of idarubicin and identifies potent inhibitors of metabolic formation of the cardiotoxic idarubicinol, which should now be tested in vivo to evaluate whether such combinations can increase the cardiac safety of idarubicin therapies while preserving its efficacy.

Ranirestat Improves Electrophysiologic but not Clinical Measures of Diabetic Polyneuropathy: A Meta-Analysis

Ranirestat, an aldose reductase inhibitor evaluated in several randomised controlled trials (RCTs) in diabetic peripheral neuropathy (DPN). However, to date, no meta-analysis has evaluated the efficacy and safety of ranirestat in DPN. We undertook this meta-analysis to address this knowledge gap. Detailed search of electronic databases for RCTs published till December 2021 was done at Cochrane register, Medline, PubMed, Embase, clinicaltrials.gov, ctri.nic.in, global health and Google Scholar using the Boolean search strategy: ((ranirestat) OR (aldose reductase inhibitor)) AND ((diabetes) OR ("diabetes mellitus")). The primary outcome was to evaluate changes in nerve conduction velocities (NCV) of different nerves. The secondary outcomes were to evaluate alterations in amplitudes, F-wave latencies of nerves, modified Toronto Clinical Neuropathy Score (mTCNS) and adverse events. Data from 5 studies involving 1461 patients with DPN was analysed to establish the impact of ranirestat (20-40 mg/day) as compared to placebo on different electrophysiologic outcomes over a median follow-up of 52 weeks. Patients receiving ranirestat had significantly greater improvement in proximal median sensory NCV [MD 0.77 m/s (95%CI: 0.50-1.05); P < 0.01; I2 = 26%], distal median sensory NCV [MD 0.91 m/s (95%CI: 0.87-0.95); P < 0.01; I2 = 0%], median motor NCV [MD 0.63 m/s (95%CI: 0.60-0.66); P < 0.01; I2 = 0%], tibial motor NCV [MD 0.46 m/s (95%CI: 0.43-0.49); P < 0.01; I2 = 0%] and peroneal motor NCV [MD 0.80 m/s (95%CI: 0.66-0.93); P < 0.01; I2 = 0%]. mTCNS was not significantly different among groups. Treatment-emergent adverse events [risk ratio (RR) 0.85 (95%CI: 0.63-1.14); P = 0.28; I2 = 0%] and severe adverse events [RR 1.35 (95%CI: 0.86-2.11); P = 0.20; I2 = 0%] were comparable across study groups. In people with established DPN with long-standing diabetes, ranirestat is safe and effective in improving electrophysiologic but not clinical DPN.

Development of Aldose Reductase Inhibitors for the Treatment of Inflammatory Disorders and Cancer: Current Drug Design Strategies and Future Directions

Aldose Reductase (AR) is an enzyme that converts glucose to sorbitol during the polyol pathway of glucose metabolism. AR has been shown to be involved in the development of secondary diabetic complications due to its involvement in causing osmotic as well as oxidative stress. Various AR inhibitors have been tested for their use to treat secondary diabetic complications, such as retinopathy, neuropathy, and nephropathy in clinical studies. Recent studies also suggest the potential role of AR in mediating various inflammatory complications. Therefore, the studies on the development and potential use of AR inhibitors to treat inflammatory complications and cancer besides diabetes are currently on the rise. Further, genetic mutagenesis studies, computer modeling, and molecular dynamics studies have helped design novel and potent AR inhibitors. This review discussed the potential new therapeutic use of AR inhibitors in targeting inflammatory disorders and cancer besides diabetic complications. Further, we summarized studies on how AR inhibitors have been designed and developed for therapeutic purposes in the last few decades.