Effect of Ranirestat on Sensory and Motor Nerve Function in Japanese Patients with Diabetic Polyneuropathy: A Randomized Double-Blind Placebo-Controlled Study

Acetyllevocarnitine Hydrochloride for the Treatment of Diabetic Peripheral Neuropathy: A Phase 3 Randomized Clinical Trial in China

Diabetic peripheral neuropathy (DPN) is a highly prevalent chronic complication in type 2 diabetes (T2D) for which no effective treatment is available. In this multicenter, randomized, double-blind, placebo-controlled phase 3 clinical trial in China, patients with T2D with DPN received acetyllevocarnitine hydrochloride (ALC; 1,500 mg/day; n = 231) or placebo (n = 227) for 24 weeks, during which antidiabetic therapy was maintained. A significantly greater reduction in modified Toronto clinical neuropathy score (mTCNS) as the primary end point occurred in the ALC group (-6.9 ± 5.3 points) compared with the placebo group (-4.7 ± 5.2 points; P < 0.001). Effect sizes (ALC 1.31 and placebo 0.85) represented a 0.65-fold improvement in ALC treatment efficacy. The mTCNS values for pain did not differ significantly between the two groups (P = 0.066), whereas the remaining 10 components of mTCNS showed significant improvement in the ALC group compared with the placebo group (P < 0.05 for all). Overall results of electrophysiological measurements were inconclusive, with significant improvement in individual measurements limited primarily to the ulnar and median nerves. Incidence of treatment-emergent adverse events was 51.2% in the ALC group, among which urinary tract infection (5.9%) and hyperlipidemia (7.9%) were most frequent.

ARTICLE HIGHLIGHTS

Pharmacological and Nonpharmacological Treatments for Painful Diabetic Peripheral Neuropathy

Diabetic peripheral neuropathy (DPN) is one of the most prevalent chronic complications of diabetes. The lifetime prevalence of DPN is thought to be >50%, and 15%-25% of patients with diabetes experience neuropathic pain, referred to as "painful DPN." Appropriate treatment of painful DPN is important because this pain contributes to a poor quality of life by causing sleep disturbance, anxiety, and depression. The basic principle for the management of painful DPN is to control hyperglycemia and other modifiable risk factors, but these may be insufficient for preventing or improving DPN. Because there is no promising diseasemodifying medication for DPN, the pain itself needs to be managed when treating painful DPN. Drugs for neuropathic pain, such as gabapentinoids, serotonin-norepinephrine reuptake inhibitors, tricyclic antidepressants, alpha-lipoic acid, sodium channel blockers, and topical capsaicin, are used for the management of painful DPN. The U.S. Food and Drug Administration (FDA) has approved pregabalin, duloxetine, tapentadol, and the 8% capsaicin patch as drugs for the treatment of painful DPN. Recently, spinal cord stimulation using electrical stimulation is approved by the FDA for the treatment for painful DPN. This review describes the currently available pharmacological and nonpharmacological treatments for painful 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.

Pharmacokinetics and Safety of Ranirestat in Patients With Hepatic Impairment

Ranirestat is an aldose reductase inhibitor hypothesized to improve diabetic neuropathy. An open-label, single-dose, parallel-group study was conducted to compare pharmacokinetic (PK) characteristics of an oral dose of ranirestat across subjects with normal hepatic function and patients with mild and moderate hepatic impairment because ranirestat is expected to be used by patients with diabetes mellitus, possibly including those with hepatic impairment. To evaluate the necessity for dose adjustment, PK profiles and tolerability were studied at the dose of 40 mg, the expected optimal clinical dose in patients with diabetic neuropathy and normal hepatic function. In total, 20 subjects, including 5, 10, and 5 subjects with normal hepatic function, mild hepatic impairment, and moderate hepatic impairment, respectively, completed the study. Serial PK sampling was conducted up to 504 hours, and PK parameters were calculated and compared between healthy subjects and patients with mild or moderate hepatic impairment. The geometric mean ratios of peak concentration and area under the concentration-time curve in patients with mild hepatic impairment (90%CI) were 86.7% (55.3% to 135.9%) and 84.7% (68.5% to 104.8%), respectively. The values in patients with moderate hepatic impairment were 81.3% (48.8% to 135.5%) and 91.7% (72.1% to 116.7%), respectively. These results demonstrated that plasma ranirestat exposure and the plasma protein binding of the drug were not substantially altered by normal, mild, or moderate hepatic impairment (protein binding 99.22%, 99.29%, and 99.00%, respectively). All adverse events were mild in severity. Based on these findings, no dose adjustment will be required for ranirestat in patients with mild or moderate hepatic impairment.

Aldose reductase inhibitor ranirestat significantly improves nerve conduction velocity in diabetic polyneuropathy: A randomized double-blind placebo-controlled study in Japan

AIMS/INTRODUCTION

Diabetic polyneuropathy is one of the most frequent diabetic complications, and impairs patients' quality of life. We evaluated the efficacy and safety of ranirestat (40 mg/day) in patients with diabetic polyneuropathy.

MATERIALS AND METHODS

This was a multicenter, placebo-controlled, randomized double-blind, parallel-group, phase III study in which 557 patients were randomly assigned to either the ranirestat or placebo group and assessed for 52 weeks. The co-primary end-points were the changes in tibial motor nerve conduction velocity and total modified Toronto Clinical Neuropathy Score as a measure of clinical symptoms.

RESULTS

There was a significant increase in tibial motor nerve conduction velocity in the ranirestat group compared with the placebo group. The difference between groups in the change at last observation was 0.52 m/s (P = 0.021). Increases in nerve conduction velocity in the ranirestat group were found not only in the tibial motor nerves, but also in the median motor nerves, proximal median sensory nerves and distal median sensory nerves. No significant differences in modified Toronto Clinical Neuropathy Score or safety parameters were found between the two groups.

CONCLUSIONS

Ranirestat (40 mg/day) was well tolerated and improved nerve conduction velocity. Regarding symptoms and signs, no detectable benefits over the placebo were observed in the ranirestat group during the 52 weeks of treatment.