Mitiglinide: a novel agent for the treatment of type 2 diabetes mellitus

A Synthetic Pathway for the Production of Benzylsuccinate in Escherichia coli

(R)-Benzylsuccinate is generated in anaerobic toluene degradation by the radical addition of toluene to fumarate and further degraded to benzoyl-CoA by a β-oxidation pathway. Using metabolic modules for benzoate transport and activation to benzoyl-CoA and the enzymes of benzylsuccinate β-oxidation, we established an artificial pathway for benzylsuccinate production in Escherichia coli, which is based on its degradation pathway running in reverse. Benzoate is supplied to the medium but needs to be converted to benzoyl-CoA by an uptake transporter and a benzoate-CoA ligase or CoA-transferase. In contrast, the second substrate succinate is endogenously produced from glucose under anaerobic conditions, and the constructed pathway includes a succinyl-CoA:benzylsuccinate CoA-transferase that activates it to the CoA-thioester. We present first evidence for the feasibility of this pathway and explore product yields under different growth conditions. Compared to aerobic cultures, the product yield increased more than 1000-fold in anaerobic glucose-fermenting cultures and showed further improvement under fumarate-respiring conditions. An important bottleneck to overcome appears to be product excretion, based on much higher recorded intracellular concentrations of benzylsuccinate, compared to those excreted. While no export system is known for benzylsuccinate, we observed an increased product yield after adding an unspecific mechanosensitive channel to the constructed pathway.

Pharmacotherapy of type 2 diabetes: An update and future directions

Type 2 diabetes (T2D) is a widely prevalent disease with substantial economic and social impact for which multiple conventional and novel pharmacotherapies are currently available; however, the landscape of T2D treatment is constantly changing as new therapies emerge and the understanding of currently available agents deepens. This review aims to provide an updated summary of the pharmacotherapeutic approach to T2D. Each class of agents is presented by mechanism of action, details of administration, side effect profile, cost, and use in certain populations including heart failure, non-alcoholic fatty liver disease, obesity, chronic kidney disease, and older individuals. We also review targets of novel therapeutic T2D agent development. Finally, we outline an up-to-date treatment approach that starts with identification of an individualized goal for glycemic control then selection, initiation, and further intensification of a personalized therapeutic plan for T2D.

Exploiting common aspects of obesity and cancer cachexia for future therapeutic strategies

Obesity and cancer cachexia are diseases at opposite ends of the BMI. However, despite the apparent dichotomy, these pathologies share some common underlying mechanisms that lead to profound metabolic perturbations. Insulin resistance, adipose tissue lipolysis, skeletal muscle atrophy and systemic inflammation are key players in both diseases. Several strategies for pharmacological treatments have been employed in obesity and cancer cachexia but demonstrated only limited effects. Therefore, there is still a need to develop novel, more effective strategies. In this review we summarize existing therapies and discuss potential novel strategies that could arise by bridging common aspects between obesity and cachexia. We discuss the potential role of macrophage manipulation and the modulation of inflammation by targeting Nuclear Receptors (NRs) as potential novel therapeutic strategies.

The vasorelaxant effect of mitiglinide via activation of voltage-dependent K+ channels and SERCA pump in aortic smooth muscle

AIMS

The vasorelaxant effects of the anti-diabetic drug, mitiglinide in phenylephrine (Phe)-pre-contracted aortic rings were examined.

MATERIALS AND METHODS

Arterial tone measurement was performed in aortic smooth muscle cells.

KEY FINDINGS

Mitiglinide dose-dependently induced vasorelaxation. Application of the large-conductance Ca²⁺-activated K⁺ (BK_Ca) channel blocker paxilline, inwardly rectifying K⁺ (Kir) channel blocker Ba²⁺, and ATP-sensitive K⁺ (K_ATP) channel blocker glibenclamide did not affect the vasorelaxant effect of mitiglinide. However, application of the voltage-dependent K⁺ (Kv) channel blocker 4-AP, effectively inhibited mitiglinide-induced vasorelaxation. Although pretreatment with the Ca²⁺ channel blocker nifedipine did not alter the mitiglinide-induced vasorelaxation, pretreatment with the sarcoplasmic/endoplasmic reticulum Ca²⁺-ATPase (SERCA) pump inhibitor thapsigargin and cyclopiazonic acid reduced the vasorelaxant effect of mitiglinide. In addition, the vasorelaxant effect of mitiglinide was not affected by the inhibitors of adenylyl cyclase, protein kinase A, guanylyl cyclase, or protein kinase G. Elimination of the endothelium and inhibition of endothelium-dependent vasorelaxant mechanisms also did not change the vasorelaxant effect of mitiglinide.

SIGNIFICANCE

We proposed that mitiglinide induces vasorelaxation via activation of Kv channels and SERCA pump. However, the vasorelaxant effects of mitiglinide did not involve other K⁺ channels, Ca²⁺ channels, PKA/PKG signaling pathways, or the endothelium.

Targeting adipose tissue in the treatment of obesity-associated diabetes

Adipose tissue regulates numerous physiological processes, and its dysfunction in obese humans is associated with disrupted metabolic homeostasis, insulin resistance and type 2 diabetes mellitus (T2DM). Although several US-approved treatments for obesity and T2DM exist, these are limited by adverse effects and a lack of effective long-term glucose control. In this Review, we provide an overview of the role of adipose tissue in metabolic homeostasis and assess emerging novel therapeutic strategies targeting adipose tissue, including adipokine-based strategies, promotion of white adipose tissue beiging as well as reduction of inflammation and fibrosis.

Pharmacogenomics of glinides

Glinides, including repaglinide, nateglinide and mitiglinide, are a type of fasting insulin secretagogue that could help to mimic early-phase insulin release, thus providing improved control of the postprandial glucose levels. Glinides stimulate insulin secretion by inhibiting ATP-sensitive potassium channels in the pancreatic β-cell membrane. Although glinides have been widely used clinically and display excellent safety and efficacy, the response to glinides varies among individuals, which is partially due to genetic factors involved in drug absorption, distribution, metabolism and targeting. Several pharmacogenomic studies have demonstrated that variants of genes involved in the pharmacokinetics or pharmacodynamics of glinides are associated with the drug response. Polymorphisms of genes involved in drug metabolism, such as CYP2C9, CYP2C8 and SLCO1B1, may influence the efficacy of glinides and the incidence of adverse effects. In addition, Type 2 diabetes mellitus susceptibility genes, such as KCNQ1, PAX4 and BETA2, also influence the efficacy of glinides. In this article, we review and discuss current pharmacogenomics researches on glinides, and hopefully provide useful data and proof for clinical application.

Effects of sitagliptin or mitiglinide as an add-on to acarbose on daily blood glucose fluctuations measured by 72 h subcutaneous continuous glucose monitoring in Japanese patients with type 2 diabetes: a prospective randomized study

OBJECTIVE

Postprandial hyperglycemia and blood glucose fluctuations increase the risk of macroangiopathy in patients with type 2 diabetes mellitus (T2DM). However, few studies have examined the effects of oral hypoglycemic drugs on blood glucose fluctuations in daily life.

METHODS

Twenty-nine T2DM patients treated with acarbose were randomized to receive either sitagliptin (14 patients) or mitiglinide (15 patients) together with acarbose for 4 weeks. Patients were then switched to a combination of 10 mg mitiglinide and 0.2 mg voglibose for 4 weeks. All patients wore a continuous glucose monitoring (CGM) device for 5 - 7 days in week 3 of each treatment period.

RESULTS

The percentage of blood glucose levels in the hyperglycemic range, blood glucose indices derived from 24-h CGM profiles and the glycemic parameters (HbA1c, glycated albumin and fasting plasma glucose) were significantly improved by adding sitagliptin or mitiglinide to ongoing acarbose therapy. These parameters also tended to improve in the mitiglinide/voglibose combination period.

CONCLUSION

Daily blood glucose fluctuations were significantly improved by adding sitagliptin or mitiglinide to acarbose, and improved after switching to the mitiglinide/voglibose combination. Larger controlled studies are needed to verify the effects of adding sitagliptin or mitiglinide to acarbose on glucose fluctuations.

Medical resource use, disturbance of daily life and burden of hypoglycemia in insulin-treated patients with diabetes: results from a European online survey

Hypoglycemia is common in patients with diabetes, and any severe hypoglycemic event can increase the fear of future hypoglycemic events. To try to reduce hypoglycemic events, many patients with diabetes maintain their blood glucose levels with a 'safety margin' (i.e., at higher than recommended values) and maintain hyperglycemia. Following this strategy leads to raised glycated hemoglobin levels, which are, consequently, linked to an increased risk of diabetic complications and increased healthcare costs. In the present survey (n = 1848), conducted in Germany, France and the UK, approximately a third of the patients were very worried about hypoglycemia, and a similar proportion reported maintaining hyperglycemia. Overall, the mean number of emergency room visits and hospitalizations (excluding emergency room visits) per patient per 12 months was 0.65 and 0.47, respectively. In addition, 10% of the patients reported that they had taken days off work because of hypoglycemia during the previous 12 months. Furthermore, 80% of diabetics in the three countries said they would value a meter that tells them when their blood glucose level is getting high/low at a particular time of the day. Thus, the survey outlines the potential scale, in a real-world setting, of 'hidden' costs associated with hypoglycemia and fear of hypoglycemia; such costs are likely to have a major detrimental impact on the overall emotional and economic burden of diabetes, which may be reduced through broader use of blood-glucose monitors for self-monitoring of blood glucose.

Mitiglinide/voglibose fixed-dose combination improves postprandial glycemic excursions in Japanese patients with type 2 diabetes mellitus

OBJECTIVE

We examined the effects of a fixed-dose combination of 10 mg mitiglinide and 0.2 mg voglibose on postprandial glycemic excursions in Japanese type 2 diabetes mellitus (T2DM) patients.

RESEARCH DESIGN AND METHODS

After a 2-week baseline period, 11 T2DM patients were treated with mitiglinide alone for 2 weeks and with the mitiglinide/voglibose combination for 6 weeks.

MAIN OUTCOME MEASURES

Self-monitoring of blood glucose (SMBG) at home before and after unified meals, metabolic parameters during meal tolerance tests, and overall glycemic control parameters.

RESULTS

Postprandial glycemic excursions after all three meals, as assessed by SMBG, were significantly lower in the combination period than in the baseline period, and after lunch and dinner in the combination period than in the mitiglinide period. The meal tolerance test confirmed that the magnitude of postprandial hyperglycemia was significantly lower, with significantly greater early-phase serum insulin secretion and sustained GLP-1 production, in the combination period compared with the baseline period. Overall glycemic control parameters also improved significantly in the combination period compared with the baseline period. These profiles suggest the combination is superior to mitiglinide alone, and may spare insulin secretion.

CONCLUSION

The mitiglinide/voglibose combination significantly reduced postprandial glycemic excursions in Japanese T2DM patients. This trial was registered with the University Hospital Medical Information Network clinical trials database (no. UMIN000007202).

Efficacy and safety of mitiglinide versus nateglinide in newly diagnose patients with type 2 diabetes mellitus: a randomized double blind trial

This study was performed to examine the efficacy and safety of mitiglinide in type 2 diabetes patients (T2DM). Enrolled patients had received treatment with diet and exercise in the previous 3 months with glycosylated haemoglobin (HbA1c) 7-10%, and were randomized to receive mitiglinide (n = 111, 5-20 mg/meal) or nateglinide (n = 114,60-120 mg/meal) for 16 weeks. Primary and secondary efficacy endpoints were assessed by the changes in HbA1c, fasting blood glucose (FBG) and postprandial glucose (PBG) levels. The baseline HbA1c value was 8.2 and 8.3% in both groups. At the end of study, the reduction of HbA1c values from baseline by mitiglinide was slightly more than that by nateglinide (-1.11% vs. -0.76%), but not statically significant (p = 0.06). Final FBG and PBG were comparable for the two treatments. There were 2.8% subjects treated with nateglinide who had hypoglycaemic episodes, but none in the mitiglinide treatment group. The results indicate that mitiglinide and nateglinide had similar effects on FBG, PBG and HbA1c in T2DM patients after the 16-week treatments.

The molecular genetics of sulfonylurea receptors in the pathogenesis and treatment of insulin secretory disorders and type 2 diabetes

Sulfonylurea receptors (SURs) form an integral part of the ATP-sensitive potassium (K(ATP)) channel complex that is present in most excitable cell types. K(ATP) channels couple cellular metabolism to electrical activity and provide a wide range of cellular functions including stimulus secretion coupling in pancreatic β cells. K(ATP) channels are composed of SURs and inward rectifier potassium channel (Kir6.x) subunits encoded by the ABCC8/9 and KCNJ8/11 genes, respectively. Recent advances in the genetics, molecular biology, and pharmacology of SURs have led to an increased understanding of these channels in the etiology and treatment of rare genetic insulin secretory disorders. Furthermore, common genetic variants in these genes are associated with an increased risk for type 2 diabetes. In this review we summarize the molecular biology, pharmacology, and physiology of SURs and K(ATP) channels, highlighting recent advances in their genetics and understanding of rare insulin secretory disorders and susceptibility to type 2 diabetes.