Remogliflozin etabonate, in a novel category of selective low-affinity sodium glucose cotransporter (SGLT2) inhibitors, exhibits antidiabetic efficacy in rodent models

Obesity: Current and potential pharmacotherapeutics and targets

Obesity is a global epidemic that contributes to a number of health complications including cardiovascular disease, type 2 diabetes, cancer and neuropsychiatric disorders. Pharmacotherapeutic strategies to treat obesity are urgently needed. Research over the past two decades has increased substantially our knowledge of central and peripheral mechanisms underlying homeostatic energy balance. Homeostatic mechanisms involve multiple components including neuronal circuits, some originating in hypothalamus and brain stem, as well as peripherally-derived satiety, hunger and adiposity signals that modulate neural activity and regulate eating behavior. Dysregulation of one or more of these homeostatic components results in obesity. Coincident with obesity, reward mechanisms that regulate hedonic aspects of food intake override the homeostatic regulation of eating. In addition to functional interactions between homeostatic and reward systems in the regulation of food intake, homeostatic signals have the ability to alter vulnerability to drug abuse. Regarding the treatment of obesity, pharmacological monotherapies primarily focus on a single protein target. FDA-approved monotherapy options include phentermine (Adipex-P®), orlistat (Xenical®), lorcaserin (Belviq®) and liraglutide (Saxenda®). However, monotherapies have limited efficacy, in part due to the recruitment of alternate and counter-regulatory pathways. Consequently, a multi-target approach may provide greater benefit. Recently, two combination products have been approved by the FDA to treat obesity, including phentermine/topiramate (Qsymia®) and naltrexone/bupropion (Contrave®). The current review provides an overview of homeostatic and reward mechanisms that regulate energy balance, potential therapeutic targets for obesity and current treatment options, including some candidate therapeutics in clinical development. Finally, challenges in anti-obesity drug development are discussed.

Effect of Sodium-Glucose Co-Transporter 2 Inhibitor, Dapagliflozin, on Renal Renin-Angiotensin System in an Animal Model of Type 2 Diabetes

Background

Renal renin-angiotensin system (RAS) activation is one of the important pathogenic mechanisms in the development of diabetic nephropathy in type 2 diabetes. The aim of this study was to investigate the effects of a sodium-glucose co-transporter 2 (SGLT-2) inhibitor, dapagliflozin, on renal RAS in an animal model with type 2 diabetes.

Methods

Dapagliflozin (1.0 mg/kg, OL-DA) or voglibose (0.6 mg/kg, OL-VO, diabetic control) (n = 10 each) was administered to Otsuka Long-Evans Tokushima Fatty (OLETF) rats for 12 weeks. We used voglibose, an alpha-glucosidase inhibitor, as a comparable counterpart to SGLT2 inhibitor because of its postprandial glucose-lowering effect without proven renoprotective effects. Control Long-Evans Tokushima Otsuka (LT) and OLETF (OL-C) rats received saline (n = 10, each). Changes in blood glucose, urine albumin, creatinine clearance, and oxidative stress were measured. Inflammatory cell infiltration, mesangial widening, and interstitial fibrosis in the kidney were evaluated by histological analysis. The effects of dapagliflozin on renal expression of the RAS components were evaluated by quantitative RT-PCR in renal tissue.

Results

After treatment, hyperglycemia and urine microalbumin levels were attenuated in both OL-DA and OL-VO rather than in the OL-C group (P < 0.05). The urine angiotensin II (Ang II) and angiotensinogen levels were significantly decreased following treatment with dapagliflozin or voglibose, but suppression of urine Ang II level was more prominent in the OL-DA than the OL-VO group (P < 0.05). The expressions of angiotensin type 1 receptor and tissue oxidative stress markers were markedly increased in OL-C rats, which were reversed by dapagliflozin or voglibose (P < 0.05, both). Inflammatory cell infiltration, mesangial widening, interstitial fibrosis, and total collagen content were significantly increased in OL-C rats, which were attenuated in OL-DA group (P < 0.05).

Conclusion

Dapagliflozin treatment showed beneficial effects on diabetic nephropathy, which might be via suppression of renal RAS component expression, oxidative stress and interstitial fibrosis in OLETF rats. We suggest that, in addition to control of hyperglycemia, partial suppression of renal RAS with an SGLT2 inhibitor would be a promising strategy for the prevention of treatment of diabetic nephropathy.

Thyroid hormone treatment decreases hepatic glucose production and renal reabsorption of glucose in alloxan-induced diabetic Wistar rats

The thyroid hormone (TH) plays an important role in glucose metabolism. Recently, we showed that the TH improves glycemia control by decreasing cytokines expression in the adipose tissue and skeletal muscle of alloxan‐induced diabetic rats, which were also shown to present primary hypothyroidism. In this context, this study aims to investigate whether the chronic treatment of diabetic rats with T3 could affect other tissues that are involved in the control of glucose homeostasis, as the liver and kidney. Adult Male Wistar rats were divided into nondiabetic, diabetic, and diabetic treated with T3 (1.5 μg/100 g BW for 4 weeks). Diabetes was induced by alloxan monohydrate (150 mg/kg, BW, i.p.). Animals showing fasting blood glucose levels greater than 250 mg/dL were selected for the study. After treatment, we measured the blood glucose, serum T3, T4, TSH, and insulin concentration, hepatic glucose production by liver perfusion, liver PEPCK, GAPDH, and pAKT expression, as well as urine glucose concentration and renal expression of SGLT2 and GLUT2. T3 reduced blood glucose, hepatic glucose production, liver PEPCK, GAPDH, and pAKT content and the renal expression of SGLT2 and increased glycosuria. Results suggest that the decreased hepatic glucose output and increased glucose excretion induced by T3 treatment are important mechanisms that contribute to reduce serum concentration of glucose, accounting for the improvement of glucose homeostasis control in diabetic rats.

Sodium-Glucose Cotransporter 2 (SGLT2) Inhibitors from Natural Products: Discovery of Next-Generation Antihyperglycemic Agents

Diabetes mellitus is a chronic condition associated with the metabolic impairment of insulin actions, leading to the development of life-threatening complications. Although many kinds of oral antihyperglycemic agents with different therapeutic mechanisms have been marketed, their undesirable adverse effects, such as hypoglycemia, weight gain, and hepato-renal toxicity, have increased demand for the discovery of novel, safer antidiabetic drugs. Since the important roles of the sodium-glucose cotransporter 2 (SGLT2) for glucose homeostasis in the kidney were recently elucidated, pharmacological inhibition of SGLT2 has been considered a promising therapeutic target for the treatment of type 2 diabetes. Since the discovery of the first natural SGLT2 inhibitor, phlorizin, several synthetic glucoside analogs have been developed and introduced into the market. Furthermore, many efforts to find new active constituents with SGLT2 inhibition from natural products are still ongoing. This review introduces the history of research on the development of early-generation SGLT2 inhibitors, and recent progress on the discovery of novel candidates for SGLT2 inhibitor from several natural products that are widely used in traditional herbal medicine.

O-Glycosylation of 4-(Substituted benzyl)-1,2-dihydro-3H-pyrazol-3-one Derivatives with 2,3,4,6-Tetra-O-acyl-α-D-glucopyranosyl Bromide via N1-Acetylation of the Pyrazole Ring

A practical preparation of 4-(substituted benzyl)-3-(2,3,4,6-tetra-O-acyl-β-D-glucopyranosyloxy)-1H-pyrazole derivative 2 is described. O-Glycosylation of 4-(substituted benzyl)-1,2-dihydro-3H-pyrazol-3-one derivative 3 was facilitated by introduction of electron-withdrawing substituents, such as an acetyl group, at the N1-position of the pyrazole ring. 1-Acetyl-4-(substituted benzyl)-1,2-dihydro-3H-pyrazol-3-one 10 reacted with 2,3,4,6-tetra-O-acyl-α-D-glucopyranosyl bromide 5 in the presence of potassium carbonate in acetonitrile to provide the 1-acetyl-4-(substituted benzyl)-3-(2,3,4,6-tetra-O-acyl-β-D-glucopyranosyloxy)-1H-pyrazole derivative 11 in high yield. When 2,3,4,6-tetra-O-pivaloyl-α-D-glucopyranosyl bromide (5b) was used as a glycosyl donor, the resulting O-glycosylated product 11 was N1-deacetylated in the presence of potassium bicarbonate in methanol without unfavorable deprotection of the glycosyl moiety to provide 2 in excellent yield. The synthetic intermediate 2b of Remogliflozin etabonate (1b) was synthesized using this strategy.

Sodium-glucose cotransporter 2 inhibition: cardioprotection by treating diabetes-a translational viewpoint explaining its potential salutary effects

Diabetes is a growing epidemic worldwide characterized by an elevated concentration of blood glucose, associated with a high incidence of cardiovascular disease and mortality. Although in general reduction of hyperglycaemia is considered a therapeutic goal, hypoglycaemic therapies do not necessarily reduce cardiovascular mortality and may even aggravate cardiovascular risk factors, such as body weight. A new class of antidiabetic drugs acts by inhibition of the sodium-glucose cotransporter 2 (SGLT2), which (partially) prevents reabsorption of glucose from the renal filtrate. The induction of glucose excretion via the urine (glycosuria) was turned into an effective strategy to reduce blood glucose. Ancillary advantages are the caloric and volumetric loss and thereby the reduction of body weight and blood pressure. Additionally, SGLT2 inhibition has been suggested to exert direct cardioprotective effects by the reduction of cardiac fibrosis, inflammation, and oxidative stress. This article summarizes the functional consequences of SGLT2 inhibition on the diabetic and hyperglycaemic organism. We especially focused on the effects on the kidney and the cardiovascular system as described in experimental studies. The interesting observations in experimental studies may extend to clinical medicine, as a recent trial reported a decrease in heart failure outcomes in patients at high cardiovascular risk. In conclusion, SGLT2 inhibition represents a novel treatment, which might be a promising target not only to (further) reduce blood glucose but also to target other cardiovascular risk factors. More research and long-term follow-ups will reveal the specific influence of SGLT2 inhibition on the circulatory system and cardiovascular outcomes.

An efficient construction of N,N-bicyclic pyrazolidinones comprising enaminonitriles via asymmetric [3+2] cycloaddition

The first thiourea catalysed asymmetric [3+2] cycloaddition reaction between azomethine imines and malanonitriles was devoloped.

Remogliflozin Etabonate Improves Fatty Liver Disease in Diet-Induced Obese Male Mice

BACKGROUND

Nonalcoholic fatty liver disease and nonalcoholic steatohepatitis (NASH) are serious conditions and are being diagnosed at an increased rate. The etiology of these hepatic disorders is not clear but involves insulin resistance and oxidative stress. Remogliflozin etabonate (Remo) is an inhibitor of the sodium glucose-dependent renal transporter 2 (SGLT2), and improves insulin sensitivity in type 2 diabetics. In the current study, we examined the effects of Remo in a diet-induced obese mouse model of NAFLD.

METHODS

After 11-weeks on High-Fat-Diet 32 (HFD32), C57BL/6J mice were obese and displayed characteristics consistent with NAFLD. Cohorts of obese animals were continued on HFD32 for an additional 4-week treatment period with or without Remo.

RESULTS

Treatment with Remo for 4 weeks markedly lowered both plasma alanine aminotransferase (76%) and aspartate aminotransferase (48%), and reduced both liver weight and hepatic triglyceride content by 42% and 40%, respectively. Remo also reduced hepatic mRNA content for tumor necrosis factor (TNF)-α (69%), and monocyte chemoattractant protein (MCP)-1 (69%). The diet-induced increase in thiobarbituric acid-reactive substances, a marker of oxidative stress, was reduced following treatment with Remo, as measured in both liver homogenates (22%) and serum (37%). Finally, the oxygen radical absorbance capacity (ORAC) in three different SGLT2 inhibitors was determined: remogliflozin, canagliflozin and dapagliflozin. Only remogliflozin had any significant ORAC activity.

CONCLUSIONS

Remo significantly improved markers associated with NAFLD in this animal model, and may be an effective compound for the treatment of NASH and NAFLD due to its insulin-sensitizing and antioxidant properties.

Remogliflozin etabonate: a novel SGLT2 inhibitor for treatment of diabetes mellitus

INTRODUCTION

Inhibitors of sodium-glucose co-transporter type 2 (SGLT2) represent a new class of anti-hyperglycemic agents with a unique mechanism of action. These drugs lower blood glucose by increasing urinary glucose excretion. Remogliflozin etabonate (RE) is a prodrug of remogliflozin, an SGLT2 inhibitor under development.

AREAS COVERED

The following article reviews all of the clinical studies published regarding metabolism, drug interaction, safety and efficacy of RE in healthy subjects, patients with type 1 and type 2 diabetes.

EXPERT OPINION

Available data suggest low potential for RE to interact with other drugs affecting the P450 system. Compared with placebo, RE reduces hemoglobin A1c (HbA1c) levels by an average of 0.5 - 1.0% after 12 weeks of therapy in drug-naive patients with type 2 diabetes. Because of its relatively short half-life, RE may be slightly more effective when used twice daily than once daily. One preliminary study also showed that RE decreased plasma glucose levels in type 1 diabetes. Advantages of RE include modest weight loss of ∼ 2 kg, low risk of hypoglycemia, and a trend toward decrease in blood pressure. The commonest adverse effects of RE are genital mycotic infections, urinary tract infections, and dizziness. However, further studies are needed to establish its long-term safety and efficacy, and to determine whether it has specific advantages over currently approved SGLT2 inhibitors.

An evaluation of US patent 2015065565 (A1) for a new class of SGLT2 inhibitors for treatment 1 of type II diabetes mellitus

INTRODUCTION

Type 2 diabetes mellitus (T2DM) is a growing and serious global health problem. Pharmacological inhibition of the sodium-glucose cotransporter-2 (SGLT2; SLC5A2) increases urinary glucose excretion, decreasing plasma glucose levels in an insulin-independent manner. Agents that inhibit SGLT2 have recently become available for clinical therapy of T2DM.

AREAS COVERED

The patent claims a new class of SGLT2 inhibitors: derivatives of dioxa-bicyclo[3.2.1]octane-2,3,4-triol (including ertugliflozin; PF-04971729). The invention describes the design, synthesis and pharmacological tests related to ertugliflozin, which could ultimately lead to efficacious therapy for T2DM alone or in combination with other anti-diabetic agents.

EXPERT OPINION

Ertugliflozin is likely to be of great clinical significance in the near future. Continued analysis of ertugliflozin derivatives to now validate safe and efficacious treatment of T2DM in a larger number of clinical subjects over an extended period is needed to further support clinical utility. Identification, and discussion, of likely contra-indications is also needed.

SLC transporters as therapeutic targets: emerging opportunities

Solute carrier (SLC) transporters - a family of more than 300 membrane-bound proteins that facilitate the transport of a wide array of substrates across biological membranes - have important roles in physiological processes ranging from the cellular uptake of nutrients to the absorption of drugs and other xenobiotics. Several classes of marketed drugs target well-known SLC transporters, such as neurotransmitter transporters, and human genetic studies have provided powerful insight into the roles of more-recently characterized SLC transporters in both rare and common diseases, indicating a wealth of new therapeutic opportunities. This Review summarizes knowledge on the roles of SLC transporters in human disease, describes strategies to target such transporters, and highlights current and investigational drugs that modulate SLC transporters, as well as promising drug targets.

Pharmacokinetics and Pharmacodynamics of the SGLT2 Inhibitor Remogliflozin Etabonate in Subjects with Mild and Moderate Renal Impairment

Remogliflozin etabonate (RE), the prodrug of remogliflozin, is an inhibitor of the sodium glucose-dependent renal transporter 2 (SGLT2), enabling urinary glucose excretion to reduce hyperglycemia for the treatment of type 2 diabetes. Renal function declines more rapidly in patients with type 2 diabetes, making it difficult or unsafe to continue on some antidiabetic therapeutics. In an initial effort to understand the potential utility of RE in patients with renal impairment, the pharmacodynamics and pharmacokinetics of RE were evaluated in a single oral dose (250 mg) in patients with renal impairment as compared with control subjects. As shown by pharmacodynamic measurements of urinary glucose excretion, there was no clinically significant reduction in the ability of remogliflozin to inhibit SGLT2. In addition, there were no significant changes in area under the curve (from 0 to infinity) or half-life of remogliflozin, suggesting renal impairment does not alter the pharmacokinetics of remogliflozin. In contrast to other SGLT2 inhibitors which accumulate in patients with renal impairment, adjustment of the dosage of RE in subjects with mild or moderate renal impairment is not indicated based on the observations in this study.

Inhibition of the glucose transporter SGLT2 with dapagliflozin in pancreatic alpha cells triggers glucagon secretion

Type 2 diabetes (T2D) is characterized by chronic hyperglycemia resulting from a deficiency in insulin signaling, because of insulin resistance and/or defects in insulin secretion; it is also associated with increases in glucagon and endogenous glucose production (EGP). Gliflozins, including dapagliflozin, are a new class of approved oral antidiabetic agents that specifically inhibit sodium-glucose co-transporter 2 (SGLT2) function in the kidney, thus preventing renal glucose reabsorption and increasing glycosuria in diabetic individuals while reducing hyperglycemia. However, gliflozin treatment in subjects with T2D increases both plasma glucagon and EGP by unknown mechanisms. In spite of the rise in EGP, T2D patients treated with gliflozin have lower blood glucose levels than those receiving placebo, possibly because of increased glycosuria; however, the resulting increase in plasma glucagon levels represents a possible concerning side effect, especially in a patient population already affected by hyperglucagonemia. Here we demonstrate that SGLT2 is expressed in glucagon-secreting alpha cells of the pancreatic islets. We further found that expression of SLC5A2 (which encodes SGLT2) was lower and glucagon (GCG) gene expression was higher in islets from T2D individuals and in normal islets exposed to chronic hyperglycemia than in islets from non-diabetics. Moreover, hepatocyte nuclear factor 4-α (HNF4A) is specifically expressed in human alpha cells, in which it controls SLC5A2 expression, and its expression is downregulated by hyperglycemia. In addition, inhibition of either SLC5A2 via siRNA-induced gene silencing or SGLT2 via dapagliflozin treatment in human islets triggered glucagon secretion through KATP channel activation. Finally, we found that dapagliflozin treatment further promotes glucagon secretion and hepatic gluconeogenesis in healthy mice, thereby limiting the decrease of plasma glucose induced by fasting. Collectively, these results identify a heretofore unknown role of SGLT2 and designate dapagliflozin an alpha cell secretagogue.

Potentiation of insulin-mediated glucose lowering without elevated hypoglycemia risk by a small molecule insulin receptor modulator

Insulin resistance is the key feature of type 2 diabetes and is manifested as attenuated insulin receptor (IR) signaling in response to same levels of insulin binding. Several small molecule IR activators have been identified and reported to exhibit insulin sensitization properties. One of these molecules, TLK19781 (Cmpd1), was investigated to examine its IR sensitizing action in vivo. Our data demonstrate that Cmpd1, at doses that produced minimal efficacy in the absence of insulin, potentiated insulin action during an OGTT in non-diabetic mice and enhanced insulin-mediated glucose lowering in diabetic mice. Interestingly, different from insulin alone, Cmpd1 combined with insulin showed enhanced efficacy and duration of action without increased hypoglycemia. To explore the mechanism underlying the apparent glucose dependent efficacy, tissue insulin signaling was compared in healthy and diabetic mice. Cmpd1 enhanced insulin’s effects on IR phosphorylation in both healthy and diabetic mice. In contrast, the compound potentiated insulin’s effects on Akt phosphorylation in diabetic but not in non-diabetic mice. These differential effects on signaling corresponding to glucose levels could be part of the mechanism for reduced hypoglycemia risk. The in vivo efficacy of Cmpd1 is specific and dependent on IR expression. Results from these studies support the idea of targeting IR for insulin sensitization, which carries low hypoglycemia risk by standalone treatment and could improve the effectiveness of insulin therapies.

Beneficial effects of canagliflozin in combination with pioglitazone on insulin sensitivity in rodent models of obese type 2 diabetes

BACKGROUND

Despite its insulin sensitizing effects, pioglitazone may induce weight gain leading to an increased risk of development of insulin resistance. A novel sodium glucose co-transporter 2 (SGLT2) inhibitor, canagliflozin, provides not only glycemic control but also body weight reduction through an insulin-independent mechanism. The aim of this study was to investigate the combined effects of these agents on body weight control and insulin sensitivity.

METHODS

Effects of combination therapy with canagliflozin and pioglitazone were evaluated in established diabetic KK-Ay mice and prediabetic Zucker diabetic fatty (ZDF) rats.

RESULTS

In the KK-Ay mice, the combination therapy further improved glycemic control compared with canagliflozin or pioglitazone monotherapy. Furthermore, the combination significantly attenuated body weight and fat gain induced by pioglitazone and improved hyperinsulinemia. In the ZDF rats, early intervention with pioglitazone monotherapy almost completely prevented the progressive development of hyperglycemia, and no further improvement was observed by add-on treatment with canagliflozin. However, the combination significantly reduced pioglitazone-induced weight gain and adiposity and improved the Matsuda index, suggesting improved whole-body insulin sensitivity.

CONCLUSIONS

Our study indicates that combination therapy with canagliflozin and pioglitazone improves insulin sensitivity partly by preventing glucotoxicity and, at least partly, by attenuating pioglitazone-induced body weight gain in two different obese diabetic animal models. This combination therapy may prove to be a valuable option for the treatment and prevention of obese type 2 diabetes.

Molecular Modeling Studies of Thiophenyl C-Aryl Glucoside SGLT2 Inhibitors as Potential Antidiabetic Agents

A QSAR study on thiophenyl derivatives as SGLT2 inhibitors as potential antidiabetic agents was performed with thirty-three compounds. Comparison of the obtained results indicated the superiority of the genetic algorithm over the simulated annealing and stepwise forward-backward variable method for feature selection. The best 2D QSAR model showed satisfactory statistical parameters for the data set (r (2) = 0.8499, q (2) = 0.8267, and pred_r (2) = 0.7729) with four descriptors describing the nature of substituent groups and the environment of the substitution site. Evaluation of the model implied that electron-rich substitution position improves the inhibitory activity. The good predictive 3D-QSAR models by k-nearest neighbor (kNN) method for molecular field analysis (MFA) have cross-validated coefficient q (2) value of 0.7663 and predicted r (2) value of 0.7386. The results have showed that thiophenyl groups are necessary for activity and halogen, bulky, and less bulky groups in thiophenyl nucleus enhanced the biological activity. These studies are promising for the development of novel SGLT2 inhibitor, which may have potent antidiabetic activity.

Asymmetric synthesis of pyrazoles and pyrazolones employing the reactivity of pyrazolin-5-one derivatives

The various catalytic asymmetric strategies employing organo- and metal-catalysts utilized pyrazolin-5-one derivatives for the synthesis of potentially bioactive enantiopure pyrazoles and pyrazolones are presented.

Lowering plasma glucose concentration by inhibiting renal sodium-glucose cotransport

Maintaining normoglycaemia not only reduces the risk of diabetic microvascular complications but also corrects the metabolic abnormalities that contribute to the development and progression of hyperglycaemia, that is insulin resistance and beta-cell dysfunction. Progressive beta-cell failure, in addition to side effects associated with many current antidiabetic agents, for example hypoglycaemia and weight gain, presents major obstacles to the achievement of the recommended goal of glycaemic control in patients with type 2 diabetes mellitus (T2DM). Thus, novel effective therapies are needed for optimal glucose control in subjects with T2DM. Most recently, specific inhibitors of the renal sodium-glucose cotransporter 2 (SGLT2) have been developed to produce glucosuria and lower the plasma glucose concentration. Because of the iR unique mechanism of action, which is independent of insulin secretion and insulin action, these agents are effective in lowering the plasma glucose concentration in all stages of the disease and can be combined with all other antidiabetic agents. In this review, we will summarize the available data concerning the mechanism of action, efficacy and safety of this novel class of antidiabetic agents.

Sodium-glucose transporter-2 (SGLT2; SLC5A2) enhances cellular uptake of aminoglycosides

Aminoglycoside antibiotics, like gentamicin, continue to be clinically essential worldwide to treat life-threatening bacterial infections. Yet, the ototoxic and nephrotoxic side-effects of these drugs remain serious complications. A major site of gentamicin uptake and toxicity resides within kidney proximal tubules that also heavily express electrogenic sodium-glucose transporter-2 (SGLT2; SLC5A2) in vivo. We hypothesized that SGLT2 traffics gentamicin, and promotes cellular toxicity. We confirmed in vitro expression of SGLT2 in proximal tubule-derived KPT2 cells, and absence in distal tubule-derived KDT3 cells. D-glucose competitively decreased the uptake of 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG), a fluorescent analog of glucose, and fluorescently-tagged gentamicin (GTTR) by KPT2 cells. Phlorizin, an SGLT2 antagonist, strongly inhibited uptake of 2-NBDG and GTTR by KPT2 cells in a dose- and time-dependent manner. GTTR uptake was elevated in KDT3 cells transfected with SGLT2 (compared to controls); and this enhanced uptake was attenuated by phlorizin. Knock-down of SGLT2 expression by siRNA reduced gentamicin-induced cytotoxicity. In vivo, SGLT2 was robustly expressed in kidney proximal tubule cells of heterozygous, but not null, mice. Phlorizin decreased GTTR uptake by kidney proximal tubule cells in Sglt2^+/− mice, but not in Sglt2^−/− mice. However, serum GTTR levels were elevated in Sglt2^−/− mice compared to Sglt2^+/− mice, and in phlorizin-treated Sglt2^+/− mice compared to vehicle-treated Sglt2^+/− mice. Loss of SGLT2 function by antagonism or by gene deletion did not affect gentamicin cochlear loading or auditory function. Phlorizin did not protect wild-type mice from kanamycin-induced ototoxicity. We conclude that SGLT2 can traffic gentamicin and contribute to gentamicin-induced cytotoxicity.

Tofogliflozin, a novel sodium-glucose co-transporter 2 inhibitor, improves renal and pancreatic function in db/db mice

BACKGROUND AND PURPOSE

Although inhibition of renal sodium-glucose co-transporter 2 (SGLT2) has a stable glucose-lowering effect in patients with type 2 diabetes, the effect of SGLT2 inhibition on renal dysfunction in type 2 diabetes remains to be determined. To evaluate the renoprotective effect of SGLT2 inhibition more precisely, we compared the effects of tofogliflozin (a specific SGLT2 inhibitor) with those of losartan (an angiotensin II receptor antagonist) on renal function and beta-cell function in db/db mice.

EXPERIMENTAL APPROACH

The effects of 8-week tofogliflozin or losartan treatment on renal and beta-cell function were investigated in db/db mice by quantitative image analysis of glomerular size, mesangial matrix expansion and islet beta-cell mass. Blood glucose, glycated Hb and insulin levels, along with urinary albumin and creatinine were measured

KEY RESULTS

Tofogliflozin suppressed plasma glucose and glycated Hb and preserved pancreatic beta-cell mass and plasma insulin levels. No improvement of glycaemic conditions or insulin level was observed with losartan treatment. Although the urinary albumin/creatinine ratio of untreated db/db mice gradually increased from baseline, tofogliflozin or losartan treatment prevented this increase (by 50-70%). Tofogliflozin, but not losartan, attenuated glomerular hypertrophy. Neither tofogliflozin nor losartan altered matrix expansion.

CONCLUSIONS AND IMPLICATIONS

Long-term inhibition of renal SGLT2 by tofogliflozin not only preserved pancreatic beta-cell function, but also prevented kidney dysfunction in a mouse model of type 2 diabetes. These findings suggest that long-term use of tofogliflozin in patients with type 2 diabetes may prevent progression of diabetic nephropathy.

Long-term treatment with the sodium glucose cotransporter 2 inhibitor, dapagliflozin, ameliorates glucose homeostasis and diabetic nephropathy in db/db mice

Inhibition of sodium glucose cotransporter 2 (SGLT2) has been reported as a new therapeutic strategy for treating diabetes. However, the effect of SGLT2 inhibitors on the kidney is unknown. In addition, whether SGLT2 inhibitors have an anti-inflammatory or antioxidative stress effect is still unclear. In this study, to resolve these issues, we evaluated the effects of the SGLT2 inhibitor, dapagliflozin, using a mouse model of type 2 diabetes and cultured proximal tubular epithelial (mProx24) cells. Male db/db mice were administered 0.1 or 1.0 mg/kg of dapagliflozin for 12 weeks. Body weight, blood pressure, blood glucose, hemoglobin A1c, albuminuria and creatinine clearance were measured. Mesangial matrix accumulation and interstitial fibrosis in the kidney and pancreatic β-cell mass were evaluated by histological analysis. Furthermore, gene expression of inflammatory mediators, such as osteopontin, monocyte chemoattractant protein-1 and transforming growth factor-β, was evaluated by quantitative reverse transcriptase-PCR. In addition, oxidative stress was evaluated by dihydroethidium and NADPH oxidase 4 staining. Administration of 0.1 or 1.0 mg/kg of dapagliflozin ameliorated hyperglycemia, β-cell damage and albuminuria in db/db mice. Serum creatinine, creatinine clearance and blood pressure were not affected by administration of dapagliflozin, but glomerular mesangial expansion and interstitial fibrosis were suppressed in a dose-dependent manner. Dapagliflozin treatment markedly decreased macrophage infiltration and the gene expression of inflammation and oxidative stress in the kidney of db/db mice. Moreover, dapagliflozin suppressed the high-glucose-induced gene expression of inflammatory cytokines and oxidative stress in cultured mProx24 cells. These data suggest that dapagliflozin ameliorates diabetic nephropathy by improving hyperglycemia along with inhibiting inflammation and oxidative stress.

Clinical implication of SGLT2 inhibitors in type 2 diabetes

Treatment of type 2 diabetes mellitus (T2DM) continues to present challenges, with many patients failing to achieve glycemic targets. Despite the availability of many oral and injectable anti-diabetic agents, therapeutic efficacy is often offset by undesirable side effects such as hypoglycemia, weight gain and cardiovascular complications. Therefore, the search for new therapeutic agents with an improved benefit-risk profile continues. Recent research has focused on the kidney as a potential therapeutic target, especially because maximal renal glucose reabsorption is increased in T2DM. Under normal physiological conditions, nearly all filtered glucose is reabsorbed in the proximal tubule of the nephron via the sodium/glucose co-transporter 2 (SGLT2). SGLT2-inhibitors are a new class of oral anti-diabetes, which reduce hyperglycemia by increasing urinary glucose excretion independently of insulin secretion or action. Canagliflozin and dapagliflozin in US market, and ipragliflozin and luseogliflozin in Japan market are now available for glycemic control in type 2 diabetics. There are several phase III clinical ongoing trials involving this new class of medications. This review examines some of the key efficacy and safety data from clinical trials of the SGLT2 inhibitors approved, and their future perspectives in the treatment of T2DM.

SGLT2 inhibitors in the treatment of type 2 diabetes

The kidney plays an important role in glucose homeostasis via its production, utilization, and, most importantly, reabsorption of glucose from glomerular filtrate which is largely mediated via the sodium glucose co-transporter 2 (SGLT2). Pharmacological inhibition of SGLT2 increases urinary glucose excretion and decreases plasma glucose levels in an insulin-independent manner. Agents that inhibit SGLT2 represent a novel class of drugs, which has recently become available for treatment of type 2 diabetes. This article summarizes the rationale for use of these agents and reviews available clinical data on their efficacy, safety, and risks/benefits.

SHR3824, a novel selective inhibitor of renal sodium glucose cotransporter 2, exhibits antidiabetic efficacy in rodent models

AIM

The sodium glucose cotransporter 2 (SGLT2) plays an important role in renal glucose reabsorption, thus serves as a new target for the treatment of diabetes. The purpose of this study was to evaluate SHR3824 as a novel selective SGLT2 inhibitor and to characterize its in vivo effects on glucose homeostasis. The effects of chronic administration of SHR3824 on peripheral insulin sensitivity and pancreatic β-cell function were also investigated.

METHODS

The in vitro potency and selectivity of SHR3824 were assessed in HEK293 cells transfected with human SGLT2 or SGLT1. Acute and multi-dose studies were performed on ICR mice, GK rats and db/db mice to assess the ability of SHR3824 to enhance urinary glucose excretion and improve blood glucose levels. 2-Deoxyglucose uptake and insulin immunohistochemical staining were performed in the soleus muscle and pancreas, respectively, of db/db mice. A selective SGLT2 inhibitor BMS512148 (dapagliflozin) was taken as positive control.

RESULTS

SHR3824 potently inhibited human SGLT2 in vitro, but exerted much weak inhibition on human SGLT1 (the IC50 values of SHR3824 against human SGLT2 and SGLT1 were 2.38 and 4324 nmol/L, respectively). Acute oral administration of SHR3824 (0.3, 1.0, 3.0 mg/kg) dose-dependently improved glucose tolerance in ICR mice, and reduced hyperglycemia by increasing urinary glucose excretion in GK rats and db/db mice. Chronic oral administration of SHR3824 (0.3, 1.0, 3.0 mg·kg(-1)·d(-1)) dose-dependently reduced blood glucose and HbA1c levels in GK rats and db/db mice, and significantly increased insulin-stimulated glucose uptake in the soleus muscles and enhanced insulin staining in the islet cells of db/db mice.

CONCLUSION

SHR3824 is a potent and selective SGLT2 inhibitor and exhibits antidiabetic efficacy in several rodent models, suggesting its potential as a new therapeutic agent for the treatment of type 2 diabetes.

Synthesis of l-rhamnose derived chiral bicyclic triazoles as novel sodium-glucose transporter (SGLT) inhibitors

Fused chiral bicyclic 1,2,3-triazoles synthesized from commercially available natural l-rhamnose exhibited excellent SGLT inhibition activity.

Combination of the sodium-glucose cotransporter-2 inhibitor empagliflozin with orlistat or sibutramine further improves the body-weight reduction and glucose homeostasis of obese rats fed a cafeteria diet

The present study assessed the potential of the sodium glucose-linked transporter (SGLT)-2 inhibitor empagliflozin to decrease body weight when administered alone or in combination with the clinically effective weight-loss agents orlistat and sibutramine in obese rats fed a cafeteria diet. Female Wistar rats were exposed to a cafeteria diet to induce obesity. Empagliflozin was dosed once daily (10, 30, and 60 mg/kg) for 28 days. Combination studies were subsequently performed using a submaximal empagliflozin dose (10 mg/kg) with either sibutramine or orlistat. Body weight, food, and water intake were recorded daily. The effect of drug treatment on glucose tolerance, relevant plasma parameters, and carcass composition was determined. Empagliflozin dose-dependently reduced body weight, plasma leptin, and body fat though increased urinary glucose excretion. The combination of empagliflozin and orlistat significantly reduced body weight compared to animals treated with either drug alone, and significantly improved glucose tolerance, plasma insulin, and leptin compared to vehicle-treated controls. The effect of sibutramine to improve glycemic control in an oral glucose-tolerance test was also significantly increased, with empagliflozin and combination treatment leading to a reduction in carcass fat greater than that observed with either drug alone. These data demonstrate that empagliflozin reduces body weight in cafeteria-fed obese rats. In combination studies, empagliflozin further improved the body-weight or body-fat loss of animals in comparison to orlistat or sibutramine alone. Such studies may indicate improved strategies for the treatment of obese patients with prediabetes or type 2 diabetes.

Exploring glycosuria as a mechanism for weight and fat mass reduction. A pilot study with remogliflozin etabonate and sergliflozin etabonate in healthy obese subjects

Inhibitors of sodium-dependent glucose co-transporter 2 (SGLT2) increase glucose excretion in the urine and improve blood glucose in Type 2 diabetes mellitus. Glycosuria provides an energy and osmotic drain that could alter body composition. We therefore conducted a pilot study comparing the effects on body composition of two SGLT2 inhibitors, remogliflozin etabonate (RE) 250 mg TID (n = 9) and sergliflozin etabonate (SE) (1000 mg TID) (n = 9), with placebo (n = 12) in obese non-diabetic subjects. Both drugs were well tolerated during 8 weeks of dosing, and the most common adverse event was headache. No urinary tract infections were observed, but there was one case of vaginal candidiasis in the RE group. As expected, RE and SE increased urine glucose excretion, with no change in the placebo group. All the subjects lost weight over 8 weeks, irrespective of treatment assignment. There was a reduction in TBW measured by D₂O dilution in the RE group that was significantly greater than placebo (1.4 kg, p = 0.029). This was corroborated by calculation of fat-free mass using a quantitative magnetic resonance technique. All but one subject had a measurable decrease in fat mass. There was significant between-subject variability of weight and fat loss, and no statistically significant differences were observed between groups. Despite a lack of a difference in weight and fat mass loss, the leptin/adiponectin ratio, a measure of insulin resistance, was significantly decreased in the RE group when compared to placebo and SE, suggesting that this SGTL-2 inhibitor may improve metabolic health independent of a change in fat mass.

First human dose-escalation study with remogliflozin etabonate, a selective inhibitor of the sodium-glucose transporter 2 (SGLT2), in healthy subjects and in subjects with type 2 diabetes mellitus

Background

Remogliflozin etabonate (RE) is the prodrug of remogliflozin, a selective inhibitor of the renal sodium-dependent glucose transporter 2 (SGLT2), which could increase urine glucose excretion (UGE) and lower plasma glucose in humans.

Methods

This double-blind, randomized, placebo-controlled, single-dose, dose-escalation, crossover study is the first human trial designed to evaluate safety, tolerability, pharmacokinetics (PK) and pharmacodynamics of RE. All subjects received single oral doses of either RE or placebo separated by approximately 2 week intervals. In Part A, 10 healthy subjects participated in 5 dosing periods where they received RE (20 mg, 50 mg, 150 mg, 500 mg, or 1000 mg) or placebo (4:1 active to placebo ratio per treatment period). In Part B, 6 subjects with type 2 diabetes mellitus (T2DM) participated in 3 dose periods where they received RE (50 mg and 500 mg) or placebo (2:1 active to placebo per treatment period). The study protocol was registered with the NIH clinical trials data base with identifier NCT01571661.

Results

RE was generally well-tolerated; there were no serious adverse events. In both populations, RE was rapidly absorbed and converted to remogliflozin (time to maximum plasma concentration [C_max;T_max] approximately 1 h). Generally, exposure to remogliflozin was proportional to the administered dose. RE was rapidly eliminated (mean T_½ of ~25 min; mean plasma T_½ for remogliflozin was 120 min) and was independent of dose. All subjects showed dose-dependent increases in 24-hour UGE, which plateaued at approximately 200 to 250 mmol glucose with RE doses ≥150 mg. In T2DM subjects, increased plasma glucose following OGTT was attenuated by RE in a drug-dependent fashion, but there were no clear trends in plasma insulin. There were no apparent effects of treatment on plasma or urine electrolytes.

Conclusions

The results support progression of RE as a potential treatment for T2DM.

Trial registration

ClinicalTrials.gov NCT01571661

Inhibition of the sodium glucose co-transporter-2: its beneficial action and potential combination therapy for type 2 diabetes mellitus

Sodium glucose co-transporter-2 (SGLT2) inhibitors are an emerging class of glucose-lowering drugs in the management of type 2 diabetes mellitus (T2DM). In this context, SGLT2 is a low-affinity, high-capacity transporter that is expressed predominantly in the proximal renal tubules. The rationale for using SGLT2 inhibition as a drug for T2DM is derived from early evidence obtained from individuals with familial renal glycosuria, due to a SGLT2 mutation, which exhibits decreased renal tubular reabsorption of glucose in the absence of hyperglycaemia or any other signs of dysfunction. Thus, reduction of glucose reabsorption by SGLT2 inhibition represents a novel T2DM treatment approach. In light of the emerging role of SGLT2 inhibition in controlling glucose homeostasis, the current review provides a critical appraisal of the rationale, overviews of structural differences between SGLT2 inhibitors and summarizes recent preclinical and clinical studies. The physiological actions of SGLT2 inhibition in relation to insulin sensitivity, islet morphology, inflammation, body weight and blood pressure are reviewed. Finally, the safety and tolerability of SGLT2 inhibitors are also discussed in relation to their potential to provide insulin independence and enhance β-cell function, as well as their potential for synergistic/additive effects if used in combination with other antidiabetic drugs.

Safety, pharmacokinetics and pharmacodynamics of remogliflozin etabonate, a novel SGLT2 inhibitor, and metformin when co-administered in subjects with type 2 diabetes mellitus

Background

The sodium-dependent glucose co-transporter-2 (SGLT2) is expressed in absorptive epithelia of the renal tubules. Remogliflozin etabonate (RE) is the prodrug of remogliflozin, the active entity that inhibits SGLT2. An inhibitor of this pathway would enhance urinary glucose excretion (UGE), and potentially improve plasma glucose concentrations in diabetic patients. RE is intended for use for the treatment of type 2 diabetes mellitus (T2DM) as monotherapy and in combination with existing therapies. Metformin, a dimethylbiguanide, is an effective oral antihyperglycemic agent widely used for the treatment of T2DM.

Methods

This was a randomized, open-label, repeat-dose, two-sequence, cross-over study in 13 subjects with T2DM. Subjects were randomized to one of two treatment sequences in which they received either metformin alone, RE alone, or both over three, 3-day treatment periods separated by two non-treatment intervals of variable duration. On the evening before each treatment period, subjects were admitted and confined to the clinical site for the duration of the 3-day treatment period. Pharmacokinetic, pharmacodynamic (urine glucose and fasting plasma glucose), and safety (adverse events, vital signs, ECG, clinical laboratory parameters including lactic acid) assessments were performed at check-in and throughout the treatment periods. Pharmacokinetic sampling occurred on Day 3 of each treatment period.

Results

This study demonstrated the lack of effect of RE on steady state metformin pharmacokinetics. Metformin did not affect the AUC of RE, remogliflozin, or its active metabolite, GSK279782, although C_max values were slightly lower for remogliflozin and its metabolite after co-administration with metformin compared with administration of RE alone. Metformin did not alter the pharmacodynamic effects (UGE) of RE. Concomitant administration of metformin and RE was well tolerated with minimal hypoglycemia, no serious adverse events, and no increase in lactic acid.

Conclusions

Coadministration of metformin and RE was well tolerated in this study. The results support continued development of RE as a treatment for T2DM.

Trial registration

ClinicalTrials.gov, NCT00376038

Ipragliflozin and other sodium-glucose cotransporter-2 (SGLT2) inhibitors in the treatment of type 2 diabetes: preclinical and clinical data

Sodium-glucose cotransporter-2 (SGLT2) is expressed in the proximal tubules of the kidneys and plays a key role in renal glucose reabsorption. A novel class of antidiabetic medications, SGLT2-selective inhibitors attempt to improve glycemic control in diabetics by preventing glucose from being reabsorbed through SGLT2 and re-entering circulation. Ipragliflozin is an SGLT2 inhibitor in Phase 3 clinical development for the treatment of type 2 diabetes mellitus (T2DM). In this review, we summarize recent animal and human studies on ipragliflozin and other SGLT2 inhibitors including dapagliflozin, canagliflozin, empagliflozin, tofogliflozin, and luseogliflozin. These agents all show potent and selective SGLT2 inhibition in vitro and reduce blood glucose levels and HbA1c in both diabetic animal models and patients with T2DM. SGLT2 inhibitors offer several advantages over other classes of hypoglycemic agents. Due to their insulin-independent mode of action, SGLT2 inhibitors provide steady glucose control without major risk for hypoglycemia and may also reverse β-cell dysfunction and insulin resistance. Other favorable effects of SGLT2 inhibitors include a reduction in both body weight and blood pressure. SGLT2 inhibitors are safe and well tolerated and can easily be combined with other classes of antidiabetic medications to achieve tighter glycemic control. The long-term safety and efficacy of these agents are under evaluation.

SGLT2 inhibition: a novel prospective strategy in treatment of diabetes mellitus

The role of the kidney in glucose homeostasis and the potential of the kidney as a therapeutic target in type 2 diabetes is little appreciated. Hyperglycemia is an important pathogenic component in the development of microvascular and macrovascular complications in type 2 diabetes mellitus. Inhibition of renal tubular glucose re-absorption that leads to glycosuria has been proposed as a new mechanism to attain normoglycemia and thus prevent and diminish these complications, thus representing an innovative therapeutic strategy for the treatment of hyperglycemia and/or obesity in patients with type 1 or type 2 diabetes by enhancing glucose and energy loss through the urine. Sodium glucose co-transporter 2 (SGLT2) has a key role in re-absorption of glucose in kidney. Competitive inhibitors of SGLT2 have been discovered and a few of them have also been advanced in clinical trials for the treatment of diabetes.