Pharmacodynamics of Vildagliptin in Patients With Type 2 Diabetes During OGTT

A systematic review on the clinical pharmacokinetics of vildagliptin in healthy and disease populations

INTRODUCTION

Vildagliptin, a dipeptidyl peptidase-4 inhibitor, is indicated to cure type 2 diabetes mellitus (T2DM). This systematic literature search aims to assess the current knowledge about the clinical pharmacokinetics (PK) of vildagliptin to provide recommendations for clinical use to prevent the harmful effects of this drug.

METHODS

The PubMed, Science Direct, EBSCO, Cochrane Central Register of Controlled Trials, and Google Scholar databases were screened for articles related to the clinical PK of vildagliptin using systematic search strategies.

RESULTS

The literature search identified 2118 records, among which 28 were subsumed in this systematic review that fulfilled the inclusion standards.

CONCLUSIONS

This systematic review can help dose optimization among critically ill patients (e.g. renal impairment) without exposing them to the drug's toxic effects.

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.

Role of Dipeptidyl Peptidase 4 Inhibitors in Antidiabetic Treatment

In recent years, important changes have occurred in the field of diabetes treatment. The focus of the treatment of diabetic patients has shifted from the control of blood glucose itself to the overall management of risk factors, while adjusting blood glucose goals according to individualization. In addition, regulators need to approve new antidiabetic drugs which have been tested for cardiovascular safety. Thus, the newest class of drugs has been shown to reduce major adverse cardiovascular events, including sodium-glucose transporter 2 (SGLT2) and some glucagon like peptide 1 receptor (GLP1) analog. As such, they have a prominent place in the hyperglycemia treatment algorithms. In recent years, the role of DPP4 inhibitors (DPP4i) has been modified. DPP4i have a favorable safety profile and anti-inflammatory profile, do not cause hypoglycemia or weight gain, and do not require dose escalation. In addition, it can also be applied to some types of chronic kidney disease patients and elderly patients with diabetes. Overall, DPP4i, as a class of safe oral hypoglycemic agents, have a role in the management of diabetic patients, and there is extensive experience in their use.

Glucose-lowering action through targeting islet dysfunction in type 2 diabetes: Focus on dipeptidyl peptidase-4 inhibition

Dipeptidyl peptidase-4 (DPP-4) inhibition is a glucose-lowering medication for type 2 diabetes. It works through stimulation of insulin secretion and inhibition of glucagon secretion in a glucose-dependent manner, resulting in lowered fasting and postprandial glycemia with low risk of hypoglycemia. As impaired insulin secretion and augmented glucagon secretion are key factors underlying hyperglycemia in type 2 diabetes, DPP-4 inhibition represents a therapy that targets the underlying mechanisms of the disease. If insufficient in monotherapy, it can preferably be used in combination with metformin, which targets insulin resistance, and also in combination with sodium-glucose cotransporter 2 inhibition, thiazolidinediones and insulin, which target other mechanisms. In individuals of East Asian origin, islet dysfunction is of particular importance for the development of type 2 diabetes. Consequently, it has been shown in several studies that DPP-4 is efficient in these populations. This mini-review highlights the islet mechanisms of DPP-4 inhibition, islet dysfunction as a key factor for hyperglycemia in type 2 diabetes and that, consequently, DPP-4 is of particular value in populations where islet dysfunction is central, such as in individuals of East Asian origin.

Safety, Pharmacokinetics, and Pharmacodynamics of a Dipeptidyl Peptidase-4 Inhibitor: A Randomized, Double-Blinded, Placebo-Controlled Daily Administration of Fotagliptin Benzoate for 14 Days for Type 2 Diabetes Mellitus

This study investigated the pharmacokinetics, pharmacodynamics, and safety of fotagliptin benzoate (fotagliptin), a dipeptidyl peptidase-4 (DPP-4) inhibitor, in Chinese patients with type 2 diabetes mellitus (T2DM). In a randomized, double-blinded, placebo-controlled study, 10 and 4 patients with T2DM were randomized and received, respectively, once-daily oral fotagliptin (24 mg) or placebo, for 14 days. The pharmacokinetics and pharmacodynamics were assessed throughout the study, including monitoring DPP-4, glucagon-like peptide-1 (GLP-1), glycosylated hemoglobin, and fasting blood glucose. Fotagliptin was rapidly absorbed, and the median time to maximum concentration value was ∼1.5 hours. Plasma fotagliptin levels were stable after 14 days of once-daily dosage. The accumulation ratios for the area under the plasma concentration-time curve of fotagliptin, M1, and M2-1, were 1.19 ± 0.10, 1.59 ± 0.27, and 1.39 ± 0.26, respectively. The durations for DPP-4 inhibition >80% in the fotagliptin group on days 1 and 14 were 23.5 and 24.0 hours, respectively. The concentrations of GLP-1 were higher on days 1 and 14 than at the baseline. No serious complications occurred. Fotagliptin showed favorable pharmacokinetics and pharmacodynamics and was well tolerated. Treatment with fotagliptin can achieve high DPP-4 inhibition and increase plasma GLP-1. A once-per-day dosing regimen may be recommended as clinically efficacious.

Dipeptidyl peptidase 4 inhibitors in the treatment of type 2 diabetes mellitus

Dipeptidyl peptidase 4 inhibitors (DPP4i) have been available for treating type 2 diabetes mellitus since 2006. Although they are a diverse group, DPP4i are all small, orally available molecules that interact with the catalytic site of DPP4 without disturbing any of its other known functions, including its effects on the immune system. DPP4i have no intrinsic glucose-lowering activity, so their efficacy as anti-diabetic agents is related directly to their ability to inhibit DPP4 activity and is mediated through the effects of the substrates they protect. Of these, the incretin hormone, glucagon-like peptide 1, is probably the most important. As the effects of glucagon-like peptide 1 are glucose-dependent, the risk of hypoglycaemia with DPP4i is low. Class effects, which are directly related to the mechanism of action, are common to all DPP4i; these include their overall good safety profile and tolerability, as well as their efficacy in improving glycaemic control, but also, potentially, a small increased risk of acute pancreatitis. Compound-specific effects are those related to their differing chemistries and/or pharmacokinetic profiles. These compound-specific effects could affect the way in which individual DPP4i are used therapeutically and potentially explain off-target adverse effects, such as hospitalization for heart failure, which is seen only with one DPP4i. Overall, DPP4i have a favourable therapeutic profile and are safe and effective in the majority of patients with type 2 diabetes mellitus.

Fucoidan from Ascophyllum nodosum Suppresses Postprandial Hyperglycemia by Inhibiting Na+/Glucose Cotransporter 1 Activity

We previously demonstrated that fucoidan with a type II structure inhibited postprandial hyperglycemia by suppressing glucose uptake, but the mechanism remains elusive. Here, we aimed to assess whether the effect of glucose absorption inhibition was related to the basic structure of fucoidans and preliminarily clarified the underlying mechanism. Fucoidans with type II structure and type I structure were prepared from Ascophyllumnodosum (AnF) or Laminariajaponica (LjF) and Kjellmaniellacrassifolia (KcF), respectively. The effects of various fucoidans on suppressing postprandial hyperglycemia were investigated using in vitro (Caco-2 monolayer model), semi-in vivo (everted gut sac model), and in vivo (oral glucose tolerance test, OGTT) assays. The results showed that only AnF with a type II structure, but not LjF or KcF with type I structure, could inhibit the glucose transport in the Caco-2 monolayer and everted gut sac models. A similar result was seen in the OGTT of Kunming mice and leptin receptor-deficient (db/db) mice, where only AnF could effectively inhibit glucose transport into the bloodstream. Furthermore, AnF (400 mg/kg/d) treatment decreased the fasting blood glucose, HbA1c, and fasting insulin levels, while increasing the serum glucagon-like peptide-1 (GLP-1) level in obese leptin receptor-deficient (db/db) mice. Furthermore, surface plasmon resonance (SPR) analysis revealed the specific binding of AnF to Na+/glucose cotransporter 1 (SGLT1), which indicated the effect of AnF on postprandial hyperglycemia could be due to its suppression on SGLT1 activity. Taken together, this study suggests that AnF with a type II structure can be a promising candidate for hyperglycemia treatment.

The efficacy and safety of dipeptidyl peptidase-4 inhibitors compared to other oral glucose-lowering medications in the treatment of type 2 diabetes

INTRODUCTION

The dipeptidyl peptidase-4 inhibitors (DPP-4is), which belong to the class of incretin-based medications, are recommended as second or third-line therapies in guidelines for the management of type 2 diabetes mellitus. They have a favorable drug tolerability and safety profile compared to other glucose-lowering agents.

OBJECTIVE

This review discusses data concerning the use of DPP-4is and their cardiovascular profile, and gives an updated comparison with the other oral glucose-lowering medications with regards to safety and efficacy. Currently available original studies, abstracts, reviews articles, systematic reviews and meta-analyses were included in the review.

DISCUSSION

DPP4is are moderately efficient in decreasing the HbA1c by an average of 0.5% as monotherapy, and 1.0% in combination therapy with other drugs. They have a good tolerability and safety profile compared to other glucose-lowering drugs. However, there are possible risks pertaining to acute pancreatitis and pancreatic cancer.

CONCLUSION

Cardiovascular outcome trials thus far have proven the cardiovascular safety for ischemic events in patients treated with sitagliptin, saxagliptin, alogliptin, linagliptin and vildagliptin. Data showing increased rate of hospitalisation in the case of saxagliptin did not seem to be a class effect.

Sitagliptin Increases Beta-Cell Function and Decreases Insulin Resistance in Newly Diagnosed Vietnamese Patients with Type 2 Diabetes Mellitus

INTRODUCTION

To investigate effects of Sitagliptin on the enhancement of beta-cell function, reducing insulin resistance, serum glucagon like peptide-1 (GLP-1) concentrations and blood glucose in patients with type 2 diabetes mellitus (T2D) and suggest one of the underlying mechanisms on beta-cell function and insulin resistance.

PATIENTS AND METHODS

This was a cross-sectional and observational study in comparison to the control group. A study population of 44 newly diagnosed patients with T2D treated with Sitagliptin with a dose of 100 mg/day for 3 months was analyzed to compare 52 healthy participants. Indices for beta-cell function, peripheral insulin sensitivity, and insulin resistance were calculated with homeostasis model assessment 2 (HOMA2) calculator and compared. Serum GLP-1 concentrations were analyzed, and regression analysis was conducted to find the correlations between GLP-1 and beta-cell function and insulin resistance.

RESULTS

Newly diagnosed patients with T2D witnessed a significant reduction in beta-cell function, serum GLP-1 concentrations at the time of diagnosis. After treatment with Sitagliptin 100 mg/day, they achieved significant improvements in beta-cell function, peripheral insulin sensitivity and insulin resistance. Serum GLP-1 concentrations were increased significantly to those levels in the control group and correlated with peripheral insulin sensitivity and insulin resistance in patients whose beta-cell functions improved.

CONCLUSION

Sitagliptin improved beta-cell function, insulin resistance and blood glucose in newly diagnosed patients with T2D. Meanwhile, Sitagliptin ameliorated serum GLP-1 concentrations, which contributed to the enhancement of beta-cell.

Vildagliptin, an Anti-diabetic Drug of the DPP-4 Inhibitor, Induces Vasodilation via Kv Channel and SERCA Pump Activation in Aortic Smooth Muscle

This study investigated vildagliptin-induced vasodilation and its related mechanisms using phenylephrine induced precontracted rabbit aortic rings. Vildagliptin induced vasodilation in a concentration-dependent manner. Pretreatment with the large-conductance Ca²⁺-activated K⁺ channel blocker paxilline, ATP-sensitive K⁺ channel blocker glibenclamide, and inwardly rectifying K⁺ channel blocker Ba²⁺ did not affect the vasodilatory effects of vildagliptin. However, application of the voltage-dependent K⁺ (Kv) channel inhibitor 4-aminopyridine significantly reduced the vasodilatory effects of vildagliptin. In addition, application of either of two sarcoplasmic/endoplasmic reticulum Ca²⁺-ATPase (SERCA) inhibitors, thapsigargin or cyclopiazonic acid, effectively inhibited the vasodilatory effects of vildagliptin. These vasodilatory effects were not affected by pretreatment with adenylyl cyclase, protein kinase A (PKA), guanylyl cyclase, or protein kinase G (PKG) inhibitors, or by removal of the endothelium. From these results, we concluded that vildagliptin induced vasodilation via activation of Kv channels and the SERCA pump. However, other K⁺ channels, PKA/PKG-related signaling cascades associated with vascular dilation, and the endothelium were not involved in vildagliptin-induced vasodilation.

Repurposing anti-diabetic drugs for the treatment of Parkinson's disease: Rationale and clinical experience

The most pressing need in Parkinson's disease (PD) clinical practice is to identify agents that might slow down, stop or reverse the neurodegenerative process of Parkinson's disease and therefore avoid the onset of the most disabling, dopa-refractory symptoms of the disease. These include dementia, speech and swallowing problems, poor balance and falling. To date, there have been no agents which have yet had robust trial data to confirm positive effects at slowing down the neurodegenerative disease process of PD. In this chapter we will review the reasons why there is growing interest in drugs currently licensed for the treatment of diabetes as agents which may slow down disease progression in PD, including a review of the published trials regarding exenatide, a GLP-1 receptor agonist licensed to treat type 2 diabetes, and recently shown to be associated with reduced severity of PD in a randomized, placebo controlled washout design trial of 60 patients treated for 48 weeks. This subject is now a major area of interest for multiple pharmaceutical companies hoping to bring GLP-1 receptor agonists forward as treatment options in PD.

Pharmacology of dipeptidyl peptidase-4 inhibitors and its use in the management of metabolic syndrome: a comprehensive review on drug repositioning

OBJECTIVES

Despite advances in our understanding of metabolic syndrome (MetS) and the treatment of each of its components separately, currently there is no single therapy approved to manage it as a single condition. Since multi-drug treatment increases drug interactions, decreases patient compliance and increases health costs, it is important to introduce single therapies that improve all of the MetS components.

EVIDENCE ACQUISITION

We conducted a PubMed, Scopus, Google Scholar, Web of Science, US FDA, utdo.ir and clinicaltrial.gov search, gathered the most relevant preclinical and clinical studies that have been published since 2010, and discussed the beneficial effects of dipeptidyl peptidase (DPP)-4 inhibitors to prevent and treat different constituent of the MetS as a single therapy. Furthermore, the pharmacology of DPP-4 inhibitors, focusing on pharmacodynamics, pharmacokinetics, drug interactions and their side effects are also reviewed.

RESULTS

DPP-4 inhibitors or gliptins are a new class of oral anti-diabetic drugs that seem safe drugs with no severe side effects, commonly GI disturbance, infection and inflammatory bowel disease. They increase mass and function of pancreatic β-cells, and insulin sensitivity in liver, muscle and adipose tissue. It has been noted that gliptin therapy decreases dyslipidemia. DPP-4 inhibitors increase fatty oxidation, and cholesterol efflux, and decrease hepatic triglyceride synthase and de novo lipogenesis. They delay gastric emptying time and lead to satiety. Besides, gliptin therapy has anti-inflammatory and anti-atherogenic impacts, and improves endothelial function and reduces vascular stiffness.

CONCLUSION

The gathered data prove the efficacy of DPP-4 inhibitors in managing MetS in some levels beyond anti-diabetic effects. This review could be a lead for designing new DPP-4 inhibitors with greatest effects on MetS in future. Introducing drugs with polypharmacologic effects could increase the patient's compliance and decrease the health cost that there is not in multi-drug therapy. Graphical abstract ᅟ.

Insights Into GLP-1 and GIP Actions Emerging From Vildagliptin Mechanism Studies in Man

Vildagliptin blocks glucagon like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) inactivation of the meal induced increases in GLP-1 and GIP so that elevated GLP-1 and GIP levels are maintained over 24 h. The primary insulin secretion effect of vildagliptin is to improve the impaired sensitivity of the β-cells to glucose in subjects with impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) and in patients with type 2 diabetes mellitus (T2DM); this effect was seen acutely and maintained over at least 2 years in patients with T2DM. Vildagliptin was also associated with improved β-cell function that is likely secondary to the improved metabolic state. Although there was no evidence of restoration of β-cell mass, the preponderance of the vildagliptin data does indicate that for at least 2 years β-cell function was maintained in vildagliptin treated patients but not in the untreated patients. Vildagliptin suppressed an inappropriate glucagon response to an oral glucose challenge in patients with T2DM, to a mixed meal challenge in patients with T2DM and type 1 diabetes mellitus, and to a mixed meal challenge in subjects with IGT and IFG. The improved glucagon response was maintained for at least 2 years in patients with T2DM and there was no change in the glucagon response in normoglycemic individuals. Vildagliptin lowered glucose levels into the normal range without increasing hypoglycemia. These hypoglycemic benefits appear to be secondary in large part to the improved sensitivity of both the β and α-cell to glucose. In the case of the α-cell, if glucose levels are high, GLP-1 attenuates the glucagon levels and if glucose levels are low, GIP increases glucagon levels. Vildagliptin reduces fatty acid flux from the adipocyte leading to reduced liver fat which in turn leads to increased glucose utilization. The reduced glycosuria and reduced lipo-toxicity associated with vildagliptin therapy does not lead to weight gain presumably due to increased fat mobilization and oxidation during meals and to reduced fat extraction from the gut.

Vildagliptin/pioglitazone combination improved the overall glycemic control in type I diabetic rats

Type I diabetes (TID) is generally assumed to be caused by an immune associated, if not directly immune-mediated, destruction of pancreatic β-cells. In patients with long-term diabetes, the pancreas lacks insulin-producing cells and the residual β-cells are unable to regenerate. Patients with TID are subjected to a lifelong insulin therapy which shows risks of hypoglycemia, suboptimal control and ketosis. In this study, we investigated the potential role of vildagliptin (Vilda) alone or in combination with pioglitazone (Pio), as treatment regimens for TID using streptozotocin (STZ)-induced TID model in rats. Daily oral administration of Vilda (5 mg/kg) alone or in combination with Pio (20 mg/kg) for 7 weeks significantly reduced blood glucose levels and HbA1c. It increased serum insulin levels and decreased serum glucagon. It also showed a strong antioxidant activity. Immunohistochemical analysis showed a marked improvement in β-cells in treated groups when compared with the diabetic group, which appeared in the normal cellular and architecture restoration of β-cells in the islets of Langerhans. Vilda alone or in combination with Pio has the ability to improve the overall glycemic control in type I diabetic rats and may be considered a hopeful and effective remedy for TID.

Efficacy and safety of combination therapy with an α-glucosidase inhibitor and a dipeptidyl peptidase-4 inhibitor in patients with type 2 diabetes mellitus: A systematic review with meta-analysis

AIMS/INTRODUCTION

The combination of dipeptidyl peptidase-4 (DPP4) inhibitors and α-glucosidase inhibitors (AGIs) might provide an additive or synergistic glucose-lowering effect, as they have a complementary mode of action. In the present study, we examined the efficacy and safety of the addition of a DPP4 inhibitor to patients with type 2 diabetes inadequately controlled with an AGI.

MATERIALS AND METHODS

We carried out an electronic search of MEDLINE, EMBASE, the Cochrane Library and Clinicaltrials.gov through October 2016. Randomized controlled trials written in English that compared DPP4 inhibitors plus AGI (DPP4i/AGI) and placebo plus AGI (PCB/AGI) in patients with type 2 diabetes were selected. Data on the study characteristics, efficacy and safety outcomes were extracted, and the risk of potential biases was assessed. The efficacy and safety of DPP4i/AGI and PCB/AGI were compared.

RESULTS

Of 756 potentially relevant published articles and 40 registered trials, five studies including 845 patients randomized to DPP4i/AGI and 832 patients randomized to PCB/AGI were included for meta-analysis. Compared with PCB/AGI, DPP4i/AGI showed a greater reduction in glycated hemoglobin (weighted mean difference -1.2%, 95% confidence interval -1.6 to -0.8), fasting plasma glucose and 2-h postprandial plasma glucose levels, with no increase in bodyweight. The risks of hypoglycemia and gastrointestinal adverse events were similar between DPP4i/AGI and PCB/AGI.

CONCLUSIONS

The addition of a DPP4 inhibitor to patients with type 2 diabetes inadequately controlled with an AGI achieved better glycemic control without further increasing the risk of weight gain and hypoglycemia.

Effect of Zishen Jiangtang Pill, a Chinese Herbal Product, on Rats with Diabetic Osteoporosis

Diabetic osteoporosis (DO) is a complication of diabetes. Zishen Jiangtang Pill (ZJP) is a Chinese herbal product which has been used in clinic to maintain blood glucose level and bone density for decades. However, the evidence about its mechanism on diabetes and osteoporosis is still unknown. The aim of this study is to investigate therapeutic effect of ZJP on DO in streptozotocin- (STZ-) induced rats. Rats were randomly assigned to 4 groups: one control group (CON), one model group (MOD), and two ZJP treatment groups (1.5 and 3.0 g/kg/d). All rats were treated for 8 weeks. Results showed that ZJP decreased the blood glucose level during OGTT and prevented the changes of FBG and Fins. Similarly, ZJP inhibited the changes of BCa, P, TRACP-5b, CTX-1, BALP, and BGP and the reduction of BMD. In parallel, 1H-NMR metabolomic studies showed that ZJP significantly altered the metabolic fingerprints of blood and urine level. These findings suggest that ZJP can effectively improve glucose metabolism, abnormal bone metabolism, and metabolic disorders in DO rats, which may be a useful alternative medicine for DO therapy.

The Role of Glucagon in the Pathophysiology and Treatment of Type 2 Diabetes

Type 2 diabetes is a disease involving both inadequate insulin levels and increased glucagon levels. While glucagon and insulin work together to achieve optimal plasma glucose concentrations in healthy individuals, the usual regulatory balance between these 2 critical pancreatic hormones is awry in patients with diabetes. Although clinical discussion often focuses on the role of insulin, glucagon is equally important in understanding type 2 diabetes. Furthermore, an awareness of the role of glucagon is essential to appreciate differences in the mechanisms of action of various classes of glucose-lowering therapies. Newer drug classes such as dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists improve glycemic control, in part, by affecting glucagon levels. This review provides an overview of the effect of glucose-lowering therapies on glucagon on the basis of an extensive PubMed literature search to identify clinical studies of glucose-lowering therapies in type 2 diabetes that included assessment of glucagon. Clinical practice currently benefits from available therapies that impact the glucagon regulatory pathway. As clinicians look to the future, improved treatment strategies are likely to emerge that will either use currently available therapies whose mechanisms of action complement each other or take advantage of new therapies based on an improved understanding of glucagon pathophysiology.

Do we know the true mechanism of action of the DPP-4 inhibitors?

The prevalence of type 2 diabetes is increasing, which is alarming because of its serious complications. Anti-diabetic treatment aims to control glucose homeostasis as tightly as possible in order to reduce these complications. Dipeptidyl peptidase-4 (DPP-4) inhibitors are a recent addition to the anti-diabetic treatment modalities, and have become widely accepted because of their good efficacy, their benign side-effect profile and their low hypoglycaemia risk. The actions of DPP-4 inhibitors are not direct, but rather are mediated indirectly through preservation of the substrates they protect from degradation. The two incretin hormones, glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide, are known substrates, but other incretin-independent mechanisms may also be involved. It seems likely therefore that the mechanisms of action of DPP-4 inhibitors are more complex than originally thought, and may involve several substrates and encompass local paracrine, systemic endocrine and neural pathways, which are discussed here.

Evaluation of drug efficacy of DPP-4 inhibitors based on theoretical analysis with pharmacokinetics and pharmacodynamics

Dipeptidyl peptidase-4 (DPP-4) inhibitors are used clinically as therapeutic agents for the treatment of diabetes. To determine the rate of DPP-4 inhibition induced by these inhibitors, pharmacokinetic and pharmacodynamic parameters were used to theoretically examine the relationship between the rate of DPP-4 inhibition and clinical efficacy following the administration of four different DPP-4 inhibitors (sitagliptin, vildagliptin, alogliptin, linagliptin) by focusing on the increase in the level of glucagon-like peptide-1 (GLP-1) induced by their administration. On the basis of the relationship shown, changes in clinical efficacy in association with dose change were examined in order to discuss clinical dosage from the standpoint of proper usage. The results indicate that a high rate of DPP-4 inhibition is necessary for the onset of the effect of an administered the DPP-4 inhibitor and that the average value for the DPP-4 inhibition rate can be utilized as a common parameter of clinical efficacy. Furthermore, the efficacy profiles of the present DPP-4 inhibitors could be demonstrated on the basis of an increase in the GLP-1 level. It is considered that the present findings provide useful information for promoting the proper clinical use of DPP-4 inhibitors. Copyright © 2016 John Wiley & Sons, Ltd.

Simultaneous Quantification of Antidiabetic Agents in Human Plasma by a UPLC-QToF-MS Method

An ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry method for the simultaneous quantification of chlorpropamide, glibenclamide, gliclazide, glimepiride, metformin, nateglinide, pioglitazone, rosiglitazone, and vildagliptin in human plasma was developed and validated, using isoniazid and sulfaquinoxaline as internal standards. Following plasma protein precipitation using acetonitrile with 1% formic acid, chromatographic separation was performed on a cyano column using gradient elution with water and acetonitrile, both containing 0.1% formic acid. Detection was performed in a quadrupole time-of-flight analyzer, using electrospray ionization operated in the positive mode. Data from validation studies demonstrated that the new method is highly sensitive, selective, precise (RSD < 10%), accurate (RE < 12%), linear (r > 0.99), free of matrix and has no residual effects. The developed method was successfully applied to volunteers' plasma samples. Hence, this method was demonstrated to be appropriate for clinical monitoring of antidiabetic agents.

Pharmacological Actions of Glucagon-Like Peptide-1, Gastric Inhibitory Polypeptide, and Glucagon

Glucagon family of peptide hormones is a group of structurally related brain-gut peptides that exert their pleiotropic actions through interactions with unique members of class B1 G protein-coupled receptors (GPCRs). They are key regulators of hormonal homeostasis and are important drug targets for metabolic disorders such as type-2 diabetes mellitus (T2DM), obesity, and dysregulations of the nervous systems such as migraine, anxiety, depression, neurodegeneration, psychiatric disorders, and cardiovascular diseases. The current review aims to provide a detailed overview of the current understanding of the pharmacological actions and therapeutic advances of three members within this family including glucagon-like peptide-1 (GLP-1), gastric inhibitory polypeptide (GIP), and glucagon.

Teneligliptin, a Dipeptidyl Peptidase-4 Inhibitor, Improves Early-Phase Insulin Secretion in Drug-Naïve Patients with Type 2 Diabetes

Introduction

It remains unknown whether dipeptidyl peptidase-4 (DPP-4) inhibitors improve early-phase insulin secretion in Japanese patients with type 2 diabetes (T2D), a disease characterized by impaired insulin secretion. We investigated the changes in insulin secretion before and after treatment with the DPP-4 inhibitor teneligliptin in patients with T2D with a low insulinogenic index (IGI) determined by the oral glucose tolerance test (OGTT).

Methods

An open-label, prospective clinical study was conducted. Thirteen drug-naïve patients (mean age 55.5 ± 3.9 years) with T2D underwent OGTT before and after teneligliptin 20 mg/day monotherapy. Plasma levels of glucose (PG), insulin, and C-peptide were measured at 0, 30, 60, 90, and 120 min after glucose loading in the OGTT. Homeostasis model assessment (HOMA)-β, IGI, and the total or incremental area under the curve (AUC) for PG and insulin were measured. AUC_120min for the secretory units of islets in transplantation (SUIT) index was also measured.

Results

HbA1c significantly decreased from 8.3 ± 0.4 % at baseline to 6.3 ± 0.2 % after 12 weeks of teneligliptin treatment (p < 0.05). Incremental AUC_120min PG also significantly decreased, and β-cell function assessed by IGI_30min, AUC_120min insulin, and the AUC_120min SUIT index significantly increased (0.16 ± 0.05 vs. 0.28 ± 0.06, 2692 ± 333 µU·2h/mL vs. 3537 ± 361 µU·2h/mL, and 4261 ± 442 vs. 8290 ± 1147, respectively; all p < 0.05). HOMA-β was unchanged. The reduction in incremental AUC_120min PG was significantly associated with the augmentation of IGI_30min and the AUC_120min SUIT index. No severe adverse events were observed.

Conclusions

Twelve weeks of teneligliptin treatment improved IGI_30min, AUC_120min, and the SUIT index in drug-naïve Japanese patients with T2D.

Effects of vildagliptin versus saxagliptin on daily acute glucose fluctuations in Chinese patients with T2DM inadequately controlled with a combination of metformin and sulfonylurea

Objective The present study aimed to compare the effects of the dipeptidyl peptidase-4 (DPP-4) inhibitors vildagliptin and saxagliptin on 24 hour acute glucose fluctuations in Chinese patients with type 2 diabetes mellitus (T2DM) inadequately controlled with a combination of metformin and sulfonylurea. Research design and methods This was a 24 week, prospective, randomized, open-label, active-controlled study. Patients (N = 73) with T2DM who had inadequate glycemic control (HbA1c 7.0%-10.0%) with a stable dosage of metformin plus gliclazide for more than 3 months were randomized to receive either vildagliptin 50 mg twice daily (BID, n = 37) or saxagliptin 5 mg once daily (QD, n = 36). Change in mean amplitude of glycemic excursions (MAGE) was assessed at the end of 24 weeks. Results At baseline, the mean (±SD) age was 62.9 ± 6.55 years, disease duration was 7.0 ± 2.33 years, and HbA1c was 8.4 ± 0.68%. After 24 weeks of treatment, the MAGE decreased from 5.81 ± 1.16 mmol/L to 4.06 ± 0.86 mmol/L (p<0.001) in the vildagliptin group and from 5.66 ± 1.14 mmol/L to 4.79 ± 1.25 mmol/L (p = 0.003) in the saxagliptin group. The mean change in MAGE in the vildagliptin group was significantly greater than that in the saxagliptin group (1.74 ± 0.48 mmol/L vs. 0.87 ± 0.40 mmol/L, p<0.001). The mean change in HbA1c, from baseline to the study endpoint, in the vildagliptin and saxagliptin groups, was 1.22 ± 0.40% and 1.07 ± 0.36%, respectively, with no significant difference between the groups (p = 0.091). The overall safety and tolerability of vildagliptin and saxagliptin were similar. The limitations of the study were a small number of patients and open-label administration of the study drug. Conclusion Vildagliptin produced a significantly greater reduction in acute glucose fluctuations compared with saxagliptin when added to a dual combination of metformin and sulfonylurea in Chinese patients with T2DM. Chinese clinical trial registration number ChiCTR-TRC-13003858.

Improved glucose regulation in type 2 diabetic patients with DPP-4 inhibitors: focus on alpha and beta cell function and lipid metabolism

Inhibition of dipeptidyl peptidase-4 (DPP-4) is an established glucose-lowering strategy for the management of type 2 diabetes mellitus. DPP-4 inhibitors reduce both fasting and postprandial plasma glucose levels, resulting in reduced HbA1c with low risk for hypoglycaemia and weight gain. They act primarily by preventing inactivation of the incretin hormones glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1, thereby prolonging the enhanced endogenous levels of these hormones after meal ingestion. This in turn causes islet and extrapancreatic effects, including increased glucose sensing in islet alpha and beta cells. These effects result in increased insulin secretion and decreased glucagon secretion being more effective in hyperglycaemic states and reduced insulin secretion and increased glucagon secretion being more effective during hypoglycaemia. Other secondary pharmacological actions of DPP-4 inhibitors include mobilisation and burning of fat during meals, decrease in fat extraction from the gut, reduction of fasting lipolysis and liver fat and increase in LDL particle size. These actions contribute to the clinical effects of DPP-4 inhibition, and the reduced demand for insulin could also lead to a durability benefit. This review summarises the current knowledge of the secondary pharmacological actions of DPP-4 inhibitors that lead to improved glucose regulation in patients with type 2 diabetes, focusing on alpha and beta cell function and lipid metabolism.

Suppression of lung metastases by the CD26/DPP4 inhibitor Vildagliptin in mice

Metastases rather than primary cancers determine nowadays the survival of patients. One of the most common primary malignancies is colorectal cancer and this type of tumor is characterized by a high tendency to spread metastases to the lung and liver. CD26/DPP4 is a transmembrane molecule with enzymatic functions which cleaves biologically active peptides. Recently, CD26/DPP4 has become the focus of cancer research and it was shown that CD26/DPP4-positive cancer cells display increased metastatic activity. Here, we tested if the CD26/DPP4-inhibitor Vildagliptin suppresses the development and growth of mouse colorectal lung metastases. This inhibitor of CD26/DPP4 was employed on mouse (C57BL/6) colorectal lung metastases, established by intravenous injection of the syngeneic cell line MC38. For mechanistic analysis, a subcutaneous tumor model was used. The treatment with Vildagliptin significantly suppressed both, the incidence and growth of lung metastases. Autophagy markers (LC3, p62, and ATF4) decreased, apoptosis increased (TUNEL, pH3/Ki-76), and the cell cycle regulator pCDC2 was inhibited. In conclusion, we here showed an anti-tumor effect of Vildagliptin via downregulation of autophagy resulting in increased apoptosis and modulation of the cell cycle. We therefore propose Vildagliptin for the evaluation as a new therapeutic approach for the treatment of colorectal cancer lung metastases.

A randomized, placebo-controlled, double-blind, phase 3 trial to evaluate the efficacy and safety of anagliptin in drug-naïve patients with type 2 diabetes

The aim of this study was to evaluate the efficacy and safety of anagliptin in drug-naïve patients with type 2 diabetes in a double-blind randomized placebo-controlled study. A total of 109 patients were randomized to 100 mg (n=37) or 200 mg (n=33) anagliptin twice daily or placebo (n=39). The primary objective was to alter HbA1c levels from baseline at a 24-week endpoint. The overall baseline mean age and body mass index were 56.20 ± 9.77 years and 25.01 ± 2.97 kg/m(2), respectively, and the HbA1c level was of 7.14 ± 0.69 %. Anagliptin at 100 mg and 200 mg produced significant reductions in HbA1c (-0.50 ± 0.45 % and -0.51 ± 0.55%, respectively), and the placebo treatment resulted in an increase in HbA1c by 0.23 ± 0.62 %. Both doses of anagliptin produced significant decreases in fasting plasma glucose (-0.53 ± 1.25 mmol/L and -0.72 ± 1.25 mmol/L, respectively) and the proinsulin/insulin ratio (-0.04 ± 0.15 and -0.07 ± 0.18, respectively) compared with placebo. No meaningful body weight changes from baseline were observed in three groups. Plasma dipeptidyl peptidase (DPP)-4 activity was significantly inhibited after 24 weeks of anagliptin treatment, and >75% and >90% inhibitions were observed during the meal tolerance tests with 100 mg and 200 mg anagliptin, respectively. The incidences of adverse or serious adverse events were similar among the three study groups. Twice-daily anagliptin therapy effectively inhibited DPP-4 activity and improved glycemic control and was well-tolerated in patients with type 2 diabetes.

DPP-4 inhibition and islet function

During recent years, dipeptidyl peptidase‐4 (DPP‐4) inhibition has been included in the clinical management of type 2 diabetes, both as monotherapy and as add‐on to several other therapies. DPP‐4 inhibition prevents the inactivation of the incretin hormones, glucose‐dependent insulinotropic polypeptide (GIP) and glucagon‐like peptide‐1 (GLP‐1). This results in stimulation of insulin secretion and inhibition of glucagon secretion, and there is also a potential β‐cell preservation effect, as judged from rodent studies; that is, it might target the key islet dysfunction in the disease. In type 2 diabetes. This reduces 24‐h glucose levels and reduces HbA_1c by ≈ 0.8–1.1% from baseline levels of 7.7–8.5%. DPP‐4 inhibition is safe, with a very low risk for adverse events including hypoglycemia, and it prevents weight gain. The present review summarizes the studies on the influence of DPP‐4 inhibition on islet function. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00184.x, 2012)

Recent approaches to medicinal chemistry and therapeutic potential of dipeptidyl peptidase-4 (DPP-4) inhibitors

Dipeptidyl peptidase-4 (DPP-4) is one of the widely explored novel targets for Type 2 diabetes mellitus (T2DM) currently. Research has been focused on the strategy to preserve the endogenous glucagon like peptide (GLP)-1 activity by inhibiting the DPP-4 action. The DPP-4 inhibitors are weight neutral, well tolerated and give better glycaemic control over a longer duration of time compared to existing conventional therapies. The journey of DPP-4 inhibitors in the market started from the launch of sitagliptin in 2006 to latest drug teneligliptin in 2012. This review is mainly focusing on the recent medicinal aspects and advancements in the designing of DPP-4 inhibitors with the therapeutic potential of DPP-4 as a target to convey more clarity in the diffused data.

Dipeptidyl peptidase-4 inhibition in patients with type 2 diabetes treated with saxagliptin, sitagliptin, or vildagliptin

INTRODUCTION

Saxagliptin, sitagliptin, and vildagliptin are dipeptidyl peptidase-4 (DPP-4) inhibitors widely approved for use in patients with type 2 diabetes. Using a crossover design, the present study compared trough levels of DPP-4 inhibition provided by these agents in a single cohort of patients with type 2 diabetes.

METHODS

This was a randomized, placebo-controlled, open-label, five-period crossover study. Eligible patients were 18-65 years of age, either treatment-naïve or off prior antihyperglycemic agent therapy for at least 6 or 12 weeks (depending on the prior therapy), and had glycated hemoglobin (HbA1C) ≥6.5% and ≤10.0%. In separate study periods, patients received 5 mg saxagliptin q.d. (saxa-5), 100 mg sitagliptin q.d. (sita-100), 50 mg vildagliptin q.d. (vilda-50-q.d.), 50 mg vildagliptin b.i.d. (vilda-50-b.i.d.), or placebo for 5 days. The primary endpoint was trough %DPP-4 inhibition, derived by comparing DPP-4 activity 24 h after the Day-5 morning dose with predose activity in the same period and analyzed using a linear mixed-effects model with fixed-effects terms for treatment and period.

RESULTS

Mean (range) baseline HbA1C was 7.4% (6.4-9.0%; N = 22). Least-squares (LS) mean trough %DPP-4 inhibition was 73.5%, 91.7%, 28.9%, 90.6%, and 3.5% after saxa-5, sita-100, vilda-50-q.d., vilda-50-b.i.d., and placebo, respectively. In patients treated with sita-100, the LS-mean difference in trough %DPP-4 inhibition was 18.2% greater than with saxa-5 (p < 0.001), 62.9% greater than with vilda-50-q.d. (p < 0.001), 1.1% greater than with vilda-50-b.i.d. (p = 0.128), and 87.8% greater than with placebo (p < 0.001). Mean %DPP-4 inhibition was nearly maximal at 12 h postdose regardless of active treatment. Thus, these between-group comparisons at trough primarily reflected differences in duration of action. Adverse events reported during the study were transient and mild or moderate in intensity.

CONCLUSION

Once daily treatment with sitagliptin provided trough DPP-4 inhibition significantly greater than saxagliptin or vildagliptin administered once daily, and similar to that provided by vildagliptin administered twice daily.

Effects of combination therapy with vildagliptin and valsartan in a mouse model of type 2 diabetes

Background

Dipeptidyl peptidase-4 (DPP-4) inhibitors modulate incretin hormones and exert anti-diabetic effects in type 2 diabetes mellitus. Treatment with angiotensin II type 1 receptor blockers (ARB) is a proven successful intervention for hypertension with type 2 diabetes. The present study investigated the combined effects of the DPP-4 inhibitor vildagliptin and the ARB valsartan in a mouse model of type 2 diabetes.

Methods

C57BL/6 J mice fed with high-fat diet (HFD) or db/db mice were treated with placebo, phloridzin (PHZ), vildagliptin alone (ViL), valsartan alone (VaL) or ViL with VaL (ViLVaL) for 8 weeks.

Results

Glucose metabolism was improved in response to PHZ, ViL and ViLVaL in both HFD and db/db mice. Upon glucose challenge, ViLVaL showed the greatest suppression of blood glucose excursions, with increased insulin secretion, in db/db mice. ViLVaL treatment also showed an improvement of insulin sensitivity in db/db mice. Serum inflammatory cytokines were significantly decreased, and adiponectin was highest, in the ViLVaL group. ViLVaL improved insulin signaling and attenuated stress signaling in liver with amelioration of hepatic steatosis due to activated fatty acid oxidation in db/db mice. Furthermore, immunohistochemical analysis of the pancreas revealed that the combination treatment resulted in an increased expression of insulin and PDX-1, and increased insulin content.

Conclusions

The combination therapy of ViL and VaL improves both pancreatic beta-cell function and insulin sensitivity, with a reduction of the inflammatory and cell stress milieu in mouse models of T2DM. Our results suggest that this combination therapy exerts additive or even synergistic benefits to treat T2DM.

Vildagliptin in the Treatment of Type 2 Diabetes Mellitus

Novel therapeutic approaches are continuously being researched in type 2 diabetes. The incretin class of anti-diabetic agents, consisting of glucagon-like peptide-1 agonists and dipeptidyl peptidase-4 inhibitors, has already found an important place in the current guidelines. Vildagliptin is a potent dipeptidyl peptidase-4 inhibitor, with numerous trials in type 2 diabetes treatment, both in monotherapy and in combination therapy. This review focuses on vildagliptin pharmacological properties, clinical efficacy and safety, and pharmacoeconomic data.

A pilot randomized, placebo controlled, double blind phase I trial of the novel SIRT1 activator SRT2104 in elderly volunteers

BACKGROUND

SRT2104 has been developed as a selective small molecule activator of SIRT1, a NAD(+)-dependent deacetylase involved in the regulation of energy homeostasis and the modulation of various metabolic pathways, including glucose metabolism, oxidative stress and lipid metabolism. SIRT1 has been suggested as putative therapeutic target in multiple age-related diseases including type 2 diabetes and dyslipidemias. We report the first clinical trial of SRT2104 in elderly volunteers.

METHODS

Oral doses of 0.5 or 2.0 g SRT2104 or matching placebo were administered once daily for 28 days. Pharmacokinetic samples were collected through 24 hours post-dose on days 1 and 28. Multiple pharmacodynamic endpoints were explored with oral glucose tolerance tests (OGTT), serum lipid profiles, magnetic resonance imaging (MRI) for assessment of whole body visceral and subcutaneous fat, maximal aerobic capacity test and muscle 31P magnetic resonance spectroscopy (MRS) for estimation of mitochondrial oxidative capacity.

RESULTS

SRT2104 was generally safe and well tolerated. Pharmacokinetic exposure increased less than dose-proportionally. Mean Tmax was 2-4 hours with elimination half-life of 15-20 hours. Serum cholesterol, LDL levels and triglycerides decreased with treatment. No significant changes in OGTT responses were observed. 31P MRS showed trends for more rapid calculated adenosine diphosphate (ADP) and phosphocreatine (PCr) recoveries after exercise, consistent with increased mitochondrial oxidative phosphorylation.

CONCLUSIONS

SRT2104 can be safely administered in elderly individuals and has biological effects in humans that are consistent with SIRT1 activation. The results of this study support further development of SRT2104 and may be useful in dose selection for future clinical trials in patients.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00964340.

Clinical pharmacokinetics and pharmacodynamics of vildagliptin

Vildagliptin is an orally active, potent and selective dipeptidyl peptidase-4 (DPP-4) inhibitor, shown to be effective and well tolerated in patients with type 2 diabetes mellitus (T2DM) as either monotherapy or in combination with other anti-diabetic agents. Vildagliptin possesses several desirable pharmacokinetic properties that contribute to its lower variability and low potential for drug interaction. Following oral administration, vildagliptin is rapidly and well absorbed with an absolute bioavailability of 85%. An approximately dose-proportional increase in exposure to vildagliptin over the dose range of 25-200 mg has been reported. Food does not have a clinically relevant impact on the pharmacokinetics of vildagliptin, and it can be taken without regard to food. Vildagliptin is minimally bound to plasma proteins (9.3%) and, on the basis of a volume of distribution of 71 L, it is considered to distribute extensively into extravascular spaces. Renal clearance of vildagliptin (13 L/h) accounts for 33% of the total body clearance after intravenous administration (41 L/h). The primary elimination pathway is hydrolysis by multiple tissues/organs. The DPP-4 enzyme contributes to the formation of the major hydrolysis metabolite, LAY151; therefore, vildagliptin is also a substrate of DPP-4. Vildagliptin has a low potential for drug interactions, as cytochrome P450 (CYP) enzymes are minimally (<1.6%) involved in the overall metabolism. Clinical pharmacokinetic studies have reported the lack of drug interaction with several drugs (metformin, pioglitazone, glyburide, simvastatin, amlodipine, valsartan, ramipril, digoxin and warfarin) that are likely to be frequently co-administered to patients with T2DM. In particular, vildagliptin does not affect the pharmacokinetics of pioglitazone, glyburide, warfarin and simvastatin; therefore, it is not expected to affect the pharmacokinetics of a drug that is a substrate for CYP2C8, CYP2C9 or CYP3A4. In the elderly, vildagliptin exposure increases by approximately 30%, which is considered to be mostly attributable to compromised renal function in the elderly population and is not considered to be clinically relevant. Vildagliptin has been demonstrated to be efficacious, safe and well tolerated in elderly patients with T2DM without dose adjustment. In subjects with varying degrees of renal impairment, vildagliptin exposure increases by approximately 2-fold; however, the increase in the exposure does not correlate with the severity of renal impairment. The lack of a clear correlation between the increased exposure and the severity of renal impairment is considered to be attributable to the fact that the kidneys contribute to both the excretion and the hydrolysis metabolism of vildagliptin. Hepatic impairment, gender, body mass index (BMI) and ethnicity do not have an influence on the pharmacokinetics of vildagliptin. These findings suggest that vildagliptin can be used in a diverse patient population without dose adjustment. Oral administration of vildagliptin to patients with T2DM completely inhibits DPP-4 activity at a variety of doses. The onset of DPP-4 inhibition is rapid, and the duration of DPP-4 inhibition is dose dependent. Vildagliptin is a potent inhibitor of the DPP-4 enzyme, with a concentration required to achieve 50% DPP-4 inhibition (IC(50)) of 4.5 nmol/L in patients with T2DM. Similar potency of DPP-4 inhibition by vildagliptin has been reported in different ethnic groups, indicating that ethnicity does not affect the pharmacodynamics of vildagliptin. Vildagliptin significantly increases the active glucagon-like peptide 1 (GLP-1) levels by approximately 2- to 3-fold and glucose-dependent insulinotropic polypeptide (GIP) levels by approximately 5-fold, and significantly suppresses the postprandial glucagon levels in response to a meal or following an oral glucose tolerance test (OGTT) in patients with T2DM. Vildagliptin significantly reduces both fasting and postprandial glucose levels over the dose range of 50-100 mg daily (administered either once daily or twice daily), and there are no substantial additional benefits of doses greater than 50 mg twice daily. The primary clinical dosing regimen is 50 mg twice daily as monotherapy or in combination with metformin. Vildagliptin increases the insulin levels following an OGTT and an intravenous glucose tolerance test (IVGTT), and the stimulation of insulin secretion is glucose dependent. Vildagliptin has been shown to improve beta-cell function on the basis of pharmacodynamic modelling taking the reduced glucose levels into account. The improvement of beta-cell function by vildagliptin has been confirmed after chronic treatment with vildagliptin for up to 2 years. Reduction of the endogenous glucose production appears to contribute to the glucose-lowering effects. Unlike the GLP-1 receptor agonists, vildagliptin does not affect gastric emptying, and this is consistent with the favourable gastrointestinal safety profile. Vildagliptin improves the sensitivity of the alpha cell to glucose in patients with T2DM by enhancing the alpha-cell responsiveness to both suppressive effects of hyperglycaemia and stimulatory effects of hypoglycaemia. Consistently, a lower incidence of hypoglycaemic events with vildagliptin is reported when it is used as either monotherapy or in combination with other anti-diabetic agents, such as metformin or insulin, as compared with a sulphonylurea. Numerous long-term clinical trials of up to 2 years have demonstrated that vildagliptin 50 mg once daily or twice daily is effective, safe and well tolerated in patients with T2DM as either monotherapy or in combination with a variety of other anti-diabetic agents.

Vildagliptin added to metformin on β-cell function after a euglycemic hyperinsulinemic and hyperglycemic clamp in type 2 diabetes patients

BACKGROUND

This study evaluated the effect of vildagliptin + metformin on glycemic control and β-cell function in type 2 diabetes patients.

SUBJECTS AND METHODS

One hundred seventy-one type 2 diabetes patients, naive to antidiabetes therapy and with poor glycemic control, were instructed to take metformin for 8±2 months up to a mean dosage of 2,500±500 mg/day; then they were randomly assigned to add vildaglipin 50 mg twice a day or placebo for 12 months. We evaluated at 3, 6, 9, and 12 months: body mass index, glycemic control, fasting plasma insulin, homeostasis model assessment insulin resistance index (HOMA-IR), homeostasis model assessment β-cell function index (HOMA-β), fasting plasma proinsulin, proinsulin/fasting plasma insulin ratio, C-peptide, glucagon, adiponectin, and high-sensitivity C-reactive protein. Before and at 12 months after the addition of vildagliptin, patients underwent a combined euglycemic hyperinsulinemic and hyperglycemic clamp, with subsequent arginine stimulation, to assess insulin sensitivity and insulin secretion.

RESULTS

After 12 months of treatment, vildagliptin + metformin gave a better decrease of body weight, glycemic control, HOMA-IR, and glucagon and a better increase of HOMA-β compared with placebo + metformin. Regarding the measures of β-cell function, treatment-induced changes in M-value, first- and second-phase C-peptide response to glucose, and C-peptide response to arginine were significantly higher in the vildagliptin + metformin group compared with the placebo + metformin group.

CONCLUSION

The addition of vildagliptin to metformin gave a better improvement of glycemic control, insulin resistance, and β-cell function compared with metformin alone.

Pharmacology of dipeptidyl peptidase-4 inhibitors: similarities and differences

The dipeptidyl peptidase (DPP)-4 inhibitors, which enhance glucose-dependent insulin secretion from pancreatic β cells by preventing DPP-4-mediated degradation of endogenously released incretin hormones, represent a new therapeutic approach to the management of type 2 diabetes mellitus. The 'first-in-class' DPP-4 inhibitor, sitagliptin, was approved in 2006; it was followed by vildagliptin (available in the EU and many other countries since 2007, although approval in the US is still pending), saxagliptin (in 2009), alogliptin (in 2010, presently only in Japan) and linagliptin, which was approved in the US in May 2011 and is undergoing regulatory review in Japan and the EU. As the number of DPP-4 inhibitors on the market increases, potential differences among the different members of the class become important when deciding which agent is best suited for an individual patient. The aim of this review is to provide a comprehensive and updated comparison of the pharmacodynamic and pharmacokinetic properties of DPP-4 inhibitors, and to pinpoint pharmacological differences of potential interest for their use in therapy. Despite their common mechanism of action, these agents show significant structural heterogeneity that could translate into different pharmacological properties. At the pharmacokinetic level, DPP-4 inhibitors have important differences, including half-life, systemic exposure, bioavailability, protein binding, metabolism, presence of active metabolites and excretion routes. These differences could be relevant, especially in patients with renal or hepatic impairment, and when considering combination therapy. At the pharmacodynamic level, the data available so far indicate a similar glucose-lowering efficacy of DPP-4 inhibitors, either as monotherapy or in combination with other hypoglycaemic drugs, a similar weight-neutral effect, and a comparable safety and tolerability profile. Data on nonglycaemic parameters are scant at present and do not allow a comparison among DPP-4 inhibitors. Several phase III trials of DPP-4 inhibitors are currently ongoing; these trials, along with post-marketing surveillance data, will hopefully increase our knowledge about the long-term efficacy and safety of DPP-4 inhibitor therapy, the effect on pancreatic cell function and peripheral glucose metabolism, and the effect on cardiovascular outcomes in patients with type 2 diabetes.

DPP-4 inhibitors in the treatment of type 2 diabetes

Although being a primary objective in the management of type 2 diabetes, optimal glycaemic control is difficult to achieve and usually not maintained over time. Type 2 diabetes is a complex pathology, comprising altered insulin sensitivity and impaired insulin secretion. Recent advances in the understanding of the physiological functions of incretins and their degrading enzyme dipeptidyl-peptidase (DPP)-4 have led to the 'discovery' of a new class of oral anti-diabetic drugs. Several DPP-4 inhibitors (or gliptins) with different chemical structures are now available. These agents inhibit the degradation of the incretins glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) and hence potentiate glucose-dependent insulin secretion. DPP-4 inhibitors inhibit DPP-4 activity by almost 100% in vitro, maintaining a ≥ 80% inhibition throughout the treatment period in vivo, thus prolonging GLP-1 half-life, and significantly reducing HbA1c generally by -0.7 to 0.8% as well as fasting and post-prandial glycaemia. They are well-tolerated with no weight gain and few adverse effects, and, of particular interest, no increase in hypoglycaemic episodes. Although different by their chemical structure and pharmacokinetic properties, the DPP4 inhibitors currently available have proven similar glucose lowering efficacy.

Quantitative model of the relationship between dipeptidyl peptidase-4 (DPP-4) inhibition and response: meta-analysis of alogliptin, saxagliptin, sitagliptin, and vildagliptin efficacy results

Dipeptidyl peptidase-4 (DPP-4) inhibition is a well- characterized treatment for type 2 diabetes mellitus (T2DM). The objective of this model-based meta-analysis was to describe the time course of HbA1c response after dosing with alogliptin (ALOG), saxagliptin (SAXA), sitagliptin (SITA), or vildagliptin (VILD). Publicly available data involving late-stage or marketed DPP-4 inhibitors were leveraged for the analysis. Nonlinear mixed-effects modeling was performed to describe the relationship between DPP-4 inhibition and mean response over time. Plots of the relationship between metrics of DPP-4 inhibition (ie, weighted average inhibition [WAI], time above 80% inhibition, and trough inhibition) and response after 12 weeks of daily dosing were evaluated. The WAI was most closely related to outcome, although other metrics performed well. A model was constructed that included fixed effects for placebo and drug and random effects for intertrial variability and residual error. The relationship between WAI and outcome was nonlinear, with an increasing response up to 98% WAI. Response to DPP-4 inhibitors could be described with a single drug effect. The WAI appears to be a useful index of DPP-4 inhibition related to HbA1c. Biomarker to response relationships informed by model-based meta-analysis can be leveraged to support study designs including optimization of dose, duration of therapy, and patient population.

Mechanisms of action of the dipeptidyl peptidase-4 inhibitor vildagliptin in humans

Inhibition of dipeptidyl peptidase-4 (DPP-4) by vildagliptin prevents degradation of glucagon-like peptide-1 (GLP-1) and reduces glycaemia in patients with type 2 diabetes mellitus, with low risk for hypoglycaemia and no weight gain. Vildagliptin binds covalently to the catalytic site of DPP-4, eliciting prolonged enzyme inhibition. This raises intact GLP-1 levels, both after meal ingestion and in the fasting state. Vildagliptin has been shown to stimulate insulin secretion and inhibit glucagon secretion in a glucose-dependent manner. At hypoglycaemic levels, the counterregulatory glucagon response is enhanced relative to baseline by vildagliptin. Vildagliptin also inhibits hepatic glucose production, mainly through changes in islet hormone secretion, and improves insulin sensitivity, as determined with a variety of methods. These effects underlie the improved glycaemia with low risk for hypoglycaemia. Vildagliptin also suppresses postprandial triglyceride (TG)-rich lipoprotein levels after ingestion of a fat-rich meal and reduces fasting lipolysis, suggesting inhibition of fat absorption and reduced TG stores in non-fat tissues. The large body of knowledge on vildagliptin regarding enzyme binding, incretin and islet hormone secretion and glucose and lipid metabolism is summarized, with discussion of the integrated mechanisms and comparison with other DPP-4 inhibitors and GLP-1 receptor activators, where appropriate.

Advances in the treatment of type 2 diabetes mellitus

There is a rising worldwide prevalence of diabetes, especially type 2 diabetes mellitus (T2DM), which is one of the most challenging health problems in the 21st century. The associated complications of diabetes, such as cardiovascular disease, peripheral vascular disease, stroke, diabetic neuropathy, amputations, renal failure, and blindness result in increasing disability, reduced life expectancy, and enormous health costs. T2DM is a polygenic disease characterized by multiple defects in insulin action in tissues and defects in pancreatic insulin secretion, which eventually leads to loss of pancreatic insulin-secreting cells. The treatment goals for T2DM patients are effective control of blood glucose, blood pressure, and lipids (if elevated) and, ultimately, to avert the serious complications associated with sustained tissue exposure to excessively high glucose concentrations. Prevention and control of diabetes with diet, weight control, and physical activity has been difficult. Treatment of T2DM has centered on increasing insulin levels, either by direct insulin administration or oral agents that promote insulin secretion, improving sensitivity to insulin in tissues, or reducing the rate of carbohydrate absorption from the gastrointestinal tract. This review presents comprehensive and up-to-date information on the mechanism(s) of action, efficacy, pharmacokinetics, pleiotropic effects, drug interactions, and adverse effects of the newer antidiabetic drugs, including (1) peroxisome proliferator-activated-receptor-γ agonists (thiazolidinediones, pioglitazone, and rosiglitazone); (2) the incretin, glucagon-like peptide-) receptor agonists (incretin-mimetics, exenatide. and liraglutide), (3) inhibitors of dipeptidyl-peptidase-4 (incretin enhancers, sitagliptin, and vildagliptin), (4) short-acting, nonsulfonylurea secretagogue, meglitinides (repaglinide and nateglinide), (5) amylin anlog-pramlintide, (6) α-glucosidase inhibitors (miglitol and voglibose), and (7) colesevelam (a bile acid sequestrant). In addition, information is presented on drug candidates in clinical trials, experimental compounds, and some plants used in the traditional treatment of diabetes based on experimental evidence. In the opinion of this reviewer, therapy based on orally active incretins and incretin mimetics with long duration of action that will be efficacious, preserve the β-cell number/function, and block the progression of diabetes will be highly desirable. However, major changes in lifestyle factors such as diet and, especially, exercise will also be needed if the growing burden of diabetes is to be contained.

Vildagliptin: a review of its use in type 2 diabetes mellitus

Vildagliptin (Galvus®, Jalra®, Xiliarx®) is an orally administered dipeptidyl peptidase-4 (DPP-4) inhibitor. In patients with type 2 diabetes mellitus, vildagliptin 50 mg twice daily is indicated for use in combination with metformin or a thiazolidinedione, and vildagliptin 50 mg once daily is indicated for use in combination with a sulfonylurea. A fixed-dose combination of vildagliptin/metformin (Eucreas®, Icandra®, Zomarist®) is also available. This article reviews the clinical efficacy and tolerability of vildagliptin in patients with type 2 diabetes, as well as summarizing its pharmacological properties. The efficacy of monotherapy or combination therapy with oral vildagliptin in patients with type 2 diabetes has been examined in randomized, double-blind, multicentre trials. Monotherapy with vildagliptin 50 mg once or twice daily reduced glycosylated haemoglobin (HbA(1c)) from baseline to a significantly greater extent than placebo, according to the results of 12- to 52-week trials in patients with type 2 diabetes. In terms of the reduction from baseline in HbA(1c) seen in active comparator trials of 12-104 weeks' duration, the noninferiority of vildagliptin 50 mg twice daily was established versus acarbose or rosiglitazone, the noninferiority of vildagliptin 100 mg once daily (an off-label dosage) versus metformin was established in elderly patients and vildagliptin 50 mg twice daily was more effective than voglibose; however, the noninferiority of vildagliptin 50 mg twice daily versus metformin or gliclazide was not established in two other trials. Combination therapy with vildagliptin 50 mg twice daily plus metformin improved HbA(1c) to a significantly greater extent than monotherapy with metformin and/or vildagliptin alone in patients with type 2 diabetes whose disease was inadequately controlled by metformin monotherapy or who were treatment naive, according to the results of 12- or 24-week trials. In addition, vildagliptin 50 mg twice daily plus metformin demonstrated noninferiority to pioglitazone plus metformin, glimepiride plus metformin or gliclazide plus metformin in terms of the change from baseline in HbA(1c) after 24 or 52 weeks' therapy in patients with inadequately controlled type 2 diabetes. The addition of vildagliptin 50 mg twice daily to pioglitazone or vildagliptin 50 mg once daily to glimepiride improved HbA(1c) to a significantly greater extent than a thiazolidinedione or glimepiride alone in patients with type 2 diabetes whose disease was inadequately controlled, according to the results of 24-week trials. Oral vildagliptin 50 mg once or twice daily was generally well tolerated in patients with type 2 diabetes. In particular, vildagliptin was associated with a low risk of hypoglycaemia and was weight neutral. Increases in transaminase levels were sometimes observed with a vildagliptin dosage of 100 mg once daily in clinical trials, and liver function should be monitored in patients receiving vildagliptin. However, meta-analyses of clinical trial data suggested that vildagliptin 50 mg once or twice daily was not associated with an increased risk of hepatic adverse events, transaminase elevations ≥3 × the upper limit of normal, pancreatitis, cardiovascular or cerebrovascular events, infections or skin-related toxicity. In conclusion, vildagliptin is an important option for use in combination with metformin, a sulfonylurea or a thiazolidinedione in patients with type 2 diabetes who require combination therapy.

The efficacy and safety of vildagliptin in the GALIANT trial: chronic kidney disease and other applications

The number of mechanistically novel antidiabetes agents has dramatically increased over the past few years. Dipeptidyl peptidase-4 (DPP-4) inhibitors in particular have emerged as clinically efficacious oral agents for diabetes management with a low incidence of side effects. The Galvus in Addition to Metformin versus Tzd/Metformin in Lowering HbA1c (GALIANT) trial showed that vildagliptin as an add-on therapy was noninferior to thiazolidinedione therapy with regard to reduction in hemoglobin A1c, with both drugs having a similar incidence of side effects in patients with normal and impaired renal function. DPP-4 inhibitors have a low incidence of hypoglycemia without significant weight gain and there is strong evidence that the administration of vildagliptin results in improved α- and β-cell function. New data suggest that DPP-4 inhibitors might also have a role in the setting of myocardial infarction and lipid management, and in the prevention of Type 2 diabetes.

Hormonal and metabolic effects of morning or evening dosing of the dipeptidyl peptidase IV inhibitor vildagliptin in patients with type 2 diabetes

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Vildagliptin is an orally active, potent inhibitor of dipeptidyl peptidase IV and was developed for the treatment of type 2 diabetes. In clinical trials, once or twice daily dosing with vildagliptin (up to 100 mg day(-1)) has been shown to reduce endogenous glucose production and fasting plasma glucose in patients with type 2 diabetes. The comparative efficacy of vildagliptin under a morning vs. evening dosing regimen has not previously been determined.

WHAT THIS STUDY ADDS

Once daily dosing with vildagliptin 100 mg for 28 days improved glycaemic control in patients with type 2 diabetes independent of whether vildagliptin was administered in the morning or evening. Morning or evening dosing with vildagliptin had similar effects on 24 h glycaemic control and plasma concentrations of the hormones insulin, glucagon and glucagon-like peptide 1.

AIM

This randomized, double-blind, crossover study compared post-prandial hormonal and metabolic effects of vildagliptin, (an oral, potent, selective inhibitor of dipeptidyl peptidase IV [DPP-4]) administered morning or evening in patients with type 2 diabetes.

METHODS

Forty-eight patients were randomized to once daily vildagliptin 100 mg administered before breakfast or before dinner for 28 days then crossed over to the other dosing regimen. Blood was sampled frequently after each dose at baseline (day -1) and on days 28 and 56 to assess pharmacodynamic parameters.

RESULTS

Vildagliptin inhibited DPP-4 activity (>80% for 15.5 h post-dose), and increased active glucagon-like peptide-1 compared with placebo. Both regimens reduced total glucose exposure compared with placebo (area under the 0-24 h effect-time curve [AUE(0,24 h)]: morning -467 mg dl(-1) h, P= 0.014; evening -574 mg dl(-1) h, P= 0.003) with no difference between regimens (P= 0.430). Reductions in daytime glucose exposure (AUE(0,10.5 h)) were similar between regimens. Reduction in night-time exposure (AUE(10.5,24 h) was greater with evening than morning dosing (-336 vs.-218 mg dl(-1) h, P= 0.192). Only evening dosing significantly reduced fasting plasma glucose (-13 mg dl(-1), P= 0.032) compared with placebo. Insulin exposure was greater with evening dosing (evening 407 microU ml(-1) h; morning 354 microU ml(-1) h, P= 0.050).

CONCLUSIONS

Both morning and evening dosing of once daily vildagliptin 100 mg significantly reduced post-prandial glucose in patients with type 2 diabetes; only evening dosing significantly decreased fasting plasma glucose. Although evening dosing with vildagliptin 100 mg tended to decrease night-time glucose exposure more than morning dosing, both regimens were equally effective in reducing 24 h mean glucose exposure (AUE(0,24 h)) in patients with type 2 diabetes.

Dipeptidyl peptidase-4 inhibitors in the treatment of type 2 diabetes: a comparative review

The dipeptidyl peptidase (DPP)-4 inhibitors are a new class of antihyperglycaemic agents which were developed for the treatment of type 2 diabetes by rational drug design, based on an understanding of the underlying mechanism of action and knowledge of the structure of the target enzyme. Although they differ in terms of their chemistry, they are all small molecules which are orally available. There are some differences between them in terms of their absorption, distribution, metabolism and elimination, as well as in their potency and duration of action, but their efficacy, both in terms of inhibiting plasma DPP-4 activity and as antidiabetic agents, appears to be similar. They improve glycaemic control, reducing both fasting and postprandial glucose levels to lower HbA1c levels, without weight gain and with an apparently benign adverse event profile. At present, there seems to be little to distinguish between the different inhibitors in terms of their efficacy as antidiabetic agents and their safety. Long-term accumulated clinical experience will reveal whether compound-related characteristics lead to any clinically relevant differences.

Efficacy and safety of vildagliptin/pioglitazone combination therapy in Korean patients with diabetes

AIM: To assess the efficacy and safety of vildagliptin/pioglitazone combination therapy in Korean patients with type 2 diabetes mellitus (T2DM).

METHODS: This was a post hoc analysis in Korean patients, from a 24-wk, randomized, active-controlled, double-blind, parallel-group, multicenter study. Eligible patients were aged between 18 and 80 years, drug naive, and had been diagnosed with T2DM [hemoglobin A_1c (HbA_1c): 7.5%-11.0% and fasting plasma glucose (FPG): < 270 mg/dL (< 15 mmol/L)]. Patients were randomized (1:1:1:1) to receive the vildagliptin/pioglitazone combination at 100/30 mg q.d. (high-dose) or 50/15 mg q.d. (low-dose), vildagliptin 100 mg q.d., or pioglitazone 30 mg q.d. monotherapies. The primary outcome measure was change in HbA_1c from baseline to endpoint.

RESULTS: The distribution of baseline demographic and clinical parameters was well balanced between treatment groups. The overall mean age, body mass index, HbA_1c, FPG, and duration of disease were 50.8 years, 24.6 kg/m², 8.6%, 10.1 mmol/L, and 2.2 years, respectively. Adjusted mean changes (± standard error) in HbA_1c from baseline (~8.7%) to week 24 endpoint were -2.03% ± 0.16% (high-dose, N = 34), -1.88% ± 0.15% (low-dose, N = 34), -1.31% ± 0.21% (vildagliptin, N = 36), and -1.52% ± 0.16% (pioglitazone, N = 36). The high-dose combination therapy demonstrated greater efficacy than monotherapies [vildagliptin (P = 0.029) and pioglitazone (P = 0.027)]. Percentage of patients achieving HbA_1c < 7% and ≤ 6.5% was the highest in the high-dose group (76% and 68%) followed by low-dose (58% and 47%), vildagliptin (59% and 37%), and pioglitazone (53% and 28%) groups. The overall incidence of adverse events was comparable.

CONCLUSION: In Korean patients, first-line treatment with high-dose combination therapy improved glycemic control compared to pioglitazone and vildagliptin monotherapies, consistent with results published for the overall study population.