Vildagliptin , a DPP-4 inhibitor for the twice-daily treatment of type 2 diabetes mellitus with or without metformin

Development of Long-Acting Dipeptidyl Peptidase-4 Inhibitors: Structural Evolution and Long-Acting Determinants

Considerable effort has been made to achieve less frequent dosing in the development of DPP-4 inhibitors. Enthusiasm for long-acting DPP-4 inhibitors is based on the promise that such agents with less frequent dosing regimens are associated with improved patient adherence, but the rational design of long-acting DPP-4 inhibitors remains a major challenge. In this Perspective, the development of long-acting DPP-4 inhibitors is comprehensively summarized to highlight the evolution of initial lead compounds on the path toward developing long-acting DPP-4 inhibitors over nearly three decades. The determinants for long duration of action are then examined, including the nature of the target, potency, binding kinetics, crystal structures, selectivity, and preclinical and clinical pharmacokinetic and pharmacodynamic profiles. More importantly, several possible approaches for the rational design of long-acting drugs are discussed. We hope that this information will facilitate the design and development of safer and more effective long-acting DPP-4 inhibitors and other oral drugs.

Dipeptidyl Peptidase (DPP)-IV Inhibitors with Antioxidant Potential Isolated from Natural Sources: A Novel Approach for the Management of Diabetes

Type 2 diabetes mellitus (T2DM) is characterized by hyperglycemia that is predominantly caused by insulin resistance or impaired insulin secretion, along with disturbances in carbohydrate, fat and protein metabolism. Various therapeutic approaches have been used to treat diabetes, including improvement of insulin sensitivity, inhibition of gluconeogenesis, and decreasing glucose absorption from the intestines. Recently, a novel approach has emerged using dipeptidyl peptidase-IV (DPP-IV) inhibitors as a possible agent for the treatment of T2DM without producing any side effects, such as hypoglycemia and exhaustion of pancreatic β-cells. DPP-IV inhibitors improve hyperglycemic conditions by stabilizing the postprandial level of gut hormones such as glucagon-like peptide-1, and glucose-dependent insulinotropic polypeptides, which function as incretins to help upregulate insulin secretion and β-cell mass. In this review, we summarized DPP-IV inhibitors and their mechanism of inhibition, activities of those isolated from various natural sources, and their capacity to overcome oxidative stress in disease conditions.

Insights from VERIFY: Early Combination Therapy Provides Better Glycaemic Durability Than a Stepwise Approach in Newly Diagnosed Type 2 Diabetes

The treatment aims for type 2 diabetes are to prevent complications and premature mortality, and improve quality of life. Glycaemic control is central to these aims; clinical guidelines have sought to achieve this with a stepwise approach starting with lifestyle measures and metformin, adding further medications once glycated haemoglobin (HbA_1c) levels rise above a predefined threshold. However, treatment intensification can be delayed when HbA_1c levels increase, and HbA_1c levels become inadequately controlled in many patients. Clinical inertia can result in sustained elevated levels of HbA_1c; when combined with a late diagnosis, this negatively impacts patients' prognosis. Early combination therapy using medications with complementary modes of action could achieve optimal glycaemic targets and alter the course of the disease more than metformin alone. The multinational VERIFY study (clinicaltrials.gov NCT01528254) provided evidence accrued over 5 years, demonstrating the potential of early combination therapy: time to loss of glycaemic control was nearly doubled, and more than twice the number of patients experienced extended glycaemic control, with a vildagliptin-metformin combination therapy versus metformin alone. The study also showed a delay in secondary treatment failure in patients receiving the combination. Early combination therapy therefore offers a different trajectory to the stepwise approach. Translating these findings into clinical practice will require early detection and diagnosis of type 2 diabetes plus a shift in disease management. Nonetheless, the potential benefits of sustained and continuous disease control that early combination therapy offers represent the start of a new era in early diagnosis and intensive management, to achieve the treatment aims of type 2 diabetes.

Network Pharmacology-Based Dissection of the Anti-diabetic Mechanism of Lobelia chinensis

Diabetes mellitus (DM) is a chronic inflammatory disease, and the rapidly increasing DM is becoming a major problem of global public health. Traditional Chinese medicine (TCM) has a long history of treating diabetes. It has been developed and utilized because of its good efficacy and no toxic side effects. Lobelia chinensis is a traditional whole grass herbal. With the continuous deepening of pharmacological research on TCM, the active ingredients of L. chinensis are continuously revealed, which contained the alkaloids, flavonoids, flavonoid glycosides and amino acids that have the good effects of anti-inflammatory, anti-viral and anti-diabetic. In order to further explore the targets of active ingredients and its anti-diabetic mechanism, a feasible network pharmacology analysis model based on chemical, pharmacokinetic and pharmacological data was developed by network construction method to clarify the anti-diabetic mechanism of L. chinensis. The present study conducted by gas chromatography–mass spectrometer (GC/MS), which identified 208 metabolites of L. chinensis, of which 23 ingredients may have effective pharmacological effects after absorption, distribution, metabolism, and excretion (ADME) screening. Network pharmacological analysis on the active ingredients revealed that 5-hydroxymethylfurfural in L. chinensis affects the insulin resistance signaling pathway by acting on GSK3B, TNF, and MAPK1, acacetin affects the diabetic pathway by acting on INSR, DPP4, and GSK3B, that regulate type 2 diabetes, non-insulin-dependent DM, and inflammatory diseases. These results successfully indicated the potential anti-diabetic mechanism of the active ingredients of L. chinensis.

Optimization of the benzamide fragment targeting the S2' site leads to potent dipeptidyl peptidase-IV inhibitors

Our recently successful identification of benzoic acid-based DPP-4 inhibitors spurs the further quest for in-depth structure-activity relationships (SAR) study in S₂' site DPP-4. Thus novel benzamide fragments were designed to target the S₂' site to compromise lipophilicity and improve oral activity. Exploring SAR by introduction of a variety of amide and halogen on benzene ring led to identification of several compounds, exerting moderated to excellent DPP-4 activities, in which 4'-chlorine substituted methyl amide 17g showed most potent DPP-4 activity with the IC₅₀ value of 1.6 nM. Its activity was superior to reference alogliptin. Docking study ideally verified and interpreted the obtained SAR of designed compounds. As a continuation, DPP-8/9 assays revealed the designed compounds exhibited good selectivity over DPP-8 and DPP-9. Subsequent cell-based test indicated compound 17g displayed low toxicity toward the LO2 cell line up to 100 μM. In vivo evaluation showed compound 17g robustly improved the glucose tolerance in normal mice. Importantly, 17g exhibited reasonable pharmacokinetic (PK) profiles for oral delivery. Overall, compound 17g has the potential to a safe and efficacious DPP-4 inhibitor for T2DM treatment.

Network pharmacology-based analysis on bioactive anti-diabetic compounds in Potentilla discolor bunge

ETHNOPHARMACOLOGICAL RELEVANCE

Potentilla discolor Bunge (PDB) is a commonly used herbal for alleviating diabetes mellitus and its complications. Although accumulating evidences show the anti-diabetic efficacy of PDB, the vital anti-diabetic compounds and their functional targets remain elusive.

AIM OF THE STUDY

To investigate the anti-diabetic ingredients and their functional mechanisms in PDB, gas chromatograph-mass spectrometry analysis was performed on PDB extract and 21 were testified as anti-diabetic compounds.

MATERIALS AND METHODS

Subsequently their potential protein targets were also identified. The bioinformatics analysis was implemented by network pharmacology-based approaches. STRING analysis was performed to reveal enrichment of these target proteins, protein-protein interactions, pathways and related diseases. Cytoscape was used to determine the potential protein targets for these components in PDB, indicating that 21 anti-diabetic compounds in PDB regulate 33 diabetes-related proteins in 28 signal pathways and involve 21 kinds of diabetes-related diseases. Among the 21 potential anti-diabetic components predicted by network analysis, tricetin was firstly experimentally validated at the molecular and cellular level.

RESULTS

Results indicated that this active small-molecule compound may have beneficial effects on improving glucose uptake.

CONCLUSIONS

We envisage that network analysis will be useful in screening bioactive compounds of medicinal plants.

Identification of novel uracil derivatives incorporating benzoic acid moieties as highly potent Dipeptidyl Peptidase-IV inhibitors

Dipeptidyl Peptidase-IV (DPP-4) is a validated therapeutic target for type 2 diabetes. Aiming to interact with both residues Try629 and Lys554 in S₂' site, a series of novel uracil derivatives 1a-l and 2a-i incorporating benzoic acid moieties at the N₃ position were designed and evaluated for their DPP-4 inhibitory activity. Structure-activity relationships (SAR) study led to the identification of the optimal compound 2b as a potent and selective DPP-4 inhibitor (IC₅₀ = 1.7 nM). Docking study revealed the additional salt bridge formed between the carboxylic acid and primary amine of Lys554 has a key role in the enhancement of the activity. Furthermore, compound 2b exhibited no cytotoxicity in human hepatocyte LO2 cells up to 50 μM. Subsequent in vivo evaluations revealed that the ester of 2b robustly improves the glucose tolerance in normal mice. The overall results have shown that compound 2b has the potential to a safe and efficacious treatment for T2DM.

Discovery of triazole-based uracil derivatives bearing amide moieties as novel dipeptidyl peptidase-IV inhibitors

Dipeptidyl peptidase-IV (DPP-4) is a validated target for T2DM treatment. We previously reported a novel series of triazole-based uracil derivatives bearing aliphatic carboxylic acids with potent DPP-4 inhibitory activities in vitro, but these compounds showed poor hypoglycemic effects in vivo. Herein we further optimized the triazole moiety by amidation of the carboxylic acid to improve in vivo activities. Two series of compounds 3a-f and 4a-g were designed and synthesized. By screening in DPP-4, compound 4c was identified as a potent DPP-4 inhibitor with the IC₅₀ value of 28.62 nM. Docking study revealed compound 4c has a favorable binding mode and interpreted the SAR of these analogs. DPP-8 and DPP-9 tests indicated compound 4c had excellent selectivity over DPP-8 and DPP-9. Further in vivo evaluations revealed that compound 4c showed more potent hypoglycemic activity than its corresponding carboxylic acid in ICR mice and dose-dependently reduced glucose levels in type 2 diabetic C57BL/6 mice. The overall results have shown that compound 4c could be a promising lead for further development of novel DPP-4 agents treating T2DM.

Effects of sitagliptin on circulating zinc-α2-glycoprotein levels in newly diagnosed type 2 diabetes patients: a randomized trial

OBJECTIVE

Zinc-α2-glycoprotein (ZAG) has recently been characterized as a potent metabolic regulator. However, the effects of anti-diabetic agents on circulating ZAG levels in humans remain largely unknown. To explore the possible mechanisms by which the dipeptidyl peptidase-IV (DPP-IV) inhibitor improves insulin resistance, we investigated the effect of sitagliptin, a DPP-IV inhibitor, on circulating cytokine levels in newly diagnosed type 2 diabetes (nT2DM) patients.

DESIGN AND METHODS

A subset of 141 subjects with nT2DM were assigned to receive placebo (n=47) or sitagliptin (n=94) for 3 months. Before and after treatment, subjects received a 75 g oral glucose tolerance test, euglycemic-hyperinsulinemic clamp (EHC), and measurement of ZAG and adiponectin (ADI) concentrations.

RESULTS

Circulating ZAG levels were lower in nT2DM than in control individuals (P<0.01). After 3 months of sitagliptin treatment, HbA1c, fasting plasma glucose, postprandial glucose, 2-h insulin after glucose overload, triglycerides, and homeostasis model assessment of insulin resistance (HOMA-IR) were decreased significantly compared with pre-treatment (P<0.05 or P<0.01), whereas the glucose infusion rate during the stable period of the clamp (M values) during EHC were significantly increased (P<0.01). In addition, circulating ZAG and ADI concentrations were significantly increased along with improved glucose metabolism and insulin sensitivity compared with pre-treatment (both P<0.01) and the change of ZAG (ΔZAG) was positively associated with ΔADI, ΔHOMA-IR, ΔBMI, Δfasting insulin and negatively associated with Δ tumor necrosis factor-α (TNF-α). Furthermore, sitagliptin treatment resulted in significantly lowered plasma TNF-α level (P<0.05).

CONCLUSION

A low level of circulating ZAG is associated with insulin resistance and sitagliptin treatment significantly increases circulating ZAG levels. These observations have implications in relation to the mode of action of the DPP-IV inhibitor as an insulin sensitizing agent.

Development of Sensitive and Specific Analysis of Vildagliptin in Pharmaceutical Formulation by Gas Chromatography-Mass Spectrometry

A sensitive and selective gas chromatography-mass spectrometry (GC-MS) method was developed and fully validated for the determination of vildagliptin (VIL) in pharmaceutical formulation. Prior to GC-MS analysis, VIL was efficiently derivatized with MSTFA/NH4I/β-mercaptoethanol at 60°C for 30 min. The obtained O-TMS derivative of VIL was detected by selected ion monitoring mode using the diagnostic ions m/z 223 and 252. Nandrolone was chosen as internal standard. The GC-MS method was fully validated by the following validation parameters: limit of detection (LOD) and quantitation (LOQ), linearity, precision, accuracy, specificity, stability, robustness, and ruggedness. LOD and LOQ were found to be 1.5 and 3.5 ng mL(-1), respectively. The GC-MS method is linear in the range of 3.5-300 ng mL(-1). The intra- and interday precision values were less than ≤3.62%. The intra- and interday accuracy values were found in the range of -0.26-2.06%. Finally, the GC-MS method was successfully applied to determine VIL in pharmaceutical formulation.

Safety and Efficacy of Omarigliptin (MK-3102), a Novel Once-Weekly DPP-4 Inhibitor for the Treatment of Patients With Type 2 Diabetes

OBJECTIVE

This study was conducted to determine the optimal dose of omarigliptin, a once-weekly (q.w.) dipeptidyl peptidase IV (DPP-4) inhibitor, for the treatment of patients with type 2 diabetes and evaluate the long-term safety of that dose.

RESEARCH DESIGN AND METHODS

In a multicenter, double-blind, 12-week, dose-range finding study, 685 oral antihyperglycemic agent-naïve or washed-out subjects with type 2 diabetes were randomized to one of five once-weekly doses of omarigliptin (0.25 mg, 1 mg, 3 mg, 10 mg, or 25 mg) or placebo. The primary efficacy end point was change from baseline in HbA1c, and secondary end points were 2-h postmeal glucose (PMG) and fasting plasma glucose (FPG). Analysis included all patients who received at least one dose of the study medication. Subjects who completed the base study were eligible to enter a 66-week extension study.

RESULTS

Once-weekly treatment for 12 weeks with omarigliptin provided dose-related reductions in HbA1c, 2-h PMG, and FPG. At week 12, the omarigliptin 25-mg dose provided the greatest glycemic efficacy. The placebo-adjusted least-squares mean reductions from baseline in HbA1c, 2-h PMG, and FPG were -0.72% (-7.8 mmol/mol), -2.5, and -1.3 mmol/L, respectively (all P < 0.001). The incidence of adverse events was similar across dose groups, with a low incidence of symptomatic hypoglycemia and no effect on body weight. Omarigliptin was generally well-tolerated throughout the base and extension studies.

CONCLUSIONS

Omarigliptin 25 mg q.w., compared with placebo, provided significant glucose lowering and was generally well tolerated for up to 78 weeks in patients with type 2 diabetes.

Incretin manipulation in diabetes management

Incretin-based therapies have revolutionized the medical management of type 2 diabetes mellitus (T2DM) in the 21^st century. Glucagon-like peptide-1 (GLP-1) suppresses appetite and gastric motility, and has trophic effects on pancreas, cardio-protective and renal effects. GLP-1 analogues and dipeptidyl peptidase-4 inhibitors form the incretin-based therapies. Significant reduction of hemoglobin A1c when used as monotherapy and in combination regimens, favorable effects on body weight, and low risk of hypoglycemia are their unique therapeutic benefits. Their safety and tolerability are comparable to other anti-diabetic medications. Concern about elevated risk of pancreatitis has been discarded by two recent meta-analyses. This article discusses the therapeutic manipulation of incretin system for the management of T2DM.

Design, Synthesis and Biological Evaluation of Imidazo[1,2-a]pyridine Derivatives as Novel DPP-4 Inhibitors

A new series of DPP-4 inhibitors with imidazo[1,2-a]pyridine scaffold were designed by exploiting scaffold hopping strategy and docking study. Based on docking binding model, structural modifications of 2-benzene ring and pyridine moieties of compound 5a led to the identification of compound 5d with 2, 4-dichlorophenyl group at the 2-position as a potent (IC50  = 0.13 μm), selective (DPP-8/DPP-4 = 215 and DPP-9/DPP-4 = 192) and in vivo efficacious DPP-4 inhibitor. Further, molecular docking revealed that compound 5d could retain key binding features of DPP-4 with the pyridine moiety of imidazo[1,2-a]pyridine ring providing an additional π-π interaction with Phe357 of DPP-4. Compound 5d might be a promising lead for further development of novel DPP-4 inhibitor treating T2DM.

Safety of dipeptidyl peptidase-4 inhibitors for treating type 2 diabetes

INTRODUCTION

Dipeptidyl peptidase-4 (DPP-4) inhibitors (gliptins) occupy a growing place in the armamentarium of drugs used for the management of hyperglycemia in type 2 diabetes, although some safety concerns have been raised in recent years.

AREAS COVERED

An updated review providing an analysis of available safety data (meta-analyses, randomized controlled trials, observational cohort and case-control studies and pharmacovigilance reports) with five commercialized DPP-4 inhibitors (sitagliptin, vildagliptin, saxagliptin, alogliptin, linagliptin). A special focus is given to overall safety profile; pancreatic adverse events (AEs) (acute pancreatitis, pancreatic cancer); overall cardiovascular safety (myocardial infarction and stroke); congestive heart failure concern and finally, safety in special populations (elderly, renal impairment).

EXPERT OPINION

The good tolerance/safety profile of DPP-4 inhibitors has been largely confirmed, including in more fragile populations (elderly, renal impairment) with almost no increased risk of infection or gastrointestinal AEs, no weight gain and a minimal risk of hypoglycemia. Although an increased risk of acute pancreatitis and pancreatic cancer was suspected, the complete set of available data appears reassuring so far. Cardiovascular safety of DPP-4 inhibitors has been proven but an unexpected increased risk of heart failure has been reported which should be confirmed in ongoing trials and better understood. Further postmarketing surveillance is recommended.

DPP-4 inhibitors: focus on safety

INTRODUCTION

Dipeptidyl peptidase inhibitors (DPP-4-i) are highly selective inhibitors of the enzyme DPP-4. They act by increasing levels of incretin hormones, which have potent effects on insulin and glucagon release, gastric emptying, and satiety. Our goal is to review the safety issues related to DPP-4-i.

AREAS COVERED

This review is based upon a PubMed search of the literature using keywords alogliptin, linagliptin, saxagliptin, sitagliptin and vildagliptin, DPP-4-i, glucagon-like polypeptide-1 agonists, as well as extensive personal clinical trial experience with each of these agents. The current DPP-4-i have very different chemical structures. Saxagliptin has significant cytochrome P450 metabolism and carries a risk of drug interactions. Linagliptin has primarily entero-hepatic excretion, a benefit in renally impaired patients. A concern arose related to congestive heart failure in the SAVOR TIMI trial of saxagliptin. Several major cardiac studies are underway, with two concluded. Despite lingering uncertainty related to pancreatitis and pancreatic cancer, large randomized trials have not shown an increased risk with DPP-4-i treatment. Cutaneous adverse effects occur with a low frequency with some of these agents.

EXPERT OPINION

DPP-4-i are an additional choice in the group of anti-hyperglycemics. Their principal advantage is a low incidence of hypoglycemia, making these agents desirable in patients such as the elderly and those with cardiac disease. Several large trials have hinted at less cardiac risk with DPP-4-i than with sulfonylureas. The CAROLINA Trial comparing linagliptin and glimepiride may provide a conclusive answer to this question.