Saxagliptin: a new DPP-4 inhibitor for the treatment of type 2 diabetes mellitus

DPP-4 inhibitors for treating T2DM - hype or hope? an analysis based on the current literature

DPP-4 inhibition is an interesting line of therapy for treating Type 2 Diabetes Mellitus (T2DM) and is based on promoting the incretin effect. Here, the authors have presented a brief appraisal of DPP-4 inhibitors, their modes of action, and the clinical efficiency of currently available drugs based on DPP-4 inhibitors. The safety profiles as well as future directions including their potential application in improving COVID-19 patient outcomes have also been discussed in detail. This review also highlights the existing queries and evidence gaps in DPP-4 inhibitor research. Authors have concluded that the excitement surrounding DPP-4 inhibitors is justified because in addition to controlling blood glucose level, they are good at managing risk factors associated with diabetes.

Enhanced Diabetic Wound Healing Using Electrospun Biocompatible PLGA-Based Saxagliptin Fibrous Membranes

Delayed diabetic wound healing is an adverse event that frequently leads to limb disability or loss. A novel and promising vehicle for the treatment of diabetic wounds is required for clinical purposes. The biocompatible and resorbable poly (lactic-co-glycolic acid) (PLGA)-based fibrous membranes prepared by electrospinning that provide a sustained discharge of saxagliptin for diabetic wound healing were fabricated. The concentration of released saxagliptin in Dulbecco’s phosphate-buffered saline was analyzed for 30 days using high-performance liquid chromatography. The effectiveness of the eluted saxagliptin was identified using an endothelial progenitor cell migration assay in vitro and a diabetic wound healing in vivo. Greater hydrophilicity and water storage were shown in the saxagliptin-incorporated PLGA membranes than in the pristine PLGA membranes (both p < 0.001). For diabetic wound healing, the saxagliptin membranes accelerated the wound closure rate, the dermal thickness, and the heme oxygenase-1 level over the follicle areas compared to those in the pristine PLGA group at two weeks post-treatment. The saxagliptin group also had remarkably higher expressions of insulin-like growth factor I expression and transforming growth factor-β1 than the control group (p = 0.009 and p < 0.001, respectively) in diabetic wounds after treatment. The electrospun PLGA-based saxagliptin membranes exhibited excellent biomechanical and biological features that enhanced diabetic wound closure and increased the antioxidant activity, cellular granulation, and functionality.

Cyclopropane-Fused N-Heterocycles via Aza-Heck-Triggered C(sp3)-H Functionalization Cascades

Unique examples of aza-Heck-based C(sp³)–H functionalization cascades are described. Under Pd(0)-catalyzed conditions, the aza-Heck-type cyclization of N-(pentafluorobenzoyloxy)carbamates generates alkyl–Pd(II) intermediates that effect C(sp³)–H palladation en route to cyclopropanes. Key factors that control the site selectivity of the cyclopropanation process have been elucidated such that selective access to a wide range of ring- or spiro-fused systems can be achieved.

A facile method to synthesize vildagliptin

An efficient and high-yielding synthetic method for the preparation of vildagliptin via four steps is reported. The process starts from L-proline and involves a successful reaction with chloroacetyl chloride in tetrahydrofuran to afford ( S)-1-(2-chloroacetyl)pyrrolidine-2-carboxylic acid, followed by a reaction with acetonitrile in the presence of sulfuric acid to give ( S)-1-(2-chloroacetyl)pyrrolidine-2-carbonitrile. This is then reacted with 3-aminoadamantanol to give vildagliptin. 3-Aminoadamantanol is prepared from 1-aminoadamantane hydrochloride via oxidation with sulfuric acid/nitric acid and boric acid as the catalyst followed by ethanol extraction. The overall yield is 95%.

The efficacy and safety of dipeptidyl peptidase-4 inhibitors for type 2 diabetes: a Bayesian network meta-analysis of 58 randomized controlled trials

AIMS

The aim is to evaluate the efficacy and safety of dipeptidyl peptidase-4 inhibitors (DPP4-I: sitagliptin, saxagliptin, linagliptin, vildagliptin and alogliptin) in patients with type 2 diabetes.

METHODS

We searched the Cochrane Library, PubMed, EMBASE, Chinese Biomedical Database (CBM), China National Knowledge Infrastructure (CNKI), and the Wanfang Database from inception to April, 2018. Randomized controlled trials were included if they compared the different versions of DPP4-I with each other or with placebo in treatment of type 2 diabetes. Bayesian network meta-analysis and pairwise meta-analysis were performed to evaluate the efficacy and safety of the different kinds of DPP4-I and placebo. The data were analyzed using STATA 12.0 and WinBUGS1.4 software.

RESULTS

We identified 58 eligible studies (with 31356 patients) involving 14 treatment arms. Indirect comparison results showed that except for alogliptin, a decrease was found for all DPP4-I versus the placebo for hemoglobin A1c (HbA1c) with vildagliptin50 twice daily (BID) showing the highest probability. Linagliptin5 once daily (QD) decreased the level of fasting plasma glucose (FPG) the most for all DPP4-I versus the placebo; when comparing them with each other, alogliptin25QD was more effective when compared with sitagliptin100QD and vildaglipti50BID; linagliptin5qd had the highest decrease impact on body mass index (BMI). Except for hypoglycemia and upper respiratory tract infection (URTI), there are no statistical significance on incidence of adverse events and the body weight when DPP4-I are compared with each other or with placebo.

CONCLUSION

Our network meta-analysis presents the associations of DPP4-I versus placebos on HbA1c, FPG, 2 h postprandial blood glucose (2HPPG), BMI, body weight and adverse events. DPP4-I have a lowering effect on the glycemic level (HbA1c, FPG), especially vildaglipti50BID and linagliptin10QD, respectively. Besides, linagliptin5QD has the greatest probabilities of reducing BMI. In addition, DPP4-I were associated with not increasing the incidence of adverse events. Among them, vildagliptin100QD and sitagliptin100QD have the lowest probability in reducing the incidence of hypoglycemia and URTI, respectively.

DPP-4 inhibitors and heart failure: a potential role for pharmacogenomics

There remains an ongoing controversy regarding the safety of dipeptidyl peptidase-4 (DPP-4) inhibitors and the risk of developing heart failure (HF). In addition, none of the animal studies suggested a mechanism for the DPP-4 inhibitors and HF risk. To date, advances in pharmacogenomics have enabled the identification of genetic variants in DPP-4 gene. Studies have shown that genetic polymorphisms in the gene encoding DPP-4 may be associated with potential pathways involved in HF risk. This review discusses the contradictory findings of DPP-4 inhibitors and HF and a potential role for pharmacogenomics. Pharmacogenomics of DPP-4 inhibitors is promising, and genetic information from randomized control trials is urgently needed to gain a full understanding of the safety of DPP-4 inhibitors and the risk of HF.

DPP-4 inhibitors for the treatment of type 2 diabetes: a methodology overview of systematic reviews

AIMS

To evaluate the methodological quality of systematic reviews (SRs), and summarize evidence of important outcomes from dipeptidyl peptidase-4 inhibitors (DPP4-I) in treating type 2 diabetes mellitus (T2DM).

METHODS

We included SRs of DPP4-I for the treatment of T2DM until January, 2018 by searching the Cochrane Library, PubMed, EMBASE and three Chinese databases. We evaluated the methodological qualities with the AMSTAR (Assessing the Methodological Quality of Systematic Reviews) tool and the GRADE (The Grading of Recommendations Assessment, Development and Evaluation) approach.

RESULTS

Sixty-three SRs (a total of 2,603,140 participants) receiving DPP4-I for the treatment of T2DM were included. The results of AMSTAR showed that the lowest quality was "a list of studies (included and excluded) item" with only one (1.6%) study provided, followed by the "providing a priori design" item with only four (6.3%) studies conforming to this item, the next were "the status of publication (gray literature) used as an inclusion criterion item", with only 18 (28.9%) studies conforming to these items. Only seven (11.1%) studies scored more than nine points in AMSTAR, indicating high methodological quality. For GRADE, of the 128 outcomes, high quality evidence was provided in only 28 (21.9%), moderate in 70 (54.7%), low in 27 (21.1%), and very low in three (2.3%).

CONCLUSIONS

The methodological quality of SRs of DPP4-I for type 2 diabetes mellitus is not high and there are common areas for improvement. Furthermore, the quality of evidence level is moderate and more high quality evidence is needed.

Saxagliptin add-on therapy in Chinese patients with type 2 diabetes inadequately controlled by insulin with or without metformin: Results from the SUPER study, a randomized, double-blind, placebo-controlled trial

This prospective, multicentre, phase III study (NCT02104804) evaluated the efficacy and safety of saxagliptin add-on therapy in Chinese patients with type 2 diabetes inadequately controlled by insulin ± metformin. Patients with glycated haemoglobin (HbA1c) 7.5% to 10.5% and fasting plasma glucose (FPG) <15 mmol/L (270 mg/dL) on stable insulin therapy (20-150 U/d) were randomized (1:1) to saxagliptin 5 mg once daily (N = 232) or placebo (N = 230) for 24 weeks, stratified by metformin use. The primary efficacy measure was change in HbA1c. Saxagliptin treatment resulted in a greater adjusted mean change in HbA1c from baseline to week 24 than placebo (-0.58%; P < .001), irrespective of metformin use, and a greater mean change in FPG (0.9 mmol/L [-15.9 mg/dL]; P < .001). More patients achieved HbA1c <7% with saxagliptin (11.4%) than with placebo (3.5%, P = .002). Adverse events and incidence of hypoglycaemia were similar in both groups. Overall, add-on saxagliptin 5 mg once daily significantly improved glycaemic control without increasing hypoglycaemia risk and was well tolerated in Chinese patients with type 2 diabetes inadequately controlled by insulin (± metformin).

Recent progress of the development of dipeptidyl peptidase-4 inhibitors for the treatment of type 2 diabetes mellitus

Diabetes is a fast growing chronic metabolic disorder around the world. Dipeptidyl peptidase-4 (DPP-4) is a new promising target during type 2 diabetes glycemic control. Thus, a number of potent DPP-4 inhibitors were developed and play a rapidly evolving role in the management of type 2 diabetes in recent years. This article reviews the development of synthetic and natural DPP-4 inhibitors from 2012 to 2017 and provides their physico-chemical properties, biological activities against DPP-4 and selectivity over dipeptidyl peptidase-8/9. Moreover, the glucose-lowering mechanisms and the active site of DPP-4 are also discussed. We also discuss strategies and structure-activity relationships for identifying potent DPP-4 inhibitors, which will provide useful information for developing potent DPP-4 drugs as type 2 diabtes treatments.

Efficacy and safety of saxagliptin in combination with metformin as initial therapy in Chinese patients with type 2 diabetes: Results from the START study, a multicentre, randomized, double-blind, active-controlled, phase 3 trial

AIM

To assess the efficacy and safety of saxagliptin plus metformin over 24 weeks in pharmacotherapy-naïve Chinese patients with type 2 diabetes mellitus and inadequate glycaemic control (HbA1c, 8.0%-12.0%).

RESEARCH DESIGN AND METHODS

In this multicentre, double-blind, active-controlled study (The START study: NCT02273050, clinicaltrials.gov), patients were randomized (1:1:1) to saxagliptin 5 mg plus metformin, saxagliptin 5 mg plus placebo or metformin plus placebo. Saxagliptin was taken once daily; metformin was taken once/twice daily and was titrated from 500 mg to a maximum of 2000 mg/d over 8 weeks. The primary end point was change in HbA1c from baseline to Week 24.

RESULTS

Data from 630 patients (66.5% men; mean age, 50.1 years; mean body mass index, 26.6 kg/m² ; mean HbA1c, 9.4%; mean diabetes duration, 0.81 years) were analysed. Mean reduction in HbA1c was greater with saxagliptin plus metformin (-3.0%) than with saxagliptin plus placebo (-2.1%; P < .001) or metformin plus placebo (-2.8%; P = .034). Changes in mean fasting plasma glucose, 120-minute postprandial glucose, and 180-minute postprandial glucose area under the curve were greater, and more patients achieved a therapeutic glycaemic response, with saxagliptin plus metformin than with either monotherapy. Hypoglycaemic events were infrequent (<2%). Incidence of adverse events was similar among groups; upper respiratory tract infection and diarrhoea were most common.

CONCLUSIONS

Saxagliptin 5 mg plus metformin significantly improved glycaemic control compared with either monotherapy in treatment-naïve Chinese patients with type 2 diabetes, and was well tolerated.

Dapagliflozin/Saxagliptin Fixed-Dose Tablets: A New Sodium-Glucose Cotransporter 2 and Dipeptidyl Peptidase 4 Combination for the Treatment of Type 2 Diabetes

Objective: To review the pharmacology, pharmacokinetics, efficacy, safety, and place in therapy of the fixed-dose combination (FDC) product, QTERN (dapagliflozin/saxagliptin) tablets. Data Sources: Searches of MEDLINE (1946 to July 1, 2017) were conducted using the keywords QTERN, saxagliptin, and dapagliflozin. Additional data were obtained from the prescribing information, the product dossier, and Clinicaltrials.gov . Study Selection and Data Extraction: All English language articles related to pharmacology, pharmacokinetics, efficacy, or safety of the combination therapy in human subjects were reviewed. Data Synthesis: The pharmacokinetics of saxagliptin and dapagliflozin were not affected significantly when administered as an FDC product. Saxagliptin may suppress the increased secretion of glucagon associated with dapagliflozin. The combination dapagliflozin/saxagliptin has been studied as add-on therapy to metformin in patients with uncontrolled type 2 diabetes mellitus (T2DM). The difference in hemoglobin A1C (A1C) between saxagliptin + dapagliflozin + metformin (triple therapy) and saxagliptin + metformin was −0.59 (95% CI = −0.81 to −0.37, P < 0.0001), and the difference between triple therapy and dapagliflozin + metformin was −0.27 (95% CI = −0.48 to −0.05, P = 0.0166). The combination was well tolerated when added to metformin. Conclusion: QTERN (dapagliflozin/saxagliptin) tablets are a reasonable option for patients with T2DM not controlled on metformin, but cost, insurance coverage, and a lackluster reduction in A1C will likely limit its use until more data regarding its effects on complications of diabetes and cardiovascular outcomes become available.

CB-1R and GLP-1R gene expressions and oxidative stress in the liver of diabetic rats treated with sitagliptin

BACKGROUND

Type 2 diabetes is a major health problem affecting millions of people. Controlled eating and regular physical activity are important for the management of type 2 diabetes. Dipeptidyl peptidase-4 enzyme (DPP-4) inhibitor sitagliptin is a potent agent for the treatment of type-2 diabetes. The aim of this study was to examine the effects of sitagliptin on the liver of rats with streptozotocin (STZ)-induced diabetes, in terms of (i) the expression levels of the cannabinoid 1 receptor (CB-1R) and glucagon-like peptide 1 receptor (GLP-1R), (ii) alterations in the number and localization of these peptides, and (iii) changes in histological and oxidative damage.

METHODS

Thirty-two neonatal (two-day-old) rats, which were divided into four groups, were treated with saline (control), sitagliptin (control; 1.5mg/kg/day for 15 days starting from day 5 of the experimental period), STZ (diabetes; 100mg/kg single dose), STZ+sitagliptin (diabetes+sitagliptin). After 20 days, hepatic tissues were obtained from rats.

RESULTS

The expressions of GLP-1R and CB-1R mRNA increased approximately 1.89- and 2.94-fold, respectively, in the diabetes+sitagliptin group as compared to the diabetic group. Additionally the number of GLP-1R immunopositive cells decreased and CB-1R immunopositive cells increased in comparison to the diabetic group; however, this was not statistically significant. Glutathione levels increased, but malondialdehyde and protein carbonyl levels decreased in the diabetes+sitagliptin group more than the diabetic group.

CONCLUSION

Our findings indicate that sitagliptin treatment regulates GLP-1R and CB-1R gene expressions, which are associated with appetite regulation in diabetic rat, and may decrease oxidative stress and liver tissue damage.

Postauthorization safety study of the DPP-4 inhibitor saxagliptin: a large-scale multinational family of cohort studies of five outcomes

OBJECTIVE

To evaluate the risk of serious adverse events among patients with type 2 diabetes mellitus initiating saxagliptin compared with oral antidiabetic drugs (OADs) in classes other than dipeptidyl peptidase-4 (DPP-4) inhibitors.

RESEARCH DESIGN AND METHODS

Cohort studies using 2009-2014 data from two UK medical record data sources (Clinical Practice Research Datalink, The Health Improvement Network) and two USA claims-based data sources (HealthCore Integrated Research Database, Medicare). All eligible adult patients newly prescribed saxagliptin (n=110 740) and random samples of up to 10 matched initiators of non-DPP-4 inhibitor OADs within each data source were selected (n=913 384). Outcomes were hospitalized major adverse cardiovascular events (MACE), acute kidney injury (AKI), acute liver failure (ALF), infections, and severe hypersensitivity events, evaluated using diagnostic coding algorithms and medical records. Cox regression was used to determine HRs with 95% CIs for each outcome. Meta-analyses across data sources were performed for each outcome as feasible.

RESULTS

There were no increased incidence rates or risk of MACE, AKI, ALF, infection, or severe hypersensitivity reactions among saxagliptin initiators compared with other OAD initiators within any data source. Meta-analyses demonstrated a reduced risk of hospitalization/death from MACE (HR 0.91, 95% CI 0.85 to 0.97) and no increased risk of hospitalization for infection (HR 0.97, 95% CI 0.93 to 1.02) or AKI (HR 0.99, 95% CI 0.88 to 1.11) associated with saxagliptin initiation. ALF and hypersensitivity events were too rare to permit meta-analysis.

CONCLUSIONS

Saxagliptin initiation was not associated with increased risk of MACE, infection, AKI, ALF, or severe hypersensitivity reactions in clinical practice settings.

TRIAL REGISTRATION NUMBER

NCT01086280, NCT01086293, NCT01086319, NCT01086306, and NCT01377935; Results.

Pharmacology and therapeutic implications of current drugs for type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a global epidemic that poses a major challenge to health-care systems. Improving metabolic control to approach normal glycaemia (where practical) greatly benefits long-term prognoses and justifies early, effective, sustained and safety-conscious intervention. Improvements in the understanding of the complex pathogenesis of T2DM have underpinned the development of glucose-lowering therapies with complementary mechanisms of action, which have expanded treatment options and facilitated individualized management strategies. Over the past decade, several new classes of glucose-lowering agents have been licensed, including glucagon-like peptide 1 receptor (GLP-1R) agonists, dipeptidyl peptidase 4 (DPP-4) inhibitors and sodium/glucose cotransporter 2 (SGLT2) inhibitors. These agents can be used individually or in combination with well-established treatments such as biguanides, sulfonylureas and thiazolidinediones. Although novel agents have potential advantages including low risk of hypoglycaemia and help with weight control, long-term safety has yet to be established. In this Review, we assess the pharmacokinetics, pharmacodynamics and safety profiles, including cardiovascular safety, of currently available therapies for management of hyperglycaemia in patients with T2DM within the context of disease pathogenesis and natural history. In addition, we briefly describe treatment algorithms for patients with T2DM and lessons from present therapies to inform the development of future therapies.

Saxagliptin for the treatment of diabetes - a focus on safety

INTRODUCTION

The safety of agents used to treat type 2 diabetes (T2D), a chronic disease requiring life-long intervention, is of particular interest. Saxagliptin is a potent and selective DPP-4 inhibitor that has emerged as a therapeutic option for T2D.

AREAS COVERED

Its safety was assessed in a development program of 20 phase 2/3 randomized clinical trials and in SAVOR-TIMI 53 trial that evaluated the cardiovascular outcomes. In order to capture any further safety signals, mainly in the long-term, a post-marketing safety surveillance is ongoing. This paper discusses the tolerability and safety profile of the agent, including cardiovascular, renal, pancreatic, hepatic and bone adverse events.

EXPERT OPINION

Saxagliptin is a safe therapeutic option for patients with T2D, with low risk of hypoglycemia and good tolerability. It demonstrated cardiovascular safety (including in patients with pre-existing cardiovascular disease and/or HF) and safety with respect to all-cause mortality and adverse events of special interest. In SAVOR-TIMI53, saxagliptin was associated with an unexpected increased risk of HF hospitalization, mainly in the first 12 months; a mechanistic explanation for this has not been found. Further research needs to elucidate the effect of antidiabetic drugs on the heart, by including biomarkers and echocardiographic sub-studies within large outcome trials.

Pharmacokinetic, pharmacodynamic and clinical evaluation of saxagliptin in type 2 diabetes

INTRODUCTION

Dipeptide peptidase-4 (DPP-4) inhibitors such as saxagliptin are established and efficacious oral therapies in the management of type 2 diabetes. These agents have the potential to confer significant benefits in glycemic control without the risk of weight gain and hypoglycemia, which may be associated with other medications used to treat type 2 diabetes.

AREAS COVERED

This review examines the pharmacokinetics, efficacy and tolerability of saxagliptin for the management of type 2 diabetes.

EXPERT OPINION

Saxagliptin is routinely used in the management of type 2 diabetes as monotherapy, and in combination with other oral agents and insulin. Robust clinical trials have shown consistent improvements in glycated hemoglobin, fasting and postprandial glucose levels, with few adverse effects. The agent is well tolerated with low rates of hypoglycemia in the absence of insulin or sulphonylurea therapy.

Determinants of saxagliptin use among patients with type 2 diabetes mellitus treated with oral anti-diabetic drugs

BACKGROUND

The patterns and determinants of saxagliptin use among patients with type 2 diabetes mellitus (T2DM) are unknown in real-world settings. We compared the characteristics of T2DM patients who were new initiators of saxagliptin to those who were new initiators of non-dipeptidyl peptidase-4 (DPP-4) inhibitor oral anti-diabetic drugs (OADs) and identified factors associated with saxagliptin use.

METHODS

We conducted a cross-sectional study within the Clinical Practice Research Datalink (CPRD), The Health Improvement Network (THIN), US Medicare, and the HealthCore Integrated Research Database (HIRD(SM)) across the first 36 months of saxagliptin availability (29 months for US Medicare). Patients were included if they were: 1) ≥18 years old, 2) newly prescribed saxagliptin or a non-DPP-4 inhibitor OAD, and 3) enrolled in their respective database for 180 days. For each saxagliptin initiator, we randomly selected up to ten non-DPP-4 inhibitor OAD initiators matched on age, sex, and geographic region. Conditional logistic regression was used to identify determinants of saxagliptin use.

RESULTS

We identified 64,079 saxagliptin initiators (CPRD: 1,962; THIN: 2,084; US Medicare: 51,976; HIRD(SM): 8,057) and 610,660 non-DPP-4 inhibitor OAD initiators (CPRD: 19,484; THIN: 19,936; US Medicare: 493,432; HIRD(SM): 77,808). Across all four data sources, prior OAD use, hypertension, and hyperlipidemia were associated with saxagliptin use. Saxagliptin initiation was also associated with hemoglobin A1c results >8% within the UK data sources, and a greater number of hemoglobin A1c measurements in the US data sources.

CONCLUSIONS

In these UK and US data sources, initiation of saxagliptin was associated with prior poor glycemic control, prior OAD use, and diagnoses of hypertension and hyperlipidemia.

TRIAL REGISTRATION

ClinicalTrials.gov identifiers NCT01086280 , NCT01086293 , NCT01086319 , NCT01086306 , and NCT01377935.

Immunohistochemical, apoptotic and biochemical changes by dipeptidyl peptidase-4 inhibitor-sitagliptin in type-2 diabetic rats

BACKGROUND

Diabetes is a major public health problem that is rapidly increasing in prevalence. In this study, the effects of sitagliptin, a dipeptidyl peptidase-4 inhibitor, were examined on newborn diabetic rat model.

METHODS

Wistar albino newborn rats were divided into control (Ctrl), sitagliptin (Sit), diabetic and diabetic+Sit groups. On the second day after the birth, 100mg/kg streptozotocin (STZ) was administered intraperitoneally in a single dose to induce type-2 diabetes in rats. The Sit and diabetic+Sit groups were administered sitagliptin (1.5mg/kg subcutaneous) as of the day 5 for 15 days. The pancreas sections were stained with insulin (INS), glucagon (GLU), somatostatin (SS), glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-1 receptor (GLP-1R) antibodies by the streptavidin-biotin peroxidase technique. The TUNEL method for apoptosis and biochemical analysis were performed in the pancreas and serum, respectively.

RESULTS

Body weight and blood glucose levels showed significant differences among all groups on days 11 and 20. In diabetic rats following treatment with sitagliptin, the area percentage of INS immunopositive cells increased while the area percentage of SS immunopositive cells decreased, insignificantly. A significant increase was observed on the area percentage of GLU, GLP-1 and GLP-1R immunopositive cells in the diabetic+Sit group when compared to the diabetic group. The area percentage of apoptotic cells was the same among all groups. While serum glutathione and malondialdehyde levels demonstrated insignificant alterations, the catalase and superoxide dismutase activity significantly changed among four groups.

CONCLUSION

According to our findings, sitagliptin may be a useful therapeutic agent to a certain extent of type-2 diabetic condition.

Dipeptidyl peptidase-4 inhibitors: pharmacokinetics, efficacy, tolerability and safety in renal impairment

The dipeptidyl peptidase-4 (DPP-4) inhibitors are a new class of blood glucose-lowering therapy with proven efficacy, tolerability and safety. Four of the five commercially available DPP-4 inhibitors are subject to significant renal clearance, and pharmacokinetic studies in people with renal impairment have led to lower recommended doses based on creatinine clearance in order to prevent drug accumulation. Data from these pharmacokinetic studies and from supratherapeutic doses in healthy individuals and people with uncomplicated diabetes during development suggest, however, that there is a wide therapeutic margin. This should protect against toxicity if people with renal impairment are inadvertently prescribed higher doses than recommended. Doses appropriate to renal function are associated with reductions in HbA1c that are equivalent to those observed in people with type 2 diabetes who do not have renal impairment. Recent large-scale cardiovascular safety trials of saxagliptin and alogliptin have identified heart failure as a potential concern and renal impairment may increase the risk of this complication. Although the incidence of pancreatitis does not appear to be significantly increased by DPP-4 inhibitor therapy, renal impairment is also an independent risk factor. Additional data from other ongoing DPP-4 inhibitor cardiovascular safety trials should provide a more precise assessment of the risks of these uncommon complications, including in people with renal impairment.

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.

Sensing small molecule interactions with lipid membranes by local pH modulation

Herein, we utilized a label-free sensing platform based on pH modulation to detect the interactions between tetracaine, a positively charged small molecule used as a local anesthetic, and planar supported lipid bilayers (SLBs). The SLBs were patterned inside a flow cell, allowing for various concentrations of tetracaine to be introduced over the surface in a buffer solution. Studies with membranes containing POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) yielded an equilibrium dissociation constant value of Kd = 180 ± 47 μm for this small molecule-membrane interaction. Adding cholesterol to the SLBs decreased the affinity between tetracaine and the bilayers, while this interaction tightened when POPE (1-hexadecanoyl-2-(9-Z-octadecenoyl)-sn-glycero-3-phosphoethanolamine) was added. Studies were also conducted with three negatively charged membrane lipids, POPG (1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (sodium salt)), POPS (1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-l-serine (sodium salt)), and ganglioside GM1. All three measurements gave rise to a similar tightening of the apparent Kd value compared with pure POPC membranes. The lack of chemical specificity with the identity of the negatively charged lipid indicated that the tightening was largely electrostatic. Through a direct comparison with ITC measurements, it was found that the pH modulation sensor platform offers a facile, inexpensive, highly sensitive, and rapid method for the detection of interactions between putative drug candidates and lipid bilayers. As such, this technique may potentially be exploited as a screen for drug development and analysis.

Safety of saxagliptin: rationale for and design of a series of postmarketing observational studies

PURPOSE

To describe the design and rationale of a series of postmarketing studies to examine the safety of saxagliptin, an oral dipeptidyl peptidase-4 inhibitor for the treatment of type 2 diabetes mellitus, in real-world settings.

METHODS

We are conducting a series of retrospective cohort studies using two UK (General Practice Research Database, and The Health Improvement Network) and two US (Medicare, HealthCore Integrated Research Database(SM) ) data sources. The primary outcomes of interest will include (i) hospitalization with acute liver failure, (ii) hospitalization for acute kidney injury, (iii) hospitalization for severe hypersensitivity reactions, (iv) hospitalization for severe infections, (v) hospitalization with infections associated with T-lymphocyte dysfunction (i.e., herpes zoster, tuberculosis, or nontuberculous mycobacteria), and (vi) major cardiovascular events. Diagnosis codes for the outcomes of interest will be validated by medical record review within each data source. Projected use and estimated incidence rates of outcomes of interest suggest there will be at least 80% statistical power to detect a minimum hazard ratio of 1.5 for major cardiovascular events, 2.0 for acute kidney injury and severe infections, 2.4 for acute liver failure, and 4.0 for severe hypersensitivity reactions.

RESULTS

Forthcoming.

CONCLUSIONS

This postmarketing safety assessment will provide important information regarding the safety of saxagliptin and could potentially identify important dipeptidyl peptidase-4 inhibitor class effects. The methods described may be useful to others planning similar evaluations.

Cost effectiveness of saxagliptin and metformin versus sulfonylurea and metformin in the treatment of type 2 diabetes mellitus in Germany: a Cardiff diabetes model analysis

BACKGROUND

The lack of adequate glycaemic control for patients with type 2 diabetes mellitus (T2DM), especially with existing second-line therapies, represents an unmet medical need. Of the newer therapies, the incretin-based medicines, such as saxagliptin, look promising to consolidate second-line pharmacotherapy.

OBJECTIVE

This study evaluates the long-term economic consequences of saxagliptin versus sulfonylurea (glipizide) as second-line therapy when used in combination with metformin after failure of monotherapy treatment with metformin, in patients with T2DM in Germany.

METHODS

A published discrete event simulation model with a fixed-time increment was used to model the effects of different treatment scenarios over a 40-year (life-) time horizon. Disease progression was modelled using evidence from the United Kingdom Prospective Diabetes Study (UKPDS) 68. The treatment sequence matched that of published German guidelines, and efficacy and safety data were derived from published sources. The model assumes that quality-adjusted life-years (QALYs) are affected by complications, hypoglycaemic events and weight change over a lifetime. Costs were specific to the German setting, where sulfonylureas are generic. Costs and effects were discounted annually at 3%. The extended perspective of the national sick funds was adopted, and recommendations from the Institute for Quality and Efficiency in Health Care (IQWiG) were considered.

RESULTS

In the base-case analysis, treatment with saxagliptin plus metformin was associated with a lower incidence of both symptomatic and severe hypoglycaemic events, resulting in an incremental benefit of 0.12 QALYs and an incremental cost-effectiveness ratio (ICER) of €13,931 per QALY gained compared with sulfonylurea plus metformin (year of costing 2009). Modest reductions in all macro- and microvascular complications were seen in those receiving saxagliptin plus metformin compared with sulfonylurea plus metformin. Sensitivity analysis showed that treatment-related weight changes, as a risk factor for complications, represent the most influential driver of cost effectiveness.

CONCLUSION

The study demonstrated improved outcomes with saxagliptin at a cost that would likely be considered acceptable in the German setting. Furthermore, the findings of the sensitivity analysis suggest that the results are robust to various assumptions concerning input variables and modelling assumptions.

A pharmacometric approach to quantify the impact of chronic kidney disease and hemodialysis on systemic drug exposure: application to saxagliptin

The draft United States Food and Drug Administration guidance recommends a dedicated pharmacokinetic (PK) study for most drugs intended for use in patients with chronic kidney disease (CKD), including stage V patients requiring hemodialysis (HD) treatment. However, clinical studies conducted in CKD patients are challenged by difficulties in recruiting stage IV and V patients not yet on dialysis, and in balancing patient characteristics among each studied CKD group. Furthermore, study design for dialysis patients often involves a single dose administered before an HD session. The design may not necessarily represent usual patient care in current clinical practice, in which multiple doses are more likely to be administered at varying times between HD sessions. Using exposure modeling of saxagliptin and its active metabolite, 5-hydroxy saxagliptin, as an example, this work illustrates how these challenges can be alleviated by modeling the impact of HD on drug exposure in clinical studies and simulating the expected exposure level in patient care. The modeled PK profiles in dialysis patients were used to understand PK profiles in patients with various CKD stages. The applied pharmacometric approach increased the efficiency of knowledge generation from existing data.

Saxagliptin for the treatment of type 2 diabetes mellitus: focus on recent studies

Dipeptidyl peptidase-4 (DPP-4) inhibitors are a class of oral antidiabetic drugs that improve glycemic control without causing weight gain or increasing hypoglycemic risk in patients with type 2 diabetes (T2DM). The efficacy and tolerability of saxagliptin, a once-daily DPP-4 inhibitor, administered as monotherapy, as add-on therapy to metformin, a sulfonylurea, or a thiazolidinedione, and as initial combination therapy with metformin, was demonstrated in pivotal 24-week clinical trials. Additional information about the clinical profile of saxagliptin was recently obtained from extension studies, head-to-head clinical trials, and post-hoc analyses. In extension studies, the efficacy and tolerability of add-on saxagliptin and initial saxagliptin-plus-metformin therapy were maintained for up to 102 weeks. Saxagliptin plus metformin was shown to be non-inferior to glipizide plus metformin in lowering glycated hemoglobin from base-line, with reduced body-weight and lower hypoglycemic risk. Post-hoc analyses indicate that the clinical benefits of saxagliptin extend across demographic subgroups and special populations. A meta-analysis found no evidence for increased cardiovascular risk in T2DM patients exposed to saxagliptin for > 1 year. On the basis of this clinical profile, saxagliptin is an attractive option for initial and add-on therapy for T2DM patients with inadequate glycemic control.

Long-term treatment with the dipeptidyl peptidase-4 inhibitor saxagliptin in patients with type 2 diabetes mellitus and renal impairment: a randomised controlled 52-week efficacy and safety study

OBJECTIVE

Therapeutic options are limited for diabetes patients with renal disease. This report presents 52-week results from a study assessing the dipeptidyl peptidase-4 inhibitor saxagliptin in patients with type 2 diabetes mellitus (T2DM) and renal impairment.

DESIGN

Double-blind study in patients stratified by baseline renal impairment (moderate, severe or end-stage renal disease [ESRD] on haemodialysis) randomised to saxagliptin 2.5 mg once daily or placebo added to other antidiabetic drugs in use at baseline, including insulin.

PATIENTS

A total of 170 adults with glycated haemoglobin (HbA(1c) ) 7-11% and creatinine clearance < 50 ml/min or ESRD were randomised and treated.

MEASUREMENTS

Absolute changes in HbA(1c) and fasting plasma glucose (FPG) from baseline to week 52 were evaluated using analysis of covariance (ANCOVA) with last observation carried forward. Repeated-measures analyses were also performed.

RESULTS

Adjusted mean decrease in HbA(1c) was greater with saxagliptin than placebo (difference, -0.73%, p < 0.001 [ANCOVA]). Reductions in adjusted mean HbA(1c) were numerically greater with saxagliptin than placebo in patients with renal impairment rated as moderate (-0.94% vs. 0.19% respectively) or severe (-0.81% vs. -0.49%), but similar to placebo for those with ESRD (-1.13% vs. -0.99%). Reductions in adjusted mean FPG were numerically greater with saxagliptin in patients with moderate or severe renal impairment. Saxagliptin was generally well tolerated; similar proportions of patients in the saxagliptin and placebo groups reported hypoglycaemic events (28% and 29% respectively).

CONCLUSIONS

Saxagliptin 2.5 mg once daily offers sustained efficacy and good tolerability for patients with T2DM and renal impairment.

Saxagliptin: A dipeptidyl peptidase-4 inhibitor in the treatment of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a metabolic disorder characterized by insulin deficiency or resistance. Management starts with single oral antidiabetic drug (OAD) but eventually switch over to combination therapy because of progressive β-cell dysfunction. Hypoglycemia, weight gain, and adverse cardiovascular events are major limitations of the available OADs (Sulfonylureas [SUs], thiazolidinediones [TZDs]). Saxagliptin, a reversible, competitive dipeptidyl peptidase-4 inhibitor, is recently approved agent in the treatment of T2DM. It acts by preventing the degradation of glucagon-like peptide – 1 and hence increases secretion of insulin and decreases secretion of glucagon. It is a well-tolerated agent with commonly reported adverse events which include upper respiratory tract infection, urinary tract infection, and headache. Hypoglycemia, weight gain, and adverse cardiovascular events are negligible as compared with other OADs. In clinical studies, saxagliptin was found to be effective and well tolerated when used as a monotherapy as well as in combination with metformin, SUs and TZDs. It is administered in the dose range of 2.5 to 5 mg once a day regardless of meal. Dosage reduction is required in patients having moderate to severe renal impairment as well as with concurrent administration of strong CYP3A4/5 inhibitors. To conclude, saxagliptin because of its novel mechanism of action (preserving beta cell function) and better tolerability profile seems to be a promising agent in the treatment of T2DM, especially in the early stage of the disease, but long-term clinical studies are required to prove its status in the management of T2DM.

Medicinal Chemistry and Applications of Incretins and DPP-4 Inhibitors in the Treatment of Type 2 Diabetes Mellitus

Diabetes mellitus (DM) is a major metabolic disorder currently affecting over 200 million people worldwide. Approximately 90% of all diabetic patients suffer from Type 2 diabetes mellitus (T2DM). The world's economy coughs out billions of dollars annually to diagnose, treat and manage patients with diabetes. It has been shown that the naturally occurring gut hormones incretins, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) can preserve the morphology and function of pancreatic beta cell. In addition, GIP and GLP-1 act on insulin receptors to facilitate insulin-receptor binding, resulting in optimal glucose metabolism. This review examines the medicinal chemistry and roles of incretins, specifically, GLP-1 and drugs which can mimic its actions and prevent its enzymatic degradation. The review discussed GLP-1 agonists such as exenatide, liraglutide, taspoglutide and albiglutide. The paper also identified and reviewed a number of inhibitors, which can block dipeptidyl peptidase 4 (DPP-4), the enzyme responsible for the rapid degradation of GLP-1. These DPP-4 inhibitors include sitagliptin, saxagliptin, vildagliptin and many others which are still in the experimental phase.

Effect of enhanced glycemic control with saxagliptin on endothelial nitric oxide release and CD40 levels in obese rats

AIM

Endothelial cell (EC) dysfunction contributes to insulin resistance in diabetes and is characterized by reduced nitric oxide (NO) release, increased nitroxidative stress and enhanced inflammation. The purpose of this study was to test the effect of improved postprandial glucose control on EC function in insulin-resistant rats as compared to fasting glucose (FG) changes.

METHODS

Obese Zucker rats were treated with 10 mg/kg/day saxagliptin, a dipeptidyl peptidase-4 (DPP4) inhibitor, for 4 or 8 weeks and compared to lean rats. NO and peroxynitrite (ONOO(-)) release from aortic and glomerular ECs was measured ex vivo using amperometric approaches and correlated with FG, postprandial glucose, insulin, soluble CD40 (sCD40) and L-citrulline levels.

RESULTS

Saxagliptin treatment improved NO production and reduced ONOO(-) release prior to any observed changes in FG levels. In untreated obese animals, NO release from aortic and glomerular ECs decreased by 22% and 31%, respectively, while ONOO(-) release increased by 26% and 40%. Saxagliptin increased aortic and glomerular NO release by 18% and 31%, respectively, with comparable reductions in ONOO(-) levels; the NO/ONOO(-) ratio, an indicator of NO synthase coupling, increased by >40%. Improved glycemic control was further associated with a reduction in sCD40 levels by more than ten-fold (from 300 ± 206 to 22 ± 22 pg/mL, p < 0.001).

CONCLUSION

These findings indicate that enhanced glycemic control with DPP4 inhibition improved NO release and reduced inflammation in a manner not predicted by FG changes alone.

Saxagliptin improves glycaemic control and is well tolerated in patients with type 2 diabetes mellitus and renal impairment

AIM

To evaluate the efficacy and safety of saxagliptin vs. placebo in patients with type 2 diabetes mellitus (T2DM) and renal impairment.

METHODS

In this multicentre, randomized, parallel-group, double-blind, placebo-controlled study, patients with glycated haemoglobin (HbA1c) 7-11% and creatinine clearance <50 ml/min were stratified by baseline renal impairment (moderate, severe or end-stage on haemodialysis), and randomized (1 : 1) to saxagliptin 2.5 mg once daily or placebo for 12 weeks. Oral antihyperglycaemic drugs and insulin therapy present at enrolment were continued throughout the study. The absolute change in HbA1c from baseline to week 12 (primary efficacy end-point) was analysed using an analysis of covariance model with last observation carried forward methodology.

RESULTS

A total of 170 patients were randomized and treated. The adjusted mean decrease from baseline to week 12 in HbA1c was statistically significantly greater in the saxagliptin group than in the placebo group; the difference between treatments was -0.42% (95% confidence interval: -0.71 to -0.12%, p = 0.007). Adjusted mean HbA1c decreases from baseline to week 12 were numerically greater with saxagliptin than with placebo in the subgroups of patients with moderate (-0.64 vs. -0.05%) and severe (-0.95 vs. -0.50%) renal impairment. HbA1c reductions were similar between saxagliptin and placebo in the subgroup with end-stage renal disease on haemodialysis (-0.84 vs. -0.87%). Saxagliptin was generally well tolerated; incidences of adverse events and hypoglycaemic events were similar to placebo.

CONCLUSIONS

Saxagliptin 2.5 mg once daily is a well-tolerated treatment option for patients with inadequately controlled T2DM and renal impairment.

Evaluation of the pharmacokinetic interaction after multiple oral doses of linagliptin and digoxin in healthy volunteers

The aim of this study was to investigate whether multiple doses of the oral and highly selective dipeptidyl peptidase-4 inhibitor linagliptin affect the steady-state pharmacokinetics of the P-glycoprotein substrate digoxin. This single-center, open-label, two-period cross-over study involved healthy subjects (n = 20), randomized to treatment sequence AB or BA, where A comprised 0.25 mg digoxin qd for 5 days, then 0.25 mg digoxin qd plus 5 mg linagliptin qd for 6 days, and B comprised 0.25 mg digoxin qd for 11 days. A treatment-free period (≥35 days for AB and 14 days for BA) separated each treatment in both sequences. There were no clinically significant changes in steady-state pharmacokinetic parameters of digoxin when it was co-administered with linagliptin. The ratio of the adjusted-by-treatment geometric mean ratios and associated 90% confidence intervals for the AUC(τ,ss), C (max,ss) and renal clearance (CL( R,0-24,ss)) of digoxin were all within the bioequivalence range 80-125%, which is important as digoxin has a narrow therapeutic range. There was a low incidence of adverse events, which were randomly distributed between treatment groups. In conclusion, linagliptin did not alter the pharmacokinetics of digoxin in this study, indicating that linagliptin does not inhibit P-glycoprotein or other transporters relevant for digoxin pharmacokinetics. These results suggest that linagliptin and digoxin can be co-administered without dose adjustment. Administration of digoxin alone and with linagliptin was well tolerated.

GLP-1 agonists and dipeptidyl-peptidase IV inhibitors

Novel therapeutic options for type 2 diabetes based on the action of the incretin hormone glucagon-like peptide-1 (GLP-1) were introduced in 2005. Incretin-based therapies consist of two classes: (1) the injectable GLP-1 receptor agonists solely acting on the GLP-1 receptor and (2) dipeptidyl-peptidase inhibitors (DPP-4 inhibitors) as oral medications raising endogenous GLP-1 and other hormone levels by inhibiting the degrading enzyme DPP-4. In type 2 diabetes therapy, incretin-based therapies are attractive and more commonly used due to their action and safety profile. Stimulation of insulin secretion and inhibition of glucagon secretion by the above-mentioned agents occur in a glucose-dependent manner. Therefore, incretin-based therapies have no intrinsic risk for hypoglycemias. GLP-1 receptor agonists allow weight loss; DPP-4 inhibitors are weight neutral. This review gives an overview on the mechanism of action and the substances and clinical data available.

Dapagliflozin: a sodium glucose cotransporter 2 inhibitor in development for type 2 diabetes

Type 2 diabetes mellitus (T2DM) is a growing worldwide epidemic. Patients face lifelong therapy to control hyperglycemia and prevent the associated complications. There are many medications, with varying mechanisms, available for the treatment of T2DM, but almost all target the declining insulin sensitivity and secretion that are associated with disease progression. Medications with such insulin-dependent mechanisms of action often lose efficacy over time, and there is increasing interest in the development of new antidiabetes medications that are not dependent upon insulin. One such approach is through the inhibition of renal glucose reuptake. Dapagliflozin, the first of a class of selective sodium glucose cotransporter 2 inhibitors, reduces renal glucose reabsorption and is currently under development for the treatment of T2DM. Here, we review the literature relating to the preclinical and clinical development of dapagliflozin.

Dipeptidylpeptidase-4 inhibitors (gliptins): focus on drug-drug interactions

Patients with type 2 diabetes mellitus (T2DM) are generally treated with many pharmacological compounds and are exposed to a high risk of drug-drug interactions. Indeed, blood glucose control usually requires a combination of various glucose-lowering agents, and the recommended global approach to reduce overall cardiovascular risk generally implies administration of several protective compounds, including HMG-CoA reductase inhibitors (statins), antihypertensive compounds and antiplatelet agents. New compounds have been developed to improve glucose-induced beta-cell secretion and glucose control, without inducing hypoglycaemia or weight gain, in patients with T2DM. Dipeptidylpeptidase-4 (DPP-4) inhibitors are novel oral glucose-lowering agents, which may be used as monotherapy or in combination with other antidiabetic compounds, metformin, thiazolidinediones or even sulfonylureas. Sitagliptin, vildagliptin and saxagliptin are already on the market, either as single agents or in fixed-dose combined formulations with metformin. Other compounds, such as alogliptin and linagliptin, are in a late phase of development. This review summarizes the available data on drug-drug interactions reported in the literature for these five DDP-4 inhibitors: sitagliptin, vildagliptin, saxagliptin, alogliptin and linagliptin. Possible pharmacokinetic interferences have been investigated between each of these compounds and various pharmacological agents, which were selected because there are other glucose-lowering agents (metformin, glibenclamide [glyburide], pioglitazone/rosiglitazone) that may be prescribed in combination with DPP-4 inhibitors, other drugs that are currently used in patients with T2DM (statins, antihypertensive agents), compounds that are known to interfere with the cytochrome P450 (CYP) system (ketoconazole, diltiazem, rifampicin [rifampin]) or with P-glycoprotein transport (ciclosporin), or agents with a narrow therapeutic safety window (warfarin, digoxin). Generally speaking, almost no drug-drug interactions or only minor drug-drug interactions have been reported between DPP-4 inhibitors and any of these drugs. The gliptins do not significantly modify the pharmacokinetic profile and exposure of the other tested drugs, and the other drugs do not significantly alter the pharmacokinetic profile of the gliptins or exposure to these. The only exception concerns saxagliptin, which is metabolized to an active metabolite by CYP3A4/5. Therefore, exposure to saxagliptin and its primary metabolite may be significantly modified when saxagliptin is coadministered with specific strong inhibitors (ketoconazole, diltiazem) or inducers (rifampicin) of CYP3A4/5 isoforms. The absence of significant drug-drug interactions could be explained by the favourable pharmacokinetic characteristics of DPP-4 inhibitors, which are not inducers or inhibitors of CYP isoforms and are not bound to plasma proteins to a great extent. Therefore, according to these pharmacokinetic findings, which were generally obtained in healthy young male subjects, no dosage adjustment is recommended when gliptins are combined with other pharmacological agents in patients with T2DM, with the exception of a reduction in the daily dosage of saxagliptin when this drug is used in association with a strong inhibitor of CYP3A4/A5. It is worth noting, however, that a reduction in the dose of sulfonylureas is usually recommended when a DPP-4 inhibitor is added, because of a pharmacodynamic interaction (rather than a pharmacokinetic interaction) between the sulfonylurea and the DPP-4 inhibitor, which may result in a higher risk of hypoglycaemia. Otherwise, any gliptin may be combined with metformin or a thiazolidinedione (pioglitazone, rosiglitazone), leading to a significant improvement in glycaemic control without an increased risk of hypoglycaemia or any other adverse event in patients with T2DM. Finally, the absence of drug-drug interactions in clinical trials in healthy subjects requires further evidence from large-scale studies, including typical subjects with T2DM - in particular, multimorbid and geriatric patients receiving polypharmacy.

Clinical overview of saxagliptin for Type 2 diabetes management

Saxagliptin (Onglyza™, Bristol-Myers Squibb, NJ, USA and AstraZeneca, DE, USA) is a potent, orally active, once-daily dipeptidyl peptidase-4 inhibitor that is indicated as an adjunct to diet and exercise alone, or in combination with metformin, a thiazolidinedione or a sulfonylurea to improve glycemic control in adults with Type 2 diabetes mellitus. By inhibiting dipeptidyl peptidase-4, saxagliptin increases concentrations of the intact forms of the incretin hormones, glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide, prolonging their effects. Saxagliptin also improves β-cell function, increases postprandial insulin secretion and reduces postprandial glucagon secretion. Saxagliptin is generally well tolerated with weight-neutral effects and a low incidence of hypoglycemia. Multicenter randomized trials have shown that saxagliptin as monotherapy, as initial therapy with metformin or as add-on therapy with metformin, a sulfonylurea or a thiazolidinedione leads to significant decreases in glycated hemoglobin levels, fasting and postprandial plasma glucose levels and higher percentages of patients attaining target glycated hemoglobin of less than 7% compared with controls.

Emerging treatment options for type 2 diabetes

Type 2 diabetes mellitus (T2DM) is rapidly increasing in prevalence and is a major public health problem. It is a progressive disease which commonly requires multiple pharmacotherapy. Current options for treatment may have undesirable side effects (particularly weight gain and hypoglycaemia) and contraindications, and little effect on disease progression. Incretin based therapy is one of several newer therapies to improve glycaemia and is available in two different forms, dipeptidyl peptidase-4 (DPP-4) inhibitors and glucagon-like peptide-1 (GLP-1) agonists. Use of these agents results in a 'glucose-dependant' increase in insulin secretion and glucagon suppression resulting in improved glycaemia with low incidence of hypoglycaemia. DPP-4 inhibitors are oral drugs which are weight neutral, while GLP-1 agonists are injected subcutaneously and help promote weight loss while improving glycaemia. GLP-1 agonists have also been shown to increase beta cell mass in rat models. Bariatric surgery is another option for the obese patient with T2DM, with blood glucose normalizing in over half of the patients following surgery. Other therapies in development for the treatment of T2DM include sodium-glucose transporter 2 (SGLT-2) inhibitors, glucagon receptor antagonists, glucokinase activators and sirtuins. In this article, we will review the various existing and emerging treatment options for T2DM.

Saxagliptin: the evidence for its place in the treatment of type 2 diabetes mellitus

INTRODUCTION

The worldwide prevalence of type 2 diabetes mellitus (T2DM) is high, and the chronically poor metabolic control that can result from T2DM is associated with a high risk for microvascular and macrovascular complications. Because of the progressive pathophysiology of T2DM, oral antidiabetic agents often fail to provide sustained glycemic control, indicating the need for new therapies. Saxagliptin (Onglyza™; Bristol-Myers Squibb Company, Princeton, NJ, USA; AstraZeneca Pharmaceuticals LP, Wilmington, DE, USA) is an oral dipeptidyl peptidase-4 inhibitor, recently approved for the treatment of T2DM.

EVIDENCE REVIEW

Saxagliptin significantly improves glycemic control vs placebo, as demonstrated by decreasing glycated hemoglobin, fasting plasma glucose, and postprandial plasma glucose levels when used as monotherapy; in initial combination with metformin; and as add-on therapy with metformin, sulfonylurea (SU), or thiazolidinedione (TZD). Saxagliptin also significantly improves β-cell function, is weight neutral, has a low risk for hypoglycemia, and has been shown to have cardiovascular safety.

PLACE IN THERAPY

The clinical profile for saxagliptin indicates that it is useful as an adjunct to diet and exercise as first-line monotherapy and in combination with metformin; or as add-on treatment for patients who cannot achieve glycemic control with a combination of diet and lifestyle changes and metformin, SU, or TZD.

Saxagliptin: a new dipeptidyl peptidase-4 inhibitor for type 2 diabetes

Type 2 diabetes mellitus is a common chronic disease that causes significant morbidity and mortality worldwide. The primary goal of treatment is to target glycemic control by maintaining the glycosylated hemoglobin (HbA1c) level near 6% to 7% without predisposing patients to hypoglycemia. Currently available antidiabetic agents work by different mechanisms to lower blood glucose levels. Unfortunately, each of them has its tolerability and safety concerns that limit use and dose titration. Dipeptidyl peptidase-4 enzyme inhibitors are novel drugs that prolong the action of incretins, and lead to increased insulin secretion and reduced hepatic glucose production. Saxagliptin is another dipeptidyl peptidase-4 (after sitagliptin) that is approved for the management of type 2 diabetes. It can be used alone or in combination with metformin, sulfonylurea, or thiazolidinedione (pioglitazone or rosiglitazone) when treatment with one drug alone provides inadequate glucose control. The usual adult dose is 2.5 to 5 mg once daily regardless of meals. A daily dose of 2.5 mg is recommended for patients with moderate to severe renal impairment or those who are taking potent CYP 3A4 inhibitors. In randomized clinical trials, saxagliptin alone lowered HbA1c levels by about 0.5%; with better efficacy seen when combined with other agents. It is well tolerated with the most common side effects being upper respiratory tract infection, headache, and urinary tract infection. In summary, saxagliptin is an option as an adjunct to lifestyle modifications and other antidiabetic agents to target glycemic control. It is also an alternative therapy for patients who have contraindications or intolerability to other antidiabetic agents.

Saxagliptin for type 2 diabetes

Saxagliptin (Onglyza™) is a potent, selective, once-daily dipeptidyl peptidase-4 (DPP-4) inhibitor indicated for improving glycemic control in patients with type 2 diabetes (T2D). By blocking DPP-4, saxagliptin increases and prolongs the effects of incretins, a group of peptide hormones released by intestinal cells after meals, which stimulate glucose-dependent insulin secretion to lower blood glucose. In controlled clinical trials, saxagliptin administered as monotherapy or in combination with metformin, glyburide, or a thiazolidinedione improved glycemic control in a clinically significant manner, reflected by significant decreases in glycated hemoglobin (monotherapy, -0.5%; add-on to metformin, thiazolidinedione, or sulfonylurea, -0.6% to 0.9%; initial combination with metformin, -2.5%), fasting plasma glucose, and postprandial glucose compared with controls. Additionally, saxagliptin improved β-cell function, reflected as increases in homeostasis model assessment (HOMA)-2β. Saxagliptin was generally well tolerated; it did not increase hypoglycemia compared with controls, and was weight neutral. A meta-analysis of Phase II and III trials showed that saxagliptin did not increase the risk of major cardiovascular events. Professional organizations have updated their guidelines for T2D to include a DPP-4 inhibitor as an early treatment option-either as initial therapy in combination with metformin, or as add-on therapy for patients whose glycemia is inadequately controlled by a single oral antidiabetic drug.