Saxagliptin given in combination with metformin as initial therapy improves glycaemic control in patients with type 2 diabetes compared with either monotherapy: a randomized controlled trial

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.

Bioequivalence of saxagliptin/metformin extended-release (XR) fixed-dose combination tablets and single-component saxagliptin and metformin XR tablets in healthy adult subjects

BACKGROUND AND OBJECTIVES

As compared with individual tablets, saxagliptin/metformin extended-release (XR) fixed-dose combination (FDC) tablets offer potential for increased patient compliance with the convenience of once-daily dosing. Two bioequivalence studies assessed the fed-state bioequivalence of saxagliptin/metformin XR 5 mg/500 mg FDC (study 1) and saxagliptin/metformin XR 5 mg/1000 mg FDC (study 2) relative to the same dosage strengths of individual component tablets administered concurrently. The effect of food on saxagliptin and metformin pharmacokinetics from the saxagliptin/metformin XR 5 mg/500 mg FDC and their steady-state pharmacokinetics from the saxagliptin/metformin XR 5 mg/1000 mg were also investigated.

METHODS

These were randomized, open-label, single-dose, three-period, three-treatment, crossover studies in healthy subjects (n = 30 in each study). The treatments in study 1 were a saxagliptin/metformin XR 5 mg/500 mg FDC tablet in the fed and fasted states on separate occasions, and saxagliptin 5 mg and metformin XR 500 mg co-administered in the fed state. The treatments in study 2 were a saxagliptin/metformin XR 5 mg/1000 mg FDC tablet in the fed state, saxagliptin 5 mg and 2 × metformin XR 500 mg co-administered in the fed state, and saxagliptin/metformin XR 5 mg/1000 mg FDC once daily for 4 days in the fed state to assess steady-state pharmacokinetics. The safety and tolerability of each treatment were also evaluated.

RESULTS

For both studies, saxagliptin and metformin in the FDCs were bioequivalent to the individual components as the limits of the 90% confidence interval of the ratio of adjusted geometric means for all key pharmacokinetic parameters were contained within 0.800 to 1.250. Compared with the fasted state, food did not have a meaningful effect on the pharmacokinetics of saxagliptin and metformin when administered as the saxagliptin/metformin XR 5 mg/500 mg FDC. The saxagliptin/metformin XR 5 mg/1000 mg FDC showed consistent pharmacokinetics at steady state without evidence of dose dumping. Co-administration of saxagliptin and metformin XR was generally safe and well tolerated as the FDCs or as individual tablets.

CONCLUSION

Saxagliptin/metformin XR 5 mg/500 mg and saxagliptin/metformin XR 5 mg/1000 mg FDCs were bioequivalent to individual tablets of saxagliptin and metformin of the same strengths. Additionally, food had little effect on the pharmacokinetics of saxagliptin and metformin administered in the saxagliptin/metformin XR 5 mg/500 mg FDC and the steady-state pharmacokinetics of the saxagliptin/metformin XR 5 mg/1000 mg FDC was consistent over time. No unexpected safety findings were observed with saxagliptin/metformin XR administration. The tolerability of the FDC of saxagliptin/metformin XR was comparable to that of the co-administered individual components. These results indicate that the safety and efficacy profile of co-administration of saxagliptin and metformin can be extended to the saxagliptin/metformin XR FDC tablets.

TRIALS REGISTRATION

ClinicalTrials.gov Identifiers: NCT01192139 and NCT01192152.

The role of incretin therapy at different stages of diabetes

The pathogenetic mechanisms causing type 2 diabetes are complex, and include a significant reduction of the incretin effect. In patients with type 2 diabetes, GLP-1 secretion may be impaired, while GIP secretion seems unaffected. In contrast, the insulinotropic activity of GIP is severely altered, whereas that of GLP-1 is maintained to a great extent. Better understanding of the role of incretin hormones in glucose homeostasis has led to the development of incretin-based therapies that complement and offer important advantages over previously used agents. Incretin-based agents have significant glucose-lowering effects, promote weight loss (or are weight-neutral), inhibit glucagon secretion while maintaining counter-regulatory mechanisms, exhibit cardiovascular benefits, and protect β-cells while possessing a low risk profile. At present, incretin-based therapies are most widely used as add on to metformin to provide sufficient glycemic control after metformin failure. However, they are also recommended as monotherapy early in the disease course, and later in triple combination. These agents may also be a promising therapeutic tool in prediabetic subjects. Therefore, a therapeutic algorithm is needed for their optimal application at different stages of diabetes, as suggested in this article.

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.

The alpha-cell as target for type 2 diabetes therapy

Glucagon is the main secretory product of the pancreatic alpha-cells. The main function of this peptide hormone is to provide sustained glucose supply to the brain and other vital organs during fasting conditions. This is exerted by stimulation of hepatic glucose production via specific G protein-coupled receptors in the hepatocytes. Type 2 diabetic patients are characterized by elevated glucagon levels contributing decisively to hyperglycemia in these patients. Accumulating evidence demonstrates that targeting the pancreatic alpha-cell and its main secretory product glucagon is a possible treatment for type 2 diabetes. Several lines of preclinical evidence have paved the way for the development of drugs, which suppress glucagon secretion or antagonize the glucagon receptor. In this review, the physiological actions of glucagon and the role of glucagon in type 2 diabetic pathophysiology are outlined. Furthermore, potential advantages and limitations of antagonizing the glucagon receptor or suppressing glucagon secretion in the treatment of type 2 diabetes are discussed with a focus on already marketed drugs and drugs in clinical development. It is concluded that the development of novel glucagon receptor antagonists are confronted with several safety issues. At present, available pharmacological agents based on the glucose-dependent glucagonostatic effects of GLP-1 represent the most favorable way to apply constraints to the alpha-cell in type 2 diabetes.

Tolerability of dipeptidyl peptidase-4 inhibitors: a review

BACKGROUND

Oral glucose-lowering agents are used to treat patients with type 2 diabetes mellitus (T2DM). Most patients require multiple agents to maintain glycemic targets. Dipeptidyl peptidase-4 (DPP-4) inhibitors are administered as monotherapy and in combination therapy for the treatment of T2DM.

OBJECTIVE

The aim of this article was to provide a thorough review of published tolerability data on 5 DPP-4 inhibitors.

METHODS

PubMed and Web of Science were searched for English-language clinical trials published from January 2000 to June 2001, using the following key words: dipeptidyl peptidase-4 inhibitor, vildagliptin, alogliptin, sitagliptin, saxagliptin, linagliptin, safety, tolerability, efficacy, effect, AE, and adverse effect. Studies were considered for inclusion if they were randomized, double-blind trials performed in patients ≥18 years of age with T2DM and with a hemoglobin A(1c) of ≥6.5%; included ≥1 arm that received monotherapy with DPP-4; and reported adverse events (AEs). Studies in patients with a history of type 1 or secondary forms of diabetes, significant diabetic complications or cardiovascular disease within the 6 months before the start of the study, hepatic disease or abnormalities, and/or renal abnormalities were excluded.

RESULTS

A total of 45 clinical trials, 5 pharmacokinetic studies, and 28 meta-analyses or reviews were included. The duration of studies ranged from 7 days to 104 weeks. The most commonly reported AEs were nasopharyngitis, upper respiratory infections, all-cause infections, headache, gastrointestinal symptoms, and musculoskeletal pain. Based on the findings from the studies, the DPP-4 inhibitors had minimal impact on weight and were not associated with an increased risk for hypoglycemia relative to placebo. Rates of nasopharyngitis were higher with the DDP-4 inhibitors than with placebo. Pancreatitis was reported at lower rates with the DPP-4 inhibitors compared with other oral antihyperglycemic agents. Cardiovascular events were limited, and postmarketing studies are ongoing.

CONCLUSIONS

The tolerability of DPP-4 inhibitors is supported by published clinical trials. The rates of weight gain, gastrointestinal AEs, and hypoglycemia were minimal with the DPP-4 inhibitors studied.

Efficacy and safety of saxagliptin added to metformin in Asian people with type 2 diabetes mellitus: a randomized controlled trial

AIM

To assess efficacy and safety of saxagliptin added to metformin versus placebo plus metformin in Asian patients with type 2 diabetes mellitus (T2DM) and inadequate glycemic control on metformin alone.

METHODS

Adults (HbA(1c) 7.0-10.0%, on stable metformin ≥ 1500 mg/day) were randomized 1:1 to saxagliptin 5mg daily plus metformin (n = 283) or placebo plus metformin (n = 287). The primary end point was HbA(1c) change from baseline to Week 24.

RESULTS

Saxagliptin plus metformin provided significant adjusted mean decreases versus placebo plus metformin (p ≤ 0.0052) in HbA(1c) (-0.78% versus -0.37%), fasting plasma glucose (-1.14 mmol/L versus -0.58 mmol/L), and postprandial glucose area under the curve from 0 to 180 min (-315 mmol min/L versus -160 mmol min/L). Significantly more saxagliptin-treated patients achieved a therapeutic glycemic response (HbA(1c)<7.0%) (46.5% versus 30.5%; p = 0.0001). The proportion of patients experiencing adverse events (excluding hypoglycemia) was similar for saxagliptin plus metformin (42.8%) versus placebo plus metformin (40.8%). Hypoglycemic events were reported in 1.4% of patients in each group.

CONCLUSION

Saxagliptin added to metformin significantly improved glycemic control and was well tolerated in Asian patients with T2DM who had inadequate glycemic control with metformin and diet and lifestyle modification.

The design and rationale of the saxagliptin assessment of vascular outcomes recorded in patients with diabetes mellitus-thrombolysis in myocardial infarction (SAVOR-TIMI) 53 study

OBJECTIVES

Saxagliptin, a dipeptidyl peptidase 4 inhibitor, improves glycemic control in patients with type 2 diabetes mellitus (T2DM) by increasing endogenous active, intact glucagon-like peptide 1 and glucose-dependent insulinotropic polypeptide in response to food, which augments insulin secretion and decreases glucagon release.

RESEARCH DESIGN AND METHODS

SAVOR-TIMI 53 is a phase 4, randomized, double-blind, placebo-controlled trial conducted in 25 countries that is designed to evaluate the safety and efficacy of saxagliptin during long-term treatment of approximately 16,500 patients with T2DM. Eligible patients who are either treatment naive or on any background antidiabetic treatment (except incretin therapy) with history of established cardiovascular (CV) disease or multiple risk factors are randomized 1:1 to saxagliptin 5 mg QD (2.5 mg in subjects with moderate/severe renal impairment) or matching placebo, stratified by qualifying disease state. The primary end point is the composite of CV death, nonfatal myocardial infarction, or nonfatal ischemic stroke. The trial will continue until approximately 1,040 primary end points accrue, providing 85% power to identify a 17% relative reduction of the primary end point with saxagliptin versus placebo and 98% power to test for noninferiority of saxagliptin versus placebo (reject the upper limit of 95% CI for a hazard ratio <1.3 at a 1-sided α of .025).

CONCLUSION

SAVOR-TIMI 53 is testing the hypothesis that treatment with saxagliptin is safe and reduces CV events in high-risk patients with T2DM.

Effects of insulin and other antihyperglycaemic agents on lipid profiles of patients with diabetes

Increased morbidity and mortality risk due to diabetes-associated cardiovascular diseases is partly associated with hyperglycaemia as well as dyslipidaemia. Pharmacological treatment of diabetic hyperglycaemia involves the use of the older oral antidiabetic drugs [OADs: biguanides, sulphonylureas (SUs), α-glucosidase inhibitors and thiazolidinediones], insulin (human and analogues) and/or incretin-based therapies (glucagon-like peptide-1 analogues and dipeptidyl peptidase 4 inhibitors). Many of these agents have also been suggested to improve lipid profiles in patients with diabetes. These effects may have benefits on cardiovascular risk beyond glucose-lowering actions. This review discusses the effects of OADs, insulins and incretin-based therapies on lipid variables along with the possible mechanisms and clinical implications of these findings. The effects of intensive versus conventional antihyperglycaemic therapy on cardiovascular outcomes and lipid profiles are also discussed. A major conclusion of this review is that agents within the same class of OADs can have different effects on lipid variables and that contrary to the findings in experimental models, insulin has been shown to have beneficial effects on lipid variables in clinical trials. Further studies are needed to understand the precise effect and the mechanisms of these effects of insulin on lipids.

Effects of saxagliptin on β-cell stimulation and insulin secretion in patients with type 2 diabetes

AIM

To study the effect of dipeptidyl peptidase-4 (DPP-4) inhibition with saxagliptin on β-cell function as reflected by the stimulated insulin secretion rate after an enteral glucose load in patients with type 2 diabetes.

METHODS

Patients in this randomized, parallel-group, double-blind, placebo-controlled study were drug-naïve, aged 43-69 years, with baseline haemoglobin A1c (HbA1c) 5.9-8.1%. Twenty patients received saxagliptin 5 mg once daily; 16 received placebo. Patients were assessed at baseline and week 12 by intravenous hyperglycaemic clamp (0-180 min, fasting state), and intravenous-oral hyperglycaemic clamp (180-480 min, postprandial state) following oral ingestion of 75 g glucose. Primary and secondary endpoints were percent changes from baseline in insulin secretion during postprandial and fasting states, respectively. Insulin secretion was calculated by C-peptide deconvolution.

RESULTS

After 12 weeks, saxagliptin significantly increased insulin secretion percent change from baseline during the postprandial state by an 18.5% adjusted difference versus placebo (p = 0.04), an improvement associated with increased peak plasma concentrations of intact glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide. In the fasting state, saxagliptin significantly increased insulin secretion by a 27.9% adjusted difference versus placebo (p = 0.02). Saxagliptin also improved glucagon area under the curve in the postprandial state (adjusted difference -21.8% vs. placebo, p = 0.03).

CONCLUSIONS

DPP-4 inhibition with saxagliptin improves pancreatic β-cell function in postprandial and fasting states, and decreases postprandial glucagon concentration. Given the magnitude of enhancement of the insulin response in the fasting state, further study into the effect of DPP-4 inhibition on the β-cell is warranted.

Emerging role of insulin with incretin therapies for management of type 2 diabetes

Type 2 diabetes mellitus (T2DM) is a progressive disease warranting intensification of treatment, as beta-cell function declines over time. Current treatment algorithms recommend metformin as the first-line agent, while advocating the addition of either basal-bolus or premixed insulin as the final level of intervention. Incretin therapy, including incretin mimetics or enhancers, are the latest group of drugs available for treatment of T2DM. These agents act through the incretin axis, are currently recommended as add-on agents either as second-or third-line treatment, without concurrent use of insulin. Given the novel role of incretin therapy in terms of reducing postprandial hyperglycemia, and favorable effects on weight with reduced incidence of hypoglycemia, we explore alternative options for incretin therapy in T2DM management. Furthermore, as some evidence alludes to incretins potentially increasing betacell mass and altering disease progression, we propose introducing these agents earlier in the treatment algorithm. In addition, we suggest the concurrent use of incretins with insulin, given the favorable effects especially in relation to weight gain.

Dipeptidyl peptidase-4 inhibitors and HbA1c target of <7% in type 2 diabetes: meta-analysis of randomized controlled trials

AIM

We assessed the efficacy of dipeptidyl peptidase-4 (DPP-4) inhibitors vildagliptin, sitagliptin, saxagliptin and alogliptin to reach the haemoglobin HbA1c target of <7% in people with type 2 diabetes.

METHODS

We conducted an electronic search for randomized controlled trials (RCTs) involving DPP-4 inhibitors through September 2010. RCTs were included if they lasted at least 12 weeks, included 30 patients or more and reported the proportion of patients reaching the HbA1c target of <7%.

RESULTS

A total of 43 RCTs reporting 52 comparisons met the selection criteria, which included 19 101 study participants evaluated for the primary endpoint, 10 467 treated with a DPP-4 inhibitor and 8634 treated with placebo or a comparator drug. DPP-4 inhibitors showed a statistically significant reduction in HbA1c compared to placebo and approximately 40% of participants achieved the HbA1c goal of <7%: this was associated with weight neutrality and no greater hypoglycaemia. The reduction of the HbA1c level and the rate of HbA1c goal attainment was not different from comparator drugs, with similar hypoglycaemia, and different effect on weight owing to the nature of comparator (metformin, sulfonylurea or glitazones). Baseline HbA1c was the best predictor for achievement of A1C target (overall weighted r(2) value = 0.410, p < 0.001).

CONCLUSIONS

A greater proportion of type 2 diabetic patients can achieve the HbA1c goal <7% with DPP-4 inhibitors compared to placebo, with no weight gain, and no hypoglycaemic risk when used alone; DPP-4 inhibitors were not different from comparator drugs.

From theory to clinical practice in the use of GLP-1 receptor agonists and DPP-4 inhibitors therapy

Promoting long-term adherence to lifestyle modification and choice of antidiabetic agent with low hypoglycemia risk profile and positive weight profile could be the most effective strategy in achieving sustained glycemic control and in reducing comorbidities. From this perspective, vast interest has been generated by glucagon-like peptide-1 (GLP-1) receptor agonists and dipeptidyl peptidase-4 inhibitors (DPP-4i). In this review our ten-year clinical and laboratory experience by in vitro and in vivo studies is reported. Herein, we reviewed available data on the efficacy and safety profile of GLP-1 receptor agonists and DPP-4i. The introduction of incretin hormone-based therapies represents a novel therapeutic strategy, because these drugs not only improve glycemia with minimal risk of hypoglycemia but also have other extraglycemic beneficial effects. In clinical studies, both GLP-1 receptor agonists and DPP-4i, improve β cell function indexes. All these agents showed trophic effects on beta-cell mass in animal studies. The use of these drugs is associated with positive or neucral effect on body weight and improvements in blood pressure, diabetic dyslipidemia, hepatic steazosis markets, and myocardial function. These effects have the potential to reduce the burden of cardiovascular disease, which is a major cause of mortality in patients with diabetes.

Initial combination therapy with saxagliptin and metformin provides sustained glycaemic control and is well tolerated for up to 76 weeks

AIM

To assess the efficacy and safety of saxagliptin + metformin initial combination therapy compared with saxagliptin or metformin alone over 76 weeks (24-week short-term + 52-week long-term extension) in treatment-naÏve type 2 diabetes mellitus patients with inadequate glycaemic control.

METHODS

In this phase 3, parallel-group, double-blind, active-controlled study, 1306 patients 18-77 years of age (HbA1c 8.0-12.0%) were randomized to saxagliptin 5 mg + 500 mg metformin, saxagliptin 10 mg + 500 mg metformin, saxagliptin 10 mg + placebo or 500 mg metformin + placebo. Blinded metformin was titrated during weeks 1-5 of the short-term treatment period in 500 mg/day increments to 2000 mg/day maximum in the metformin-based treatment groups. No titration of metformin was permitted during the long-term treatment period. A total of 888 patients completed the study (76 weeks), 613 without being rescued. Changes in HbA1c, fasting plasma glucose, 120-min postprandial glucose (PPG) and PPG-area under the curve (AUC) from baseline to week 76 were analysed using a repeated-measures model.

RESULTS

At 76 weeks, adjusted mean changes from baseline HbA1c (95% CI) for saxagliptin 5 mg + metformin, saxagliptin 10 mg + metformin, saxagliptin 10 mg and metformin were -2.31 (-2.44, -2.18), -2.33 (-2.46, -2.20), -1.55 (-1.70, -1.40) and -1.79% (-1.93, -1.65), respectively (post hoc and nominal p < 0.0001 vs. metformin and saxagliptin monotherapies for saxagliptin 5 mg + metformin and saxagliptin 10 mg + metformin). The proportions of patients requiring rescue or discontinuation for insufficient glycaemic control were lower for saxagliptin + metformin than for either monotherapy. Little or no attenuation in PPG-AUC or 120-min PPG was observed between weeks 24 and 76 for saxagliptin + metformin, indicating persistent efficacy. Adverse event rates were similar across groups; hypoglycaemic events occurred at a low frequency.

CONCLUSION

Saxagliptin + metformin initial combination therapy was well tolerated and produced sustained glycaemic control for up to 76 weeks, with greater improvements in glycaemic parameters compared with either drug 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.

Sitagliptin or exenatide once weekly for type 2 diabetes: comparison of the clinical trials

INTRODUCTION

There is a need for new and improved treatments for type 2 diabetes. Glucagon-like peptide 1 (GLP-1) is a gut hormone that stimulates insulin secretion and the levels of GLP-1 can be increased by inhibiting DPP-4. Sitagliptin is one of the DDP-4 inhibitors used to increase the levels of GLP-1. Exenatide is an agonist at the GLP-1 receptors, which is resistant to breakdown and has a longer action than GLP-1.

AREAS COVERED

This review compares the clinical trials of sitagliptin and exenatide once weekly in the treatment of type 2 diabetes. Only peer-reviewed trials listed on PubMed were included.

EXPERT OPINION

Both sitagliptin and exenatide once weekly are capable of reducing HbA1c and plasma glucose levels, but exenatide once weekly is more potent than sitagliptin and this may lead to different roles for these agents in the treatment of type 2 diabetes.

Predictors of response to dipeptidyl peptidase-4 inhibitors: evidence from randomized clinical trials

AIM

Dipeptidyl peptidase-4 (DPP-4) inhibitors are used in the treatment of type 2 diabetes. Available sub-group analysis of clinical trials does not allow a clear identification of predictors of therapeutic response to these drugs. The aim of this study is the assessment of predictors of response to DPP-4 inhibitors.

MATERIALS AND METHODS

A meta-analysis was performed, exploring correlation between 24-week effects on HbA(1c) of maximal doses of DPP-4 inhibitors, compared either with placebo or with other active drugs, matches to baseline characteristics of patients enrolled in 63 randomized clinical trials, either published or unpublished but disclosed on different websites were studied.

RESULTS

DPP-4 inhibitors significantly reduce HbA(1c) at 24 weeks [by 0.6 (0.5-0.7)%] when compared with placebo; no difference in HbA(1c) was observed in comparisons with thiazolidinediones and α-glucosidase inhibitors, whereas sulfonylureas and metformin produced a greater reduction of HbA(1c) , at least in the short term. DPP-4 inhibitors produced a smaller weight gain than thiazolidinediones, and showed a lower hypoglycaemia risk than sulfonylureas. The placebo-subtracted effect of DPP-4 inhibitors on HbA(1c) was greater in older patients and in those with lower fasting plasma glucose at baseline. Similar results were obtained in comparisons with thiazolidinediones and metformin.

CONCLUSIONS

Although drugs for type 2 diabetes are studied in heterogeneous samples of patients, their efficacy can be predicted by some clinical parameters. DPP-4 inhibitors appear to be more effective in older patients with mild/moderate fasting hyperglycaemia. These data could be useful for a better definition of the profile of patients who are likely to benefit most from these drugs.

Efficacy and safety of saxagliptin in older patients with type 2 diabetes mellitus

OBJECTIVE

To assess the safety and efficacy of saxagliptin (5 mg once-daily) in older patients (≥65 years of age) with inadequately controlled type 2 diabetes.

RESEARCH DESIGN AND METHODS

In this retrospective subgroup analysis, data from five randomized, double-blind, placebo-controlled, multicenter, 24-week, phase 3 trials were included. The primary studies evaluated saxagliptin 5 mg once-daily (monotherapy or add-on) in patients aged 18-77 years with HbA(1c) ≥7.0% (four studies) or ≥7.5% (add-on to glyburide study) versus placebo.

MAIN OUTCOME MEASURES

The primary efficacy endpoint of each study included in this pooled analysis was HbA(1c) change from baseline to week 24.

RESULTS

In the five-study pooled population, 279 (16.6%) patients were at least 65 years old; 142 received saxagliptin 5 mg once-daily and 137 received placebo. Treatment groups were well-balanced for baseline characteristics within each study. In older patients, the HbA(1c) adjusted mean change from a baseline of 8.1% was -0.73 ± 0.16% (mean ± SEM) with saxagliptin compared with -0.17 ± 0.14% for placebo from a baseline of 8.0%. Adverse event rates were similar with saxagliptin 5 mg once-daily compared with placebo in older patients.

CONCLUSION

The pooled subgroup analysis of saxagliptin 5 mg once-daily monotherapy and add-on therapy trials demonstrated clinically relevant and significant efficacy for reducing HbA(1c) in older (≥65 years) patients. Saxagliptin was well-tolerated in older patients with a low incidence of hypoglycemia and no weight gain.

Addressing cardiovascular risk in patients with type 2 diabetes: focus on primary care

Type 2 diabetes is a disorder of glucose and lipid metabolism associated with increased risk of macrovascular and microvascular complications. The primary focus of treating type 2 diabetes is glycemic control; simultaneous management of cardiometabolic risk factors, including blood pressure, lipid profile and overweight/obesity, has been shown to improve outcomes. All patients with diabetes require individualized combination therapy including diet and exercise intervention to help prevent microvascular and macrovascular complications. Because primary care physicians in the United States provide the majority of care for patients with type 2 diabetes, this article discusses the management of cardiovascular risk with a specific focus on primary care. In addition, mechanisms by which existing and novel antidiabetes therapies may modulate the metabolic pathways and a review of the benefits of cardiovascular risk reduction using multifactorial, primary care-focused intervention strategies will be discussed. Finally, early- and late-stage disease management strategies are discussed.

Saxagliptin: A Selective DPP-4 Inhibitor for the Treatment of Type 2 Diabetes Mellitus

The prevalence of type 2 diabetes mellitus is high and growing rapidly. Suboptimal glycemic control provides opportunities for new treatment options to improve the morbidity and mortality of this progressive disease. Saxagliptin, a selective DPP-4 inhibitor, increases endogenous incretin levels and incretin acitivty. In controlled clinical trials saxagliptin reduces both fasting and postprandial glucose and works in monotherapy and in combination with metformin, TZDs and sulfonylureas. Saxagliptin has a very favourable side effect profile and may have other beneficial non-glycemic effects. The authors review the current available evidence for the safety, efficacy and saxagliptin's place in therapy for type 2 diabetes mellitus. As understanding of the incretin hormones (GLP-1, GIP) expand we may see additional important non-glycemic effects that may affect the chronic management of type 2 diabetes mellitus.

Patient considerations and clinical utility of a fixed dose combination of saxagliptin/metformin in the treatment of type 2 diabetes

INTRODUCTION

Targeting glycated hemoglobin (HbA(1c)) levels below 7.0% is considered a primary goal of diabetes care, given its importance in obtaining a sustained reduction in microvascular, and possibly macrovascular complications.

AIM

The aim of this review was to evaluate the clinical utility of a fixed dose combination of saxagliptin/metformin in the treatment of type 2 diabetes.

EVIDENCE REVIEW

The combination of saxagliptin/metformin was well tolerated and produced sustained glycemic control for up to 76 weeks, with greater improvements in glycemic parameters compared with either drug alone. The saxagliptin/metformin combination also proved its non-inferiority compared with either sulfonylurea/metformin or sitagliptin/metformin combinations.

PLACE IN THERAPY

Clinical practice recommends lifestyle interventions together with starting metformin at the time that the type 2 diabetes mellitus is diagnosed. Once metformin fails to maintain glycemic control, the addition of DPP-4 inhibitors should be the logical choice because of their effects on HbA(1c) compared to the addition of a sulfonylurea or glitazone, and because of their positive effects on beta cell function and their neutral effects on body weight. Furthermore, DPP-4 inhibitors prevent the risk of hypoglycemia posed by sulfonylureas.

Initial combination therapy for type 2 diabetes mellitus: is it ready for prime time?

The increased prevalence of type 2 diabetes mellitus is primarily being driven by the increasing global rates of overweight/obesity. Given the magnitude of this epidemic, we can expect these metabolic abnormalities to play an increasing role in the development of cardiovascular disease. In a pathophysiologic sense, type 2 diabetes is a multiorgan, multifactorial condition, characterized by β-cell dysfunction, insulin resistance in peripheral tissues and the liver, defective incretin activity, and elevated levels of free fatty acids and proinflammatory mediators. Despite the considerable burden of disease associated with type 2 diabetes, most patients are not at, or are unable to achieve, recommended glycemic control guideline targets. In part, this is because of the relentlessly progressive nature of the disease, but it may also be attributable to the current diabetes treatment paradigm, which is characterized by ineffective lifestyle interventions, followed by monotherapy and frequent early treatment failure with prolonged periods of elevated glucose as a consequence of clinical inertia. Thus, it is most appropriate to rethink the current treatment paradigm for type 2 diabetes in the context of a more aggressive initial therapy; specifically with early initiation of combination therapy. Our current understanding of the complex pathophysiology of the disease and the progressive deterioration in glycemic control over time supports the philosophy of earlier intervention with a more comprehensive initial therapy. Thus, while control of hyperglycemia remains the paramount goal, focusing on the underlying pathophysiology of type 2 diabetes is increasingly becoming the therapeutic strategy, with the aim of potentially providing disease modification. Although this is a logical approach, it remains to be demonstrated that early combination therapy will result in disease modification in a clinical setting. Not surprisingly, the incretin-based therapies have gained a great deal of attention in the context of being a component of initial combination therapy, given their potential beneficial effects on β-cell function with lowered risk of weight gain and hypoglycemia.

Multifactorial intervention in Type 2 diabetes: the promise of incretin-based therapies

Type 2 diabetes mellitus is increasing in prevalence at alarming rates. Concurrent with its expanding prevalence is the increase in the related risk of morbidity and mortality. Because diabetic patients are prone to cardiovascular disease, treatment strategies should address the cardiovascular risk factors, including blood pressure, lipids, and body weight, in addition to the glycemic aspects of the disease. Newer agents, such as glucagon-like peptide-1 (GLP-1) analogs and dipeptidyl peptidase-4 (DPP-4) inhibitors, have varying degrees of evidence to support their effects on body weight, blood pressure, and lipid levels, beyond glycated hemoglobin reduction. While GLP-1 agonists produce a weight loss, the DPP-4 inhibitors, conversely, appear to have a weight-neutral effect. Substantial evidence demonstrates that both medications produce modest reductions in systolic blood pressure and, in some cases, diastolic blood pressure, and reduce several markers of cardiovascular risk, including C-reactive protein. Moreover, GLP-1 influences endothelial function. The effect of the incretin hormones on serum lipids are either neutral or beneficial, with small, non-significant decreases in LDL cholesterol, increases in HDL cholesterol, and occasionally significant decreases in fasting triglyceride levels. Also, they have positive effects on hepatic steatosis. Although GLP-1 agonists and DPP-4 inhibitors are at present not appropriate for primary treatment of cardiovascular risks factors, the reduction of these parameters is evidently beneficial.

Incretin-based therapies for type 2 diabetes: a nurse's perspective

Type 2 diabetes (T2D) is a serious and increasing problem in the UK. Large numbers of people are suffering from the disease, and its onset is occurring at younger ages, requiring prolonged treatment. Current therapies pose challenges for patients and health professionals, and new methods of treatment are therefore needed. This article examines a group of treatments--the incretin therapies--which have recently become available. It considers the clinical evidence for these therapies relevant to UK-based prescribing, and their potential benefits for patients with T2D. Awareness of these therapies, the evidence supporting them, and the clinical recommendations for their use will allow diabetes nurses to expand treatment options for patients with T2D.

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.

Saxagliptin is non-inferior to glipizide in patients with type 2 diabetes mellitus inadequately controlled on metformin alone: a 52-week randomised controlled trial

AIM

To assess the efficacy and safety of saxagliptin vs. glipizide as add-on therapy to metformin in patients with type 2 diabetes mellitus and inadequate glycaemic control on metformin alone.

METHODS AND PATIENTS

A total of 858 patients [age ≥ 18 years; glycated haemoglobin (HbA(1c) ) > 6.5 - 10.0%; on stable metformin doses ≥ 1500 mg/day] were randomised 1 : 1 to saxagliptin 5 mg/day or glipizide up-titrated as needed from 5 to 20 mg/day for 52 weeks. The primary objective was to assess if the change from baseline HbA(1c) achieved with saxagliptin plus metformin was non-inferior to glipizide plus metformin.

RESULTS

The per-protocol analysis demonstrated non-inferiority of saxagliptin vs. glipizide; adjusted mean changes from baseline HbA(1c) were -0.74% vs. -0.80%, respectively; the between-group difference was 0.06% (95% CI, -0.05% to 0.16%). Treatment with saxagliptin vs. glipizide was associated with a significantly smaller proportion of patients with hypoglycaemic events (3.0% vs. 36.3%; p < 0.0001) and a divergent impact on body weight (adjusted mean change from baseline -1.1 kg with saxagliptin vs. 1.1 kg with glipizide; p < 0.0001). There was a significantly smaller rise in HbA(1c) (%/week) from week 24 to 52 with saxagliptin vs. glipizide (0.001% vs. 0.004%; p = 0.04) indicating a sustained glycaemic effect beyond week 24. Excluding hypoglycaemic events, the proportion of patients experiencing adverse events (AEs) was similar (60.0% saxagliptin vs. 56.7% glipizide); treatment-related AEs were less common with saxagliptin vs. glipizide (9.8% vs. 31.2%), attributable to the higher frequency of hypoglycaemia in glipizide patients. Discontinuation rates resulting from AEs were similar (∼4%).

CONCLUSION

Saxagliptin plus metformin was well tolerated, provided a sustained HbA(1c) reduction over 52 weeks, and was non-inferior to glipizide plus metformin, with reduced body weight and a significantly lower risk of hypoglycaemia.

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 and metformin XR combination therapy provides glycemic control over 24 hours in patients with T2DM inadequately controlled with metformin

OBJECTIVE

To assess 24-hour glycemic control with saxagliptin compared with placebo as add-on treatment to metformin in patients with type 2 diabetes mellitus (T2DM) and inadequate glycemic control.

RESEARCH DESIGN AND METHODS

This was a 4-week, multicenter, randomized, double-blind, placebo-controlled Phase IIIb trial comparing the antihyperglycemic activity of saxagliptin 5 mg once daily in combination with a stable dose of metformin extended release (XR) vs. placebo in combination with metformin XR in patients with T2DM inadequately controlled (screening glycated hemoglobin [HbA(1c)] 7-10%) with stable doses of metformin immediate release or metformin XR ≥ 1500 mg/day. Ninety-three adult patients were randomized and received treatment. The primary outcome measure was change from baseline to week 4 in 24-hour mean weighted glucose (MWG).

RESULTS

The reduction from baseline in 24-hour MWG was significantly greater for saxagliptin 5 mg + metformin XR (-13.8 mg/dL; -0.77 mmol/L) compared with placebo + metformin XR (3.0 mg/dL; 0.17 mmol/L) (p = 0.0001). At week 4, the mean decrease in plasma glucose was sustained through a 24-hour period in saxagliptin-treated patients. Treatment with saxagliptin 5 mg + metformin XR resulted in significant mean reductions from baseline in 4-hour mean weighted postprandial glucose (PPG), 2-hour PPG, 3-day average mean daily glucose, and fasting plasma glucose levels compared with placebo + metformin XR (p ≤ 0.001). The proportion of adverse events (AEs) was similar in the two treatment groups, with no reported hypoglycemic AEs in saxagliptin-treated patients. The 4-week evaluation period may have been insufficient to evaluate longer term effects on hyperglycemia or to identify additional AEs.

CONCLUSIONS

In patients with T2DM treated with metformin XR, saxagliptin 5 mg orally administered once daily in the evening for 4 weeks effectively lowered plasma glucose concentrations through the 24-hour dosing interval and was well tolerated.

Efficacy and safety of saxagliptin in combination with metformin compared with sitagliptin in combination with metformin in adult patients with type 2 diabetes mellitus

BACKGROUND

Dipeptidyl peptidase-4 inhibitors improve glycaemic control in patients with type 2 diabetes mellitus when used as monotherapy or in combination with other anti-diabetic drugs (metformin, sulphonylurea, or thiazolidinedione). This 18-week, phase 3b, multicentre, double-blind, noninferiority trial compared the efficacy and safety of two dipeptidyl peptidase-4 inhibitors, saxagliptin and sitagliptin, in patients whose glycaemia was inadequately controlled with metformin.

METHODS

Adult type 2 diabetes mellitus patients (N = 801) with glycated haemoglobin (HbA(1c)) 6.5-10% on stable metformin doses (1500-3000 mg/day) were randomized 1 : 1 to add-on 5 mg saxagliptin or 100 mg sitagliptin once daily for 18 weeks. The primary efficacy analysis was a comparison of the change from baseline HbA(1c) at week 18 in per-protocol patients. Noninferiority was concluded if the upper limit of the two-sided 95% confidence interval of the HbA(1c) difference between treatments was < 0.3%.

RESULTS

The adjusted mean changes in HbA(1c) following the addition of saxagliptin or sitagliptin to stable metformin therapy were - 0.52 and - 0.62%, respectively. The between-group difference was 0.09% (95% confidence interval, - 0.01 to 0.20%), demonstrating noninferiority. Both treatments were generally well tolerated; incidence and types of adverse events were comparable between groups. Hypoglycaemic events, mostly mild, were reported in approximately 3% of patients in each treatment group. Body weight declined by a mean of 0.4 kg in both groups.

CONCLUSIONS

Saxagliptin added to metformin therapy was effective in improving glycaemic control in patients with type 2 diabetes mellitus inadequately controlled by metformin alone; saxagliptin plus metformin was noninferior to sitagliptin plus metformin, and was generally well tolerated.

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.

Incretin-based therapy in chronic kidney disease

Type 2 diabetes mellitus (T2DM) with concomitant CKD is an emerging clinical and public health problem reaching epidemic proportions in the United States. Achieving and maintaining glycemic targets in clinical practice are significant challenges in majority of the patients with T2DM and CKD, and this has created significant barriers for clinicians managing these patients. Commonly used antihyperglycemic agents are either contraindicated or lack efficacy and safety information in this population. Recently, 2 distinct classes of agents that augment incretin hormone action have been added to the therapeutic armamentarium targeting hyperglycemia. This review will discuss the literature examining the efficacy and safety of incretin-based therapies in T2DM and the available evidence for their use in CKD.

Overcoming challenges in Type 2 diabetes management to improve patient outcomes

As obesity and Type 2 diabetes mellitus reach epidemic proportions worldwide, glycemic control and prevention of complications have become even more critical. We searched studies published between January 2006 and January 2010 to identify and discuss the challenges facing healthcare professionals and patients in reaching glycemic targets. MEDLINE and Derwent Drug File searches were conducted with the following search terms: Type 2 diabetes mellitus, medication adherence, antihyperglycemic agents, glucose control, and clinical inertia. In this article we will outline the commonly used medications and present the advantages and disadvantages of each class of drug. Additionally, we will present the dipeptidyl peptidase-4 inhibitors and their place in the treatment of patients with Type 2 diabetes mellitus.

Managing type 2 diabetes in the primary care setting: beyond glucocentricity

Successful management of type 2 diabetes mellitus (T2DM) requires attention to additional conditions often associated with hyperglycemia including overweight or obesity, dyslipidemia and hypertension, as each has some relationship with microvascular or macrovascular complications. Because control of cardiovascular risk factors is as important as glucose control in T2DM, these risk factors need to be addressed, and it is critical that antidiabetes medications do not exacerbate these risk factors. A patient-centered approach to treatment in which clinicians maximize patient involvement in the selection of antidiabetes therapy may lead to increased adherence and improved clinical outcomes. The incretin hormones, which include glucagon-like peptide-1 (GLP-1), are involved in glucoregulation and have become an important focus of T2DM research and treatment. Incretin-based therapies, such as the glucagon-like peptide-1 receptor agonists and the dipeptidyl peptidase-IV inhibitors, have shown beneficial effects on hyperglycemia, weight, blood pressure and lipids with a low incidence of hypoglycemia.

Evaluation of the potential for pharmacokinetic and pharmacodynamic interactions between dutogliptin, a novel DPP4 inhibitor, and metformin, in type 2 diabetic patients

OBJECTIVE

Dutogliptin is a novel, orally available, potent, and selective DPP4 inhibitor that improves glycemic control in type 2 diabetic patients. The objective of this study was to evaluate the potential pharmacokinetic and pharmacodynamic interactions, as well as the tolerability, of dutogliptin and metformin alone and in combination in type 2 diabetic patients.

METHODS

This was a single-center, randomized, open-label, 3-way, crossover study in type 2 diabetic patients. All patients received three treatment regimens, each of 5 days duration in order to reach steady state: 400 mg once daily of dutogliptin (the anticipated clinical dose); 1000 mg metformin twice daily (maximum effective clinical dose); and concomitant administration of 400 mg dutogliptin once daily and 1000 mg metformin twice daily.

RESULTS

Co-administration of dutogliptin and metformin did not alter the pharmacokinetics of either agent. The geometric mean ratio, GMR (dutogliptin + metformin/dutogliptin) of the area under the plasma concentration-time curve (AUC(0-24h)) at steady state was 0.91 (90% CI: 0.79-1.06; p = 0.29); the GMR of the maximum plasma concentrations (C(max)) was 0.95 (90% CI: 0.76-1.19; p = 0.70); the time to maximum plasma concentrations (T(max)) was essentially the same for dutogliptin with or without metformin. The GMR (dutogliptin + metformin/metformin) of AUC(0-12h) at steady state was 0.99 (90% CI: 0.84-1.17; p = 0.93); the GMR of C(max) was 0.91 (90% CI: 0.79-1.04; p = 0.18); T(max) was comparable for metformin with or without dutogliptin. Metformin added to dutogliptin had no effect on plasma DPP4 inhibition. All three treatment regimens were well tolerated.

CONCLUSIONS

In this small, multiple dose study, the steady state pharmacokinetics of either dutogliptin or metformin were not altered by co-administration of the two agents. Dutogliptin and metformin were well tolerated either alone or in combination and co-administered metformin did not alter the ex vivo DPP4 inhibition by dutogliptin. There is no need to consider pharmacokinetic and pharmacodynamic interactions when determining the dosage of either agent for co-administration. A phase 3 clinical trial is underway to provide more definitive data on the safety and efficacy of dutogliptin administered on a background of metformin treatment.

Dipeptidyl peptidase-4 inhibitors for the treatment of type 2 diabetes mellitus

Type 2 diabetes mellitus traditionally has been characterized by insulin resistance and beta-cell dysfunction, leading to hyperglycemia and eventual micro- and macrovascular complications. Dipeptidyl peptidase-4 (DPP-4) inhibitors are a relatively new class of drugs available for the management of type 2 diabetes. In order to provide a comprehensive evaluation and comparison of the pharmacology, pharmacokinetics, efficacy, and safety of the DPP-4 inhibitors-sitagliptin, vildagliptin, saxagliptin, and alogliptin-in the treatment of type 2 diabetes, we conducted a MEDLINE search (1966-July 2009) for pertinent English-language articles. Abstracts of the annual meetings of the American Diabetes Association and European Association for the Study of Diabetes from 2005-2009 were also searched. As a drug class, the DPP-4 inhibitors have become widely accepted in clinical practice because of their low risk of hypoglycemia, favorable adverse-effect profile, and once-daily dosing. They are weight neutral (do not cause weight gain or loss) and appear to decrease beta-cell apoptosis and increase beta-cell survival. Because clinical studies directly comparing agents from this class have not, to our knowledge, been conducted, making comparisons in terms of efficacy and safety will become difficult for clinicians as more agents become available. Based on information from preclinical, clinical, and postmarketing data, there does not appear to be a compelling advantage of one DPP-4 inhibitor over another in terms of efficacy, safety, or ease of clinical use. Although theoretical advantages exist for agents with a higher specificity for DPP-4 inhibition versus inhibition of other isoenzymes associated with toxicity, comparative studies and/or increased clinical experience with this class of drug will determine the clinical advantages, if any, of one agent over another.

Type 2 diabetes comorbidities and treatment challenges: rationale for DPP-4 inhibitors

The management of type 2 diabetes is designed to reduce disease-related complications and improve long-term outcomes. Achieving glycemic control is a critical component of this process. The selection of drug therapy for reducing blood glucose is made more challenging when patients already have complications or comorbid conditions (eg, high risk for hypoglycemia, obesity, renal impairment). Dipeptidyl peptidase-4 (DPP-4) inhibitors are a new class of antihyperglycemic drugs that block degradation of incretin hormones. By enhancing and prolonging incretin effects, DPP-4 inhibitors stimulate glucose-dependent insulin secretion and also reduce glucagon secretion. This results in improved glycemic control, as reflected by decreases in glycated hemoglobin (HbA1c), fasting plasma glucose, and postprandial plasma glucose. Dipeptidyl peptidase-4 inhibitors also have the potential to improve beta-cell function. In randomized clinical trials, the DPP-4 inhibitors saxagliptin and sitagliptin reduced HbA1c by 0.5% to 0.8%, compared with placebo, whether used as monotherapy or in combination with another agent. As initial combination therapy with metformin, saxagliptin and sitagliptin have demonstrated reductions in HbA1c of 2.5% and 1.9%, respectively. The efficacy of the DPP-4 inhibitors was maintained during treatment for up to 2 years, and did not differ in the elderly compared with younger adults. Dipeptidyl peptidase-4 inhibitors offer efficacy similar to other drug classes, and are well tolerated with a lower risk of hypoglycemia, weight-neutral effects, and a low propensity for drug-drug interactions. On the basis of their clinical profiles, the DPP-4 inhibitors are emerging as an attractive option for improving glycemic control in patients with type 2 diabetes. Saxagliptin and sitagliptin are approved for use as initial therapy in combination with metformin, as monotherapy, as well as in combination with metformin, a sulfonylurea, or a thiazolidinedione in patients not adequately controlled by these agents alone.