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

Sitagliptin: a review of its use in patients with type 2 diabetes mellitus

Sitagliptin (Januvia(®), Xelevia™, Glactiv(®), Tesavel(®)) is an orally administered, potent and highly selective inhibitor of dipeptidyl peptidase-4 (DPP-4) and was the first agent of its class to be approved for use in the management of adults with type 2 diabetes. Numerous randomized placebo- or active comparator-controlled trials have demonstrated the efficacy of sitagliptin in terms of improving glycaemic control in patients with type 2 diabetes, including its use as monotherapy, initial combination therapy (usually with fixed-dose combinations of sitagliptin/metformin), or add-on therapy to metformin or to other antihyperglycaemic drugs, with or without metformin. The primary endpoint of the clinical trials was the reduction from baseline in glycosylated haemoglobin (HbA1c), although sitagliptin also showed beneficial effects for other endpoints, such as the proportion of patients who achieved target HbA1c, and reductions from baseline in fasting plasma glucose (FPG) levels and 2-h postprandial glucose (PPG) levels. Sitagliptin was generally well tolerated in clinical trials, had a low risk of hypoglycaemia (although this depends on background therapy) and had a neutral effect on body weight. Despite concerns regarding a possible increased risk of rare pancreatic adverse events (e.g. pancreatitis) with glucagon-like peptide-1 (GLP-1)-based therapies, such as GLP-1 receptor agonists and DPP-4 inhibitors, no causal association has been found; regulators in Europe recently conducted a review of available data, concluding that there is little evidence that these drugs could cause pancreatic inflammation or pancreatic cancer. A similar review is planned in the USA and postmarketing surveillance will continue. Thus, oral sitagliptin is an effective and generally well tolerated treatment option for the management of patients with type 2 diabetes.

Overview of saxagliptin efficacy and safety in patients with type 2 diabetes and cardiovascular disease or risk factors for cardiovascular disease

Most individuals with type 2 diabetes mellitus have or will develop multiple independent risk factors for cardiovascular disease, particularly coronary artery disease (CAD). CAD is the leading cause of morbidity and mortality among individuals with type 2 diabetes mellitus, and treating these patients is challenging. The risk of hypoglycemia, weight gain, or fluid retention with some diabetes medications should be considered when developing a treatment plan for individuals with a history of CAD or at risk for CAD. Dipeptidyl peptidase-4 inhibitors are oral antihyperglycemic agents that inhibit the breakdown of the incretin hormones glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide, resulting in increased glucose-dependent insulin secretion and suppression of glucagon secretion. Saxagliptin is a potent and selective dipeptidyl peptidase-4 inhibitor that improves glycemic control and is generally well tolerated when used as monotherapy and as add-on therapy to other antihyperglycemic medications. This review summarizes findings from recently published post hoc analyses of saxagliptin clinical trials that have been conducted in patients with and without a history of cardiovascular disease and in patients with and without various risk factors for cardiovascular disease. The results show that saxagliptin was generally well tolerated and consistently improved glycemic control, as assessed by reductions from baseline in glycated hemoglobin, fasting plasma glucose concentration, and postprandial glucose concentration, regardless of the presence or absence of baseline cardiovascular disease, hypertension, statin use, number of cardiovascular risk factors, or high Framingham 10-year cardiovascular risk score.

Observational and clinical trial findings on the comparative effectiveness of diabetes drugs showed agreement

OBJECTIVES

This study compares an observational study of diabetes treatment effectiveness to randomized controlled trials to assess their convergent validity.

STUDY DESIGN AND SETTING

Multivariate models were developed using observational data to describe change in hemoglobin A1c (HbA1c; % unit) and weight (kilograms) after addition of a second-line oral diabetes drug to metformin monotherapy. Randomized trials of these scenarios were systematically identified. The models were used to simulate each trial, and simulated and actual results were compared by linear regression and meta-analysis.

RESULTS

Thirty-two randomized trials of second-line diabetes oral therapy were identified. For all outcomes and drugs studied, simulation and actual results correlated (P < 0.001). There were no statistically significant differences between meta-analyzed randomized and simulated results for effect on HbA1c. For effect on weight, results were qualitatively comparable, but for sulfonylureas, the simulated weight gain was nominally greater than seen in the randomized controlled trials.

CONCLUSION

An observational study of diabetes drug effectiveness showed convergent validity with randomized data. This supports cautious use of the observational research to draw conclusions about drug effectiveness in populations not studied in clinical trials. This approach may be useful in other situations where observational and randomized data need integration.

Saxagliptin efficacy and safety in patients with type 2 diabetes receiving concomitant statin therapy

AIMS

To examine whether concomitant statin therapy affects glycemic control with saxagliptin 2.5 and 5mg/d in patients with type 2 diabetes mellitus (T2DM).

METHODS

Efficacy and safety were analyzed post hoc for pooled data from 9 saxagliptin randomized, placebo-controlled trials with a primary 24-week treatment period (4 monotherapy, 2 add-on to metformin, 1 each add-on to a sulfonylurea, thiazolidinedione, or insulin±metformin). Safety was also assessed in an 11-study, 24-week pool and an extended 20-study pool, which included 9 additional 4- to 52-week randomized studies. Comparisons were performed for patient groups defined by baseline statin use.

RESULTS

Saxagliptin produced greater mean reductions in glycated hemoglobin than placebo, with no interaction between treatment and baseline statin use (P=0.47). In patients receiving saxagliptin 2.5 and 5mg and placebo, the proportion of patients with ≥1 adverse event (AE) was 78.1%, 64.0%, and 63.2%, respectively, in patients with any statin use and 70.6%, 57.9%, and 55.0% in patients with no statin use. Serious AEs, deaths, and symptomatic confirmed hypoglycemia (fingerstick glucose ≤50mg/dL) were few and similar, irrespective of baseline statin use.

CONCLUSIONS

Saxagliptin improves glycemic control and is generally well tolerated in patients with T2DM, irrespective of concomitant statin therapy.

Treatment of type 2 diabetes, lifestyle, GLP1 agonists and DPP4 inhibitors

In recent years the treatment focus for type 2 diabetes has shifted to prevention by lifestyle change and to more aggressive reduction of blood sugars during the early stage of treatment. Weight reduction is an important goal for many people with type 2 diabetes. Bariatric surgery is no longer considered a last resort treatment. Glucagon-like peptide-1 agonists given by injection are emerging as a useful treatment since they not only lower blood sugar but are associated with a modest weight reduction. The role of the oral dipeptidyl peptidase 4 inhibitors is emerging as second line treatment ahead of sulphonylureas due to a possible beneficial effect on the beta cell and weight neutrality. Drugs which inhibit glucose re-absorption in the kidney, sodium/glucose co-transport 2 inhibitors, may have a role in the treatment of diabetes. Insulin treatment still remains the cornerstone of treatment in many patients with type 2 diabetes.

Safety of saxagliptin: events of special interest in 9156 patients with type 2 diabetes mellitus

BACKGROUND

A post hoc pooled analysis was undertaken to evaluate the safety of saxagliptin in patients with type 2 diabetes mellitus, with attention to events of special interest for dipeptidyl peptidase-4 inhibitors.

METHODS

Pooled analyses were performed for 20 randomized controlled studies (N = 9156) of saxagliptin as monotherapy or add-on therapy, and a subset of 11 saxagliptin + metformin studies. Adverse events and events of special interest (gastrointestinal adverse events, infections, hypersensitivity, pancreatitis, skin lesions, lymphopenia, thrombocytopenia, hypoglycaemia, bone fracture, severe cutaneous adverse reactions, opportunistic infection, angioedema, malignancy, worsening renal function, and specific laboratory events) were assessed; incidence rates (events/100 person-years) and incidence rates ratios (saxagliptin/control) were calculated (Mantel-Haenszel method).

RESULTS

In both pooled datasets, the incidence rates for deaths, serious adverse events, discontinuations due to adverse events, pancreatitis, malignancy, and most other events of special interest, excepting bone fractures and hypersensitivity, were similar between treatments, with 95% confidence intervals (CIs) for incidence rates ratios including 1. In the 20-study pool, the incidence rates per 100 person-years was higher with saxagliptin versus control for bone fractures [1.1 vs 0.6; incidence rates ratio (95% CI), 1.81 (1.04-3.28)] and hypersensitivity adverse events [1.3 vs 0.8; 1.67 (1.01-2.87)].

CONCLUSIONS

Pooled data from 20 studies confirm that saxagliptin has a favourable safety and benefit-risk profile.

Cardiovascular safety of combination therapies with incretin-based drugs and metformin compared with a combination of metformin and sulphonylurea in type 2 diabetes mellitus--a retrospective nationwide study

AIM

Dipeptidyl peptidase-4 (DPP-4) inhibitors and glucagon-like peptide-1 (GLP-1) agonists are widely used in combinations with metformin in the treatment of type 2 diabetes; however, data on long-term safety compared with conventional combination therapies are limited.

METHODS

Danish individuals without prior myocardial infarction or stroke that initiated combinations of metformin with sulphonylurea (SU), DPP-4 inhibitors, GLP-1 agonists or insulin between 9 May 2007 and 31 December 2011 were followed up for the risk of all-cause mortality, cardiovascular (CV) mortality or a combined end point of myocardial infarction, stroke and CV mortality. Rate ratios (RR) were calculated using time-dependent multivariable Poisson regression analysis.

RESULTS

A total of 40 028 patients (59% men, mean age 60 ± 13 years) used metformin with SU (n = 25 092), DPP-4 inhibitor (n = 11 138), GLP-1 agonist (n = 4345) or insulin (n = 6858). Crude incidence rates per 1000 patient years for the combined end point were 18 (SU), 10 (DPP-4 inhibitor), 8 (GLP-1 agonist) and 21 (insulin). In adjusted analyses with metformin + SU as reference, metformin + DPP-4 inhibitor was associated with an RR of 0.65 (0.54-0.80) for mortality, an RR of 0.57 (0.40-0.80) for CV mortality and an RR of 0.70 (0.57-0.85) for the combined end point. For metformin + GLP-1 agonist, the RR for mortality was 0.77 (0.51-1.17), for CV mortality 0.89 (0.47-1.68), and for the combined end point 0.82 (0.55-1.21).

CONCLUSION

Incretin-based drugs combined with metformin were safe compared with conventional combinations of glucose-lowering therapy. Use of incretin-based therapy may be target for strategies to lower CV risk in type 2 diabetes, although it should be recognized that the multivariable analysis may not have fully accounted for important baseline differences.

Evidence-based practice use of incretin-based therapy in the natural history of diabetes

The incretin class of anti-hyperglycemic agents, including glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-inhibitors, is an important addition to the therapeutic armamentarium for the management of appropriate patients with type 2 diabetes mellitus as an adjunct to diet and exercise and/or with the agents metformin, sulfonylureas, thiazolidinediones, or any combination thereof. More recently, US Food and Drug Administration (FDA)-approved indications for incretins were expanded to include use with basal insulin. This review article takes an evidence-based practice approach in discussing the importance of aggressive treatment for diabetes, the principles of incretin physiology and pathophysiology, use of glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors, and patient types and contexts where incretin therapy has been found beneficial, from metabolic syndrome to overt diabetes.

Comparative effectiveness of dipeptidylpeptidase-4 inhibitors in type 2 diabetes: a systematic review and mixed treatment comparison

OBJECTIVE

To compare the safety and efficacy of the dipeptidylpeptidase-4 (DPP-4) inhibitors in patients with type 2 diabetes and inadequate glycemic control.

DESIGN

Systematic review of randomized controlled trials (RCTs), health economic evaluation studies, systematic reviews, and meta-analyses, followed by primary Bayesian mixed treatment comparison meta-analyses (MTCs), and secondary frequentist direct-comparison meta-analyses using a random-effects model. Outcomes were reported as weighted mean change from baseline, or odds ratio (OR) with 95% credible interval.

DATA SOURCES

MEDLINE, MEDLINE In-Process, EMBASE, and BIOSIS via Dialog ProQuest; Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews via EBSCO; four diabetes and two technical congress abstracts; and health technology assessment organization websites.

ELIGIBILITY CRITERIA

Patients with type 2 diabetes and inadequate glycemic control receiving any pharmacological anti-diabetic treatment.

DATA EXTRACTION AND ANALYSIS

Title/abstracts were reviewed for eligibility, followed by full-text review of publications remaining after first pass. A three-person team filtered articles and an independent reviewer checked a random selection (10%) of filtered articles. Data extraction and quality assessment of studies were also independently reviewed. Five DPP-4 inhibitors (alogliptin, linagliptin, saxagliptin, sitagliptin, and vildagliptin) were compared via meta-analysis (where data were available) as monotherapy, dual therapy (plus metformin, sulfonylurea, pioglitazone, or insulin), and triple therapy (plus metformin/sulfonylurea).

RESULTS

The review identified 6,601 articles; 163 met inclusion criteria and 85 publications from 83 RCTs contained sufficient or appropriate data for analysis. MTCs demonstrated no differences between DPP-4 inhibitors in mean change from baseline in glycosylated hemoglobin (HbA1c) or body weight, or the proportions of patients achieving HbA1c <7% or experiencing a hypoglycemic event, apart from in patients on alogliptin plus metformin, who achieved HbA1c <7% more frequently than those treated with saxagliptin plus metformin [OR 6.41 (95% CI 3.15-11.98) versus 2.17 (95% CI 1.56-2.95)].

CONCLUSIONS

This systematic review and MTC showed similar efficacy and safety for DPP-4 inhibitors as treatment for type 2 diabetes, either as monotherapy or combination therapy.

Management of unmet needs in type 2 diabetes mellitus: the role of incretin agents

The leading cause of morbidity and mortality in type 2 diabetes mellitus is cardiovascular disease. There is a need for type 2 diabetes therapies that act in concert with available agents to provide adequate glycemic control without causing hypoglycemia and weight gain, which are associated with increases in cardiovascular risk. Incretin-based agents-dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists-are the newest class of antihyperglycemic therapies. Liraglutide and exenatide, glucagon-like peptide-1 receptor agonists recently approved in Canada, have been shown to effectively lower blood glucose levels while also having beneficial effects on body weight and systolic blood pressure. The objective of this article is to review and discuss incretin-based agents, with a focus on their effects on blood glucose control, body weight and cardiovascular risk factors in patients with type 2 diabetes. Relevant data were obtained by literature search using the EMBASE, MEDLINE and PubMed databases.

Baseline glycemic parameters predict the hemoglobin A1c response to DPP-4 inhibitors : meta-regression analysis of 78 randomized controlled trials with 20,053 patients

Ability to predict which patients might benefit more of therapy might facilitate personalization of treatment. The aim of this study was to obtain information about clinical characteristics which might predict the HbA1c response to DPP-4 inhibitors. We conducted an electronic search without restriction for randomized controlled trials (RCTs) involving DPP-4 inhibitors (vildagliptin, sitagliptin, saxagliptin, linagliptin, and alogliptin). RCTs were included if they lasted at least 12 weeks, reported the effect of DPP-4 inhibitors on HbA1c level, and the number of patients in any arm was >30. We did a meta-regression analysis. Seventy-eight articles were eligible, with 79 arms and 20,503 patients. For all arms, the decrease of HbA1c was -0.74 % (95 % CI -0.80 to -0.67 %), with considerable heterogeneity (I (2) = 97 %, P < 0.0001): the greatest HbA1c decrease was seen at 52 weeks (8 arms, 3,338 patients, -0.88 %, 95 % CI -1.10 to -0.66 %). In univariate meta-regression analysis, baseline HbA1c explained 22 % of variance of the HbA1c response to treatment, while fasting glucose and type of DPP-4 inhibitor explained an additional 19 and 12 %, respectively; age, duration of treatment, previous therapy, and type of statistical analysis of RCTs were without influence. In the multivariate meta-regression model, baseline HbA1c, fasting glucose, and type of DPP-4 inhibitor explained 61 % of total variance. The HbA1c response to DPP-4 inhibitors can be modulated mainly by baseline HbA1c and fasting glucose levels: a greater absolute reduction of baseline HbA1c is seen in patients with higher baseline HbA1c and lower fasting glucose level.

The pharmacokinetic considerations and adverse effects of DPP-4 inhibitors [corrected]

INTRODUCTION

Dipeptidyl-peptidase-4 (DPP-4) inhibitors are a class of anti-hyperglycemic agents with proven efficacy in patients with type 2 diabetes mellitus (T2DM).

AREAS COVERED

This review considers the pharmacokinetic profile, adverse effects and drug interactions of DPP-4 inhibitors. DPP-4 inhibitors have certain differences in their structure, metabolism, route of elimination and selectivity for DPP-4 over structurally related enzymes, such as DPP-8/DPP-9. They have a low potential for drug interactions, with the exception of saxagliptin that is largely metabolized by cytochrome CYP3A4/A5. Reports of pancreatitis and pancreatic cancer have raised concerns regarding the safety of DPP-4 inhibitors and are under investigation. Post-marketing surveillance has revealed less common adverse effects, especially a number of skin- and immune-related adverse effects. These issues are covered in the present review.

EXPERT OPINION

DPP-4 inhibitors are useful and efficient drugs. DPP-4 inhibitors have similar mechanism of action and similar efficacy. However, DPP-4 inhibitors have certain differences in their pharmacokinetic properties that may be associated with different clinical effects and adverse event profiles. Although clinical trials indicated a favorable safety profile, post-marketing reports revealed certain safety aspects that need further investigation. Certainly, more research is needed to clarify if the differences among DPP-4 inhibitors could lead to a different clinical and safety profile.

Reshaping diabetes care: the fundamental role of dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists in clinical practice

OBJECTIVE

To update clinicians on the most recent safety and efficacy data on current incretin-based strategies for the treatment of type 2 diabetes (T2D).

METHODS

Title searches were conducted in the Pubmed database to identify literature pertaining to the safety and efficacy of glucagon-like peptide-1 receptor agonists (GLP-1RAs) and dipeptidyl peptidase-4 (DPP-4) inhibitors. Product-specific title searches included the terms exenatide, liraglutide, linagliptin, saxagliptin, sitagliptin, and vildagliptin.

RESULTS

The recent literature has introduced us to newer DPP-4 inhibitors and longer-acting GLP-1RAs, updated meta-analyses assessing the safety and efficacy of incretin-based therapies, and studies exploring the use of incretin-based treatments in broader clinical settings such as combination therapy with insulin. Meta-analyses have demonstrated placebo-adjusted glycated hemoglobin (HbA1c) reductions of ~1% with GLP-1RAs and 0.6 to 0.8% with DPP-4 inhibitors and have suggested cardioprotective effects such as reduction of cardiovascular events and improvement of lipid profile. As a class, these agents have consistently demonstrated low risks of hypoglycemia relative to other agents.

CONCLUSION

Incretin-based therapies are characterized by an overall favorable safety profile and weight effect, a low risk of hypoglycemia, and clinically meaningful improvements in HbA1c. Based on an expanding and favorable literature describing their use in various patient populations, the guidelines of the American Association of Clinical Endocrinologists and the recently updated guidelines from the American Diabetes Association assign these agents a central role in the treatment of T2D.

A randomized controlled trial of the efficacy and safety of twice-daily saxagliptin plus metformin combination therapy in patients with type 2 diabetes and inadequate glycemic control on metformin monotherapy

BACKGROUND

To compare the safety and efficacy of saxagliptin 2.5 mg twice daily (BID) versus placebo add-on therapy to metformin immediate release (IR) in patients with type 2 diabetes and inadequate glycemic control with metformin alone.

METHODS

This multicenter, 12-week, double-blind, parallel-group trial enrolled adult outpatients with type 2 diabetes (glycated hemoglobin [HbA1c] 7.0%-10.0%) on stable metformin IR monotherapy (≥1500 mg, BID for ≥8 weeks). Patients were randomized to double-blind saxagliptin 2.5 mg BID or placebo added on to metformin IR following a 2-week, single-blind, placebo add-on therapy lead-in period. The primary end point was the change from baseline to week 12 in HbA1c. Key secondary end points included change from baseline to week 12 in fasting plasma glucose (FPG) and the proportion of patients achieving HbA1c <7.0% or HbA1c ≤ 6.5% at week 12. Efficacy was analyzed in all patients who received randomized study drug with ≥1 postbaseline assessment. Safety was assessed in all treated patients.

RESULTS

In total, 74 patients were randomized to double-blind saxagliptin add-on therapy and 86 to placebo add-on therapy. At week 12, least-squares mean changes (95% CI) from baseline HbA1c (adjusted for baseline HbA1c) were significantly greater (P = 0.006) in the saxagliptin + metformin group -0.56% (-0.74% to -0.38%) versus the placebo + metformin group -0.22% (-0.39% to -0.06%). Adjusted mean changes from baseline in FPG were numerically greater with saxagliptin versus placebo; the difference (95% CI) -9.5 mg/dL (-21.7 to 2.7) was not statistically significant (P = 0.12). A numerically greater proportion of patients in the saxagliptin group than the placebo group achieved HbA1c < 7.0% (37.5% vs 24.2%) or HbA1c ≤6.5% (24.6% vs 10.7%). There were no unexpected safety findings. Hypoglycemia occurred in 4 patients (5.4%) in the saxagliptin group and 1 patient (1.2%) in the placebo group; confirmed hypoglycemia (symptoms plus fingerstick glucose ≤50 mg/dL) occurred in 1 patient in the placebo group.

CONCLUSIONS

Addition of saxagliptin 2.5 mg BID to metformin therapy in patients with type 2 diabetes and inadequate glycemic control on metformin monotherapy reduced HbA1c compared with placebo added to metformin, with an adverse events profile similar to placebo and no unexpected safety findings.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00885378.

Assessment of the cardiovascular safety of saxagliptin in patients with type 2 diabetes mellitus: pooled analysis of 20 clinical trials

BACKGROUND

It is important to establish the cardiovascular (CV) safety profile of novel antidiabetic drugs.

METHODS

Pooled analyses were performed of 20 randomized controlled studies (N = 9156) of saxagliptin as monotherapy or add-on therapy in patients with type 2 diabetes mellitus (T2DM) as well as a subset of 11 saxagliptin + metformin studies. Adjudicated major adverse CV events (MACE; CV death, myocardial infarction [MI], and stroke) and investigator-reported heart failure were assessed, and incidence rates (IRs; events/100 patient-years) and IR ratios (IRRs; saxagliptin/control) were calculated (Mantel-Haenszel method).

RESULTS

In pooled datasets, the IR point estimates for MACE and individual components of CV death, MI, and stroke favored saxagliptin, but the 95% CI included 1. IRR (95% CI) for MACE in the 20-study pool was 0.74 (0.45, 1.25). The Cox proportional hazard ratio (95% CI) was 0.75 (0.46, 1.21), suggesting no increased risk of MACE in the 20-study pool. In the 11-study saxagliptin + metformin pool, the IRR for MACE was 0.93 (0.44, 1.99). In the 20-study pool, the IRR for heart failure was 0.55 (0.27, 1.12).

CONCLUSIONS

Analysis of pooled data from 20 clinical trials in patients with T2DM suggests that saxagliptin is not associated with an increased CV risk.

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.

Dipeptidyl peptidase-4 inhibitors in cardioprotection: a promising therapeutic approach

Cardiovascular diseases are major killers in all developed societies and rapidly becoming the leading cause of morbidity and mortality in the developing world. Patients with diabetes mellitus are at particular risk of developing cardiovascular diseases. The present treatment options for management of diabetes have expanded since the development of glucagon-like peptide-1 agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors. There is a growing body of evidence that these agents may have cardioprotective effects even in patients who do not have diabetes. Here, we discuss this evidence as well as pathways that DPP-4 inhibitors target in the cardiovascular system. These agents over time will find an appropriate place in the management of cardiovascular diseases.

Dipeptidyl peptidase-4 inhibitors in type 2 diabetes therapy--focus on alogliptin

Type 2 diabetes mellitus is a complex and progressive disease that is showing an apparently unstoppable increase worldwide. Although there is general agreement on the first-line use of metformin in most patients with type 2 diabetes, the ideal drug sequence after metformin failure is an area of increasing uncertainty. New treatment strategies target pancreatic islet dysfunction, in particular gut-derived incretin hormones. Inhibition of the enzyme dipeptidyl peptidase-4 (DPP-4) slows degradation of endogenous glucagon-like peptide-1 (GLP-1) and thereby enhances and prolongs the action of the endogenous incretin hormones. The five available DPP-4 inhibitors, also known as 'gliptins' (sitagliptin, vildagliptin, saxagliptin, linagliptin, alogliptin), are small molecules used orally with similar overall clinical efficacy and safety profiles in patients with type 2 diabetes. The main differences between the five gliptins on the market include: potency, target selectivity, oral bioavailability, long or short half-life, high or low binding to plasma proteins, metabolism, presence of active or inactive metabolites, excretion routes, dosage adjustment for renal and liver insufficiency, and potential drug-drug interactions. On average, treatment with gliptins is expected to produce a mean glycated hemoglobin (HbA1c) decrease of 0.5%-0.8%, with about 40% of diabetic subjects at target for the HbA1c goal <7%. There are very few studies comparing DPP-4 inhibitors. Alogliptin as monotherapy or added to metformin, pioglitazone, glibenclamide, voglibose, or insulin therapy significantly improves glycemic control compared with placebo in adult or elderly patients with inadequately controlled type 2 diabetes. In the EXAMINE trial, alogliptin is being compared with placebo on cardiovascular outcomes in approximately 5,400 patients with type 2 diabetes. In clinical studies, DPP-4 inhibitors were generally safe and well tolerated. However, there are limited data on their tolerability, due to their relatively recent marketing approval. Alogliptin will be used most when avoidance of hypoglycemic events is paramount, such as in patients with congestive heart failure, renal failure, and liver disease, and in the elderly.

Safety and efficacy of sitagliptin-metformin in fixed combination for the treatment of type 2 diabetes mellitus

The biguanide, metformin, is considered first-line treatment for type 2 diabetes. Sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor acts through the incretin pathway and has a glucose dependent mode of action. The complementary hypoglycemic properties of these drugs make fixed dose combination treatment an attractive prospect. Evidence from recent clinical trials suggests a beneficial effect of the combination on efficacy, demonstrated by significant improvement of hemoglobin A1c (HbA1c), fasting and postprandial glucose levels. The fixed dose combination is likely to have greater patient tolerability compared with monotherapy with either agent because of low rates of hypoglycemia, weight neutrality, and lower rates of side effects. High acquisition cost and paucity of long-term safety data are, however, potential barriers to their wider use. An overview of the pharmacology and clinical outcomes from recent trials of the metformin-sitagliptin combination and how the combination could fit into the type 2 diabetes treatment algorithm is presented in this review.

Cardiovascular effects of dipeptidyl peptidase-4 inhibitors: from risk factors to clinical outcomes

Dipeptidyl peptidase-4 (DPP-4) inhibitors (gliptins) are oral incretin-based glucose-lowering agents with proven efficacy and safety in the management of type 2 diabetes mellitus (T2DM). In addition, preclinical data and mechanistic studies suggest a possible additional non-glycemic beneficial action on blood vessels and the heart, via both glucagon-like peptide-1-dependent and glucagon-like peptide-1-independent effects. As a matter of fact, DPP-4 inhibitors improve several cardiovascular risk factors: they improve glucose control (mainly by reducing the risk of postprandial hyperglycemia) and are weight neutral; may lower blood pressure somewhat; improve postprandial (and even fasting) lipemia; reduce inflammatory markers; diminish oxidative stress; improve endothelial function; and reduce platelet aggregation in patients with T2DM. In addition, positive effects on the myocardium have been described in patients with ischemic heart disease. Results of post hoc analyses of phase 2/3 controlled trials suggest a possible cardioprotective effect with a trend (sometimes significant) toward lower incidence of major cardiovascular events with sitagliptin, vildagliptin, saxagliptin, linagliptin, or alogliptin compared with placebo or other active glucose-lowering agents. However, the definite relationship between DPP-4 inhibition and better cardiovascular outcomes remains to be proven. Major prospective clinical trials involving various DPP-4 inhibitors with predefined cardiovascular outcomes are under way in patients with T2DM and a high-risk cardiovascular profile: the Sitagliptin Cardiovascular Outcome Study (TECOS) on sitagliptin, the Saxagliptin Assessment of Vascular Outcomes Recorded in Patients With Diabetes Mellitus-Thrombolysis in Myocardial Infarction (SAVOR-TIMI) 53 trial on saxagliptin, the Cardiovascular Outcomes Study of Alogliptin in Subjects With Type 2 Diabetes and Acute Coronary Syndrome (EXAMINE) trial on alogliptin, and the Cardiovascular Outcome Study of Linagliptin Versus Glimepiride in Patients With Type 2 Diabetes (CAROLINA) on linagliptin. If these trials confirm that a DPP-4 inhibitor can reduce the cardiovascular burden of T2DM, it would be major progress that would dramatically influence the management of the disease.

Efficacy and safety of the dipeptidyl peptidase-4 inhibitor gemigliptin compared with sitagliptin added to ongoing metformin therapy in patients with type 2 diabetes inadequately controlled with metformin alone

AIMS

This study was designed to assess the efficacy and safety of a dipeptidyl peptidase-4 inhibitor, gemigliptin versus sitagliptin added to metformin in patients with type 2 diabetes.

METHODS

We conducted a double-blind, randomized, active-controlled trial in 425 Asian patients with inadequately controlled type 2 diabetes being treated with metformin alone. Eligible patients were randomized into three groups: 50 mg gemigliptin qd, 25 mg gemigliptin bid or sitagliptin 100 mg qd added to ongoing metformin treatment for 24 weeks. Haemoglobin A1c (HbA1c) and fasting plasma glucose (FPG) were measured periodically, and oral glucose tolerance tests were performed at baseline and 24 weeks after starting the treatment regimen.

RESULTS

Twenty-four weeks later, adding gemigliptin (50 mg/day) to ongoing metformin therapy significantly improved glycaemic control. Reduction in HbA1c caused by 50 mg gemigliptin qd (-0.77% ± 0.8) was non-inferior to that caused by 100 mg sitagliptin qd (-0.8% ± 0.85). Proportion of patients achieving HbA1c <7% while taking 25 mg gemigliptin bid (50%) or 50 mg gemigliptin qd (54.07%) was comparable to the results with 100 mg sitagliptin qd (48.87%). There were significant decreases in FPG, postprandial glucose and AUC0-2 h glucose, as well as increases in GLP-1 and β cell sensitivity to glucose (supported by homeostasis model assessment of β-cell function, postprandial 2-h c-peptide and insulinogenic index) in patients receiving gemigliptin treatment with their metformin therapy. There was no increased risk of adverse effects with this dose of gemigliptin compared with sitagliptin 100 mg qd.

CONCLUSIONS

Addition of gemigliptin 50 mg daily to metformin was shown to be efficacious, well tolerated and non-inferior to sitagliptin in patients with type 2 diabetes mellitus.

The place of GLP-1-based therapy in diabetes management: differences between DPP-4 inhibitors and GLP-1 receptor agonists

Type 2 diabetes is a progressive disease characterized by the need for additional antidiabetic agents overtime to maintain a stable level of glycemic control. The discovery of the glucagon like peptide 1, 1 of the 2 major incretins, was pivotal to the development of novel therapies, which can be used in individuals with type 2 diabetes. Two classes of drugs, GLP-1 receptor agonists and dipeptidyl peptidase inhibitors, provide comparable or superior glycemic effects to previous antidiabetic agents without increasing side effects, such as weight gain and hypoglycemia. Therefore, they represent valuable additions to the current therapeutic options for type 2 diabetes.

Evolving therapeutic options for type 2 diabetes mellitus: an overview

INTRODUCTION

Many oral antidiabetic drugs (OADs) are available for patients with type 2 diabetes mellitus (T2DM). However, it is recognized that additional therapies are needed and several new compounds are in advanced stages of development.

PURPOSE

This narrative review considers the essential features of a successful OAD, the main classes of OADs that are currently used, and the therapies that may be available in the upcoming years.

RESULTS AND CONCLUSIONS

The first OADs (sulfonylureas and biguanides) were discovered by chance. Although effective in reducing blood glucose levels, early sulfonylureas were associated with significant off-target effects, and the biguanide phenformin was discontinued due to adverse events. Although metformin is in the same drug class, it has a better safety profile and is now recommended as first-line treatment, except when contraindicated. Nonetheless, many patients require additional glucose control (even on metformin) with an agent that has a complementary mechanism of action. Developments in bench science have facilitated the selection of agents for specific therapeutic targets, with the thiazolidinediones providing an interesting example. This OAD class initially appeared encouraging, yet in clinical practice was associated with safety concerns. As a result, newer agents, such as dipeptidyl peptidase-4 inhibitors, are undergoing more rigorous safety evaluations than OADs of previous generations. Promising compounds with novel mechanisms of action include the sodium-glucose co-transporter 2 inhibitors, the G-protein-coupled receptor agonists, and the balanced dual peroxisome proliferator-activated receptor-α/γ agonists. There is optimism that in the next few years, novel classes of OADs that are currently under development will offer additional blood glucose control options via complementary mechanisms of action. However, history has shown that compounds of the same class can have different safety profiles and treatment effects. Therefore, high-quality clinical trial evidence is needed for every compound.

Efficacy and safety of dipeptidyl peptidase-4 inhibitors in combination with metformin

INTRODUCTION

Use of dipeptidyl peptidase-4 (DPP-4) inhibitors is prevalent for the treatment of type 2 diabetes since they have fewer adverse effects compared with other non-insulin medications currently available; however, as monotherapy, the glycosylated hemoglobin (HbA1c)-lowering power of these agents is moderate. The aim of this article is to evaluate the current literature regarding the safety and efficacy of DPP-4 inhibitors in combination with metformin.

METHODS

A literature search was conducted through MEDLINE (from 1950 to October 2012), PubMed (from 1966 to October 2012), EMBASE (from 1966 to October 2012), and International Pharmaceutical Abstracts (from 1970 to October 2012) using the search terms "sitagliptin," "linagliptin," "alogliptin," "vildagliptin," "saxagliptin," and "metformin." Studies that did not evaluate the DPP-4 inhibitors in combination with metformin and those that were not phase 3, were excluded.

RESULTS

Many of the studies evaluated DPP-4 inhibitors in combination with metformin versus glucagon-like peptide-1 (GLP-1) agonists, placebo, DPP-4 inhibitors as monotherapy, thiazolidinediones, and sulfonylureas. The results of these noninferiority trials were that DPP-4 inhibitors as a whole are noninferior to either each other or other agents except for GLP-1 agonists. Also, in superiority studies, GLP-1 agonists proved to have greater HbA1c lowering.

CONCLUSION

In summary, DPP-4 inhibitors play a vital role in the treatment of diabetes. They have relatively limited adverse effects, especially regarding hypoglycemia. DPP-4 inhibitors in combination with metformin are generally well tolerated and are available as combination products to reduce pill burden and enhance compliance. The limitations to DPP-4 inhibitors are the lack of outcomes data and more limited HbA1c lowering than other medications currently approved for the treatment of type 2 diabetes. However, as previously stated, thiazolidinediones, glinides, sulfonylureas, pramlinitide, and GLP-1 agonists are all quite beneficial in HbA1c lowering but are not without major adverse effects. Therefore, DPP-4 inhibitors have a vital role as an oral add-on agent for the treatment of type 2 diabetes.

Glucagon-like peptide-1 and its cardiovascular effects

Recently, the crucial role of GLP-1 in cardiovascular disease has been suggested by both preclinical and clinical studies. In vivo and in vitro studies have demonstrated cardio-protective effects of GLP-1 by activating cell survival signal pathways, which have greatly reduced ischemia/reperfusion injury and also cardiac dysfunction in various congestive heart failure animal models. Clinically, beneficial effects of GLP-1 have been shown in patients with myocardial infarction, hypertension, and heart failure, and 2 classes of incretin enhancers, GLP-1 receptor agonists and DPP-4 inhibitors, are currently available for the treatment of type 2 diabetes mellitus. In this review, we will summarize the role of incretins in various cardiovascular events such as hypertension and heart failure and postprandial lipoprotein secretion, and discuss their molecular mechanisms and potentials as a new therapeutic as well as preventive drug type for reducing cardiovascular events in both diabetic and nondiabetic patients.

A novel model-based meta-analysis to indirectly estimate the comparative efficacy of two medications: an example using DPP-4 inhibitors, sitagliptin and linagliptin, in treatment of type 2 diabetes mellitus

OBJECTIVES

To develop a longitudinal statistical model to indirectly estimate the comparative efficacies of two drugs, using model-based meta-analysis (MBMA). Comparison of two oral dipeptidyl peptidase (DPP)-4 inhibitors, sitagliptin and linagliptin, for type 2 diabetes mellitus (T2DM) treatment was used as an example.

DESIGN

Systematic review with MBMA.

DATA SOURCES

MEDLINE, EMBASE, http://www.ClinicalTrials.gov, Cochrane review of DPP-4 inhibitors for T2DM, sitagliptin trials on Food and Drug Administration website to December 2011 and linagliptin data from the manufacturer.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Double-blind, randomised controlled clinical trials, ≥12 weeks' duration, that analysed sitagliptin or linagliptin efficacies as changes in glycated haemoglobin (HbA1c) levels, in adults with T2DM and HbA1c >7%, irrespective of background medication. MODEL DEVELOPMENT AND APPLICATION: A Bayesian model was fitted (Markov Chain Monte Carlo method). The final model described HbA1c levels as function of time, dose, baseline HbA1c, washout status/duration and ethnicity. Other covariates showed no major impact on model parameters and were not included. For the indirect comparison, a population of 1000 patients was simulated from the model with a racial composition reflecting the average racial distribution of the linagliptin trials, and baseline HbA1c of 8%.

RESULTS

The model was developed using longitudinal data from 11 234 patients (10 linagliptin, 15 sitagliptin trials), and assessed by internal evaluation techniques, demonstrating that the model adequately described the observations. Simulations showed both linagliptin 5 mg and sitagliptin 100 mg reduced HbA1c by 0.81% (placebo-adjusted) at week 24. Credible intervals for participants without washout were -0.88 to -0.75 (linagliptin) and -0.89 to -0.73 (sitagliptin), and for those with washout, -0.91 to -0.76 (linagliptin) and -0.91 to -0.75 (sitagliptin).

CONCLUSIONS

This study demonstrates the use of longitudinal MBMA in the field of diabetes treatment. Based on an example evaluating HbA1c reduction with linagliptin versus sitagliptin, the model used seems a valid approach for indirect drug comparisons.

A patient-centred approach to treatment with incretin-based agents in patients with type 2 diabetes

WHAT IS KNOWN AND OBJECTIVE

The 2012 position statement from the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) recommends a haemoglobin A1c level of <7% for most patients with type 2 diabetes (T2D). Initial therapy consists of lifestyle changes plus metformin, with an emphasis on a patient-centred approach to management. Addition of incretin-based therapy is recommended as an add-on after metformin failure, and later on in combination with basal insulin. Basal insulin is recommended from the onset in patients with A1c ≥10%. The possibility of incorporating incretin-based therapy in the patient-centred approach will be investigated both in the literature and clinical experience.

COMMENT

Incretin-based therapy targets multiple dysfunctional organ systems in T2D and provides sustained glycaemic control, with extraglycaemic benefits and low risk of hypoglycaemia. To initiate an incretin-based therapy that best fits an individual patient's needs, the patient's A1c level, preference and comorbid conditions should be considered along with any drug safety and adherence-related issues.

WHAT IS NEW AND CONCLUSION

There is good evidence to support the patient-centred approach to T2D management. This approach allows patient treatment goals and personal preferences to be matched with the clinical profile(s) of one or more agents to formulate a treatment plan that can best achieve the goals. Incretin-based therapies are an important class of agents to consider after metformin monotherapy failure and later in combination with basal insulin. By matching patient needs with the clinical profiles of the various treatment options, pharmacists can actively engage in the practice of patient-centred care and management.

Cardiovascular effects of gliptins

Dipeptidyl peptidase 4 (DPP-4) inhibitors (commonly referred to as gliptins) are a novel class of oral antihyperglycaemic agents with demonstrated efficacy in the treatment of type 2 diabetes mellitus (T2DM). Preclinical data and mechanistic studies have indicated a possible beneficial action on blood vessels and the heart, via both glucagon-like peptide 1 (GLP-1)-dependent and GLP-1-independent effects. DPP-4 inhibition increases the concentration of many peptides with potential vasoactive and cardioprotective effects. Clinically, DPP-4 inhibitors improve several risk factors in patients with T2DM. They improve blood glucose control (mainly by reducing postprandial glycaemia), are weight neutral (or even induce modest weight loss), lower blood pressure, improve postprandial lipaemia, reduce inflammatory markers, diminish oxidative stress, and improve endothelial function. Some positive effects on the heart have also been described in patients with ischaemic heart disease or congestive heart failure, although their clinical relevance requires further investigation. Post-hoc analyses of phase II-III, controlled trials suggest a possible cardioprotective effect with a trend for a lower incidence of major cardiovascular events with gliptins than with placebo or active agents. However, the actual relationship between DPP-4 inhibition and cardiovascular outcomes remains to be proven. Major prospective clinical trials with predefined cardiovascular outcomes and involving various DPP-4 inhibitors are now underway in patients with T2DM and a high-risk cardiovascular profile.

Incretin-based therapies for type 2 diabetes mellitus: a review of direct comparisons of efficacy, safety and patient satisfaction

BACKGROUND

Clinical trials comparing incretin-based therapies-glucagon-like peptide-1 receptor agonists (exenatide-twice daily and once weekly-and once-daily liraglutide) and dipeptidyl peptidase-4 inhibitors (vildagliptin, sitagliptin, saxagliptin and linagliptin)-with placebo and oral antidiabetic drugs show that these therapies effectively control glycaemia, with low risk of hypoglycaemia. Glucagon-like peptide-1 receptor agonists are associated with weight loss and reductions in systolic blood pressure, while dipeptidyl peptidase-4 inhibitors are weight-neutral. Based on this, the National Institute for Health and Clinical Excellence recommends using these agents in patients with type 2 diabetes for whom excess weight and/or hypoglycaemia are problematic.

AIM OF THE REVIEW

This review aims to help decision making when selecting and using incretin-based therapies in type 2 diabetes.

METHODS

A search or MEDLINE and Cochrane clinical trials databases, limited to clinical trials in humans, was performed using the search criteria 'exenatide or liraglutide or vildagliptin or sitagliptin, or saxagliptin or linagliptin'. Abstracts presented at recent American Diabetes Association and European Association for the Study of Diabetes meetings were also searched. Eighteen clinical trials directly comparing incretin-based therapies were identified.

RESULTS

Glucagon-like peptide-1 receptor agonists achieved significantly greater reductions in glycated hemoglobin and weight than dipeptidyl peptidase-4 inhibitors, which have a neutral effect on weight. Between-treatment differences were clinically important. Gastrointestinal side effects were more frequent with glucagon-like peptide-1 receptor agonists versus dipeptidyl peptidase-4 inhibitors. Comparisons between glucagon-like peptide-1 receptor agonists and between dipeptidyl peptidase-4 inhibitors showed that differences within the available agents in the two sub-classes are small. Greater treatment satisfaction was reported with glucagon-like peptide-1 receptor agonists versus dipeptidyl peptidase-4 inhibitors.

CONCLUSION

Glucagon-like peptide-1 receptor agonists achieve greater glycated hemoglobin reductions than dipeptidyl peptidase-4 inhibitors, with concomitant weight loss. Probably due to the greater efficacy of glucagon-like peptide-1 receptor agonists, patient satisfaction is greater with these agents compared with dipeptidyl peptidase-4 inhibitors despite injectable versus oral administration and more frequent gastrointestinal side effects with the agonists.

A review of the efficacy and safety of oral antidiabetic drugs

INTRODUCTION

Additional oral antidiabetic agents to metformin, sulfonylureas (SU) and thiazolidinediones (TZD) are approved for the treatment of type 2 diabetes.

AREAS COVERED

The efficacy and safety of metformin, SUs, TZDs, dipeptidyl peptidase-IV (DPP-4) inhibitors, meglitinide analogs, α-glucosidase inhibitors (AGIs), bile-acid sequestrants (BAS) and bromocriptine will be reviewed.

EXPERT OPINION

Several new oral agents have been approved for type 2 diabetes management in recent years. It is important to understand the efficacy and safety of these medications in addition to the older agents to best maximize oral drug therapy for diabetes. Of the recently introduced oral hypoglycemic/antihyperglycemic agents, the DPP-4 inhibitors are moderately efficacious compared with mainstay treatment with metformin with a low side-effect profile and have good efficacy in combination with other oral agents and insulin. They are a recommended alternative when metformin use is limited by gastrointestinal (GI) side effects or when SU treatment results in significant hypoglycemia or weight gain. Meglitinide analogs are limited by their frequent dosing, expense and hypoglycemia (repaglinide > nateglinide), while AGIs are also limited by their dosing schedule and GI side-effect profile. BAS and bromocriptine have the lowest efficacy with regard to HbA(1c) reduction, also are plagued by GI adverse reactions, but have a low risk of hypoglycemia.

Longer term safety of dipeptidyl peptidase-4 inhibitors in patients with type 2 diabetes mellitus: systematic review and meta-analysis

Dipeptidyl peptidase-4 (DPP-4) inhibitors are oral antidiabetic agents that hold the potential of slowing the progress of type 2 diabetes mellitus. Their long-term safety is still a subject of debate. A systematic review of randomized, controlled trials was undertaken to comprehensively profile the safety of chronic treatment of type 2 diabetes mellitus with DPP-4 inhibitors. We searched data sources including MEDLINE, CENTRAL, publishers' and manufacturers' databases. Eligible trials were double-blind, randomized, placebo or active-controlled trials with ≥18 weeks duration in patients with type 2 diabetes reporting safety outcomes. Meta-analysis was performed separately for trials in which the control group received placebo (44 studies), another gliptin (3 studies) and any other antidiabetic drug (20 studies). Risk ratios with 95% confidence intervals were computed using a Mantel-Haenszel fixed-effect model for general safety outcomes, hypoglycaemia and adverse events by system organ class. Of 307 publications retrieved, 67 randomized, controlled trials met the eligibility criteria and were included in this review (4 alogliptin, 8 linagliptin, 8 saxagliptin, 20 sitagliptin, and 27 vildagliptin trials). Adverse events with gliptin treatment were at placebo level (relative risk (RR) 1.02 [0.99, 1.04]). No increased risk of infections was detectable (RR 0.98 [0.93, 1.05] compared to placebo and 1.02 [0.97, 1.07] compared to other antidiabetic drugs). Asthenia (RR 1.57 [1.09, 2.27]) as well as cardiac (RR 1.37 [1.00, 1.89]) and vascular disorders (RR 1.74 [1.05, 2.86] for linagliptin) emerged as adverse events associated with DPP-4 inhibitor treatment. The risk of hypoglycaemia was low with DPP-4 inhibitor treatment (RR 0.92 [0.74, 1.15] compared to placebo, RR 0.20 [0.17, 0.24] compared to sulphonylureas) in the absence of sulphonylurea or insulin co-therapy, but significantly elevated for combination therapy of sulphonylurea or insulin with sitagliptin or linagliptin (RR 1.86 [1.46, 2.37] compared to placebo). A large body of data supports the long-term safety of gliptin treatment and refutes an increased risk of infections. Further research is needed to clarify a possible link to asthenia, cardiac and vascular events. For combination therapy with insulin or insulin secretagogues, a careful choice of the agent used may limit the risk of hypoglycaemia.

Combination of glibenclamide-metformin HCl for the treatment of type 2 diabetes mellitus

INTRODUCTION

Combination of glibenclamide (glyburide in the U.S.) and metformin hydrochloride simultaneously addresses two different but complimentary mechanisms to improve glycemic control in type 2 diabetes.

AREAS COVERED

The pharmacokinetics, efficacy, and side effect profile of the oral combination of glibenclamide-metformin are reviewed.

EXPERT OPINION

Those patients, uncontrolled with single oral agent sulfonylurea or metformin alone, benefit from combination glibenclamide-metformin. There is improvement in fasting plasma glucose, HbA(1C), and post-prandial glucose control, and patients are more likely to achieve a HbA(1C) < 7%. Initiation should be started at the lowest doses and titrated to get the desired effect. Combination therapy allows for reduced pill burden while treating a multifactorial disease by two different mechanisms. Practitioners should be cognizant of risks of hypoglycemia and the theoretical potential for lactic acidosis in the elderly and those with renal impairment. We caution the use of glibenclamide-metformin in patients at risk for cardiovascular disease. Therapy should be individualized, but overall, combination of glibenclamide-metformin should be considered in patients, without renal or cardiovascular impairment, who are not controlled on monotherapy alone. Alternatively, practitioners may want to weigh the efficacy and safety of available dipeptidyl-peptidase-4 inhibitor-metformin combinations to those of glibenclamide-metformin when considering combination therapy.

Comparative clinical pharmacokinetics of dipeptidyl peptidase-4 inhibitors

Dipeptidyl peptidase-4 (DPP-4) inhibitors collectively comprise a presently unique form of disease management for persons with type 2 diabetes mellitus. The aim of this review is to compare the clinical pharmacokinetics of available DPP-4 inhibitors (alogliptin, linagliptin, saxagliptin, sitagliptin and vildagliptin) for the purpose of identifying potential selection preferences according to individual patient variables and co-morbidities. DPP-4 inhibitors are readily absorbed orally. Following oral ingestion, absorption occurs mainly in the small intestine, with median times to maximum (peak) plasma concentration ranging from 1 to 3 hours. The fraction of each dose absorbed ranges from approximately 30% with linagliptin to 75-87% for all others. Numerical differences in maximum (peak) plasma drug concentrations and areas under the plasma concentration-time curve among the DPP-4 inhibitors vary by an order of magnitude. However, functional capacity measured in terms of glucose-lowering ability remains comparable among all available DPP-4 inhibitors. Distribution of DPP-4 inhibitors is strongly influenced by both lipophilicity and protein binding. Apparent volumes of distribution (V(d)) for most agents range from 70 to 300 L. Linagliptin exhibits a V(d) of more than 1000 L, indicating widespread distribution into tissues. Binding to target proteins in plasma and peripheral tissues exerts a major influence upon broadening linagliptin distribution. DPP-4 inhibitor metabolism is widely variable, with reported terminal half-lives ranging from approximately 3 to more than 200 hours. Complex relationships between rates of receptor binding and dissociation appear to strongly influence the durations of action of those DPP-4 inhibitors with comparatively shorter half-lives. Durations of activity often are not reflective of clearance and, with the exception of vildagliptin which may be administered either once daily in the evening or twice daily, these medications are effective when used with a once-daily dosing schedule. Saxagliptin and, to a lesser extent, sitagliptin are largely metabolized by hepatic cytochrome P450 (CYP) 3A4 and 3A5 isoforms. With the exception of the primary hydroxylated metabolite of saxagliptin, which is 2-fold less potent than its parent molecule, metabolic products of hepatic biotransformation are minimally active and none appreciably contribute to either the therapeutic or the toxic effects of DPP-4 inhibitors. No DPP-4 inhibitor has been shown to inhibit or to induce hepatic CYP-mediated drug metabolism. Accordingly, the number of clinically significant drug-drug interactions associated with these agents is minimal, with only saxagliptin necessitating dose adjustment if administered concurrently with medications that strongly inhibit CYP3A4. Linagliptin undergoes enterohepatic cycling with a large majority (85%) of the absorbed dose eliminated in faeces via biliary excretion. Other DPP-4 inhibitors predominantly undergo renal excretion, with 60-85% of each dose eliminated as unchanged parent compound in the urine. Systematic reviews of clinical trials suggest that the overall efficacy of DPP-4 inhibitors in patients with type 2 diabetes generally is similar. Apart from these generalizations, pharmacokinetic distinctions that potentially influence product selection are tentative. When considered in total, data reviewed in this report suggest that the best overall balance between potency and the clinical pharmacokinetic characteristics of distribution, metabolism and elimination may be observed with linagliptin followed closely by vildagliptin, saxagliptin, sitagliptin and alogliptin.

Glycaemic efficacy of glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors as add-on therapy to metformin in subjects with type 2 diabetes-a review and meta analysis

AIMS

During recent years, two strategies of incretin-based therapy [glucagon-like peptide-1 (GLP-1) receptor agonism and dipeptidyl peptidase-4 (DPP-4) inhibition] have entered the market for pharmacological management of type 2 diabetes. A main indication for this therapy is as add-on to on-going metformin therapy in subjects with type 2 diabetes who have insufficient glycaemic control with metformin alone. The aim of this study was to compare improvements in glycaemic control and changes in body weight, as well as adverse events, in comparable studies with incretin-based therapy as add-on to metformin.

METHODS

Studies having a duration of 16-30 weeks were identified from PubMed.

RESULTS

A total of 27 study groups in 21 studies fulfilled the criteria of examining incretin-based therapy as add-on to metformin at clinically recommended doses in patients with type 2 diabetes for 16-30 weeks; 7 of these used a short-acting GLP-1 receptor agonist (exenatide BID), 7 used longer acting GLP-1 receptor agonists (liraglutide or exenatide LAR), whereas 14 studies examined DPP-4 inhibitors. In all studies, incretin-based therapy reduced HbA1c concentrations. The reduction in HbA1c was significantly greater in study groups with long-acting GLP-1 receptor agonists than with the other two groups (both p < 0.001), whereas there were no differences between exenatide BID and DPP-4 inhibitors. Across all study groups, there was a negative linear correlation between baseline HbA1c and change in HbA1c (r = -0.70; p < 0.001). Fasting glucose also fell significantly more in study groups given liraglutide or exenatide LAR than in those given exenatide BID or DPP-4 inhibitors (both p < 0.001). Furthermore, body weight was reduced by a similar extent in the two groups with GLP-1 receptor agonists and was not significantly altered in the groups with DPP-4 inhibitors. Lipids, blood pressure and heart rate were not reported consistently, which did not allow general conclusions. Adverse events were rare, apart from increased incidence of nausea and vomiting with GLP-1 receptor agonists.

CONCLUSION

Incretin-based therapy efficiently improves glycaemia when added to metformin in patients with type 2 diabetes, and within 16-30 weeks there is a more pronounced reduction in HbA1c with long-acting GLP-1 receptor agonists (liraglutide and exenatide LAR) than with exenatide BID and DPP-4 inhibitors, although the magnitude of the effect is dependent on the baseline values. Both strategies appear to be associated with a very low risk of adverse events, including hypoglycaemia. Finally, the injectable GLP-1 receptor agonists also reduce body weight (whereas the DPP-4 inhibitors are weight neutral) but are also associated with a greater incidence of gastrointestinal side effects and a tendency to increase heart rate.

Drug-induced hypoglycaemia in type 2 diabetes

INTRODUCTION

Hypoglycaemia is a side effect caused by some therapies for type 2 diabetes, which can cause physical, social and psychological harm. Hypoglycaemia also prevents attainment of treatment goals and satisfactory glycaemic control.

AREAS COVERED

The risk of hypoglycaemia associated with commonly prescribed therapies, including metformin, sulphonylureas, dipeptidyl peptidase-4 enzyme (DPP-4) inhibitors, glucagon-like peptide-1 (GLP-1) agonists and thiazolidinediones, is reviewed in this paper (insulin-induced hypoglycaemia is not included). Other medications that are frequently co-prescribed in type 2 diabetes are also discussed, including anti-hypertensive drugs, antibiotics and fibrates, along with various important patient-related risk factors.

EXPERT OPINION

Hypoglycaemia is a common and potentially dangerous side effect of some medications used for type 2 diabetes. The risk of hypoglycaemia should always be considered when selecting and implementing a therapy, with a focus on the individual. Future research into new therapies should measure the frequency of hypoglycaemia prospectively and accurately. Hypoglycaemia has been shown to be a potentially life-threatening metabolic stress; therefore therapies that effectively manage diabetes without the risk of hypoglycaemia are likely to be favoured in the future.

Saxagliptin and sitagliptin in adult patients with type 2 diabetes: a systematic review and meta-analysis

The objective of this study is to compare the efficacy and safety of sitagliptin and saxagliptin with placebo and other hypoglycaemic medications in adults with type 2 diabetes. We searched MEDLINE®, Embase, the Cochrane Library and the International Pharmaceuticals from their inception through 3 February 2011. Studies were included of adults with type 2 diabetes that were 12 weeks or more in duration. Meta-analyses were conducted when included studies were homogenous enough to justify combining their results. A total of 32 articles met inclusion criteria. Sitagliptin 100 mg monotherapy and saxagliptin 5 mg resulted in greater HbA1c reduction compared to placebo [weighted mean difference (WMD) -0.82%, 95% CI -0.95 to -0.70 and WMD -0.70, 95% CI -0.84 to -0.56, respectively]. Sitagliptin was similar to sulfonylureas for HbA1c reduction (WMD 0.08%, 95% CI 0-0.16, 3 trials) and to saxagliptin in one head-to-head trial. There was no statistically significant difference in hypoglycaemia between sitagliptin (pooled RR 1.55, 95% CI 0.55-4.36) or saxagliptin (pooled RR 1.04, 95% CI 0.28-3.81) and placebo. Sitagliptin and saxagliptin result in similar modest HbA1c reductions and do not increase the risk of hypoglycaemia unless combined with other therapies. Their role in the long-term treatment of type 2 diabetes remains unclear given the lack of long-term data on efficacy, harms and health outcomes.

Efficacy of GLP-1 receptor agonists and DPP-4 inhibitors: meta-analysis and systematic review

BACKGROUND

Considerable clinical data on the treatment of type 2 diabetes with incretin-based therapies (glucagon-like peptide 1 receptor agonists [GLP-1RAs] and dipeptidyl-peptidase IV [DPP-4] inhibitors) are available.

OBJECTIVE

This meta-analysis was performed to support the understanding of the overall evidence by summarizing the findings from studies of the incretin-based therapies.

METHODS

The MEDLINE, EMBASE, BIOSIS, and BIOSIS trial databases were searched for relevant literature published between January 1, 1990, and June 30, 2011. Search terms included GLP-1, DPP-4, the names of drugs that have been approved by the US Food and Drug Administration for the treatment of diabetes, and the names of drugs that have not been approved but are in late-stage research. Studies were included if they were randomized controlled trials of 12 to 52 weeks' duration and having change from baseline in hemoglobin (Hb) A(1c) as the primary end point. The random effects meta-analyses models examined HbA(1c), fasting plasma glucose (FPG), and body weight for individual therapies, but did not compare effects between therapies.

RESULTS

The reviewers identified 362 unique clinical studies, of which 80 were eligible for inclusion in the present meta-analysis. Mean baseline HbA(1c) values ranged from 7.4% to 10.3% (GLP-1RA studies) and 7.2% to 9.3% (DPP-4 inhibitor studies). The highest maintenance doses of the GLP-1RAs and the DPP-4 inhibitors were associated with changes from baseline in mean HbA(1c) of -1.1% to -1.6% and -0.6% to -1.1%, respectively. Mean reductions in FPG with exenatide once weekly (QW) or liraglutide once daily were apparently greater than those with exenatide twice daily (BID) and the DPP-4 inhibitors, with the exception of vildagliptin. Mean weight losses with the GLP-1RAs and the DPP-4 inhibitors were >-2.0 and -0.2 to -0.6 kg, respectively. The limitations of the present analysis included a lack of adjustment for placebo use and interstudy heterogeneity associated with differences in methodology (eg, management of concurrent medications, blinding, criteria for treatment discontinuation).

CONCLUSIONS

All of the incretin-based therapies in the present meta-analysis were associated with significant reductions from baseline in HbA(1c) and FPG. Further direct comparative studies between the GLP-1RAs and the DPP-4 inhibitors and within the GLP-1RA class are justified.