Sulfonylureas and cardiovascular effects: from experimental data to clinical use. Available data in humans and clinical applications

The role of sulfonylureas in the treatment of type 2 diabetes

INTRODUCTION

Type 2 diabetes (T2D) is increasingly prevalent and associated with increased risk for cardiovascular and renal disease. After lifestyle modification, metformin is usually the first-line pharmacotherapy and sulfonylureas are traditionally added after metformin failure. However, with newer glucose lowering drugs that may have less risk of hypoglycemia or that may reduce cardiovascular and renal events, the position of sulfonylureas is being reevaluated.

AREAS COVERED

In this article, the authors review relevant publications related to the use of sulfonylureas.

EXPERT OPINION

Sulfonylureas are potent glucose lowering drugs. The risk of hypoglycemia varies with different drugs within the class and can be minimized by using the safer drugs, possibly in lower doses. Cardiovascular events do not appear to be increased with some of the newer generation drugs. The durability of glycemic control also appears comparable to other newer agents. Sulfonylureas are the preferred treatment for some types of monogenic diabetes and selection of T2D patients who may have greater benefit from sulfonylureas based on certain phenotypes and genotypes is likely to be refined further by precision medicine. Sulfonylureas are inexpensive and readily available everywhere and they are still the most frequently used second-line treatment for T2D in many parts of the world.

The Impact of Antidiabetic Therapies on Diastolic Dysfunction and Diabetic Cardiomyopathy

Diabetic cardiomyopathy is more prevalent in people with type 2 diabetes mellitus (T2DM) than previously recognized, while often being characterized by diastolic dysfunction in the absence of systolic dysfunction. This likely contributes to why heart failure with preserved ejection fraction is enriched in people with T2DM vs. heart failure with reduced ejection fraction. Due to revised mandates from major health regulatory agencies, all therapies being developed for the treatment of T2DM must now undergo rigorous assessment of their cardiovascular risk profiles prior to approval. As such, we now have data from tens of thousands of subjects with T2DM demonstrating the impact of major therapies including the sodium-glucose co-transporter 2 (SGLT2) inhibitors, glucagon-like peptide-1 receptor (GLP-1R) agonists, and dipeptidyl peptidase 4 (DPP-4) inhibitors on cardiovascular outcomes. Evidence to date suggests that both SGLT2 inhibitors and GLP-1R agonists improve cardiovascular outcomes, whereas DPP-4 inhibitors appear to be cardiovascular neutral, though evidence is lacking to determine the overall utility of these therapies on diastolic dysfunction or diabetic cardiomyopathy in subjects with T2DM. We herein will review the overall impact SLGT2 inhibitors, GLP-1R agonists, and DPP-4 inhibitors have on major parameters of diastolic function, while also highlighting the potential mechanisms of action responsible. A more complete understanding of how these therapies influence diastolic dysfunction will undoubtedly play a major role in how we manage cardiovascular disease in subjects with T2DM.

Comparative Safety of Sulfonylureas and the Risk of Sudden Cardiac Arrest and Ventricular Arrhythmia

OBJECTIVE

To examine the association between individual antidiabetic sulfonylureas and outpatient-originating sudden cardiac arrest and ventricular arrhythmia (SCA/VA).

RESEARCH DESIGN AND METHODS

We conducted a retrospective cohort study using 1999-2010 U.S. Medicaid claims from five large states. Exposures were determined by incident use of glyburide, glimepiride, or glipizide. Glipizide served as the reference exposure, as its effects are believed to be highly pancreas specific. Outcomes were ascertained by a validated ICD-9-based algorithm indicative of SCA/VA (positive predictive value ∼85%). Potential confounding was addressed by adjustment for multinomial high-dimensional propensity scores included as continuous variables in a Cox proportional hazards model.

RESULTS

Of sulfonylurea users under study (N = 519,272), 60.3% were female and 34.9% non-Hispanic Caucasian, and the median age was 58.0 years. In 176,889 person-years of sulfonylurea exposure, we identified 632 SCA/VA events (50.5% were immediately fatal) for a crude incidence rate of 3.6 per 1,000 person-years. Compared with glipizide, propensity score-adjusted hazard ratios for SCA/VA were 0.82 (95% CI 0.69-0.98) for glyburide and 1.10 (0.89-1.36) for glimepiride. Numerous secondary analyses showed a very similar effect estimate for glyburide; yet, not all CIs excluded the null.

CONCLUSIONS

Glyburide may be associated with a lower risk of SCA/VA than glipizide, consistent with a very small clinical trial suggesting that glyburide may reduce ventricular tachycardia and isolated ventricular premature complexes. This potential benefit must be contextualized by considering putative effects of different sulfonylureas on other cardiovascular end points, cerebrovascular end points, all-cause death, and hypoglycemia.

Pharmacologic Differences of Sulfonylureas and the Risk of Adverse Cardiovascular and Hypoglycemic Events

OBJECTIVE

Sulfonylureas have been associated with an increased risk of cardiovascular adverse events and hypoglycemia, but it is unclear if these risks vary with different agents. We assessed whether the risks of acute myocardial infarction, ischemic stroke, cardiovascular death, all-cause mortality, and severe hypoglycemia differ between sulfonylureas grouped according to pancreas specificity and duration of action.

RESEARCH DESIGN AND METHODS

Using the U.K. Clinical Practice Research Datalink, linked with the Hospital Episodes Statistics and the Office for National Statistics databases, we conducted a cohort study among patients with type 2 diabetes initiating monotherapy with sulfonylureas between 1998 and 2013. Adjusted hazard ratios (HRs) and 95% CIs were estimated using Cox proportional hazards models, comparing use of pancreas-nonspecific, long-acting sulfonylureas (glyburide/glimepiride) to pancreas-specific, short-acting sulfonylureas (gliclazide/glipizide/tolbutamide).

RESULTS

The cohort included 17,604 sulfonylurea initiators (mean [SD] follow-up 1.2 [1.5] years). Compared with specific, short-acting sulfonylureas (15,741 initiators), nonspecific, long-acting sulfonylureas (1,863 initiators) were not associated with an increased risk of acute myocardial infarction (HR 0.86; CI 0.55-1.34), ischemic stroke (HR 0.92; CI 0.59-1.45), cardiovascular death (HR 1.01; CI 0.72-1.40), or all-cause mortality (HR 0.81; CI 0.66-1.003), but with an increased risk of severe hypoglycemia (HR 2.83; CI 1.64-4.88).

CONCLUSIONS

The nonspecific, long-acting sulfonylureas glyburide and glimepiride do not have an increased risk of cardiovascular adverse events compared with the specific, short-acting sulfonylureas gliclazide, glipizide, and tolbutamide. However, nonspecific, long-acting sulfonylureas glyburide and glimepiride have an increased risk of severe hypoglycemia.

Pro- and Antiarrhythmic Actions of Sulfonylureas: Mechanistic and Clinical Evidence

Sulfonylureas are the most commonly used second-line drug class for treating type 2 diabetes mellitus (T2DM). While the cardiovascular safety of sulfonylureas has been examined in several trials and nonrandomized studies, little is known of their specific effects on sudden cardiac arrest (SCA) and related serious arrhythmic outcomes. This knowledge gap is striking, because persons with DM are at increased risk of SCA. In this review, we explore the influence of sulfonylureas on the risk of serious arrhythmias, with specific foci on ischemic preconditioning, cardiac excitability, and serious hypoglycemia as putative mechanisms. Elucidating the relationship between individual sulfonylureas and serious arrhythmias is critical, especially as the diabetes epidemic intensifies and SCA incidence increases in persons with diabetes.

Review: Sulphonylureas and cardiovascular risk: facts and controversies

Cardiovascular complications are the principal cause of death in type 2 diabetes. The importance of glycaemic control in preventing cardiovascular complications has been demonstrated. However, some oral antidiabetic agents and especially some sulphonylureas (SU) have been accused of having a deleterious effect on cardiovascular risk. A retrospective analysis of the administrative database of Saskatchewan Health for 5,795 subjects, identified by their first-ever dispensation for an oral antidiabetic agent, suggests that a higher exposure to SUs was associated with increased mortality. Nevertheless, the effects of SUs on cardiac ATP-sensitive potassium channels in experimental studies vary between agents and studies, so that the clinical relevance of this phenomenon is unclear. Moreover, 11 years of follow-up of patients randomised to glibenclamide or chlorpropamide in the United Kingdom Prospective Diabetes Study demonstrated no adverse effects on a range of cardiovascular end points. Despite SU structural differences and differences in binding to cardiac SU receptors, the clinical evidence base does not support the selection of one sulphonylurea over another on the basis of ischaemic preconditioning, possibly because ischaemic preconditioning may be blunted or absent in diabetes. The main objective remains the prevention or delay of diabetic complications through improvement of glycaemic control together with other cardiovascular risk factors.

Hypoglycemia and Cardiovascular Disease: Lessons from Outcome Studies

Severe hypoglycemia is recognized to be one of the strongest predictors of macrovascular events, adverse clinical outcomes, and mortality in patients with type 2 diabetes. Large clinical trials have reported an increased hazard ratio for all-cause mortality and cardiovascular events in patients with type 2 diabetes and severe hypoglycemia. However, these trials also reported an increased hypoglycemia-associated mortality rate in patients allocated to standard treatment by a factor of 1.5-2 despite a significant 50 % to 70 % lower incidence of hypoglycemia compared to the intensive treatment group. Although the potential for a causal relationship has been demonstrated in mechanistic studies, the evidence from large prospective studies suggest that other pre-existing cardiovascular risk factors in addition to hypoglycemia may be the major link to the final cardiovascular event, and that a low blood glucose level can trigger these events in patients with a high cardiovascular risk.

Cardiovascular safety of sulphonylureas: over 40 years of continuous controversy without an answer

More than 40 years after publication of the University Group Diabetes Program trial, the cardiovascular safety of sulphonylureas is still contentious. Although several hypotheses linking sulphonylureas to adverse cardiovascular effects exist, none provide conclusive evidence. Adding to the controversy, current clinical trials and observational studies provide inconsistent, and sometimes conflicting, evidence for the cardiovascular effects of sulphonylureas. Overall, observational evidence suggests that an increased risk of adverse cardiovascular outcomes is associated with sulphonylureas; however, these data may be subject to residual confounding and bias. Although evidence from randomized controlled trials has suggested a neutral effect, the majority of these studies were not specifically designed to assess the effect of sulphonylureas on adverse cardiovascular event risk. Current ongoing large clinical trials may provide some clarity on the cardiovascular safety of sulphonylureas, but the results are not expected for several years. With the continued uncertainties concerning the cardiovascular safety of all antidiabetic drugs, a clear answer with regard to sulphonylureas is warranted. The objectives of the present article were to provide an overview of the controversy surrounding sulphonylurea-related cardiovascular effects, to discuss the limitations of the current literature, and to provide recommendations for future studies aiming to elucidate the true relationship between sulphonylureas and adverse cardiovascular effects in people with type 2 diabetes.

Comparative cardiovascular safety of insulin secretagogues following hospitalization for ischemic heart disease among type 2 diabetes patients: a cohort study

AIM

To evaluate the association between insulin secretagogues and adverse cardiovascular sequelae in type 2 diabetes patients hospitalized for ischemic heart disease (IHD).

METHODS

Administrative health records from Alberta, Canada between 1998 and 2010 were used to identify 2,254 gliclazide, 3,289 glyburide and 740 repaglinide users prior to an IHD-related hospitalization. Multivariable Cox regression models were used to compare the 30-day risk of a composite outcome of all-cause mortality or new onset of atrial fibrillation, stroke, heart failure or myocardial infarction according to insulin secretagogue use.

RESULTS

Mean (SD) age was 76.1 (6.9) years, and 60.7% were men. The composite outcome occurred in 322 (30.2%) gliclazide users, 455 (28.1%) glyburide users and 81 (23.4%) repaglinide users within 30 days of IHD hospitalization. There were no differences in risk for glyburide use (adjusted hazard ratio [aHR] 0.91; 95% confidence interval [CI] 0.78-1.05) or repaglinide use (aHR 0.80; 95% CI 0.63-1.03) compared to gliclazide. Similar results were observed in analyses for each element of the composite outcome.

CONCLUSIONS

In older patients with type 2 diabetes hospitalized for IHD, prior use of gliclazide, glyburide, or repaglinide appears to be associated with a similar risk of adverse cardiovascular sequelae.

[Cardiovascular safety of non-insulin anti-diabetic drugs. Scientific position statement of SEMERGEN]

Diabetes increases the risk of both microvascular and macrovascular complications. Although reducing plasma glucose levels to recommended targets decreases the risk of microvascular outcomes, the effects of anti-diabetic drugs on macrovascular complications and cardiovascular death are of concern. In fact, it has been suggested that some anti-diabetic agents could even be harmful for cardiovascular outcomes. In this context, several health care regulatory agencies have established the need for performing clinical trials specifically designed to assess the cardiovascular safety of anti-diabetic drugs. The results of 2 clinical trials have recently been published that provide important information on the cardiovascular safety of dipeptidyl peptidase 4 (DPP-4) inhibitors. The aim of this document was to review the available evidence on the cardiovascular safety of non-insulin anti-diabetic drugs and provide practical recommendations on their use in this context.

Optimal therapy of type 2 diabetes: a controversial challenge

Type 2 diabetes mellitus (T2DM) is one of the most common chronic disorders in older adults and the number of elderly diabetic subjects is growing worldwide. Nonetheless, the diagnosis of T2DM in elderly population is often missed or delayed until an acute metabolic emergency occurs. Accumulating evidence suggests that both aging and environmental factors contribute to the high prevalence of diabetes in the elderly. Clinical management of T2DM in elderly subjects presents unique challenges because of the multifaceted geriatric scenario. Diabetes significantly lowers the chances of "successful" aging, notably it increases functional limitations and impairs quality of life. In this regard, older diabetic patients have a high burden of comorbidities, diabetes-related complications, physical disability, cognitive impairment and malnutrition, and they are more susceptible to the complications of dysglycemia and polypharmacy. Several national and international organizations have delivered guidelines to implement optimal therapy in older diabetic patients based on individualized treatment goals. This means appreciation of the heterogeneity of the disease as generated by life expectancy, functional reserve, social support, as well as personal preference. This paper will review current treatments for achieving glycemic targets in elderly diabetic patients, and discuss the potential role of emerging treatments in this patient population.

Risk of acute coronary events associated with glyburide compared with gliclazide use in patients with type 2 diabetes: a nested case-control study

AIM

Sulfonylureas might increase the risk of adverse cardiovascular events; however, emerging evidence suggests there may be important differences amongst these drugs. Some, like glyburide, inhibit KATP channels in the heart and pancreas, while others, like gliclazide, are more likely to selectively inhibit KATP channels in the pancreas. We hypothesized that the risk of acute coronary syndrome (ACS) events would be higher in patients using glyburide compared with gliclazide.

METHODS

This nested case-control study used administrative health data from Alberta, Canada. New users of glyburide or gliclazide aged ≥66 years between 1998 and 2010 were included. Cases were individuals with an ACS-related hospitalization or death. Up to four controls were matched based on birth year, sex, cohort-entry year and follow-up time. Multivariable conditional logistic regression was used to estimate adjusted odds ratios (OR), controlling for baseline drug use and co-morbidities.

RESULTS

Our cohort included 7441 gliclazide and 13 884 glyburide users; 51.4% men, mean (s.d.) age 75.5 (6.6) years and mean (s.d.) duration of follow-up 5.5 (4.0) years. A total of 4239 patients had an ACS-related hospitalization or death and were matched to 16 723 controls. Compared with gliclazide use, glyburide use was associated with a higher risk (adjusted OR 1.14; 95% CI 1.06-1.23) of ACS-related hospitalization or death over 5.5 years (number needed to harm: 50).

CONCLUSION

In this observational study, glyburide use was associated with a 14% higher risk of ACS events compared with gliclazide use. Although the difference is small and probably to have implications at the population level rather than the individual patient or clinician, any causal inferences regarding sulfonylurea use and adverse cardiovascular risk should be tested in a large-scale randomized controlled trial.

Does hypoglycaemia increase the risk of cardiovascular events? A report from the ORIGIN trial

AIMS

Hypoglycaemia caused by glucose-lowering therapy has been linked to cardiovascular (CV) events. The ORIGIN trial provides an opportunity to further assess this relationship.

METHODS AND RESULTS

A total of 12 537 participants with dysglycaemia and high CV-risk were randomized to basal insulin glargine titrated to a fasting glucose of ≤ 5.3 mmol/L (95 mg/dL) or standard glycaemic care. Non-severe hypoglycaemia was defined as symptoms confirmed by glucose ≤ 54 mg/dL and severe hypoglycaemia as a requirement for assistance or glucose ≤ 36 mg/dL. Outcomes were: (i) the composite of CV death, non-fatal myocardial infarction or stroke; (ii) mortality; (iii) CV mortality; and (iv) arrhythmic death. Hazards were estimated before and after adjustment for a hypoglycaemia propensity score. During a median of 6.2 years (IQR: 5.8-6.7), non-severe hypoglycaemic episodes occurred in 41.7 and 14.4% glargine and standard group participants, respectively, while severe episodes occurred in 5.7 and 1.8%, respectively. Non-severe hypoglycaemia was not associated with any outcome following adjustment. Conversely, severe hypoglycaemia was associated with a greater risk for the primary outcome (HR: 1.58; 95% CI: 1.24-2.02, P < 0.001), mortality (HR: 1.74; 95% CI: 1.39-2.19, P < 0.001), CV death (HR: 1.71; 95% CI: 1.27-2.30, P < 0.001) and arrhythmic death (HR: 1.77; 95% CI: 1.17-2.67, P = 0.007). Similar findings were noted for severe nocturnal hypoglycaemia for the primary outcome and mortality. The severe hypoglycaemia hazard for all four outcomes was higher with standard care than with insulin glargine.

CONCLUSION

Severe hypoglycaemia is associated with an increased risk for CV outcomes in people at high CV risk and dysglycaemia. Although allocation to insulin glargine vs. standard care was associated with an increased risk of severe and non-severe hypoglycaemia, the relative risk of CV outcomes with hypoglycaemia was lower with insulin glargine-based glucose-lowering therapy than with the standard glycaemic control. Trial Registration (ORIGIN ClinicalTrials.gov number NCT00069784).

Effects of metformin versus glipizide on cardiovascular outcomes in patients with type 2 diabetes and coronary artery disease

OBJECTIVE

The two major classes of antidiabetic drugs, sulfonylureas and metformin, may differentially affect macrovascular complications and mortality in diabetic patients. We compared the long-term effects of glipizide and metformin on the major cardiovascular events in type 2 diabetic patients who had a history of coronary artery disease (CAD).

RESEARCH DESIGN AND METHODS

This study is a multicenter, randomized, double-blind, placebo-controlled clinical trial. A total of 304 type 2 diabetic patients with CAD, mean age = 63.3 years (range, 36-80 years), were enrolled. Participants were randomly assigned to receive either glipizide (30 mg daily) or metformin (1.5 g daily) for 3 years. The primary end points were times to the composite of recurrent cardiovascular events, including death from a cardiovascular cause, death from any cause, nonfatal myocardial infarction, nonfatal stroke, or arterial revascularization.

RESULTS

At the end of study drug administration, both groups achieved a significant decrease in the level of glycated hemoglobin (7.1% in the glipizide group and 7.0% in the metformin group). At a median follow-up of 5.0 years, 91 participants had developed 103 primary end points. Intention-to-treat analysis showed an adjusted hazard ratio (HR) of 0.54 (95% CI 0.30-0.90; P = 0.026) for the composites of cardiovascular events among the patients that received metformin, compared with glipizide. The secondary end points and adverse events were not significantly different between the two groups.

CONCLUSIONS

Treatment with metformin for 3 years substantially reduced major cardiovascular events in a median follow-up of 5.0 years compared with glipizide. Our results indicated a potential benefit of metformin therapy on cardiovascular outcomes in high-risk patients.

Variations in tissue selectivity amongst insulin secretagogues: a systematic review

AIM

Insulin secretagogues promote insulin release by binding to sulfonylurea receptors on pancreatic β-cells (SUR1). However, these drugs also bind to receptor isoforms on cardiac myocytes (SUR2A) and vascular smooth muscle (SUR2B). Binding to SUR2A/SUR2B may inhibit ischaemic preconditioning, an endogenous protective mechanism enabling cardiac tissue to survive periods of ischaemia. This study was designed to identify insulin secretagogues that selectively bind to SUR1 when given at therapeutic doses.

METHODS

Using accepted systematic review methods, three electronic databases were searched from inception to 13 June 2011. Original studies measuring the half-maximal inhibitory concentration (IC(50)) for an insulin secretagogue on K(ATP) channels using standard electrophysiological techniques were included. Steady-state concentrations (C(SS)) were estimated from the usual oral dose and clearance values for each drug.

RESULTS

Data were extracted from 27 studies meeting all inclusion criteria. IC(50) values for SUR1 were below those for SUR2A/SUR2B for all insulin secretagogues and addition of C(SS) values identified three distinct patterns. The C(SS) for gliclazide, glipizide, mitiglinide and nateglinide lie between IC(50) values for SUR1 and SUR2A/SUR2B, suggesting that these drugs bind selectively to pancreatic receptors. The C(SS) for glimepiride and glyburide (glibenclamide) was above IC(50) values for all three isoforms, suggesting these drugs are non-selective. Tolbutamide and repaglinide may have partial pancreatic receptor selectivity because IC(50) values for SUR1 and SUR2A/SUR2B overlapped somewhat, with the C(SS) in the midst of these values.

CONCLUSIONS

Insulin secretagogues display different tissue selectivity characteristics at therapeutic doses. This may translate into different levels of cardiovascular risk.

The potential effects of anti-diabetic medications on myocardial ischemia-reperfusion injury

Heart disease and stroke account for 65% of the deaths in people with diabetes mellitus (DM). DM and hyperglycemia cause systemic inflammation, endothelial dysfunction, a hypercoagulable state with impaired fibrinolysis and increased platelet degranulation, and reduced coronary collateral blood flow. DM also interferes with myocardial protection afforded by preconditioning and postconditioning. Newer anti-diabetic agents should not only reduce serum glucose and HbA1c levels, but also improve cardiovascular outcomes. The older sulfonylurea agent, glyburide, abolishes the benefits of ischemic and pharmacologic preconditioning, but newer sulfonylurea agents, such as glimepiride, may not interfere with preconditioning. GLP-1 analogs and sitagliptin, an oral dipeptidyl peptidase IV inhibitor, limit myocardial infarct size in animal models by increasing intracellular cAMP levels and activating protein kinase A, whereas metformin protects the heart by activating AMP-activated protein kinase. Both thiazolidinediones (rosiglitazone and pioglitazone) limit infarct size in animal models. The protective effect of pioglitazone is dependent on downstream activation of cytosolic phospholipase A(2) and cyclooxygenase-2 with subsequent increased production of 15-epi-lipoxin A(4), prostacyclin and 15-d-PGJ(2). We conclude that agents used to treat DM have additional actions that have been shown to affect the ability of the heart to protect itself against ischemia-reperfusion injury in preclinical models. However, the effects of these agents in doses used in the clinical setting to minimize ischemia-reperfusion injury and to affect clinical outcomes in patients with DM have yet to be shown. The clinical implications as well as the mechanisms of protection should be further studied.

Impact of type of preadmission sulfonylureas on mortality and cardiovascular outcomes in diabetic patients with acute myocardial infarction

BACKGROUND

The impact of antidiabetic medications on clinical outcomes in patients developing acute myocardial infarction (MI) is controversial. We sought to determine whether in-hospital outcomes in patients who were on sulfonylureas (SUs) when they developed their MIs differed from that of diabetic patients not receiving SUs and whether clinical outcomes were related to the pancreatic cells specificity of SUs.

METHODS AND RESULTS

We analyzed the outcomes of the 1310 diabetic patients included in the nationwide French Registry of Acute ST-Elevation and Non-ST-Elevation Myocardial Infarction in 2005. Medications used before the acute episode were recorded. In-hospital complications were analyzed according to prior antidiabetic treatment. Mortality was lower in patients previously treated with SUs (3.9%) vs. those on other oral medications (6.4%), insulin (9.4%), or no medication (8.4%) (P = 0.014). Among SU-treated patients, in-hospital mortality was lower in patients receiving pancreatic cells-specific SUs (gliclazide or glimepiride) (2.7%), compared with glibenclamide (7.5%) (P = 0.019). Arrhythmias and ischemic complications were also less frequent in patients receiving gliclazide/glimepiride. The lower risk in patients receiving gliclazide/glimepiride vs. glibenclamide persisted after multivariate adjustment (odds ratio 0.15; 95% confidence interval 0.04-0.56) and in propensity score-matched cohorts.

CONCLUSION

In this nationwide registry of patients hospitalized for acute MI, no hazard was associated with the use of SUs before the acute episode. In addition, patients previously receiving gliclazide/glimepiride had improved in-hospital outcomes, compared with those on glibenclamide.

Risk of bleeding with single, dual, or triple therapy with warfarin, aspirin, and clopidogrel in patients with atrial fibrillation

BACKGROUND

Patients with atrial fibrillation (AF) often require anticoagulation and platelet inhibition, but data are limited on the bleeding risk of combination therapy.

METHODS

We performed a cohort study using nationwide registries to identify all Danish patients surviving first-time hospitalization for AF between January 1, 1997, and December 31, 2006, and their posthospital therapy of warfarin, aspirin, clopidogrel, and combinations of these drugs. Cox proportional hazards models were used to estimate risks of nonfatal and fatal bleeding.

RESULTS

A total of 82,854 of 118,606 patients (69.9%) surviving AF hospitalization had at least 1 prescription filled for warfarin, aspirin, or clopidogrel after discharge. During mean (SD) follow-up of 3.3 (2.6) years, 13,573 patients (11.4%) experienced a nonfatal or fatal bleeding. The crude incidence rate for bleeding was highest for dual clopidogrel and warfarin therapy (13.9% per patient-year) and triple therapy (15.7% per patient-year). Using warfarin monotherapy as a reference, the hazard ratio (95% confidence interval) for the combined end point was 0.93 (0.88-0.98) for aspirin, 1.06 (0.87-1.29) for clopidogrel, 1.66 (1.34-2.04) for aspirin-clopidogrel, 1.83 (1.72-1.96) for warfarin-aspirin, 3.08 (2.32-3.91) for warfarin-clopidogrel, and 3.70 (2.89-4.76) for warfarin-aspirin-clopidogrel.

CONCLUSIONS

In patients with AF, all combinations of warfarin, aspirin, and clopidogrel are associated with increased risk of nonfatal and fatal bleeding. Dual warfarin and clopidogrel therapy and triple therapy carried a more than 3-fold higher risk than did warfarin monotherapy.

Sulfonylureas and prognosis after myocardial infarction in patients with diabetes: a population-based follow-up study

BACKGROUND

The cardiovascular safety, including risk of myocardial infarction (MI), of individual sulfonylureas (SUs) may differ. It remains uncertain whether treatment with individual SUs influences prognosis following MI.

METHODS

We conducted a nationwide population-based follow-up study among all Danish patients hospitalized with first-time MI from 1996 to 2004. From the national health databases, we identified 3930 MI patients who used SUs at the time of admission. We computed mortality rates and rates of MI and heart failure readmission according to type of SU and used Cox's proportional hazards regression analysis to compute hazard ratios (HRs) as estimates of relative risk controlling for differences in prognostic covariates.

RESULTS

The 30-day and 1-year mortality after MI among SU users was 22.0% and 35.3%, respectively. We found no substantial differences in 30-day and 1-year mortality among users of different SUs. Use of gliclazide in monotherapy showed a trend towards lower mortality; adjusted HR of 1-year mortality 0.70 (95% CI: 0.48-1.00). Users of the different SUs appeared to have similar risks of new MI and heart failure following MI.

CONCLUSIONS

The prognosis after MI was not substantially influenced by the choice of SU.

Oral glyburide, but not glimepiride, blocks the infarct-size limiting effects of pioglitazone

BACKGROUND

Many patients with type 2 diabetes mellitus receive several oral hypoglycemic agents, including sulfonylurea drugs. Intravenous glyburide (Glyb), a sulfonylurea agent, blocks the protective effects of "ischemic" and pharmacologic preconditioning in various animal models without affecting myocardial infarct size when administered alone. However, there are conflicting results when other sulfonylurea drugs are used. Pioglitazone (PIO) reduces infarct size in the rat. We asked whether oral Glyb and glimepiride (Glim) affect the infarct size-limiting effects of PIO.

METHODS

Sprague-Dawley rats received 3-day oral treatment with: PIO (5 mg/kg/day); PIO + Glyb (10 mg/kg/day); PIO + Glim (4 mg/kg/day) or water alone (experiment 1) or PIO (5 mg/kg/day) with or without 5-hydroxydecanoate (5HD, 10 mg/kg), a specific mitochondrial ATP-sensitive K+ channels inhibitor, administered intravenously 30 min before coronary artery ligation. PIO, Glyb and Glim were administered by oral gavage. Sugar 5% was added to water to prevent hypoglycemia. Rats underwent 30 min coronary artery occlusion and 4 h reperfusion (n = 6 in each group). Ischemic area at risk was assessed by blue dye and infarct size by triphenyl-tetrazolium-chloride.

RESULTS

Body weight and the size of the area at risk were comparable among groups. Infarct size (% of the area at risk) was significantly smaller in the PIO (14.3 +/- 1.1%; p < 0.001) and PIO + Glim (13.2 +/- 0.8%; p < 0.001) groups than in the control group (37.7 +/- 1.2%). Glyb completely blocked the effect of PIO (43.0 +/- 1.7%; p < 0.001). Glim did not affect the protective effect of PIO (p = 0.993). 5HD blocked the protective effect of PIO (infarct size 48.5 +/- 0.8% versus 14.8 +/- 0.6%, respectively; p < 0.0001). In conclusion, the infarct size limiting effects of PIO are dependent on activation of mitochondrial ATP-sensitive K+ channels. Oral Glyb, but not Glim, blocks the infarct size limiting effects of PIO. It is plausible that Glyb affects other pleiotropic effects of PIO and thus may attenuate favorable effects on cardiovascular outcomes. In contrast, Glim does not attenuate the protective effect of PIO.

Insulin-secretagogue activity of p-methoxycinnamic acid in rats, perfused rat pancreas and pancreatic beta-cell line

This study investigated the effect of p-methoxycinnamic acid (p-MCA) on plasma glucose and insulin concentrations in normal and streptozotocin-induced diabetic rats. In both fasting and glucose-loading conditions, an oral administration of p-MCA (40-100 mg/kg) significantly decreased plasma glucose and also increased plasma insulin concentrations in both normal and diabetic rats. The onset of the p-MCA-induced antihyperglycaemia/hypoglycaemia was observed at 1 hr after administration. In perfused rat pancreas, p-MCA (10-100 microM) stimulated insulin secretion about 1.4- and 3.1-fold of basal-control group. In addition, p-MCA (10 microM) enhanced glucose-induced insulin secretion. Moreover, p-MCA stimulated insulin secretion and increased intracellular Ca(2+) concentration ([Ca(2+)](i)) in insulinoma-1 cells. Taken together, our findings suggested that p-MCA exerted antihyperglycaemic/hypoglycaemic effect by stimulating insulin secretion from pancreas and could be developed into a new potential for therapeutic agent used in type 2 diabetic patients.

Effect of rosiglitazone on the risk of myocardial infarction and death from cardiovascular causes

BACKGROUND

Rosiglitazone is widely used to treat patients with type 2 diabetes mellitus, but its effect on cardiovascular morbidity and mortality has not been determined.

METHODS

We conducted searches of the published literature, the Web site of the Food and Drug Administration, and a clinical-trials registry maintained by the drug manufacturer (GlaxoSmithKline). Criteria for inclusion in our meta-analysis included a study duration of more than 24 weeks, the use of a randomized control group not receiving rosiglitazone, and the availability of outcome data for myocardial infarction and death from cardiovascular causes. Of 116 potentially relevant studies, 42 trials met the inclusion criteria. We tabulated all occurrences of myocardial infarction and death from cardiovascular causes.

RESULTS

Data were combined by means of a fixed-effects model. In the 42 trials, the mean age of the subjects was approximately 56 years, and the mean baseline glycated hemoglobin level was approximately 8.2%. In the rosiglitazone group, as compared with the control group, the odds ratio for myocardial infarction was 1.43 (95% confidence interval [CI], 1.03 to 1.98; P=0.03), and the odds ratio for death from cardiovascular causes was 1.64 (95% CI, 0.98 to 2.74; P=0.06).

CONCLUSIONS

Rosiglitazone was associated with a significant increase in the risk of myocardial infarction and with an increase in the risk of death from cardiovascular causes that had borderline significance. Our study was limited by a lack of access to original source data, which would have enabled time-to-event analysis. Despite these limitations, patients and providers should consider the potential for serious adverse cardiovascular effects of treatment with rosiglitazone for type 2 diabetes.

Diabetes mellitus and anesthesia

Diabetes mellitus is an extremely common condition with specific associated comorbidity. Its incidence is rising. Diabetic patients have more perioperative complications than nondiabetic patients. These complications may be related to the presence of organ damage secondary to the diabetes, rather than the defects in carbohydrate metabolism themselves, or to perioperative hyperglycemia. Several new drugs are available for the treatment of diabetes, and these are associated with specific and significant side effects, and varying lengths of action with which the anesthetist should be familiar. Few data are available regarding recommendations for fasting in the presence of these newer drugs. In the postoperative period and during cardiac surgery, hyperglycemia has been shown to be detrimental, and should probably be sought and managed aggressively. The incidence of intraoperative hyperglycemia in noncardiac surgery patients is not as well-defined, nor are the effects of aggressive management.

Cardiovascular disease prevention in patients with type 2 diabetes: The role of oral anti-diabetic agents

Multiple risk factor intervention is essential in order to prevent cardiovascular (CV) disease in patients with diabetes. Therefore, to reduce atherothrombotic events, an ideal oral anti-diabetic agent should be able to modulate most, and preferably all, cardiovascular risk factors associated with diabetes. Of the currently available agents, the insulin sensitisers (metformin, thiazolidinediones) seem to have most promise in cardiovascular protection. Metformin has a positive effect on several CV risk factors; outcome studies have shown that this agent reduces cardiac events in overweight subjects with diabetes. In a similar manner, thiazolidinediones (rosiglitazone, pioglitazone) have a wide spectrum of activity, favourably modulating most risk factors, with evidence to suggest a reduction in CV events with this class of drugs. Agents in the sulphonylurea group have beneficial, though inconsistent, effects on some risk factors but outcome studies have failed to show a cardioprotective role for these agents. New classes of drugs to manage type 2 diabetes are currently at various stages of development and their role in prevention of cardiovascular disease awaits evaluation. At present, first-line management of insulin-resistant type 2 diabetes should utilise metformin, with the addition of thiazolidinediones and sulphonylureas to achieve optimal glycaemic control.

Drug interactions of clinical importance with antihyperglycaemic agents: an update

Because management of type 2 diabetes mellitus usually involves combined pharmacological therapy to obtain adequate glucose control and treatment of concurrent pathologies (especially dyslipidaemia and arterial hypertension), drug-drug interactions must be carefully considered with antihyperglycaemic drugs. Additive glucose-lowering effects have been extensively reported when combining sulphonylureas (or the new insulin secretagogues, meglitinide derivatives, i.e. nateglinide and repaglinide) with metformin, sulphonylureas (or meglitinide derivatives) with thiazolidinediones (also called glitazones) and the biguanide compound metformin with thiazolidinediones. Interest in combining alpha-glucosidase inhibitors with either sulphonylureas (or meglitinide derivatives), metformin or thiazolidinediones has also been demonstrated. These combinations result in lower glycosylated haemoglobin (HbA(1c)), fasting glucose and postprandial glucose levels than with either monotherapy. Even if modest pharmacokinetic interferences have been reported with some combinations, they do not appear to have important clinical consequences. No significant adverse effects, except a higher risk of hypoglycaemic episodes that may be attributed to better glycaemic control, occur with any combination. Challenging the classical dual therapy with sulphonylurea plus metformin, there is a recent trend to use alternative dual combinations (sulphonylurea plus thiazolidinedione or metformin plus thiazolidinedione). In addition, triple therapy with the addition of a thiazolidinedione to the metformin-sulphonylurea combination has been recently evaluated and allows glucose targets to be reached before insulin therapy is considered. This triple therapy appears to be safe, with no deleterious drug-drug interactions being reported so far.Potential interferences may also occur between glucose-lowering agents and other drugs, and such drug-drug interactions may have important clinical implications. Relevant pharmacological agents are those that are widely coadministered in diabetic patients (e.g. lipid-lowering agents, antihypertensive agents); those that have a narrow efficacy/toxicity ratio (e.g. digoxin, warfarin); or those that are known to induce (rifampicin [rifampin]) or inhibit (fluconazole) the cytochrome P450 (CYP) system. Metformin is currently a key compound in the pharmacological management of type 2 diabetes, used either alone or in combination with other antihyperglycaemics. There are no clinically relevant metabolic interactions with metformin, because this compound is not metabolised and does not inhibit the metabolism of other drugs. In contrast, sulphonylureas, meglitinide derivatives and thiazolidinediones are extensively metabolised in the liver via the CYP system and thus, may be subject to drug-drug metabolic interactions. Many HMG-CoA reductase inhibitors (statins) are also metabolised via the CYP system. Even if modest pharmacokinetic interactions may occur, it is not clear whether drug-drug interactions between oral antihyperglycaemic agents and statins may have clinical consequences regarding both efficacy and safety. In contrast, a marked pharmacokinetic interference has been reported between gemfibrozil and repaglinide and, to a lesser extent, between gemfibrozil and rosiglitazone. This leads to a drastic increase in plasma concentrations of each antihyperglycaemic agent when they are coadministered with the fibric acid derivative, and an increased risk of adverse effects. Some antihypertensive agents may favour hypoglycaemic episodes when co-prescribed with sulphonylureas or meglitinide derivatives, especially ACE inhibitors, but this effect seems to result from a pharmacodynamic drug-drug interaction rather than from a pharmacokinetic drug-drug interaction. No, or only modest, interferences have been described with glucose-lowering agents and other pharmacological compounds such as digoxin or warfarin. The effects of inducers or inhibitors of CYP isoenzymes on the metabolism and pharmacokinetics of the glucose-lowering agents of each pharmacological class has been tested. Significantly increased (with CYP inhibitors) or decreased (with CYP inducers) plasma levels of sulphonylureas, meglitinide derivatives and thiazolidinediones have been reported in healthy volunteers, and these pharmacokinetic changes may lead to enhanced or reduced glucose-lowering action, and thus hypoglycaemia or worsening of metabolic control, respectively. In addition, some case reports have evidenced potential drug-drug interactions with various antihyperglycaemic agents that are usually associated with a higher risk of hypoglycaemia.

Sulfonylureas and the risk of myocardial infarction

Patients with diabetes mellitus have an increased risk of coronary artery diseases such as myocardial infarction. Sulfonylureas are used in the treatment of diabetes mellitus and have been linked with adverse cardiovascular effects due to an apparent effect on myocardial ischemic preconditioning. Individual sulfonylureas differ pharmacologically and may have different effects. Although the hypotheses were stimulated by animal studies and experimental studies using intermediate end points, data on the possible clinical implications in humans remain sparse. However, recent data seem reassuring.

Dose-response relation between sulfonylurea drugs and mortality in type 2 diabetes mellitus: a population-based cohort study

BACKGROUND

Over the past 30 years, the relation between use of sulfonylureas to treat type 2 diabetes and the risk of cardiovascular events has been vigorously debated. The purpose of this study was to determine if the risk of death changes with level of exposure to sulfonylurea drugs.

METHODS

This was a retrospective, inception cohort study using administrative data from Saskatchewan Health (1991-1999). The 5795 subjects, identified by their first-ever dispensation for an oral antidiabetic agent, were grouped according to their use of such agents during follow-up. Potential subjects using insulin or combination therapy were excluded. Exposure level was defined by daily dose and degree of adherence. Separate multivariate Cox proportional-hazard models were constructed for each monotherapy group and used to calculate the risk of death associated with higher versus lower exposure category. Disease severity indicators were identified among the administrative data and entered as covariates in each model. The main outcomes were all-cause mortality and death from an acute ischemic event.

RESULTS

The mean age of the cohort members was 66.3 (standard deviation [SD] 13.4) years; 43.4% were female; and their mean duration of follow-up was 4.6 (SD 2.1) years. First-generation sulfonylureas were used exclusively by 120 subjects; glyburide, by 4138; and metformin, by 1537. A greater risk of death was associated with higher daily doses of the first-generation sulfonylureas (adjusted hazard ratio [HR] 2.1, 95% confidence interval [CI] 1.0-4.7) and glyburide (HR 1.3, 95% CI 1.2-1.4), but not metformin (HR 0.8, 95% CI 0.7-1.1). Similar associations were observed for death caused by an acute ischemic event.

INTERPRETATION

Higher exposure to sulfonylureas was associated with increased mortality among patients newly treated for type 2 diabetes. The same relation was not observed with metformin. This implies that the manner in which blood glucose concentration is lowered may be as important as achieving recommended glucose targets.

Glimepiride induces nitric oxide production in human coronary artery endothelial cells via a PI3-kinase-Akt dependent pathway

Diabetes mellitus is one of the major risk factors for coronary artery disease (CAD). A recent study reported that glimepiride, a new third-generation sulfonylurea, inhibited the formation of atheromatous plaques in high-cholesterol fed rabbits. However, the mechanism by which glimepiride induces atheroprotection remains unknown. In the present study, we tested the hypothesis that glimepiride may stimulate NO production in vascular endothelial cells. Human coronary artery endothelial cells (HCAECs) were treated with glimepiride, glibenclamide or vehicle, and NO release was measured. Akt phosphorylation was evaluated by Western blot. The effects of LY294002, a specific PI3-kinase inhibitor, and antisense oligonucleotides directed to Akt, on glimepiride-induced NO production were examined. Glimepiride (0.1-10 microM), but not glibenclamide, induced NO production, significantly increasing it by 1.8-fold (n=6, p<0.05). LY294002 inhibited glimepiride-induced NO production by 68%. Akt was rapidly phosphorylated by glimepiride and antisense oligonucleotides directed to Akt completely inhibited glimepiride-induced NO production. These data demonstrate that glimepiride induces NO production in HCAECs by activating PI3-kinase and Akt, and also suggest that use of glimepiride in type 2 diabetes may show promise for preventing CAD in addition to lowering glucose levels.