Troglitazone combination therapy in obese type 2 diabetic patients poorly controlled with alpha-glucosidase inhibitors

Safety and efficacy of low dose pioglitazone compared with standard dose pioglitazone in type 2 diabetes with chronic kidney disease: A randomized controlled trial

Background

Choices of hypoglycemic agents for patients with type 2 diabetes and chronic kidney disease (CKD) are limited. Available data among patients with CKD suggest that pioglitazone was effective and safe, with no increase in serious adverse effects. However, weight gain and fluid retention are major clinical problems for pioglitazone among patients with CKD. We conducted this study to compare the efficacy and side effects of low dose pioglitazone with standard dose pioglitazone among patients with type 2 diabetes and CKD.

Methods

A total of 75 patients with type 2 diabetes and CKD and inadequate glycemic control receiving any pharmacological antidiabetic treatment were randomly assigned to 2 groups. One group consisted of 37 patients treated with standard dose pioglitazone (15 mg/day) and another group consisted of 38 patients treated with low dose pioglitazone (7.5 mg/day). Glycosylated hemoglobinA1c (HbA1c) and metabolic profiles were monitored every 8 weeks for 24 weeks. Body composition was assessed using bio-electrical impedance analysis (BIA).

Results

After 6 months of therapy, HbA1c levels decreased in both standard and low dose pioglitazone groups. The mean changes in HbA1c for standard and low dose pioglitazone were 1.1±1.6 and -1.4±1.5 (P = 0.543), respectively. Compared with low dose pioglitazone, standard dose pioglitazone treatment led to a greater increase in body weight, fat mass, total body water and extracellular water composition. No major adverse effects including hypoglycemia, congestive heart failure and abnormal liver function were identified.

Conclusion

Pioglitazone 7.5 mg once daily treatments presented similar glycemic control to standard dose pioglitazone and exhibited beneficial effects on weight gain and fluid retention among patients with type 2 diabetes and CKD.

PPAR agonists for the treatment of cardiovascular disease in patients with diabetes

Diabetes is a complex disease defined by hyperglycaemia; however, strong associations with abdominal obesity, hypertension and dyslipidaemia contribute to the high risk of cardiovascular disease. Although aggressive glycaemic control reduces microvascular complications, the evidence for macrovascular complications is less certain. The theoretical benefits of the mode of action of peroxisome proliferator-activated receptor (PPAR) agonists are clear. In clinical practice, PPAR-α agonists such as fibrates improve dyslipidaemia, while PPAR-γ agonists such as thiazolidinediones improve insulin resistance and diabetes control. However, although these agents are traditionally classed according to their target, they have different and sometimes conflicting clinical benefit and adverse event profiles. It is speculated that this is because of differing properties and specificities for the PPAR receptors (each of which targets specific genes). This is most obvious in the impact on cardiovascular outcomes--in clinical trials pioglitazone appeared to reduce cardiovascular events, whereas rosiglitazone potentially increased the risk of myocardial infarction. The development of a dual PPAR-α/γ agonist may prove beneficial in effectively managing glycaemic control and improving dyslipidaemia in patients with type 2 diabetes. Yet, development of agents such as muraglitazar and tesaglitazar has been hindered by various serious adverse events. Aleglitazar, a balanced dual PPAR-α/γ agonist, is currently the most advanced in clinical development and has shown promising results in phase II clinical trials with beneficial effects on glucose and lipid variables. A phase III study, ALECARDIO, is ongoing and will establish whether improvements in laboratory test profiles translate into an improvement in cardiovascular outcomes.

Reversible mitral and aortic regurgitation due to pioglitazone

OBJECTIVE

To report the occurrence of pioglitazone-induced reversible valvular regurgitant lesions.

METHODS

Clinical, laboratory, and imaging data are reported on a patient with known type 2 diabetes mellitus, who was prescribed pioglitazone to achieve better glycemic control.

RESULTS

We present a case report of a 50-year-old woman, in whom diabetes had been diagnosed 5 years previously, who developed severe mitral and aortic regurgitation during 5 months of treatment with pioglitazone along with clinical and laboratory indications of fluid retention. Echocardiography 5 months after discontinued use of pioglitazone showed regression of regurgitant lesions and normalization of pertinent laboratory variables.

CONCLUSION

Five months of treatment with pioglitazone could potentially induce major cardiac valvular dysfunction, which was reversible in our patient. This report emphasizes the importance of carefully monitoring patients during treatment with thiazolidinediones.

The safety of thiazolidinediones

INTRODUCTION

The prevalence of type 2 diabetes mellitus (T2DM) has reached epidemic proportions. Many new therapies have emerged, including thiazolidinediones (TZDs), selective agonists of PPAR-γ, now used as both primary and add-on therapies. Given that T2DM is a lifetime disease, there is a need for assurance that new drugs are both safe and effective. Recent concern about the cardiovascular safety of one of the new drugs, rosiglitazone, is the stimulus for this review.

AREAS COVERED

The safety of pioglitazone and rosiglitazone under the headings of liver safety, cardiovascular safety, fluid retention, weight gain and bone fractures is reviewed based on a PubMed search of the years 1997 through June 2010. This review also describes the magnitude of the risks of the TZDs and provides a recommendation on the use of TZDs.

EXPERT OPINION

Liver safety is no longer an issue with the TZDs. There are no significant differences between rosiglitazone and pioglitazone in fluid retention, weight gain and bone fractures. However, pioglitazone tends to be cardioprotective while rosiglitazone is cardiotoxic. There is no current justification for prescribing rosiglitazone.

Glitazone use associated with diabetic macular edema

PURPOSE

To determine the ocular safety of glitazones in patients with diabetes, we investigated the association of diabetic macular edema (DME) in a large population of glitazone users.

DESIGN

Prospective cohort study.

METHODS

The study was conducted at Kaiser Permanente Southern California. About 170,000 persons with diabetes were identified using the Diabetes Case Identification Database. Glitazone drug use was obtained from the pharmacy database. The main outcome measure was the development of macular edema (ME). The chi2 test was used to compare proportions and t tests were used for means. Logistic regression analysis was used to adjust for potential confounding variables.

RESULTS

In 2006, there were 996 new cases of ME. Glitazone users were more likely to develop ME in 2006 (odds ratio [OR], 2.6; 95% confidence interval [CI], 2.4 to 3.0). After excluding patients who did not have the drug benefit, did not have an eye exam, and had a HgA1c <7.0, glitazone use was still associated with an increased risk of developing ME (OR, 1.6; 95% CI, 1.4 to 1.8).

CONCLUSION

The current study appears to show that the glitazone class of drug is associated with DME. After adjusting for confounding factors of age, glycemic control, and insulin use, glitazones are still modestly associated with DME. A more in-depth study will need to be done to evaluate the role of other confounding factors. When treating patients with DME, ophthalmologists should consider the role of the glitazones.

Fixed-dose combination of pioglitazone and glimepiride in the treatment of Type 2 diabetes mellitus

Type 2 diabetes is characterized by impaired insulin sensitivity and disturbances in β-cell function. While glimepiride stimulates β-cell secretion and leads to a reduction of blood glucose levels, pioglitazone activates peroxisome proliferator-activated receptor-γ and improves insulin resistance. Combining these two modes of action has been shown to improve glucose and lipid metabolism, and to improve the overall cardiovascular risk in patients with Type 2 diabetes. The combination of glimepiride and pioglitazone is generally well tolerated and a fixed combination may lead to an improved compliance in patients. The purpose of this review is to evaluate the clinical data that has been published on this combination, appearing to represent a convenient way to obtain therapeutic targets in patients with Type 2 diabetes mellitus.

Kidney-specific gene targeting: insight into thiazolidinedione-induced fluid retention

Conditional gene targeting technique, which is based on the use of Cre-loxP or Flp/FRT systems, has been increasingly used to study gene function of a particular cell type in vivo. The introduction of this technique to the kidney field is relatively recent but has already provided important insights into physiological or pathological functions of a number of genes in the kidney. This technique has recently been used to inactivate the peroxisome proliferator-activated receptor subtype gamma in the collecting duct, which leads to remarkable blockade of body weight gains and plasma volume expansion associated with thiazolidinediones. This finding not only helps understand pharmacology of the novel class of antidiabetic drugs, but also uncovers an important role of peroxisome proliferator-activated receptor subtype gamma in regulation of distal nephron fluid reabsorption. The present review represents an example for the use of the modern technique to address complex clinical problems. It is anticipated that over next few years this technique will be used by an increasing number of investigators for studying gene function in the kidney.

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.

The insulin sensitiser pioglitazone does not influence skin microcirculatory function in patients with type 2 diabetes treated with insulin

AIMS/HYPOTHESIS

Insulin resistance is associated with abnormal microvascular function. Treatment with insulin sensitisers may provoke oedema, suggesting microvascular effects. The mechanisms underlying the peripheral oedema observed during glucose-lowering treatment with thiazolidinediones are unclear. Therefore we examined the effect of pioglitazone on microvascular variables involved in oedema formation.

METHODS

Subjects (40-80 years) with type 2 diabetes and on insulin were randomised to 9 weeks of pioglitazone therapy (30 mg/day; n=14) or placebo (n=15). The following assessments were performed at baseline and 9 weeks: microvascular filtration capacity; isovolumetric venous pressure; capillary pressure; capillary recruitment following venous or arterial occlusion; postural vasoconstriction; and maximum blood flow. A number of haematological variables were also measured including vascular endothelium growth factor (VEGF), IL-6 and C-reactive protein (CRP).

RESULTS

Pioglitazone did not significantly influence any microcirculatory variable as compared with placebo (analysis of covariance [ANCOVA] for microvascular filtration capacity for the two groups, p=0.26). Mean VEGF increased with pioglitazone (61.1 pg/ml), but not significantly more than placebo (9.76 pg/ml, p=0.94). HbA(1c) levels and the inflammatory markers IL-6 and CRP decreased with pioglitazone compared with placebo (ANCOVA: p=0.009, p=0.001 and p=0.004, respectively).

CONCLUSIONS/INTERPRETATION

Pioglitazone improved glycaemic control and inflammatory markers over 9 weeks but had no effect on microcirculatory variables associated with oedema or insulin resistance in type 2 diabetic patients treated with insulin.

Collecting duct-specific deletion of peroxisome proliferator-activated receptor gamma blocks thiazolidinedione-induced fluid retention

The peroxisome proliferator-activated receptor subtype gamma (PPARgamma) ligands, namely the synthetic insulin-sensitizing thiazolidinedione (TZD) compounds, have demonstrated great potential in the treatment of type II diabetes. However, their clinical applicability is limited by a common and serious side effect of edema. To address the mechanism of TZD-induced edema, we generated mice with collecting duct (CD)-specific disruption of the PPARgamma gene. We found that mice with CD knockout of this receptor were resistant to the rosiglitazone- (RGZ) induced increases in body weight and plasma volume expansion found in control mice expressing PPARgamma in the CD. RGZ reduced urinary sodium excretion in control and not in conditional knockout mice. Furthermore, RGZ stimulated sodium transport in primary cultures of CD cells expressing PPARgamma and not in cells lacking this receptor. These findings demonstrate a PPARgamma-dependent pathway in regulation of sodium transport in the CD that underlies TZD-induced fluid retention.

Thiazolidinedione therapy: the benefits of aggressive and early use in type 2 diabetes

Type 2 diabetes is now a global epidemic, with the number of people affected worldwide predicted to more than double to 300 million by the year 2025. While the importance of good glycemic control in countering the microvascular and macrovascular complications of diabetes is widely recognized, monotherapy with sulfonylureas or metformin achieves target blood glucose levels in only a minority of patients. Consequently, there is a pressing need for new treatment strategies that are more effective in providing sustained glycemic control and so reducing the burden of morbidity and mortality associated with diabetes and its complications. There is growing evidence of the benefits of early intervention with aggressive treatment strategies in improving glycemic control and reducing diabetic complications. To provide sustained control, such strategies need to address the combination of insulin resistance and beta-cell dysfunction that underlies most cases of type 2 diabetes. At the same time, treatment needs to address not only glycemic control but also the range of cardiovascular risk factors that are often found clustered together in patients with type 2 diabetes. This paper reviews the rationale and evidence for early combination therapy including a thiazolidinedione in improving glycemic control, and considers the potential for such aggressive therapy in reducing diabetic complications.

Troglitazone: the discovery and development of a novel therapy for the treatment of Type 2 diabetes mellitus

Prior to the introduction of troglitazone, it had been more than 30 years since the last significant improvement in antidiabetic therapy. In view of the pressing need for more effective oral agents for the treatment of Type 2 diabetes mellitus, troglitazone was granted priority review by the FDA and was launched in the USA in 1997. The first of the thiazolidinedione insulin sensitizing agents, troglitazone was quickly followed by rosiglitazone and pioglitazone. The glitazones proved to be effective not only in lowering blood glucose, but also to have beneficial effects on cardiovascular risk. Troglitazone was subsequently withdrawn because of concerns about hepatotoxicity, which appears to be less of a problem with rosiglitazone and pioglitazone. Recent insights into the molecular mechanism of action of the glitazones, which are ligands for the peroxisome proliferator-activated receptors, open the prospect of designing more effective, selective and safer antidiabetic agents. This document will review the history of troglitazone from discovery through clinical development.

A comparison of the effects of rosiglitazone and glyburide on cardiovascular function and glycemic control in patients with type 2 diabetes

OBJECTIVE

This open-label, active-controlled study investigated the cardiac safety and antihyperglycemic effect of rosiglitazone (RSG) in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Of the 203 patients randomly assigned to RSG (4 mg b.i.d.) or glyburide (GLB) (titrated to achieve optimal glycemic control for the first 8 weeks only to limit the risk of hypoglycemia; mean 10.5 mg/day), 118 had an echocardiogram performed at week 52. Left ventricular (LV) mass index, ejection fraction, and left ventricular end-diastolic volume were assessed by M-mode echocardiography at baseline and weeks 12, 28, and 52; 24-h ambulatory blood pressure was assessed at baseline and at weeks 28 and 52. Glycemic control was assessed by measuring fasting plasma glucose (FPG) and HbA(1c).

RESULTS

Neither treatment produced an increase in LV mass index that exceeded 1 SD. Ejection fraction did not change in either group. Both groups had clinically insignificant increases in LV end-diastolic volume. RSG, but not GLB, caused a statistically significant reduction in ambulatory diastolic blood pressure. Both treatments reduced HbA(1c) and FPG.

CONCLUSIONS

A total of 52 weeks of therapy with RSG (4 mg b.i.d.) did not adversely affect cardiac structure or function in patients with type 2 diabetes and produced significant and sustained reductions in hyperglycemia. Decreases in ambulatory diastolic blood pressure with RSG were superior to those with GLB.

Thiazolidinedione-induced edema

Edema is an adverse event associated with thiazolidinedione therapy The potential for mild-to-moderate peripheral edema with thiazolidinedione is known, especially in patients who have heart failure or use insulin. Our experience reveals that patients who do not have heart failure or do not use insulin also can develop moderate-to-severe edema that necessitates discontinuation of the thiazolidinedione. A 77-year-old man developed ankle, hand, and facial swelling 2 weeks after starting rosiglitazone. After discontinuing the drug, his edema resolved. A 75-year-old man developed bilateral lower leg edema 6 months after switching from troglitazone to pioglitazone. He was hospitalized for 51 days and, after aggressive diuresis and discontinuation of pioglitazone, was discharged with a weight loss of 30 pounds. A 53-year-old man developed lower leg edema 4 weeks after rosiglitazone was increased from 4 mg once/day to 4 mg twice/day. Rosiglitazone was discontinued and the edema resolved. Until the mechanism of action responsible for fluid overload is known, we suggest that thiazolidinediones be administered with caution in all patients.

Insulin sensitiser drugs

Insulin resistance is the predominant early pathological defect in Type 2 diabetes. As well as being a risk factor for the development of Type 2 diabetes, insulin resistance is also associated with increased cardiovascular risk and other metabolic disturbances including visceral adiposity, hyperinsulinaemia, impaired glucose tolerance, hypertension and dyslipidaemia [1-4]. The newest approach to oral antidiabetic therapy is to target improvements in insulin sensitivity at muscle, adipose tissue and hepatic level. This results in improvements in glycaemic control and other features of the insulin resistance syndrome, with potential long-term benefits in preventing/delaying the onset of diabetic complications and macrovascular disease.