Pharmacokinetics of rosiglitazone in patients with end-stage renal disease

Physiologically based pharmacokinetic modeling of CYP2C8 substrate rosiglitazone and its metabolite to predict metabolic drug-drug interaction

Rosiglitazone is an activator of nuclear peroxisome proliferator-activated (PPAR) receptor gamma used in the treatment of type 2 diabetes mellitus. The elimination of rosiglitazone occurs mainly via metabolism, with major contribution by enzyme cytochrome P450 (CYP) 2C8. Primary routes of rosiglitazone metabolism are N-demethylation and hydroxylation. Modulation of CYP2C8 activity by co-administered drugs lead to prominent changes in the exposure of rosiglitazone and its metabolites. Here, we attempt to develop mechanistic parent-metabolite physiologically based pharmacokinetic (PBPK) model for rosiglitazone. Our goal is to predict potential drug-drug interaction (DDI) and consequent changes in metabolite N-desmethyl rosiglitazone exposure. The PBPK modeling was performed in the PKSim® software using clinical pharmacokinetics data from literature. The contribution to N-desmethyl rosiglitazone formation by CYP2C8 was delineated using vitro metabolite formation rates from recombinant enzyme system. Developed model was verified for prediction of rosiglitazone DDI potential and its metabolite exposure based on observed clinical DDI studies. Developed model exhibited good predictive performance both for rosiglitazone and N-desmethyl rosiglitazone respectively, evaluated based on commonly acceptable criteria. In conclusion, developed model helps with prediction of CYP2C8 DDI using rosiglitazone as a substrate, as well as changes in metabolite exposure. In vitro data for metabolite formation can be successfully utilized to translate to in vivo conditions.

MitoToxy assay: A novel cell-based method for the assessment of metabolic toxicity in a multiwell plate format using a lactate FRET nanosensor, Laconic

Mitochondrial toxicity is a primary source of pre-clinical drug attrition, black box warning and post-market drug withdrawal. Methods that detect mitochondrial toxicity as early as possible during the drug development process are required. Here we introduce a new method for detecting mitochondrial toxicity based on MDA-MB-231 cells stably expressing the genetically encoded FRET lactate indicator, Laconic. The method takes advantage of the high cytosolic lactate accumulation observed during mitochondrial stress, regardless of the specific toxicity mechanism, explained by compensatory glycolytic activation. Using a standard multi-well plate reader, dose-response curve experiments allowed the sensitivity of the methodology to detect metabolic toxicity induced by classical mitochondrial toxicants. Suitability for high-throughput screening applications was evaluated resulting in a Z’-factor > 0.5 and CV% < 20 inter-assay variability. A pilot screening allowed sensitive detection of commercial drugs that were previously withdrawn from the market due to liver/cardiac toxicity issues, such as camptothecin, ciglitazone, troglitazone, rosiglitazone, and terfenadine, in ten minutes. We envisage that the availability of this technology, based on a fluorescent genetically encoded indicator, will allow direct assessment of mitochondrial metabolism, and will make the early detection of mitochondrial toxicity in the drug development process possible, saving time and resources.

Is the management of diabetes different in dialysis patients?

Diabetes is highly and increasingly prevalent in the dialysis population and negatively impacts both quality and quantity of life. Nevertheless, the best approach to these patients is still debatable. The question of whether the management of diabetes should be different in dialysis patients does not have a clear yes or no answer but is divided into too many sub-issues that should be carefully considered. In this review, lifestyle, cardiovascular risk, and hyperglycemia management are explored, emphasizing the possible pros and cons of a similar approach to diabetes in dialysis patients compared to the general population.

Therapeutic Considerations for Antihyperglycemic Agents in Diabetic Kidney Disease

Diabetic kidney disease is among the most frequent complications of diabetes, with approximately 50% of patients with ESRD attributed to diabetes in developed countries. Although intensive glycemic management has been shown to delay the onset and progression of increased urinary albumin excretion and reduced GFR in patients with diabetes, conservative dose selection and adjustment of antihyperglycemic medications are necessary to balance glycemic control with safety. A growing body of literature is providing valuable insight into the cardiovascular and renal safety and efficacy of newer antihyperglycemic medications in the dipeptidyl peptidase-4 inhibitor, glucagon-like peptide-1 receptor agonist, and sodium-glucose cotransporter 2 inhibitor classes of medications. Ongoing studies will continue to inform future use of these agents in patients with diabetic kidney disease.

Anti-Hyperglycemic Agents and New-Onset Acute Myocardial Infarction in Diabetic Patients with End-Stage Renal Disease Undergoing Dialysis

BACKGROUND

Diabetes and chronic kidney disease (CKD) are a high-stakes combination for cardiovascular disease. Patients with decreased kidney function and end-stage renal disease (ESRD) have increased risk of hypoglycemia when attaining better glycemic control, leading to higher risk of myocardial infarction (MI). For these patients, which kinds of anti-hyperglycemic agents would be associated with higher risk of MI is not clear.

METHODS

We identified patients from a nation-wide database called Registry for Catastrophic Illness, which encompassed almost 100% of the patients receiving dialysis therapy in Taiwan from 1995 to 2008. Patients with diabetes and ESRD were selected as the study cohort. Propensity score adjustment and Cox's proportional hazards regression model were used to estimate the hazard ratios (HRs) for new-onset MI.

RESULTS

Among 15,161 patients, 39% received insulin, 40% received sulfonylureas, 18% received meglitinides and 3% received thiazolidinedione (TZD). After a median follow-up of 1,357 days, the incidence of MI was significant increase in patients taking sulfonylureas (HR = 1.523, 95% confidence interval [CI] = 1.331-1.744), meglitinides (HR = 1.251, 95% CI = 1.048-1.494) and TZD (HR = 1.515, 95% CI = 1.071-2.145) by using patients receiving insulin therapy as the reference group. The risk of MI remains higher in other three groups in subgroup analyses.

CONCLUSIONS

In conclusion, among diabetic patients with ESRD undergoing dialysis, the use of sulfonylureas, meglitinides and TZD are associated with higher risk of new-onset MI as compared with insulin.

Diabetes therapies in hemodialysis patients: Dipeptidase-4 inhibitors

Although several previous studies have been published on the effects of dipeptidase-4 (DPP-4) inhibitors in diabetic hemodialysis (HD) patients, the findings have yet to be reviewed comprehensively. Eyesight failure caused by diabetic retinopathy and aging-related dementia make multiple daily insulin injections difficult for HD patients. Therefore, we reviewed the effects of DPP-4 inhibitors with a focus on oral antidiabetic drugs as a new treatment strategy in HD patients with diabetes. The following 7 DPP-4 inhibitors are available worldwide: sitagliptin, vildagliptin, alogliptin, linagliptin, teneligliptin, anagliptin, and saxagliptin. All of these are administered once daily with dose adjustments in HD patients. Four types of oral antidiabetic drugs can be administered for combination oral therapy with DPP-4 inhibitors, including sulfonylureas, meglitinide, thiazolidinediones, and alpha-glucosidase inhibitor. Nine studies examined the antidiabetic effects in HD patients. Treatments decreased hemoglobin A1c and glycated albumin levels by 0.3% to 1.3% and 1.7% to 4.9%, respectively. The efficacy of DPP-4 inhibitor treatment is high among HD patients, and no patients exhibited significant severe adverse effects such as hypoglycemia and liver dysfunction. DPP-4 inhibitors are key drugs in new treatment strategies for HD patients with diabetes and with limited choices for diabetes treatment.

Diabetic kidney disease: a report from an ADA Consensus Conference

The incidence and prevalence of diabetes mellitus have grown significantly throughout the world, due primarily to the increase in type 2 diabetes. This overall increase in the number of people with diabetes has had a major impact on development of diabetic kidney disease (DKD), one of the most frequent complications of both types of diabetes. DKD is the leading cause of end-stage renal disease (ESRD), accounting for approximately 50% of cases in the developed world. Although incidence rates for ESRD attributable to DKD have recently stabilized, these rates continue to rise in high-risk groups such as middle-aged African Americans, Native Americans, and Hispanics. The costs of care for people with DKD are extraordinarily high. In the Medicare population alone, DKD-related expenditures among this mostly older group were nearly $25 billion in 2011. Due to the high human and societal costs, the Consensus Conference on Chronic Kidney Disease and Diabetes was convened by the American Diabetes Association in collaboration with the American Society of Nephrology and the National Kidney Foundation to appraise issues regarding patient management, highlighting current practices and new directions. Major topic areas in DKD included 1) identification and monitoring, 2) cardiovascular disease and management of dyslipidemia, 3) hypertension and use of renin-angiotensin-aldosterone system blockade and mineralocorticoid receptor blockade, 4) glycemia measurement, hypoglycemia, and drug therapies, 5) nutrition and general care in advanced-stage chronic kidney disease, 6) children and adolescents, and 7) multidisciplinary approaches and medical home models for health care delivery. This current state summary and research recommendations are designed to guide advances in care and the generation of new knowledge that will meaningfully improve life for people with DKD.

Sources of interindividual variability

The efficacy, safety, and tolerability of drugs are dependent on numerous factors that influence their disposition. A dose that is efficacious and safe for one individual may result in sub-therapeutic or toxic blood concentrations in other individuals. A major source of this variability in drug response is drug metabolism, where differences in pre-systemic and systemic biotransformation efficiency result in variable degrees of systemic exposure (e.g., AUC, C max, and/or C min) following administration of a fixed dose.Interindividual differences in drug biotransformation have been studied extensively. It is well recognized that both intrinsic (such as genetics, age, sex, and disease states) and extrinsic (such as diet, chemical exposures from the environment, and even sunlight) factors play a significant role. For the family of cytochrome P450 enzymes, the most critical of the drug metabolizing enzymes, genetic variation can result in the complete absence or enhanced expression of a functional enzyme. In addition, up- and down-regulation of gene expression, in response to an altered cellular environment, can achieve the same range of metabolic function (phenotype), but often in a less reliably predictable and time-dependent manner. Understanding the mechanistic basis for drug disposition and response variability is essential if we are to move beyond the era of empirical, trial-and-error dose selection and into an age of personalized medicine that brings with it true improvements in health outcomes in the therapeutic treatment of disease.

Pharmacokinetic considerations for the treatment of diabetes in patients with chronic kidney disease

INTRODUCTION

People with chronic kidney disease (CKD) of stages 3 - 5 (creatinine clearance < 60 ml/min) represent ≈ 25% of patients with type 2 diabetes mellitus (T2DM), but the problem is underrecognized or neglected in clinical practice. However, most oral antidiabetic agents have limitations in case of renal impairment (RI), either because they require a dose adjustment or because they are contraindicated for safety reasons.

AREAS COVERED

The author performed an extensive literature search to analyze the influence of RI on the pharmacokinetics (PK) of glucose-lowering agents and the potential consequences for clinical practice.

EXPERT OPINION

As a result of PK interferences and for safety reasons, the daily dose should be reduced according to glomerular filtration rate (GFR) or even the drug is contraindicated in presence of severe CKD. This is the case for metformin (risk of lactic acidosis) and for many sulfonylureas (risk of hypoglycemia). At present, however, the exact GFR cutoff for metformin use is controversial. New antidiabetic agents are better tolerated in case of CKD, although clinical experience remains quite limited for most of them. The dose of DPP-4 inhibitors should be reduced (except for linagliptin), whereas both the efficacy and safety of SGLT2 inhibitors are questionable in presence of CKD.

Cardiac ion channel modulation by the hypoglycaemic agent rosiglitazone

The hypoglycaemic thiazolidinedione rosiglitazone is used clinically in the treatment of type 2 diabetes. However, in 2010, information relating to rosiglitazone-associated increased cardiovascular risk led the European Medicines Agency to recommend suspension of marketing authorizations for rosiglitazone-containing anti-diabetes drugs, while the US Food and Drug Administration recommended significant restriction on the agent's use. Two timely studies in this issue of the British Journal of Phrarmacology provide new information regarding modification of cardiac cellular electrophysiology by rosiglitazone. Szentandrássy et al. demonstrate canine ventricular action potential modification and concentration-dependent suppression of L-type Ca current and of transient outward and rapid delayed rectifier K currents. Jeong et al. demonstrate concentration-dependent inhibition of recombinant K(v) 4.3 channels, providing mechanistic insight into the likely molecular basis of transient outward K current inhibition by the compound. Further studies using diabetic models would be of value to determine whether, in a diabetic setting, rosiglitazone modification of these channels could affect the risk of arrhythmia at clinically relevant drug concentrations.

Rapid and contrasting effects of rosiglitazone on transient receptor potential TRPM3 and TRPC5 channels

The aim of this study was to generate new insight into chemical regulation of transient receptor potential (TRP) channels with relevance to glucose homeostasis and the metabolic syndrome. Human TRP melastatin 2 (TRPM2), TRPM3, and TRP canonical 5 (TRPC5) were conditionally overexpressed in human embryonic kidney 293 cells and studied by using calcium-measurement and patch-clamp techniques. Rosiglitazone and other peroxisome proliferator-activated receptor-γ (PPAR-γ) agonists were investigated. TRPM2 was unaffected by rosiglitazone at concentrations up to 10 μM but was inhibited completely at higher concentrations (IC(50), ∼22.5 μM). TRPM3 was more potently inhibited, with effects occurring in a biphasic concentration-dependent manner such that there was approximately 20% inhibition at low concentrations (0.1-1 μM) and full inhibition at higher concentrations (IC(50), 5-10 μM). PPAR-γ antagonism by 2-chloro-5-nitrobenzanilide (GW9662) did not prevent inhibition of TRPM3 by rosiglitazone. TRPC5 was strongly stimulated by rosiglitazone at concentrations of ≥10 μM (EC(50), ∼30 μM). Effects on TRPM3 and TRPC5 occurred rapidly and reversibly. Troglitazone and pioglitazone inhibited TRPM3 (IC(50), 12 μM) but lacked effect on TRPC5, suggesting no relevance of PPAR-γ or the thiazolidinedione moiety to rosiglitazone stimulation of TRPC5. A rosiglitazone-related but nonthiazolidinedione PPAR-γ agonist, N-(2-benzoylphenyl)-O-[2-(methyl-2-pyridinylamino)ethyl]-l-tyrosine (GW1929), was a weak stimulator of TRPM3 and TRPC5. The natural PPAR-γ agonist 15-deoxy prostaglandin J(2), had no effect on TRPM3 or TRPC5. The data suggest that rosiglitazone contains chemical moieties that rapidly, strongly, and differentially modulate TRP channels independently of PPAR-γ, potentially contributing to biological consequences of the agent and providing the basis for novel TRP channel pharmacology.

[Diagnosis, treatment and prevention of renal diseases in HIV infected patients. Recommendations of the Spanish AIDS Study Group/National AIDS Plan]

The incidence of opportunistic infections and tumours in HIV-infected patients has sharply declined in the HAART era. At the same time there has been a growing increase of other diseases not directly linked to immunodeficiency. Renal diseases are an increasing cause of morbidity and mortality among HIV-infected patients. In the general population, chronic renal failure has considerable multiorgan repercussions that have particular implications in patients with HIV infection. The detection of occult or subclinical chronic kidney disease is crucial since effective measures for delaying progression exist. Furthermore, the deterioration in glomerular filtration should prompt clinicians to adjust doses of some antiretroviral agents and other drugs used for treating associated comorbidities. Suppression of viral replication, strict control of blood pressure, dyslipidemia and diabetes mellitus, and avoidance of nephrotoxic drugs in certain patients are fundamental components of programs aimed to prevent renal damage and delaying progression of chronic kidney disease in patients with HIV. Renal transplantation and dialysis have also special implications in HIV-infected patients. In this article, we summarise the updated clinical practice guidelines for the evaluation, management and prevention of renal diseases in HIV-infected patients from a panel of experts in HIV and nephrologists on behalf of the Spanish AIDS Study Group (GESIDA) and the National AIDS Plan.

Antidiabetic medication use and prevalence of chronic kidney disease among patients with type 2 diabetes mellitus in the United States

OBJECTIVES

The aims of this study were to estimate the proportion of patients with type 2 diabetes mellitus (DM) in the United States with different stages of chronic kidney disease (CKD) and to describe glycemic control and antidiabetic drug use among them.

METHODS

Using data from the Fourth National Health and Nutrition Examination Survey (NHANES IV) for the years 1999 through 2004, we performed a cross-sectional analysis of patients with type 2 DM aged >or=20 years at the time of the survey interview. CKD stages were categorized according to the classification system established by the National Kidney Foundation Kidney Disease Outcomes Quality Initiative. Anti-diabetic medication use among these patients was described using self-reported survey responses as well as survey medication files.

RESULTS

A total of 1462 patients with type 2 DM were included in the analysis. Men and women constituted 48.3% and 51.7% of the study sample, respectively; 15.6% received a DM diagnosis <2 years ago, and 36.2% received their diagnosis >10 years ago. CKD was present in 39.7% of patients with DM. Mean (SE) glycosylated hemoglobin was lower in more advanced CKD stages, from stage 1 (8.35% [0.23%]) to combined stages 4 and 5 (6.63% [0.15%]). Based on the medication file data, the proportion of patients with CKD using 1 antidiabetic medication was higher as CKD progressed, from 36.3% at stage 1 to 62.9% at stages 4 and 5 (P = 0.007). By self-report, the proportion of patients with CKD using insulin alone was 6.7% at stage 1 and 38.8% at stages 4 and 5 (P < 0.001). The proportion of patients using oral antidiabetic agents alone was 69.0% at stage 1 and 43.4% at stages 4 and 5 (P < 0.001).

CONCLUSIONS

Our results indicate that 39.7% of adult patients with type 2 DM in the United States had some degree of CKD, as measured in NHANES IV for the years 1999 through 2004. This finding reinforces the need to screen patients with type 2 DM for CKD and to prevent the cascade of events leading to nephropathy by implementing adequate glycemic and blood pressure controls, especially in the early stages of CKD. Our data also reinforce the need for developing more oral antidiabetic therapies for patients with advanced CKD and type 2 DM, because treatment options for this group are limited.

Selection and dosing of medications for management of diabetes in patients with advanced kidney disease

Diabetes mellitus is a leading cause of kidney disease worldwide. A large and expanding array of treatments for diabetes is available to improve glycemic control, including newer classes of drugs, such as thiazolidinediones and incretin-based therapies. The presence of impaired kidney function with reduced glomerular filtration rate should influence choices, dosing, and monitoring of hypoglycemic agents, as some agents require a dosing adjustment in patients with kidney disease and some are entirely contraindicated. This article reviews the clinical use of insulin and other antidiabetic therapies, focusing on pharmacokinetic properties and dosing in patients with advanced kidney disease.

Induction of hepatic cytochrome P450 enzymes: methods, mechanisms, recommendations, and in vitro-in vivo correlations

Induction of drug-clearance pathways (Phase 1 and 2 enzymes and transporters) can have important clinical consequences. Inducers can (1) increase the clearance of other drugs, resulting in a decreased therapeutic effect, (2) increase the activation of pro-drugs, causing an alteration in their efficacy and pharmacokinetics, and (3) increase the bioactivation of drugs that contribute to hepatotoxicity via reactive intermediates. Nuclear receptors are key mediators of drug-induced changes in the expression of drug-clearance pathways. However, species differences in nuclear receptor activation make the prediction of cytochrome P450 (CYP) induction in humans from data derived from animal models problematic. Thus, in vitro human-relevant model systems are increasingly used to evaluate enzyme induction. In this review, the authors' current understanding of the mechanisms of enzyme induction and the in vitro methods for assessing the induction potential of new drugs will be discussed. Relevant issues and considerations surrounding proper study design and the interpretation of in vitro results will be discussed in light of the current US Food and Drug Administration (FDA) recommendations.

Diabetic nephropathy in the elderly

Renal impairment is frequent in aged diabetic patients, notably with type 2 diabetes. It results from a multifactorial pathogeny, particularly the combined actions of hyperglycaemia, arterial hypertension and ageing. Diabetic nephropathy (DN) is associated with an increased cardiovascular mortality. DN often leads to end stage renal failure (ESRF) which causes specific problems of decision and practical organization of extra-renal epuration in diabetic and aged patients. In the absence of renal biopsy, clinical signs are often insufficient to assess the diabetic origin of a nephropathy in an elderly diabetic patient. Prevention of DN is principally based on tight glycaemic and blood pressure control. The progression of renal lesions can be retarded by strict blood pressure control, notably by blocking of the renin-angiotensin system, if well tolerated in aged patients. It is absolutely necessary to avoid the worsening of renal lesions by potentially nephrotoxic products, notably non steroidal anti-inflammatory drugs (NSAIDs) and iodinated contrast media. At the stage of renal failure, it is important to adapt the antidiabetic treatment, and in the majority of the cases, to switch to insulin when glomerular filtration rate (GFR) is below 30 ml/mn/1.73 m2.

Regulation of the atherogenic properties of vascular smooth muscle proteoglycans by oral anti-hyperglycemic agents

The present study aimed to investigate the actions of several classes of oral hypoglycemic agents [e.g., sulfonylureas (SUs), biguanides (BGs) and thiazolidinediones (TZDs)] in an in vitro model of lipid binding based on the "response to retention" hypothesis of atherogenesis. The incorporation of [(35)S]-SO(4) into proteoglycans synthesized by human vascular smooth muscle cells (VSMCs) was assessed by cetylpyridinium chloride (CPC) precipitation method, proteoglycan electrophoretic mobility was evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and binding to low-density lipoprotein (LDL) was assessed by gel mobility shift assay (GMSA). The SUs evaluated showed no effect on [(35)S]-SO(4) incorporation into proteoglycans. Only one BG, phenformin, caused a concentration-related inhibition of proteoglycan synthesis under basal conditions and in the presence of transforming growth factor-beta1 (TGF-beta1), caused by an inhibition of proteoglycan core protein synthesis secondary to a reduction in total protein synthesis. However, neither metformin nor phenformin (30-300 micromol/l) had any effect on the electrophoretic mobility of proteoglycans. The TZDs--troglitazone (TRO), rosiglitazone (ROS), and pioglitazone (PIO) (10, 30, and 30 micromol/l, respectively)--inhibited proteoglycan biosynthesis and stimulated total proteoglycan core protein synthesis, while TRO alone inhibited overall protein synthesis. All three TZDs moderately reduced the electrophoretic mobility of synthesized proteoglycans assessed by SDS-PAGE, reduced the sizes of cleaved glycosaminoglycan (GAG) chains assessed by size exclusion chromatography, and significantly reduced binding to LDL. The data indicate that TZDs show anti-atherogenic actions through the modification of proteoglycan structure, leading to a possible reduction in lipid retention in the vessel wall.

Placental transfer of rosiglitazone in the ex vivo human perfusion model

OBJECTIVE

The objective of the study was to determine transplacental passage of rosiglitazone (Avandia) using the ex vivo human placental model.

STUDY DESIGN

Perfusion studies were performed on 10 placentas from term, uncomplicated deliveries. Concentrations typical for an 8-mg oral dose (216 to 692 ng/mL) as well as 2- to 3-fold increased concentrations were tested (734 to 1261 ng/mL). Transfer of rosiglitazone was assessed and accumulation was determined using the 14C-antipyrine reference method.

RESULTS

The clearance index for low and high concentrations were 0.14 +/- 0.04 and 0.20 +/- 0.08, suggesting that the drug passes through the placenta at a relatively low rate. Fetal accumulation occurred in only 1 of 5 placentas at 16.4 ng/mL (5%) for the 8-mg dose and in 2 of 5 placentas ranging from 0 to 74 ng/mL (5% to 8%) at higher concentrations.

CONCLUSION

There is minimal transfer and fetal accumulation of rosiglitazone according to the ex vivo human perfusion model.

Platelets as a Novel Target for PPAR?? Ligands

Peroxisome proliferator-activated receptor gamma (PPARgamma) is an important transcription factor for lipid and glucose metabolism. Currently, the PPARgamma ligands rosiglitazone and pioglitazone are used for the treatment of type 2 diabetes mellitus because they are potent insulin sensitizers. Recently, PPARgamma has emerged as an important anti-inflammatory factor. Platelets, anucleate cells involved in hemostasis, have also been implicated as key contributors to inflammation, because they produce many pro-inflammatory and pro-atherogenic mediators when activated. Surprisingly, it was discovered recently that platelets contain PPARgamma and that PPARgamma ligands, both natural and synthetic, inhibit platelet activation and release of bioactive mediators. In particular, release of soluble CD40 ligand (sCD40L) and thromboxane (TXA(2)) was inhibited by PPARgamma ligands in thrombin-activated platelets. CD40L signaling induces pro-inflammatory processes in many cell types, and increased blood levels of sCD40L are closely associated with inflammation, diabetes, and cardiovascular disease. Targeting platelet PPARgamma will, therefore, be an important treatment strategy for the attenuation of chronic inflammatory processes and prevention of thrombus formation.

The metabolic effects of troglitazone in patients with diabetes and end-stage renal disease

Thiazolidinediones (TZD) are effective agents for the treatment of hyperglycemia, and appear ideal in diabetic patients with progressive or end-stage renal disease because of its predominant hepatic clearance. Troglitazone, the first available TZD for clinical use, was withdrawn due to safety concerns; however, studies completed with this agent can provide a better understanding of the class effect of TZDs. This study was an open-label, controlled clinical trial examining the safety and efficacy of troglitazone in type 2 diabetic patients with end-stage renal disease (ESRD). Twelve subjects were randomized to parallel study groups and treated for 6 mo with or without troglita-zone at a maximum dose of 600 mg/d in addition to continuing their previous diabetes medications (insulin or sulfonylurea). The results showed no significant differences in glycemic control with or without troglit-azone treatment for 6 mo. However, there was a significant reduction in insulin dosage with troglitazone treatment (22.9 +/- 7.3 units/d) than without troglita-zone treatment (54 +/- 12.9 units/d) (p < 0.05), as well as the change in the insulin dosage from baseline between the two groups (troglitazone, -8.4 units vs control, +4.3 units, p < 0.05). Weight changes and aspartate amino-transferase levels greater than 1.5 times the upper limit of normal were not observed in participants of either treatment group. This study demonstrates that troglit-azone was safe and effective for the treatment of hyper-glycemia in patients requiring dialysis, and strongly supports the clinical use of currently available TZDs in diabetic patients with renal failure.

Rosiglitazone Reduces Insulin Requirement and C-Reactive Protein Levels in Type 2 Diabetic Patients Receiving Peritoneal Dialysis

BACKGROUND

Glycemic control is important in determining the outcome of patients with diabetes on dialysis therapy. However, the choice of oral hypoglycemia agent is limited in these patients. Very often, a high dose of insulin is required because of the uremia-associated insulin-resistant state. Rosiglitazone (RSG), a thiazolidinedione, can improve insulin resistance, and its excretion does not rely on renal function. Moreover, it has an anti-inflammatory effect that might be beneficial in patients with renal failure.

METHODS

An open-label randomized study was performed in which 52 patients with type 2 diabetes on peritoneal dialysis therapy administered a constant dosage of subcutaneous insulin with stable glycemic control were randomly assigned to the administration of either RSG (fixed dose, 4 mg) plus insulin or insulin alone. Insulin was titrated to maintain hemoglobin A1c (HbA1c) and blood glucose at pretreatment levels. Study duration was 24 weeks.

RESULTS

Both groups had similar baseline demographic characteristics, HbA1c and glucose levels, insulin requirement, and C-reactive protein (CRP) levels. Insulin requirement was decreased significantly in the RSG group (27.88 +/- 17.6 to 22.4 +/- 15.21 U/d; P < 0.001). There was a significantly greater decrease in insulin dosage in the RSG than control group (-21.5% versus +0.5%; P = 0.03), whereas glycemic control was similar between groups. At the end of the study, the RSG group also had significantly lower CRP levels than the control group (2.21 versus 8.59 mg/L; P = 0.03). No significant increase in such adverse effects as hypoglycemia, liver impairment, and fluid overload was observed in the RSG group. However, the RSG group was associated with more weight gain. Multivariate regression analysis (using decrease in HbA1c and lipid levels, change in insulin dosage, and treatment with RSG, with lipid-lowering agents) showed that only treatment with RSG was an independent predictor for posttreatment CRP level (P = 0.016).

CONCLUSION

RSG in combination with insulin is well tolerated and beneficial in the treatment of patients with type 2 diabetes on peritoneal dialysis therapy by improving insulin sensitivity and decreasing inflammatory response.

Rosiglitazone is a safe and effective treatment option of new-onset diabetes mellitus after renal transplantation

The purpose of this study was to assess the safety and efficacy of the insulin sensitizer rosiglitazone in patients with new-onset diabetes mellitus (NODM) after renal transplantation. Twenty-two patients with NODM after renal transplantation were selected to receive rosiglitazone therapy. All patients received prednisone, 15 patients were treated with tacrolimus and seven patients received cyclosporine A. For 16 of the 22 patients treatment with rosiglitazone therapy was successful and mean fasting blood glucose decreased from 182 +/- 17 to 127 +/- 7 mg/dl. Six patients were not treated successfully with rosiglitazone alone, one patient needed a second oral antidiabetic agent and four patients insulin therapy. In one patient rosiglitazone was stopped because of edema after 5 days. There were no changes either in serum creatinine concentrations, or cyclosporine and tacrolimus blood levels respectively. Treatment with rosiglitazone appears to be safe and effective in patients with NODM after renal transplantation.

Use of insulin and oral hypoglycemic medications in patients with diabetes mellitus and advanced kidney disease

Diabetes mellitus is recognized as a leading cause of chronic kidney disease (CKD) and end-stage renal disease (ESRD) in the United States. There is a vast array of medications used to treat diabetes, including insulin and the sulfonylureas, as well as newer classes of drugs such as the thiazolidinediones and biguanides. In patients with reduced glomerular filtration rate (GFR), it is necessary to decrease the dosage of some of these drugs, while others are best avoided altogether. Accumulation of either the parent compound or its metabolites can result in symptomatic hypoglycemia, or in the case of metformin, significant lactic acidosis. In this article we will review the use of insulin and the various classes of oral medications used to treat type 2 diabetes mellitus, focusing on their pharmacokinetic properties and dosing in patients with advanced kidney disease.

Mechanical stretch induces monocyte chemoattractant activity via an NF-kappaB-dependent monocyte chemoattractant protein-1-mediated pathway in human mesangial cells: inhibition by rosiglitazone

Hemodynamic abnormalities are important in the pathogenesis of the glomerular damage in diabetes. Glomerular macrophage infiltration driven by the chemokine monocyte chemoattractant protein-1 (MCP-1) is an early event in diabetic nephropathy. The thiazolidinedione rosiglitazone ameliorates albumin excretion rate in diabetic patients with microalbuminuria and has anti-inflammatory properties, raising the possibility of a relationship between its renoprotective and anti-inflammatory activity. Investigated was whether mesangial cell stretching, mimicking in vitro glomerular capillary hypertension, enhances MCP-1 expression and monocyte chemoattractant activity. The effect of the combination of stretch with high glucose on MCP-1 production was studied and, finally, the effect of rosiglitazone on these processes was assessed. Stretching of human mesangial cells significantly enhanced their monocyte chemoattractant activity. This effect was mediated by MCP-1 as it was paralleled by a significant rise in both MCP-1 mRNA and protein levels and was completely abolished by MCP-1 blockade. Combined exposure to both stretch and high glucose further increased MCP-1 production. Stretch activated the IkappaB-NF-kappaB pathway, and NF-kappaB inhibition, with the use of the specific inhibitor SN50, completely abolished stretch-induced MCP-1, indicating that stretch-induced MCP-1 was NF-kappaB dependent. The addition of rosiglitazone significantly diminished stretch-induced NF-kappaB activation, MCP-1 production, and monocyte chemotaxis. In conclusion, stretching of mesangial cells stimulates their monocyte chemoattractant activity via an NF-kappaB-mediated, MCP-1-dependent pathway, and this effect is prevented by rosiglitazone.

Effects of rosiglitazone maleate when added to a sulfonylurea regimen in patients with type 2 diabetes mellitus and mild to moderate renal impairment: A post hoc analysis

BACKGROUND

Patients with type 2 diabetes mellitus (DM) and renal impairment whose disease is inadequately controlled on a sulfonylurea (SU) have limited oral combination treatment options.

OBJECTIVE

This post hoc analysis assesses the efficacy and tolerability of the insulin sensitizer rosiglitazone maleate (RSG) when added to an SU treatment regimen in patients with type 2 DM with mild to moderate renal impairment that is inadequately controlled by SU monotherapy.

METHODS

Data were pooled from 3 randomized, double-blind, placebo-controlled, parallel-group studies in which RSG or placebo was added to an SU (glibenclamide, gliclazide, or glipizide) treatment regimen for a period of 6 months. Patients were subcategorized as having mild to moderate renal impairment or normal renal function based on a baseline creatinine clearance rate of 30 to 80 mL/min or >80 mL/min, respectively, as estimated by the Cockcroft-Gault equation.

RESULTS

The population studied comprised 824 patients, 62% men and 38% women, aged 32 to 81 years, of whom 301 had mild to moderate renal impairment and 523 had normal renal function. In patients with and without renal impairment, glycemia was improved in the SU + RSG-treated group compared with the SU + placebo-treated group. The observed treatment differences between the groups were -2.6 mmol/L for fasting plasma glucose and -1.1% for glycosylated hemoglobin (for both renally impaired and nonimpaired patients). For patients receiving SU + RSG, little difference in the safety profile was found between patients with and without renal impairment.

CONCLUSION

RSG was effective and well tolerated when added to SU therapy in this population of patients with mild to moderate renal impairment.

Rosiglitazone improves glucose metabolism in nondiabetic uremic patients on CAPD

BACKGROUND

Insulin resistance, a strong risk factor for atherosclerotic vascular disease, is present in uremic patients without diabetes on continuous ambulatory peritoneal dialysis (CAPD) therapy. Amelioration of insulin resistance may reduce associated long-term cardiovascular complications. The aim of the study is to investigate the effects of rosiglitazone (ROS), an insulin sensitizer, on glucose metabolism in CAPD patients without diabetes.

METHODS

Fifteen uremic patients without diabetes on CAPD therapy were enrolled. All were administered ROS, 4 mg/d, for 12 weeks. A control group consisted of 15 age- and sex-matched healthy subjects. Oral glucose tolerance test (OGTT) results, fasting glucose and insulin levels, related blood biochemistry results, and C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) levels were determined before initiation and at 4 and 12 weeks of therapy. Insulin resistance was evaluated using the homeostasis model assessment method (HOMA-IR). A whole-body insulin sensitivity index (ISI) and insulinogenic index for insulin production were calculated from OGTT results.

RESULTS

CAPD patients showed significantly greater HOMA-IR and glucose intolerance compared with healthy controls. After 4 and 12 weeks of ROS therapy, there were no significant changes in body weight, blood pressure, dialysis adequacy, hemoglobin level, hemoglobin A(1c) level, liver function, lipid profile, or intact parathyroid hormone, CRP, IL-6, or TNF-alpha levels. There was a significant decrease in HOMA-IR (3.2 +/- 0.6, 2.2 +/- 0.4, and 2.1 +/- 0.4; P < 0.05). During the OGTT, there was a significant decrease in the area under the glucose curve and a significant increase in ISI (3.5 +/- 0.4, 5.0 +/- 0.7, and 5.3 +/- 0.7; P < 0.05), but no significant change in insulinogenic index.

CONCLUSION

ROS improved insulin resistance in CAPD patients without diabetes. Whether long-term use of ROS reduces cardiovascular risk needs further study.