Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rosiglitazone and pioglitazone are thiazolidinediones used for treatment of noninsulin-dependent diabetes mellitus. These compounds, along with troglitazone, were evaluated for the ability to induce cytochrome P450 enzymes (P450) in primary human hepatocyte cultures and to inhibit P450 in human microsomes. In induction studies, all three thiazolidinediones caused a dose-dependent increase in CYP3A4 activity and immunoreactive protein. While troglitazone was the most potent, rosiglitazone and pioglitazone generally exceeded troglitazone in absolute CYP3A4 activity achieved at concentrations > or =10 microM. A comparable concentration-dependent increase in CYP2B6 immunoreactive protein was observed with all three thiazolidinediones. Microarray analysis revealed rifampin > troglitazone > pioglitazone > rosiglitazone in terms of CYP3A4 mRNA induction potential with 10 microM compound. Inhibition studies conducted for CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP3A4, CYP2A6, and CYP2E1 showed troglitazone to be the most nonselective and potent inhibitor followed by rosiglitazone and pioglitazone. In vitro, the thiazolidinediones were strong inhibitors of CYP2C8, with K(i) values between 1.7 and 5.6 microM, and of CYP3A4, with K(i) values between 1.6 and 11.8 microM. Troglitazone, in addition, inhibited CYP2C9 (K(i) 0.6 microM). Although the inhibitory effects of the thiazolidinediones have not been demonstrated clinically, our results suggest there is potential for interactions with CYP2C8 substrates. This is the first report of in vitro induction of P450 enzymes by rosiglitazone and pioglitazone. While only the induction of CYP3A4 by troglitazone has been demonstrated in vivo, these results suggest that other thiazolidinediones may have the potential to cause clinically significant drug interactions at sufficiently high doses.
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PMID:Comparative effects of thiazolidinediones on in vitro P450 enzyme induction and inhibition. 1264 70

Rosiglitazone, a potent member of the thiazolidinedione class of oral antidiabetic agents, reduces hyperglycaemia by improving insulin sensitivity--an important underlying factor in the development of both type 2 diabetes and its related cardiovascular complications. Rosiglitazone has now been available in clinical practice for more than three years, so there is a large body of evidence supporting its efficacy and safety as an antihyperglycaemic agent in patients with type 2 diabetes. Given the significant burden imposed on patients and healthcare resources by diabetes-related cardiovascular disease (CVD), there is growing interest in the thiazolidinediones in terms of their potential to ameliorate CVD risk factors as a result of their insulin-sensitising action and thus improve cardiovascular outcomes in individuals with type 2 diabetes. As reviewed below, rosiglitazone has a beneficial impact on a number of factors associated with insulin resistance and CVD, including microalbuminuria, hypertension, dyslipidaemia, visceral fat, elevated plasminogen activator inhibitor-1 levels and increased concentrations of C-reactive protein. These thiazolidinedione compounds are not problem-free and the long-term implications of some of rosiglitazone side-effects such as weight gain, changes in LDL-cholesterol concentration and fluid retention remain to be resolved. Large-scale clinical outcome studies should give a clearer picture for rosiglitazone and related thiazolidinediones in relation to the extent of their impact on diabetes disease progression and incident cardiovascular events.
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PMID:Rosiglitazone: potential beneficial impact on cardiovascular disease. 1266 97

The effects of adding rosiglitazone to existing sulfonylurea (SU) treatment have not previously been studied in Chinese patients with type 2 diabetes and no known pre-existing hepatic impairment. Patients were randomized to receive rosiglitazone 2 mg twice daily (R4 + SU) or 4 mg twice daily (R8 + SU) or placebo (SU + P) for 24 weeks in addition to existing SU treatment. Most patients were taking concomitant glibenclamide (34%) or gliclazide (25%). Changes in glycosylated hemoglobin (HbA(1c)), fasting plasma glucose (FPG), and plasma insulin concentrations were measured. Of the 530 patients enrolled (45% male, mean age 59 years), 105 were in the SU + P group, 215 in the R4 + SU group, and 210 in the R8 + SU group. The mean baseline HbA(1c) was 9.8%, and FPG was 183.8 mg/dL. Compared with placebo, addition of rosiglitazone (2 or 4 mg twice daily) produced significant decreases in mean HbA(1c) (1.04% and 1.44%, respectively; p < 0.0001) and FPG (21.6 and 36.0 mg/dL, respectively; p < 0.0001). There were statistically significant (p < 0.0001) reductions from baseline in insulin concentration of 23.3 and 30.4 pmol/L in the R4 + SU and R8 + SU groups, respectively. Despite the high prevalence of seropositivity for hepatitis B and/or C at baseline (56%), there was no evidence of hepatotoxicity. No clinically significant changes in routine hematology, biochemistry, or electrocardiogram were observed. The addition of rosiglitazone to SU produced clinically significant improvements in glycemic control in Chinese patients with type 2 diabetes. Rosiglitazone plus SU was well tolerated irrespective of hepatitis B and C serological status.
Diabetes Technol Ther 2003
PMID:Addition of rosiglitazone to existing sulfonylurea treatment in chinese patients with type 2 diabetes and exposure to hepatitis B or C. 1272 6

Increasing evidence suggests that neurohumoral manifestations of heart failure may lead to insulin resistance, predisposing patients with heart failure to the development of glucose intolerance or worsening of existing diabetes. Theoretically, insulin-sensitizing thiazolidinediones (TZDs) should be beneficial in this patient population. A 74-year-old man with well-compensated systolic dysfunction and longstanding type 2 diabetes mellitus treated with glyburide began therapy with rosiglitazone 4 mg/day, which was increased to 8 mg/day after 1 month. Two weeks later he was seen with a 5-kg weight gain, shortness of breath, bibasilar rales, +S3 gallop, and increased jugular venous distention. Twelve days later symptoms worsened, with pulmonary edema on chest radiograph, continued weight gain, and +4 pitting edema resistant to oral diuretics. The patient was admitted to the hospital for exacerbation of heart failure. Five days after discharge he was readmitted for similar symptoms, including an 11.8-kg weight gain. He reported adherence to drug therapy and diet. Rosiglitazone was immediately discontinued and 11 days later the man's weight stabilized to 79 kg and remained between 79 and 80 kg 2 and 3 months after discharge. This case demonstrates that TZDs may precipitate weight gain and pulmonary and peripheral edema in patients with stable heart failure. Earlier reports documented similar symptoms in patients without a history of heart failure. Although current recommendations state that TZDs should not be administered to patients with New York Heart Association class III or IV disease, practitioners should be aware that these adverse effects also may occur in patients with milder forms heart failure as well as those without heart failure.
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PMID:Possible heart failure exacerbation associated with rosiglitazone: case report and literature review. 1288 8

Type 2 diabetes is associated with a marked increase in the incidence of coronary artery disease (CAD); however, the correlation between glycemia and CAD in patients with type 2 diabetes is only modestly positive. This relatively weak association between glycemia and CAD in subjects with diabetes may be caused by the existence of an atherogenic prediabetic state. In the San Antonio Heart Study, subjects who start with normal glucose tolerance and later develop type 2 diabetes have increased triglyceride levels, increased systolic blood pressure, and decreased levels of high-density lipoprotein cholesterol before the onset of type 2 diabetes. The basis for these atherogenic prediabetic changes may be related to insulin resistance rather than reduced insulin secretion. Recently, interest has focused on a possible role of fibrinolysis and increased subclinical inflammation, as determined by high-sensitivity C-reactive protein (CRP) levels. The Insulin Resistance Atherosclerosis Study found that insulin resistance, as determined by a frequently sampled glucose tolerance test, is significantly related to higher CRP levels, higher fibrinogen, and higher plasminogen activator inhibitor-1 (PAI-1) levels. The investigators also have shown that high PAI-1 and CRP levels are predictors of the development of type 2 diabetes. In addition, the Women's Health Study has shown that high CRP levels predict type 2 diabetes. Insulin-sensitizing interventions have been demonstrated to reduce these nontraditional risk factors. Rosiglitazone, an agent with insulin-sensitizing properties, decreases PAI-1 and CRP levels. Some of the adverse cardiovascular effects seen in patients with type 2 diabetes may be reversed by insulin-sensitizing agents.
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PMID:Insulin resistance, inflammation, and the prediabetic state. 1295 23

The glitazones or thiazolidinediones are ligands of the peroxisome proliferator-activated receptor gamma (PPARgamma). The glitazones are used in the treatment of diabetes, regulate adipogenesis, inflammation, cell proliferation, and induce apoptosis in several cancer cell types. High grade astrocytomas are rapidly growing tumors derived from astrocytes, for which new treatments are needed. We determined the effects of two glitazones, ciglitazone and the therapeutic rosiglitazone, on the survival of serum-deprived primary rat astrocytes and glioma cell lines C6 and U251, which were assessed by the methylthiazolyl tetrazolium assay and lactate dehydrogenase release. Rosiglitazone (5-20 microM) decreased survival of glioma cells without affecting primary astrocytes, whereas ciglitazone at 20 microM was toxic for both cell types. Ciglitazone at 10 microM was cytoprotective for primary astrocytes but toxic to glioma cells. Cell death induced by ciglitazone, but not rosiglitazone, presented apoptotic features (Hoechst staining and externalization of phosphatidylserine). Two mechanisms to explain cytotoxicity were investigated: activation of PPARgamma and production of reactive oxygen species (ROS). PPARgamma does not seem to be the main mechanism involved, because the order of efficacy for cytotoxicity, ciglitazone > rosiglitazone, was inverse of their reported affinities for activating PPARgamma. In addition, GW9662, an inhibitor of PPARgamma, only slightly attenuated cytotoxicity. However, the rapid increase in ROS production and the marked reduction of cell death with the antioxidants ebselen and N-acetylcysteine, indicate that ROS have a key role in glitazone cytotoxicity. Ciglitazone caused a dose-dependent and rapid loss (in minutes) of mitochondrial membrane potential in glioma cells. Therefore, mitochondria are a likely source of ROS and early targets of glitazone cytotoxicity. Our results highlight the potential of rosiglitazone and related compounds for the treatment of astrogliomas.
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PMID:Glitazones differentially regulate primary astrocyte and glioma cell survival. Involvement of reactive oxygen species and peroxisome proliferator-activated receptor-gamma. 1469 30

The observed reduction in macrovascular outcomes in the United Kingdom Progressive Diabetes Study (UKPDS) trial in patients with type 2 diabetes mellitus (DM), treated intensively with insulin or sulfonylureas, was of borderline significance (p = 0.052). This may be because of the role of factors other than glycemic control in the etiology of macrovascular disease. The UKPDS and other studies have suggested that lipid parameters are potent predictors of adverse outcomes in patients with type 2 DM. In patients with DM, dyslipidemia is characterized by elevated serum triglycerides and low high density lipoprotein-cholesterol (HDL-C) with normal total serum cholesterol levels and usually accompanied by an elevation of atherogenic, small, dense low density lipoprotein-cholesterol (LDL-C) particles. Dyslipidemia is only partly corrected by dietary and lifestyle modifications and pharmacological glycemic control in patients with DM. Several guidelines, including those published by the New Zealand Heart Foundation, suggest that lipid-modifying therapies are appropriate in patients considered to be at high or very high risk of a cardiac event. This includes patients with established vascular disease. Some recent studies suggest that patients with type 2 DM have risk comparable to patients without DM, but have experienced previous myocardial infarction (MI). Subgroup analysis of trials including the Scandinavian Simvastatin Survival Study (4S) and Cholesterol and Recurrent Events (CARE), which included patients with DM, have shown a significant reduction in adverse outcomes, although many patients with DM and dyslipidemia were excluded. Of lipid-lowering drugs, fibric acid derivatives are probably the most appropriate for patients with DM and dyslipidemia and their role is being evaluated in large, long-term outcome studies such as Fenofibrate Intervention and Event Lowering in Diabetes (FIELD). Thiazolidinediones, a new class of compound for treating patients with type 2 DM, primarily exert their glucose-lowering effect by increasing insulin sensitivity at the level of skeletal muscle, and to a lesser extent, at the liver by decreasing hepatic glucose output. Some of their actions are mediated through binding and activation of the peroxisome proliferator-activated receptor-gamma, a nuclear receptor that has a regulatory role in differentiation of cells, especially adipocytes. The nonhypoglycemic effects of thiazolidinediones, therefore, offer additional potential mechanisms for benefit in patients with type 2 DM and insulin resistance. Thiazolidinediones increase serum HDL-C levels. Troglitazone and pioglitazone have been shown to decrease serum triglyceride levels. Rosiglitazone, conversely has no significant effect on serum triglyceride levels. All of the thiazolidinediones increase serum LDL-C levels (pioglitazone to a lesser extent), although changes in the size of the LDL fraction may render it less susceptible to oxidation and, therefore, less atherogenic. A randomized comparative trial needs to be undertaken to determine whether true differences exist between the thiazolidinediones. Longer studies need to be undertaken to assess their effect on cardiovascular outcomes.
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PMID:Management of co-existing diabetes mellitus and dyslipidemia: defining the role of thiazolidinediones. 1472 95

Burgeoning obesity is increasing the prevalence of type II diabetes mellitus. As a consequence, there will be an even greater burden of cardiovascular disease, end-stage renal disease, blindness, and lower extremity amputations. If diagnosed, impaired glucose tolerance presents an opportunity for intervention that potentially could delay or prevent the development of diabetes. Recent prospective studies document the effectiveness of exercise and weight reduction in preventing diabetes. Metformin is less effective than intense lifestyle interventions. Acarbose, losartan, orlistat, pravastatin, ramipril, and hormone replacement therapy are associated with lower rates of the development of diabetes. The Diabetes Reduction Assessment with Ramipril and Rosiglitazone Medication (DREAM) trial and the Nateglinide and Valsartan in Impaired Glucose Tolerance Outcomes Research (NAVIGATOR) trial were designed to assess not only the prevention of diabetes but also the impact on cardiovascular morbidity and mortality.
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PMID:Preventing type II diabetes mellitus. 1505 49

Rosiglitazone is an agonist of peroxisome proliferator activated receptor-gamma (PPARgamma) and ameliorates insulin resistance in type II diabetes. In addition, it may also promote increased pancreatic beta-cell viability, although it is not known whether this effect is mediated by a direct action on the beta cell. We have investigated this possibility. Semiquantitative real-time reverse transcription-polymerase chain reaction analysis (Taqman) revealed that freshly isolated rat islets and the clonal beta-cell line, BRIN-BD11, express PPARgamma, as well as PPARalpha and PPARdelta. The levels of expression of PPARgamma were estimated by reference to adipose tissue and were found to represent approximately 60% (islets) and 30% (BRIN-BD11) of that found in freshly isolated visceral adipose tissue. Western blotting confirmed the presence of immunoreactive PPARgamma in rat (and human) islets and in BRIN-BD11 cells. Transfection of BRIN-BD11 cells with a PPARgamma-sensitive luciferase reporter construct was used to evaluate the functional competence of the endogenous PPARgamma. Luciferase activity was modestly increased by the putative endogenous ligand, 15-deoxy-Delta12,14 prostaglandin J2 (15dPGJ2). Rosiglitazone also caused activation of the luciferase reporter construct but this effect required concentrations of the drug (50-100 microm) that are beyond the expected therapeutic range. This suggests that PPARgamma is relatively insensitive to activation by rosiglitazone in BRIN-BD11 cells. Exposure of BRIN-BD11 cells to the lipotoxic effector, palmitate, caused a marked loss of viability. This was attenuated by treatment of the cells with either actinomycin D or cycloheximide suggesting that a pathway of programmed cell death was involved. Rosiglitazone failed to protect BRIN-BD11 cells from the toxic actions of palmitate at concentrations up to 50 microm. Similar results were obtained with a range of other PPARgamma agonists. Taken together, the present data suggest that, at least under in vitro conditions, thiazolidinediones do not exert direct protective effects against fatty acid-mediated cytotoxicity in pancreatic beta cells.
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PMID:Expression and functional activity of PPARgamma in pancreatic beta cells. 1523 1

Recent data have shown that peroxisome proliferator-activated receptor-gamma agonists may exert protective effects on the vascular endothelium by amelioration of insulin resistance and through direct anti-inflammatory effects. In this study we assessed the effect of rosiglitazone on biochemical and biophysical indexes of endothelial function in male, nondiabetic patients with coronary artery disease. Consecutive male subjects (n = 71) with clinically stable, angiographically documented coronary artery disease and without diabetes mellitus were investigated. Patients were randomized in a double-blind manner to placebo or rosiglitazone for a total of 24 weeks. Flow-mediated dilation (FMD) of the brachial artery, C-reactive protein, von Willebrand factor, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 levels, and parameters of glucose and lipid metabolism were measured at baseline and after 12 and 24 weeks of treatment. Rosiglitazone treatment significantly reduced C-reactive protein (median 0.56 mg/L [interquartile range 0.33 to 1.02] to 0.33 mg/L [interquartile range 0.26 to 0.40], p <0.01), von Willebrand factor (139 +/- 47 to 132 +/- 44 IU/dl, p = 0.02), insulin resistance index (p = 0.05), and mean low-density lipoprotein (LDL) density (p <0.001) compared with placebo. However, no significant differences were seen between the rosiglitazone and placebo groups with regard to brachial artery FMD, intercellular adhesion molecule-1, or vascular cell adhesion molecule-1 levels. Rosiglitazone treatment significantly increased LDL (2.62 +/- 0.72 to 2.95 +/- 0.84 mmol/L, p = 0.03) and triglyceride (1.23 +/- 0.63 to 1.56 +/- 0.98 mmol/L, p = 0.04) levels. Thus, rosiglitazone reduced markers of inflammation and endothelial activation, but this did not translate into an improvement in FMD. Increased LDL and triglyceride levels may have played a role.
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PMID:Effects of rosiglitazone on endothelial function in men with coronary artery disease without diabetes mellitus. 1524 89


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