Statin therapy for the treatment of diabetic dyslipidemia

Greater efficacy of atorvastatin versus a non-statin lipid-lowering agent against renal injury: potential role as a histone deacetylase inhibitor

Statins, 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitors have been shown to improve diabetic nephropathy. However, whether they provide protection via Histone deacetylases (HDAC) inhibition is not clear. We conducted a comparative evaluation of Atorvastatin (AT) versus the non-statin cholesterol-lowering drug, Ezetimibe (EZT) on severity of diabetic nephropathy. Streptozotocin-treated male Wistar rats were fed a cholesterol-supplemented diet and gavaged daily with vehicle, AT or EZT. Control rats received normal diet and gavaged vehicle (n = 8-9/group). Diabetes increased blood glucose, urine albumin-to-creatinine ratio (ACR), kidney pathology and HDAC activity, and reduced renal E-cadherin levels. Both AT and EZT reduced circulating cholesterol, attenuated renal pathology, and did not lower blood glucose. However, AT was significantly more effective than EZT at reducing kidney pathology and HDAC activity. Chromatin immunoprecipitation revealed a significantly higher association of acetylated H3 and H4 with the E-cadherin promoter in kidneys from AT-, relative to EZT- or vehicle-treated rats. Moreover, we demonstrated a direct effect of AT, but not EZT, on HDAC-inhibition and, H3 and H4- acetylation in primary glomerular mesangial cells. Overall, both AT and EZT attenuated diabetic nephropathy; however, AT exhibited greater efficacy despite a similar reduction in circulating cholesterol. HDAC-inhibition may underlie greater efficacy of statins in attenuating kidney injury.

Nucleotide sequencing, cloning, and expression of Capra hircus Heme Oxygenase-1 in caprine islets to promote insulin secretion in vitro

Transplantation of islets of Langerhans that have been isolated from whole pancreas is an attractive alternative for the reversal of Type 1 diabetes. However, in vitro culture of isolated pancreatic islets has been reported to cause a decrease in glucose response over time. Hence, the improvement in islet culture conditions is an important goal in islet transplantation. Heme Oxygenase-1 (HO-1) is a stress protein that has been described as an inducible protein with the capacity of preventing apoptosis and cytoprotection via radical scavenging. Therefore, this study was aimed to assess the influence of endogenous HO-1 gene transfer on insulin secretion of caprine islets. The full-length cDNA sequence of Capra hircus HO-1 was determined using specific designed primers and rapid amplification of cDNA ends of pancreatic tissue. The HO-1 cDNA was then cloned into the prokaryotic expression vectors and transfected into caprine islets using lipid carriers. Efficiency of lipid carriers to transfect caprine islets was determined by flow cytometry. Insulin secretion assay was carried out by ovine insulin ELISA. The finding demonstrated that endogenous HO-1 gene transfer could improve caprine islet function in in vitro culture. Consequently, strategies using HO-1 gene transfer to islets might lead to better outcome in islet transplantation.

Study of coronary artery calcification risk in Egyptian adolescents with type-1 diabetes

The objective of the study is to assess coronary artery calcification (CAC) among adolescents with type-1 diabetes and to determine its relation with high-sensitivity C-reactive protein (hs-CRP), dyslipidaemia, glycaemic control and microvascular complications. The study included sixty patients with type-1 diabetes. Their ages ranged from 12 to 18 years and their diabetes duration ranged between 10 and 15 years. Patients were compared with 60 healthy subjects who served as controls. Clinical examination and laboratory investigations were done for evaluation of glycaemic control and presence of microvascular complications. Lipid profile, hs-CRP and multislice spiral computed tomography were done. Hs-CRP, total cholesterol, triglycerides and low-density lipoproteins levels were significantly higher in patients with diabetes compared to controls (P < 0.001). Twelve patients with diabetes (20%) had positive CAC. The mean calcium score was significantly higher in patients with diabetes compared to controls (P < 0.05). Smoking significantly affects CAC as 50% of smokers with diabetes had evidence of CAC compared to 9.1% of non-smokers with diabetes (P < 0.001). Fifty percent of patients with diabetes on angiotensin-converting enzyme inhibitor (ACEI) had evidence of CAC compared to 0% of patients without history of ACEI therapy (P < 0.001). Diabetics with CAC had significantly elder age, longer disease duration and higher mean glycosylated hemoglobin compared to diabetics without CAC (P < 0.05). Blood pressure percentiles, albumin creatinine ratio and serum lipids were significantly higher in patients with CAC compared to those without CAC (P < 0.001). All diabetics with severe retinopathy had positive CAC compared to 0% with normal Fundus (P < 0.001). All diabetics with overt nephropathy had positive CAC compared to 13.3% and 0% in micro- and normo-albuminuric patients (P < 0.001). Young patients with diabetes have evidence of CAC. Smoking, microvascular complications and dyslipidaemia might contribute to this risk.

Reversal of voltage-dependent erectile responses in the Zucker obese-diabetic rat by rosuvastatin-altered RhoA/Rho-kinase signaling

INTRODUCTION

The combination of independent risk factors for erectile dysfunction, obesity, hypertension, and diabetes are collectively manifested in a condition known as metabolic syndrome X (MSX). However, the regulatory mechanisms responsible for the erectile dysfunction (ED) are not fully understood. Clinical studies suggest that a pleiotropic effect of statin's ability to enhance vascular relaxation might be through an impact on nitric oxide signaling or through a regulation of RhoA activation.

AIM

We hypothesized that regulatory aspects of short-term statin therapy involve the alteration of the RhoA/Rho-kinase signaling cascade and will reverse the ED seen in a rat model of MSX.

MAIN OUTCOME MEASURES

The magnitude and sensitivity of the voltage-dependent maintenance of intracavernosal blood pressure and mean arterial blood pressure. These responses were correlated with tissue protein and mRNA expression levels of RhoA and Rho kinases.

METHODS

Erectile function was evaluated by assessing voltage-dependent stimulation of the cavernosal nerve in 16-20 weeks old lean and obese-diabetic Zucker rats treated with 5 mg/kg/day of rosuvastatin intraperitoneally for 3 days. Cavernosal tissue RhoA and Rho-kinases expression levels were evaluated by real-time reverse transcriptase-polymerase chain reaction, Western blot.

RESULTS

The voltage-dependent erectile responses were suppressed by >30% in the obese-diabetic Zucker rat. The 3-day treatment with rosuvastatin partially restored the erectile response. The Rho-kinase inhibitor, H-1152, dose dependently increased the erectile responses and shifted the voltage sensitivity with statin treatment. Analysis of protein expression levels suggested elevation of RhoA and Rho kinases in obese-diabetics and statin treatment lowering Rho-kinase II. The RhoA and Rho-kinase II mRNA levels were significantly reduced in the rosuvastatin-treated obese-diabetic animals.

CONCLUSIONS

These results support a hypothesis that short-term statin therapy may lower RhoA/Rho-kinase expression levels and improve cavernosal blood pressure response to Rho-kinase inhibition and voltage-stimulation, and reversing an augmented vasoconstricted state associated with diabetes and/or hypertension in MSX.

Reversal of chemoresistance and enhancement of apoptosis by statins through down-regulation of the NF-kappaB pathway

We recently found that simvastatin can modulate the nuclear factor-kappaB (NF-kappaB) activation pathway, but whether other statins have similar effects to those of simvastatin is unknown. Therefore, we evaluated the effect six different statins on TNF-induced NF-kappaB activation in human myeloid leukemia cells. We then determined whether the combination of statins and standard chemotherapeutic agents could overcome chemoresistance and augment apoptosis. Of the six statins evaluated, only the natural statins (simvastatin, mevastatin, lovastatin, and pravastatin), not the synthetic statins (fluvastatin and atorvastatin), inhibited TNF-induced NF-kappaB activation. Simvastatin suppressed the NF-kappaB activation and potentiated the apoptosis induced by doxorubicin, paclitaxel, and 5-fluorouracil. These results suggest that different statins behave differently from one another and that they may be useful in overcoming chemoresistance.

Effects of rosuvastatin on lipids, lipoproteins and apolipoproteins in the dyslipidaemia of diabetes

AIMS

To compare the effects of rosuvastatin and atorvastatin 10 and 20 mg on plasma lipid and lipoprotein profiles in patients with Type 2 diabetes mellitus and triglycerides < or = 6.0 mmol/l.

METHODS

A double-blind, randomized, multicentre study to assess the effect of rosuvastatin and atorvastatin, at 10 mg/day for 8 weeks followed by 20 mg/day for a further 8 weeks, on low-density lipoprotein cholesterol (LDL-C), together with a range of secondary lipid and lipoprotein end points.

RESULTS

Rosuvastatin reduced mean LDL-C levels from baseline over 16 weeks by 57.4%, while atorvastatin reduced mean LDL-C levels by 46.0% over the same period. The difference in LDL-C reduction between treatments was statistically significant (P < 0.001). Rosuvastatin also produced statistically significantly greater mean reductions from baseline in levels of total cholesterol, non-high-density lipoprotein cholesterol, apolipoprotein B and lipid ratios. More patients achieved European LDL-C (< 2.5 mmol/l) and total cholesterol (< 4.5 mmol/l) goals with rosuvastatin than with atorvastatin. Rosuvastatin was associated with a significantly (P < 0.049) greater mean percentage increase in glycated haemoglobin (HbA(1c)) from baseline compared with atorvastatin; however, patients in both treatment groups maintained good glycaemic control. Both rosuvastatin and atorvastatin were well tolerated.

CONCLUSIONS

Greater reductions in LDL-C were achieved with rosuvastatin compared with equal doses of atorvastatin, enabling more patients with Type 2 diabetes to achieve European LDL-C goals.

Improved endothelial function and reduced platelet activation by chronic HMG-CoA-reductase inhibition with rosuvastatin in rats with streptozotocin-induced diabetes mellitus

Diabetes is associated with endothelial dysfunction and platelet activation, both of which may contribute to increased cardiovascular risk. We investigated whether the hydroxy-3-methyl-glutaryl CoA reductase inhibitor rosuvastatin improves endothelial function and reduces platelet activation in diabetic rats. Therefore, male Wistar rats were injected with streptozotocin (STZ, 50mg/kg i.v.) to induce insulin-deficient diabetes. Treatment with rosuvastatin (20mg/[kg day]) or vehicle was initiated 2 weeks after injection of STZ and continued for 2 weeks. Thereafter, platelet activation was assessed in fresh whole blood and vascular function was characterized in isolated aortic segments in organ bath chambers. Endothelium-dependent relaxation induced by acetylcholine was significantly attenuated in diabetic rats and improved by treatment with rosuvastatin (maximum relaxation, % of precontraction-control: 99.8+/-0.2, STZ-vehicle: 80.7+/-2.9, STZ-rosuvastatin: 98.9+/-0.7; p<0.01). Similarly, treatment with rosuvastatin significantly reduced fibrinogen-binding to activated GPIIb/IIIa (mean fluorescence-control: 161.0+/-6.9, STZ-vehicle: 207.8+/-15.9, rosuvastatin: 173.6+/-5.3; p<0.05) and P-Selectin surface expression on platelets (mean fluorescence-control: 76.5+/-7.3, STZ-vehicle: 92.1+/-5.5, rosuvastatin: 75.2+/-6.5; p<0.05), while both markers of platelet activation were increased in diabetic rats. Therefore, rosuvastatin treatment normalizes endothelial function and reduces platelet activation in diabetic rats. These effects may contribute to the reduction of cardiovascular events by statins in diabetic patients.

Ezetimibe added to ongoing statin therapy improves LDL-C goal attainment and lipid profile in patients with diabetes or metabolic syndrome

This analysis of the Ezetimibe Add-on to Statin for Effectiveness (EASE) trial examined the effectiveness and safety of ezetimibe 10 mg added to ongoing statin therapy in patients with diabetes, metabolic syndrome without diabetes, or neither disorder who had low-density lipoprotein cholesterol (LDL-C) levels exceeding National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) goals. After six weeks of treatment, ezetimibe added to statin reduced LDL-C in patients with diabetes by 28%, metabolic syndrome by 24%, or neither by 26%, compared with a 3% reduction for placebo for each group. In each group, more patients receiving ezetimibe plus statin reached LDL-C goal (67-74%) compared with those receiving placebo plus statin (19-22%). Other parameters demonstrating greater improvement with ezetimibe included triglycerides, apolipoprotein (Apo)B/Apo A-I ratio, high-density lipoprotein cholesterol (HDL-C), and C-reactive protein. Ezetimibe plus statin was well tolerated in each group. Ezetimibe added to ongoing statin therapy offers a new treatment option that is consistently effective in improvement of lipid profiles and attainment of LDL-C goals in patients with without diabetes or metabolic syndrome.

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.

Ethnic Disparities: Control of Glycemia, Blood Pressure, and LDL Cholesterol Among US Adults with Type 2 Diabetes

OBJECTIVE:

To examine ethnic disparities in the quality of diabetes care among adults with diabetes in the US through a systematic qualitative review.

DATA SOURCES:

Material published in the English language was searched from 1993 through June 2003 using PubMed, Web of Science, Cumulative Index to Nursing and Allied Health, the Cochrane Library, Combined Health Information Database, and Education Resources Information Center.

STUDY SELECTION AND DATA EXTRACTION:

Studies of patients with diabetes in which at least 50% of study participants were ethnic minorities and studies that made ethnic group comparisons were eligible. Research on individuals having prediabetes, those <18 years of age, or women with gestational diabetes were excluded. Reviewers used a reproducible search strategy. A standardized abstraction and grading of articles for publication source and content were used. Data on glycemia, blood pressure, and low-density lipoprotein cholesterol (LDL-C) were extracted in patients with diabetes. A total of 390 studies were reviewed, with 78 meeting inclusion criteria.

DATA SYNTHESIS:

Ethnic minorities had poorer outcomes of care than non-Hispanic whites. These disparities were most pronounced for glycemic control and least evident for LDL-C control. Most studies showed blood pressure to be poorly controlled among ethnic minorities.

CONCLUSIONS:

Control of risk factors for diabetes (glycemia, blood pressure, LDL-C) is challenging and requires routine assessment. These findings indicate that additional efforts are needed to promote diabetes quality of care among minority populations.

Comparison of rosuvastatin and atorvastatin for lipid lowering in patients with type 2 diabetes mellitus: results from the URANUS study

OBJECTIVE

The Use of Rosuvastatin versus Atorvastatin iN type 2 diabetes mellitUS (URANUS) study compared rosuvastatin with atorvastatin for the reduction of low-density lipoprotein cholesterol (LDL-C) in patients with type 2 diabetes.

METHODS

After a 6-week dietary run-in, patients aged > or = 18 years with type 2 diabetes and LDL-C > or = 3.3 mmol/L were randomised to double-blind treatment with rosuvastatin 10 mg (n = 232) or atorvastatin 10 mg (n = 233) for 4 weeks. Doses were then titrated up to a maximum of rosuvastatin 40 mg or atorvastatin 80 mg over 12 weeks to achieve the 1998 European LDL-C goal (<3.0 mmol/L).

RESULTS

Rosuvastatin reduced LDL-C levels significantly more than atorvastatin during the fixed-dose and titration periods (p < 0.0001). Significantly more patients reached the 1998 LDL-C goal with rosuvastatin 10 mg compared with atorvastatin 10 mg at 4 weeks (81% vs 65%, p < 0.001). At 16 weeks, significantly more patients achieved their LDL-C goal with rosuvastatin compared with atorvastatin (94% vs 88%, p < 0.05) and more patients receiving rosuvastatin remained at their starting dose with reduced requirement for dose titration. At 4 weeks, 65% of rosuvastatin patients had reached their 2003 European LDL-C goal (< 2.5 mmol/L), compared with 33% of atorvastatin patients (p < 0.0001). Both treatments were similarly well tolerated with no unexpected safety concerns.

CONCLUSION

At the start dose and following dose titration, rosuvastatin was significantly more effective than atorvastatin at reducing LDL-C and achieving European LDL-C goals in patients with type 2 diabetes.