Efficacy and safety of ezetimibe added to ongoing statin therapy for treatment of patients with primary hypercholesterolemia

Treatment of dyslipidemia in HIV

Patients infected with HIV have a high risk of developing dyslipidemia. Effective therapeutic strategies can be challenging due to an increase risk of drug interactions and other comorbidities. Understanding the underlying pathophysiology and the principles of pharmacological and non-pharmacological therapeutic interventions can be of value in the appropriate management of dyslipidemia in the HIV-infected patient.

Ezetimibe/statin combination therapy to treat patients with type 2 diabetes

Patients with diabetes represent a population at higher risk for cardiovascular disease. Diabetic dyslipidemia is characterized by the so-called atherogenic lipid triad, consisting of an increase in small dense low density lipoprotein particles and in triglyceride-rich lipoproteins, and a decrease in high-density lipoprotein cholesterol, with an increase in non-HDL cholesterol. Numerous trials have investigated the efficacy of add-on ezetimibe therapy for patients with type 2 diabetes and not controlled by statin therapy. The published data highly suggest that patients with type 2 diabetes may be more likely to benefit from ezetimibe/statin combination therapy. However, evidence specifically addressing hard clinical endpoints and prospective trials addressing differences in response between patients with or without diabetes are still needed.

Achievement of dual low-density lipoprotein cholesterol and high-sensitivity C-reactive protein targets more frequent with the addition of ezetimibe to simvastatin and associated with better outcomes in IMPROVE-IT

BACKGROUND

Statins lower low-density lipoprotein cholesterol (LDL-C) and high-sensitivity C-reactive protein (hs-CRP); addition of ezetimibe to statins further reduces LDL-C and hs-CRP. An analysis of the relationship between achieved LDL-C and hs-CRP targets and outcomes for simvastatin and ezetimibe/simvastatin was prespecified in Improved Reduction of Outcomes: Vytorin Efficacy International Trial (IMPROVE-IT).

METHODS AND RESULTS

The IMPROVE-IT trial randomly assigned 18 144 patients stabilized after acute coronary syndrome to simvastatin or ezetimibe/simvastatin. LDL-C and hs-CRP were measured at baseline and 1 month after randomization. Outcomes were assessed in those achieving one or both of the prespecified targets of LDL-C<70 mg/dL and hs-CRP<2 mg/L versus achieving neither target, adjusting for differences in baseline characteristics. An exploratory analysis examined targets of LDL-C<50 mg/dL and hs-CRP<1 mg/L. Patients meeting both targets at baseline, with no 1-month values, or with end points before 1 month were excluded. Of 15 179 patients, 39% achieved the dual LDL-C (<70 mg/dL) and hs-CRP (<2 mg/L) targets at 1 month, 14% met neither target, 14% met only the hs-CRP target, and 33% met only the LDL-C target. Those achieving dual targets had lower primary end point rates than those meeting neither target (cardiovascular death, major coronary event, or stroke; 38.9% versus 28.0%; adjusted hazard ratio, 0.73; 0.66-0.81; P<0.001). More patients treated with ezetimibe/simvastatin met dual targets than those treated with simvastatin alone (50% versus 29%, P<0.001). The association of dual-target attainment with improved outcomes was similar irrespective of treatment assignment (P-interaction=0.65). Similar findings were observed using the exploratory targets.

CONCLUSIONS

Significantly more patients treated with ezetimibe/simvastatin met prespecified and exploratory dual LDL-C and hs-CRP targets than patients treated with simvastatin alone. Reaching both LDL-C and hs-CRP targets was associated with improved outcomes after multivariable adjustment.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov; Unique identifier: NCT00202878.

The role of microsomal triglyceride transfer protein inhibitors in the treatment of patients with familial hypercholesterolemia: risks, benefits, and management

Statins fail to adequately reduce low-density lipoprotein-cholesterol (LDL-C) in patients with homozygous familial hypercholesterolemia, requiring these patients to undergo weekly or bi-weekly sessions of LDL apheresis. Although efficacious, LDL apheresis is an invasive procedure with high cost and low availability, and additional options, such as inhibitors of microsomal transfer protein (MTP), may have benefit. Inhibition of MTP reduces levels of circulating cholesterol and triglycerides by preventing the formation of very-low-density lipoprotein and chylomicrons. LDL-C levels decrease by as much as 50%. Unfortunately, adverse effects-the most common of which are gastrointestinal-related and hepatic lipid accumulation-limit broader use of the drug. Furthermore, the cardiovascular benefit of MTP inhibition remains unclear. However, MTP inhibition offers a viable additional lipid-lowering option for patients with homozygous familial hypercholesterolemia.

Effect of hydroxypropylcellulose and Tween 80 on physicochemical properties and bioavailability of ezetimibe-loaded solid dispersion

The purpose of this research was to evaluate the effect of the HPC (hydroxypropylcellulose) and Tween 80 on the physicochemical properties and oral bioavailability of ezetimibe-loaded solid dispersions. The binary solid dispersions were prepared with drug and various amounts of HPC. Likewise, ternary solid dispersions were prepared with different ratios of drug, HPC and Tween 80. Both types of solid dispersions were prepared using the solvent evaporation method. Their aqueous solubility, physicochemical properties, dissolution and oral bioavailability were investigated in comparison with the drug powder. All the solid dispersions significantly improved the drug solubility and dissolution. As the amount of HPC increased in the binary solid dispersions to 10-fold, the drug solubility and dissolution were increased accordingly. However, further increase in HPC did not result in significant differences among them. Similarly, up to 0.1-fold, Tween 80 increased the drug solubility in the ternary solid dispersions followed by no significant change. However, Tween 80 hardly affected the drug dissolution. The physicochemical analysis proved that the drug in binary and ternary solid dispersion was existed in the amorphous form. The particle-size measurements of these formulations were also not significantly different from each other, which showed that Tween 80 had no impact on physicochemical properties. The ezetimibe-loaded binary and ternary solid dispersions gave 1.6- and 1.8-fold increased oral bioavailability in rats, respectively, as compared to the drug powder; however, these values were not significantly different from each other. Thus, HPC greatly affected the solubility, dissolution and oral bioavailability of drug, but Tween 80 hardly did. Furthermore, this ezetimibe-loaded binary solid dispersion prepared only with HPC would be suggested as a potential formulation for oral administration of ezetimibe.

Ezetimibe and simvastatin modulate gut microbiota and expression of genes related to cholesterol metabolism

AIMS

Hypolipidemic drugs are prescribed in the most of cases for the treatment of cardiovascular diseases. Several studies have showed that the gut microbiota is able to regulate the host cholesterol metabolism. This study aimed to investigate the potential impact of hypolipidemic drugs on the gut microbiota in mice, and to correlate it to the regulation of cholesterol metabolism.

MAIN METHODS

Male C57Bl/6J mice were divided into four groups fed either a control diet alone (CT), or supplemented with simvastatin (0.1% w/w, Zocor®, MSD), or ezetimibe (0.021% w/w, Ezetrol®, MSD) or a combination of simvastatin and ezetimibe (0.1% and 0.021%, respectively) for one week.

KEY FINDINGS

The combination of ezetimibe and simvastatin is required to observe a drop in cholesterolemia, linked to a huge activation of hepatic SREBP-2 and the consequent increased expression of genes involved in LDL cholesterol uptake and cholesterol synthesis. The gut microbiota analysis revealed no change in total bacteria, and in major Gram positive and Gram negative bacteria, but a selective significant increase in Lactobacillus spp. in mice treated with the ezetimibe and a decrease by the combination. The changes in lactobacilli level observed in ezetimibe or combination treated-mice are negatively correlated to expression of genes related to cholesterol metabolism.

SIGNIFICANCE

The present study showed that ezetimibe taken alone is able to modify the composition of gut microbiota in favor of Lactobacillus spp. These results suggest that members of the genus Lactobacillus play an important role in cholesterol metabolism, even in normocholesterolemic mouse model.

Identification, synthesis and characterization of process related desfluoro impurity of ezetimibe and HPLC method validations

Ezetimibe, which selectively inhibits cholesterol absorption across the intestinal wall and is used as an antihyperlipidemic agent, is synthesized for commercial use as a drug substance in highly pure form. During the synthetic process development studies of ezetimibe, an impurity was detected in the final product at levels ranging from 0.05% to 0.15% in reverse phase gradient high performance liquid chromatography (HPLC) method and its molecular weight was determined by LC-MS analysis. The impurity was identified as (3R,4S)-3-((S)-3-(4-fluorophenyl)-3-hydroxypropyl)-4-(4-hydroxyphenyl)-1-phenylazetidin-2-one which is called desfluoro ezetimibe (lactam-related) impurity, synthesized and characterized, the mechanism of its formation was discussed in detail. After all standardization procedures, it was used as a reference standard during validation of HPLC method and routine analyses. In addition, content of Eze-1 desfluoro impurity in Eze-1 intermediates was specified as 0.10% to keep the formation of desfluoro ezetimibe impurity under control and the related substances HPLC method was validated accordingly.

Effects of Statin versus the Combination of Ezetimibe plus Statin on Serum Lipid Absorption Markers in Patients with Acute Coronary Syndrome

Background. The use of statins is essential for aggressive lipid-lowering treatment in acute coronary syndrome (ACS) patients with dyslipidemia. Recently, elevation of sitosterol, a lipid absorption marker, was reported to be associated with premature atherosclerosis. The purpose of the present study was to examine the impact of ezetimibe, a selective intestinal cholesterol transporter inhibitor, in ACS patients. Methods. A total of 197 ACS patients were randomized to pitavastatin + ezetimibe (n = 100) or pitavastatin (n = 97). Low-density lipoprotein cholesterol (LDL-C) and sitosterol levels were evaluated on admission and after 12 weeks. Results. After 12 weeks, the pitavastatin + ezetimibe group showed a significantly greater decrease of sitosterol (baseline versus after 12 weeks; 2.9 ± 2.5 versus 1.7 ± 1.0 ng/mL, P < 0.001) than the pitavastatin group (2.7 ± 1.5 versus 3.0 ± 1.4 ng/mL). The baseline sitosterol level was significantly higher in patients with achieved LDL-C levels ≥ 70 mg/dL than in patients with levels < 70 mg/dL (3.2 ± 2.5 versus 2.4 ± 1.3 ng/mL, P = 0.006). Conclusions. Ezetimibe plus statin therapy in ACS patients with dyslipidemia decreased LDL-C and sitosterol levels more than statin therapy solo. Sitosterol Elevation was a predictor of poor response to aggressive lipid-lowering treatment in ACS patients.

The ‘Ireland’ one-pot alcohol oxidation coupling reactions: celebrating 30 years of diverse synthesis

The Ireland one-pot oxidative coupling reaction is reviewed on the occasion of its 30^th anniversary.

Achieving goal lipid levels with ezetimibe plus statin add-on or switch therapy compared with doubling the statin dose. A pooled analysis

OBJECTIVE

Evaluate the lipid-altering effects of ezetimibe added to ongoing statin therapy, statin titration, switching from statin monotherapy to a more potent statin or to ezetimibe/simvastatin.

METHODS

A pooled analysis of patient-level data from 17 double-blind, active or placebo-controlled studies of 8667 hypercholesterolemic adults randomized to ezetimibe 10 mg added to ongoing statins, statin titration (doubling), or switching from ongoing statins to rosuvastatin (10 mg) or to ezetimibe/simvastatin (10/20 and 40 mg). Percent change from baseline in low-density lipoprotein cholesterol (LDL-C) was estimated by analysis of variance. Percent of patients who achieved LDL-C and other guideline-recommended targets, and target lipid levels by baseline distance to goal were evaluated.

RESULTS

LDL-C percent change from baseline was -26.0 for ezetimibe added to ongoing statin therapy, -27.6 for switching from ongoing statin to ezetimibe/simvastatin, -19.7 for switching to rosuvastatin 10 mg, and -9.7 for dose doubling of the ongoing statin. For patients within 0.8 mmol/L (30 mg/dL) of the target at baseline, LDL-C target attainment rates were 75.9% for adding ezetimibe to ongoing statin, 72.8% for switching to ezetimibe/simvastatin, 61.8% for switching to rosuvastatin, and 44.3% for statin dose-doubling. Similarly, improvements in other lipids and achievement of non-high-density lipoprotein cholesterol and apolipoprotein B targets among this patient group were largest for ezetimibe added to ongoing statins and switching to ezetimibe/simvastatin; switching to rosuvastatin 10 mg and statin dose-doubling were less effective.

CONCLUSIONS

Adding ezetimibe to ongoing statin therapy appeared to be an effective option for patients who do not achieve lipid-lowering goals on statins alone.

Population pharmacodynamic analysis of LDL-cholesterol lowering effects by statins and co-medications based on electronic medical records

AIMS

HMG-CoA reductase inhibitors are available for use in low density lipoprotein-cholesterol (LDL-C) lowering therapy. The purposes of this study were to develop a population pharmacodynamic (PPD) model to describe the time course for the LDL-C lowering effects of statins and assess the efficacy of combination therapy based on electronic medical records.

METHODS

Patient backgrounds, laboratory tests and prescribed drugs were collected retrospectively from electronic medical records. Patients who received atorvastatin, pitavastatin or rosuvastatin were enrolled. A physiological indirect response model was used to describe the changes observed in LDL-C concentrations. The PPD analysis was performed using nonmem 7.2.0 with the first order conditional estimation method with interaction (FOCE-INTER).

RESULTS

An indirect response Imax model, based on the 2863 LDL-C concentrations of 378 patients, successfully and quantitatively described the time course for the LDL-C lowering effects of three statins. The combination of ezetimibe, a cholesterol absorption inhibitor, decreased the LDL synthesis rate (Kin ) by 10.9%. A simulation indicated that the combined treatment of ezetimibe with rosuvastatin (2.5 mg day(-1) ) led to superior clinical responses than those with high doses of rosuvastatin (5.0 mg day(-1) ) monotherapy, even in patients with higher baseline LDL-C concentrations prior to the treatment.

CONCLUSIONS

A newly constructed PPD model supported previous evidence for the beneficial effects of ezetimibe combined with rosuvastatin. In addition, the established framework is expected to be applicable to other drugs without pharmacokinetic data in clinical practice.

Influence of previous statin therapy on cholesterol-lowering effect of ezetimibe

BACKGROUND AND OBJECTIVES

The inhibition of cholesterol absorption by ezetimibe increases cholesterol synthesis. The effect of inhibition of cholesterol synthesis on cholesterol absorption is controversial. The influence of these interactions on cholesterol levels is unknown. We investigated on the extent to which cholesterol levels were affected by the reaction of one pathway to the inhibition of the other pathway.

SUBJECTS AND METHODS

This case-controlled study enrolled 198 patients who needed cholesterol-lowering drugs. Ezetimibe (10 mg) was administered to the patients with (n=58) and without on-going statin therapy (n=58). Simvastatin (20 mg) was administered to the patients treated with (n=41) and without ezetimibe (n=41).

RESULTS

Ezetimibe without statin lowered the total cholesterol by 13.3±8.8% (p<0.001) and the low density lipoprotein-cholesterol (LDL-C) by 18.7±15.3% (p<0.001). Ezetimibe added to statin decreased the total cholesterol by 21.1±7.7% (p<0.001) and the LDL-C by 29.9±12.6% (p<0.001). The total cholesterol and LDL-C were reduced more by ezetimibe in patients with statin therapy than in those without statin therapy (p<0.001 and p<0.001, respectively). The differences in the effect of simvastatin on total cholesterol and LDL-C between the patients with and without ezetimibe showed borderline significance (p=0.10 and p=0.055, respectively).

CONCLUSION

A prior inhibition of cholesterol synthesis by statin enhanced the effect of ezetimibe on total cholesterol and LDL-C by 7.8% and 11.2%, respectively. This finding suggests that ezetimibe increased cholesterol synthesis, resulting in a significant elevation of cholesterol levels.

Gene polymorphism and frequencies of the NPC1L1 gene (rs2072183, rs217434 and rs217428) in Japanese patients with dyslipidemia

WHAT IS KNOWN AND OBJECTIVE

Niemann-Pick C1-Like 1 (NPC1L1) plays a pivotal role in intestinal cholesterol absorption. Ezetimibe is known as an inhibitor for NPC1L1 and decreases concentration of low-density lipoprotein cholesterol (LDL-C) in blood. Responses of the decrease of serum LDL-C levels to ezetimibe have been reported to be different among NPC1L1 variants. However, there are still limited data concerning the genetic variation in the NPC1L1 gene, specifically, in Japanese patients with dyslipidemia. The purpose of this study is to elucidate genotype and allele frequencies of the NPC1L1 gene in Japanese patients with dyslipidemia.

METHODS

Written informed consent was obtained from all participants. All patients were administered ezetimibe at the dose of 10 mg for once a day either alone or coadministered with statins. Patient's data were retrospectively obtained from their medical records. Genomic DNA was extracted from whole blood samples and analysed three NPC1L1 SNPs (rs2072183, rs217428 and rs217434) by the direct sequencing method.

RESULTS AND DISCUSSION

We found that there is a significant difference of genotype frequencies between healthy Japanese and dyslipidemic subjects in rs2072183. No significant differences were observed in rs217428 and rs217434; however, comparison of our data with literature reports suggests that there are significant differences in the frequencies of rs217428 and rs217434 between Canadian and Japanese dyslipidemic patients.

WHAT IS NEW AND CONCLUSION

Our study is the first report concerning the genotype and allele frequencies of the gene coding for NPC1L1 in Japanese patients with dyslipidemia. The most notable result was to demonstrate that there exists a significant difference in rs2072183 variant between healthy Japanese and dyslipidemic subjects and also found that there exists genetic variation of rs2072183 between Japanese and Canadian patients with dyslipidemia. Our results are expected to facilitate research in the proper use of ezetimibe-based mono- or combination therapies. Further studies will be required to evaluate the effects of rs2072183 on the efficacy of LDL cholesterol reduction by ezetimibe.

A reappraisal of the risks and benefits of treating to target with cholesterol lowering drugs

Atherosclerotic cardiovascular disease (CVD) is the number one cause of death globally, and lipid modification, particularly lowering of low density lipoprotein cholesterol (LDLc), is one of the cornerstones of prevention and treatment. However, even after lowering of LDLc to conventional goals, a sizeable number of patients continue to suffer cardiovascular events. More aggressive lowering of LDLc and optimization of other lipid parameters like triglycerides (TG) and high density lipoprotein cholesterol (HDLc) have been proposed as two potential strategies to address this residual risk. These strategies entail use of maximal doses of highly potent HMG CoA reductase inhibitors (statins) and combination therapy with other lipid modifying agents. Though statins in general are fairly well tolerated, adverse events like myopathy are dose related. There are further risks with combination therapy. In this article, we review the adverse effects of lipid modifying agents used alone and in combination and weigh these effects against the evidence demonstrating their efficacy in reducing cardiovascular events, cardiovascular mortality, and all cause mortality. For patients with established CVD, statins are the only group of drugs that have shown consistent reductions in hard outcomes. Though more aggressive lipid lowering with high dose potent statins can reduce rates of non fatal events and need for interventions, the incremental mortality benefits remain unclear, and their use is associated with a higher rate of drug related adverse effects. Myopathy and renal events have been a significant concern with the use of high potency statin drugs, in particular simvastatin and rosuvastatin. For patients who have not reached target LDL levels or have residual lipid abnormalities on maximal doses of statins, the addition of other agents has not been shown to improve clinical outcomes and carries an increased risk of adverse events. The clinical benefits of drugs to raise HDLc remain unproven. In patients without known cardiovascular disease, there is conflicting evidence as to the benefits of aggressive pursuit of numerical lipid targets, particularly with respect to all cause mortality. Certainly, in statin intolerant patients, alternative agents with a low side effect profile are desirable. Bile acid sequestrants are an effective and safe choice for decreasing LDLc, and omega-3 fatty acids are safe agents to decrease TG. There remains an obvious need to design and carry out large scale studies to help determine which agents, when combined with statins, have the greatest benefit on cardiovascular disease with the least added risk. These studies should be designed to assess the impact on clinical outcomes rather than surrogate endpoints, and require a comprehensive assessment and reporting of safety outcomes.

Hypolipidemic treatment of heterozygous familial hypercholesterolemia: a lifelong challenge

In familial hypercholesterolemia, a defect in low-density lipoprotein receptors causes lifelong two- to threefold elevations in serum low-density lipoprotein-cholesterol levels. This leads to early atherosclerotic changes in infancy. Lifelong hypolipidemic treatment that can be started at a young age is thus greatly needed. Early diagnosis of familial hypercholesterolemia is important, and improved DNA tests for low-density lipoprotein receptor mutations have made it possible to carry out diagnosis at birth. A low saturated-fat, low cholesterol diet can be safely started at 7 months of age. This can be accompanied by dietary stanol esters from 2 years of age. At the age of 10, statin treatment can be safely started. In adults, more aggressive hypolipidemic treatment is required in order to reach the treatment goal for serum low-density lipoprotein-cholesterol levels less than 2.5 mmol/l. This can be achieved by using high doses of statin, or preferably by combining a statin with resin or ezetimibe (Zeita), Merck and Shering-Plough Pharmaceuticals). Once started, treatment of familial hypercholesterolemia is lifelong.

Torcetrapib/atorvastatin combination therapy

Elevated blood levels of low-density lipoprotein cholesterol (LDL-C) are associated with an increased risk for atherosclerotic coronary heart disease (CHD). Atorvastatin is a statin drug that inhibits 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (the rate-limiting step of cholesterol production) and primarily lowers LDL-C levels. Atorvastatin has also been shown to significantly reduce CHD events. However, as with all statins (and all other monotherapy lipid-altering drugs), atorvastatin alone reduces the risk of CHD in only a minority of patients relative to placebo. Conversely, it is low levels of high-density lipoprotein cholesterol that are associated with increased CHD risk. Torcetrapib is a cholesteryl ester transfer protein inhibitor that primarily raises high-density lipoprotein cholesterol levels, and cholesteryl ester transfer protein inhibition has generally been shown to reduce atherosclerosis in rabbits. Taken together, atorvastatin and torcetrapib provide striking improvements in lipid levels, and complementary actions upon important lipid parameters. This review examines the chemistry, mechanism of action, pharmacokinetics, metabolism, safety/tolerability and efficacy of the combination torcetrapib/atorvastatin agent that is currently in development and that provides complementary lipid benefits towards the goal of reducing CHD risk beyond that of atorvastatin alone.

Critical appraisal of revised cholesterol guidelines for the very high-risk patient

A working group from the Adult Treatment Panel III of the national Cholesterol Educational Program issued a revised algorithm for low-density lipoprotein (LDL)-cholesterol lowering in very high-risk cardiovascular disease patients. The rationale of these recommendations was primarily established from pooled analysis of multiple clinical trials of LDL-cholesterol-lowering therapies and limited data from an acute coronary syndrome trial. In the near future, the findings of these large-scale randomized trials designed to test the hypothesis that more aggressive LDL-cholesterol therapy is accompanied by fewer cardiovascular events than less aggressive LDL-cholesterol lowering therapy, will provide the evidence needed to support or refute these new recommendations. In this article, the authors suggest that an LDL-cholesterol level of less than 70 mg/dl is unattainable and not necessary for many high-risk patients. Furthermore, the potential risks associated with high-dose statin agents in certain patients, such as the elderly, may outweigh these putative benefits.

Combination therapy with ezetimibe and simvastatin to achieve aggressive LDL reduction

A low-density lipoprotein (LDL) cholesterol goal of less than 100 mg/dl is recommended for patients at moderate to high risk of cardiovascular disease with an optional LDL goal of less than 70 mg/dl for patients at a very high risk of cardiovascular disease. Most patients will require reductions in LDL of more than 50% in order to achieve these more aggressive goals. Only a few agents will lower LDL by at least 50%. This review will focus on the efficacy and safety ezetimibe/simvastatin coadministered as a therapy with enhanced LDL-lowering efficacy, while minimizing the adverse effects of statins in a wide range of patients. Ezetimibe 10 mg/simvastatin 80 mg lowers LDL by approximately 60% and has been demonstrated to be superior to the highest doses of atorvastatin and rosuvastatin for lowering LDL and raising high-density lipoprotein.

Cardiovascular complications after transplantation: treatment options in solid organ recipients

Premature cardiovascular disease is the commonest cause of death in solid organ transplant recipients, with coronary artery disease, sudden cardiac death and heart failure being highly prevalent. There are unique factors leading to CV disease in organ transplant recipients that include underlying comorbidities, and metabolic effects of immunosuppression. As a consequence management strategies developed in the general population may have limited benefit. In this review, we will focus on renal transplantation, where most research has been carried out and, despite incomplete understanding of the disease process, the incidence of cardiovascular disease appears to be falling.

Lipid-lowering agents and hepatotoxicity

Lipid-lowering therapy is increasingly being used in patients for a variety of diseases, the most important being secondary prevention of cardiovascular disease. Many lipid-lowering drugs carry side effects that include elevations in hepatic function tests and liver toxicity. In many cases, these drugs are not prescribed or they are underprescribed because of fears of injury to the liver. This article attempts to review key trials with respect to the hepatotoxicity of these drugs. Recommendations are also provided with respect to the selection of low-risk patients and strategies to lower the risk of hepatotoxicity when prescribing these medications.

Dyslipidemic drugs in metabolic syndrome

INTRODUCTION

Metabolic syndrome predisposes to diabetes and atherosclerotic vascular disease. Statins reduce cardiovascular events, so all metabolic syndrome patients should be evaluated for dyslipidemia. Many patients fail to achieve lipid goals with statin monotherapy. Co-administration of ezetimibe (EZE) and atorvastatin (ATV) may enable more patients to achievelow-density lipoproteincholesterol (LDL-C) goal while avoiding risks of high-dose statin monotherapy.

MATERIALS AND METHODS

The present study compares rosuvastatin (Rsv) with a combination of (Atv) and (Eze). Metabolic syndrome patients, 30-70 years with LDL-C ≥130 mg/dl and a 10-year CHD risk score of 10% were randomized to double-blind treatment with (Rsv) 5 mg (n = 67) or (Atv) 10 mg+(Eze) 10 mg (n = 68) for 12 weeks.

RESULTS

LDL-C reduced significantly; (32.3% and 30.3%, P < 0.001) in (Atv)+(Eze) and (Rsv), respectively, but there was no significant difference between two arms. More patients achieved LDL-C goal of ≤100 mg/dl with (Atv)+(Eze) compared to (Rsv) (65% vs. 58%, P < 0.05). Triglycerides (TG) were reduced more with (Atv)+(Eze) compared to (Rsv) (28.1% and 21.4%, P < 0.001). Greater increase in high-density lipoprotein cholesterol (HDL-C) was observed with (Atv)+(Eze). Both treatments were well tolerated.

CONCLUSION

This study shows that the combination of (Atv)+(Eze) has more efficacy and comparable safety to that of (Rsv).

Effects of Ezetimibe on Cyclosporine Pharmacokinetics in Healthy Subjects

This single-center, open-label, 2-period crossover study investigated the effects of multiple-dose ezetimibe (EZE) on a single dose of cyclosporine (CyA). Healthy subjects received 2 treatments in random order with a 14-day washout: (1) CyA 100 mg alone and (2) EZE 20 mg for 7 days with CyA 100 mg coadministered on day 7; EZE 20 mg alone was administered on day 8. AUC(0-last) and Cmax geometric mean ratios (90% confidence interval) for ([CyA + EZE]/CyA alone) were 1.15 (1.07, 1.25) and 1.10 (0.97, 1.26), respectively. Tmax (approximately 1.3 hours) was similar with and without EZE (P >.200). Mean CyA exposure slightly increased (approximately 15%) with multiple-dose EZE 20 mg; however, this value was contained within (0.80, 1.25). The implications for chronic EZE dosing within the usual clinical paradigm of chronic CyA dosing have not been established; caution is recommended when using these agents concomitantly. CyA concentrations should be monitored in patients receiving EZE and CyA.

Interaction of Single-Dose Ezetimibe and Steady-State Cyclosporine in Renal Transplant Patients

This open-label, single-period study evaluated the single-dose pharmacokinetics of ezetimibe (EZE) 10 mg in the setting of steady-state cyclosporine (CyA) dosing in renal transplant patients. A single 10-mg dose of EZE was coadministered with the morning dose of CyA (75-150 mg twice a day). Total EZE (sum of unconjugated, parent EZE and EZE-glucuronide; EZE-total) AUC(0-last) and Cmax were compared to values derived from a prespecified database of healthy volunteers. Geometric mean ratios (90% CIs) for (EZE + CyA)/EZE alone for EZE-total AUC((0-last)) and Cmax were 3.41 (2.55, 4.56) and 3.91 (3.13, 4.89), respectively. Compared to healthy controls, EZE-total AUC((0-last)) was 3.4-fold higher in transplant patients receiving CyA; similar exposure levels were seen in a prior multiple-dose study in which EZE 50 mg was administered to healthy volunteers without dose-related toxicity. Because the long-term safety implications of both higher EZE exposures and undetermined effect on CyA are not yet understood, the clinical significance of this interaction is unknown.

Safety profile of statins alone or combined with ezetimibe: a pooled analysis of 27 studies including over 22,000 patients treated for 6-24 weeks

Aims:  The aim of this analysis was to assess the overall safety and tolerability profiles of various statins + ezetimibe vs. statin monotherapy and to explore tolerability in sub-populations grouped by age, race, and sex. Methods:  Study-level data were combined from 27 double-blind, placebo-controlled or active-comparator trials that randomized adult hypercholesterolemic patients to statin or statin + ezetimibe for 6-24 weeks. In the full cohort, % patients with AEs within treatment groups (statin: N = 10,517; statin + ezetimibe: N = 11,714) was assessed by logistic regression with terms for first-/second-line therapy (first line = drug-naïve or rendered drug-naïve by washout at study entry; second line = ongoing statin at study entry or statin run-in), trial within first-/second-line therapy, and treatment. The same model was fitted for age (< 65, ≥ 65 years), sex, race (white, black, other) and first-/second-line subgroups with additional terms for subgroup and subgroup-by-treatment interaction. Results:  In the full cohort, the only significant difference between treatments was consecutive AST or ALT elevations ≥ 3 × upper limit of normal (ULN) (statin: 0.35%, statin + ezetimibe: 0.56%; p = 0.017). Significantly more subjects reported ≥ 1 AE; drug-related, hepatitis-related and gastrointestinal-related AEs; and CK elevations ≥ 10 × ULN (all p ≤ 0.008) in first-line vs. second-line therapy studies with both treatments. AEs were generally similar between treatments in subgroups, and similar rates of AEs were reported within age and race subgroups; however, women reported generally higher AE rates. Conclusions:  In conclusion, in second-line studies, ongoing statin treatment at study entry likely screened out participants for previous statin-related AEs and tolerability issues. These results describe the safety profiles of widely used lipid-lowering therapies and encourage their appropriate and judicious use in certain subpopulations.

Ezetimibe therapy: mechanism of action and clinical update

The lowering of low-density lipoprotein cholesterol (LDL-C) is the primary target of therapy in the primary and secondary prevention of cardiovascular events. Although statin therapy is the mainstay for LDL-C lowering, a significant percentage of patients prescribed these agents either do not achieve targets with statin therapy alone or have partial or complete intolerance to them. For such patients, the use of adjuvant therapy capable of providing incremental LDL-C reduction is advised. One such agent is ezetimibe, a cholesterol absorption inhibitor that targets uptake at the jejunal enterocyte brush border. Its primary target of action is the cholesterol transport protein Nieman Pick C1 like 1 protein. Ezetimibe is an effective LDL-C lowering agent and is safe and well tolerated. In response to significant controversy surrounding the use and therapeutic effectiveness of this drug, we provide an update on the biochemical mechanism of action for ezetimibe, its safety and efficacy, as well as the results of recent randomized studies that support its use in a variety of clinical scenarios.

Mipomersen: a safe and effective antisense therapy adjunct to statins in patients with hypercholesterolemia

Mipomersen is an antisense oligonucleotide inhibitor of apolipoprotein (apo) B-100 currently in phase 3 of development for the treatment of hyperlipidemia in patients with a high risk for cardiovascular disease. The drug acts by inhibiting the production of apoB-100, which is the structural core for all atherogenic lipids, including low-density lipoprotein cholesterol (LDL-C). The agent has been shown to produce significant reductions in LDL-C from baseline values compared with placebos. Clinical trials have demonstrated that mipomersen reduces LDL-C up to 44% in patients with familial hypercholesterolemia and patients with significantly elevated LDL despite taking maximum doses of statins. Unlike other medications that target apoB-100, such as microsomal triglyceride transfer proteins, mipomersen does not cause hepatic steatosis or intestinal steatosis and does not affect dietary fat absorption. Adverse side effects encountered with mipomersen include flu-like symptoms, injection site reactions, and elevated liver transaminases. If future studies continue to show such promising results, mipomersen would likely be a viable additional lipid-lowering therapy for patients who are at high cardiovascular risk, intolerant to statins, and/or not at target lipid levels despite maximum doses of statin therapy. Clinical outcome studies looking at cardiovascular disease end points still need to be done.

Niemann-Pick C1-Like 1 and cholesterol uptake

Niemann-Pick C1-Like 1 (NPC1L1) is a polytopic transmembrane protein responsible for dietary cholesterol and biliary cholesterol absorption. Consistent with its functions, NPC1L1 distributes on the brush border membrane of enterocytes and the canalicular membrane of hepatocytes in humans. As the molecular target of ezetimibe, a hypocholesterolemic drug, its physiological and pathological significance has been recognized and intensively studied for years. Recently, plenty of new findings reveal the molecular mechanism of NPC1L1's role in cholesterol uptake, which may provide new insights on our understanding of cholesterol absorption. In this review, we summarized recent progress in these studies and proposed a working model, hoping to provide new perspectives on the regulation of cholesterol transport and metabolism.

Double-dose pravastatin versus add-on ezetimibe with low-dose pravastatin - effects on LDL cholesterol, cholesterol absorption, and cholesterol synthesis in Japanese patients with hypercholesterolemia (PEAS study)

AIM

This study compared the effect of doubling the dose of pravastatin with that of adding ezetimibe to low-dose pravastatin on the LDL cholesterol (LDL-C) level and on cholesterol absorption and synthesis markers. The tolerability of the 2 regimens was also compared.

METHODS

This was a multicenter, open-label, parallel-group trial. Subjects were aged from 20 to 74 years and had an LDL-C ≥ 120 mg/dL despite pravastatin therapy at 5-10 mg/day. They were randomly allocated to receive either add-on ezetimibe (10 mg/day) or double-dose pravastatin, and follow-up was performed for 12 weeks. The primary endpoints were the changes of LDL-C and apolipoprotein (apo) B levels after 12 weeks of treatment. Cholesterol absorption and synthesis markers were also determined.

RESULTS

LDL-C and apo B decreased by 16% and 14% in the ezetimibe add-on group versus 5.9% and 4.4%, respectively, in the pravastatin double-dose group. The between-group differences of these decreases were highly significant. Cholesterol absorption markers (sitosterol, campesterol, and cholestanol) were reduced by 48%, 36%, and 10%, respectively, in the ezetimibe add-on group, and were increased by 17%, 14%, and 6%, respectively, in the pravastatin double-dose group. Lathosterol (a cholesterol synthesis marker) increased by 76% in the ezetimibe add-on group and by 24% in the pravastatin double-dose group. The difference was statistically significant. No serious adverse effect was observed in either group.

CONCLUSIONS

Adding ezetimibe to low-dose pravastatin achieves greater decreases in LDL-C, apo B, and cholesterol absorption markers than doubling the dose of pravastatin.

Intestinal sterol transporters and cholesterol absorption inhibition

PURPOSE OF REVIEW

Statin therapy is the mainstay of lipid-lowering therapy; however, many patients, particularly those at high risk, do not achieve sufficient LDL-cholesterol (LDL-C) lowering. Thus, there remains an unmet medical need for more effective and well tolerated lipid-lowering agents. Guidelines recommend combining additional lipid-lowering agents with a complementary mode of action for these patients. One approach to complementing statin therapy is combination with inhibitors that block the intestinal absorption of dietary and biliary cholesterol. This review summarizes what is currently known about intestinal sterol transporters and cholesterol absorption inhibitors (CAIs).

RECENT FINDINGS

The only lipid-lowering agent currently available that specifically targets an intestinal sterol transporter (Niemann-Pick C1-like 1) is the CAI, ezetimibe. It is effective in lowering LDL-C, both when given alone and when combined with a statin. Clinical outcome data with ezetimibe combined with simvastatin have recently become available, and definitive evidence that the incremental LDL-C lowering attributable to the ezetimibe component reduces cardiovascular events beyond simvastatin alone is currently under study. Other novel CAIs have been evaluated based upon the structure and properties of ezetimibe, but none remain in development.

SUMMARY

Additional lipid-lowering agents are needed to fulfill an unmet medical need for those patients who do not achieve optimal LDL-C goals on statin monotherapy. The inhibition of cholesterol absorption is an important therapeutic strategy to reduce cholesterol levels. Based upon the demonstrated lipid-altering efficacy and safety of ezetimibe, several CAIs have been identified; all to date have been discontinued due to limited efficacy.

The effect of ezetimibe on peripheral arterial atherosclerosis depends upon statin use at baseline

BACKGROUND

Both statins and ezetimibe lower LDL-C, but ezetimibe's effect on atherosclerosis is controversial. We hypothesized that lowering LDL-C cholesterol by adding ezetimibe to statin therapy would regress atherosclerosis measured by magnetic resonance imaging (MRI) in the superficial femoral artery (SFA) in peripheral arterial disease (PAD).

METHODS

Atherosclerotic plaque volume was measured in the proximal 15-20 cm of the SFA in 67 PAD patients (age 63 ± 10, ABI 0.69 ± 0.14) at baseline and annually × 2. Statin-naïve patients (n=34) were randomized to simvastatin 40 mg (S, n=16) or simvastatin 40 mg+ezetimibe 10mg (S+E, n=18). Patients already on statins but with LDL-C >80 mg/dl had open-label ezetimibe 10mg added (E, n=33). Repeated measures models estimated changes in plaque parameters over time and between-group differences.

RESULTS

LDL-C was lower at year 1 in S+E (67 ± 7 mg/dl) than S (91 ± 8 mg/dl, p<0.05), but similar at year 2 (68 ± 10 mg/dl vs. 83 ± 11 mg/dl, respectively). Plaque volume did not change from baseline to year 2 in either S+E (11.5 ± 1.4-10.5 ± 1.3 cm(3), p=NS) or S (11.0 ± 1.5-10.5 ± 1.4 cm(3), p=NS). In E, plaque progressed from baseline to year 2 (10.0 ± 0.8-10.8 ± 0.9, p<0.01) despite a 22% decrease in LDL-C.

CONCLUSIONS

Statin initiation with or without ezetimibe in statin-naïve patients halts progression of peripheral atherosclerosis. When ezetimibe is added to patients previously on statins, peripheral atherosclerosis progressed. Thus, ezetimibe's effect on peripheral atherosclerosis may depend upon relative timing of statin therapy.

Low-density lipoprotein lowering does not improve calf muscle perfusion, energetics, or exercise performance in peripheral arterial disease

OBJECTIVES

We hypothesized that low-density lipoprotein (LDL) reduction regardless of mechanism would improve calf muscle perfusion, energetics, or walking performance in peripheral arterial disease (PAD) as measured by magnetic resonance imaging and magnetic resonance spectroscopy.

BACKGROUND

Statins improve cardiovascular outcome in PAD, and some studies suggest improved walking performance.

METHODS

Sixty-eight patients with mild to moderate symptomatic PAD (age 65 ± 11 years; ankle-brachial index [ABI] 0.69 ± 0.14) were studied at baseline and annually for 2 years after beginning simvastatin 40 mg (n = 20) or simvastatin 40 mg/ezetimibe 10 mg (n = 18) if statin naïve, or ezetimibe 10 mg (n = 30) if taking a statin. Phosphocreatine recovery time was measured by (31)P magnetic resonance spectroscopy immediately after symptom-limited calf exercise on a 1.5-T scanner. Calf perfusion was measured using first-pass contrast-enhanced magnetic resonance imaging with 0.1 mM/kg gadolinium at peak exercise. Gadolinium-enhanced magnetic resonance angiography was graded. A 6-min walk and a standardized graded Skinner-Gardner exercise treadmill test with peak Vo(2) were performed. A repeated-measures model compared changes over time.

RESULTS

LDL reduction from baseline to year 2 was greater in the simvastatin 40 mg/ezetimibe 10 mg group (116 ± 42 mg/dl to 56 ± 21 mg/dl) than in the simvastatin 40 mg group (129 ± 40 mg/dl to 90 ± 30 mg/dl, p < 0.01). LDL also decreased in the ezetimibe 10 mg group (102 ± 28 mg/dl to 79 ± 27 mg/dl, p < 0.01). Despite this, there was no difference in perfusion, metabolism, or exercise parameters between groups or over time. Resting ABI did improve over time in the ezetimibe 10 mg group and the entire study group of patients.

CONCLUSIONS

Despite effective LDL reduction in PAD, neither tissue perfusion, metabolism, nor exercise parameters improved, although rest ABI did. Thus, LDL lowering does not improve calf muscle physiology or functional capacity in PAD. (Comprehensive Magnetic Resonance of Peripheral Arterial Disease; NCT00587678).

Response by sex to statin plus ezetimibe or statin monotherapy: a pooled analysis of 22,231 hyperlipidemic patients

Background

Despite documented benefits of lipid-lowering treatment in women, a considerable number are undertreated, and fewer achieve treatment targets vs. men.

Methods

Data were combined from 27 double-blind, active or placebo-controlled studies that randomized adult hypercholesterolemic patients to statin or statin+ezetimibe. Consistency of treatment effect among men (n = 11,295) and women (n = 10,499) was assessed and percent of men and women was calculated to evaluate the between-treatment ability to achieve specified treatment levels between sexes.

Results

Baseline lipids and hs-CRP were generally higher in women vs. men. Between-treatment differences were significant for both sexes (all p < 0.001 except apolipoprotein A-I in men = 0.0389). Men treated with ezetimibe+statin experienced significantly greater changes in LDL-C (p = 0.0066), non-HDL-C, total cholesterol, triglycerides, HDL-C, apolipoprotein A-I (all p < 0.0001) and apolipoprotein B (p = 0.0055) compared with women treated with ezetimibe+statin. The odds of achieving LDL-C < 100 mg/dL, apolipoprotein B < 90 mg/dL and the dual target [LDL-C < 100 mg/dL & apoliprotein B < 90 mg/dL] was significantly greater for women vs. men and the odds of achieving hs-CRP < 1 and < 2 mg/L and dual specified levels of [LDL-C < 100 mg/dL and hs-CRP < 2 mg/L] were significantly greater for men vs. women. Women reported significantly more gall-bladder-related, gastrointestinal-related, and allergic reaction or rash-related adverse events (AEs) vs. men (no differences between treatments). Men reported significantly more CK elevations (no differences between treatments) and hepatitis-related AEs vs. women (significantly more with ezetimibe+simvastatin vs. statin).

Conclusions

These results suggest that small sex-related differences may exist in response to lipid-lowering treatment and achievement of specified lipid and hs-CRP levels, which may have implications when managing hypercholesterolemia in women.

Safety and efficacy of ezetimibe added on to rosuvastatin 5 or 10 mg versus up-titration of rosuvastatin in patients with hypercholesterolemia (the ACTE Study)

The present multicenter, 6-week, randomized, double-blind, parallel-group, clinical trial evaluated the safety and efficacy of ezetimibe (10 mg) added to stable rosuvastatin therapy versus up-titration of rosuvastatin from 5 to 10 mg or from 10 to 20 mg. The study population included 440 subjects at moderately high/high risk of coronary heart disease with low-density lipoprotein (LDL) cholesterol levels higher than the National Cholesterol Education Program Adult Treatment Panel III recommendations (<100 mg/dl for moderately high/high-risk subjects without atherosclerotic vascular disease or <70 mg/dl for high-risk subjects with atherosclerotic vascular disease). Pooled data demonstrated that ezetimibe added to stable rosuvastatin 5 mg or 10 mg reduced LDL cholesterol by 21%. In contrast, doubling rosuvastatin to 10 mg or 20 mg reduced LDL cholesterol by 5.7% (between-group difference of 15.2%, p <0.001). Individually, ezetimibe plus rosuvastatin 5 mg reduced LDL cholesterol more than did rosuvastatin 10 mg (12.3% difference, p <0.001), and ezetimibe plus rosuvastatin 10 mg reduced LDL cholesterol more than did rosuvastatin 20 mg (17.5% difference, p <0.001). Compared to rosuvastatin up-titration, ezetimibe add-on achieved significantly greater attainment of LDL cholesterol levels of <70 or <100 mg/dl (59.4% vs 30.9%, p <0.001), and <70 mg/dl in all subjects (43.8% vs 17.5%, p <0.001); produced significantly greater reductions in total cholesterol, non-high-density lipoprotein cholesterol, and apolipoprotein B (p <0.001); and resulted in similar effects on other lipid parameters. Adverse experiences were generally comparable among the groups. In conclusion, compared to up-titration doubling of the rosuvastatin dose, ezetimibe 10 mg added to stable rosuvastatin 5 mg or 10 mg produced greater improvements in many lipid parameters and achieved greater attainment of the National Cholesterol Education Program Adult Treatment Panel III recommended LDL cholesterol targets in subjects with elevated LDL cholesterol and at moderately high/high coronary heart disease risk.

Niemann-pick C1-like 1 (NPC1L1) protein in intestinal and hepatic cholesterol transport

Increased blood cholesterol is an independent risk factor for atherosclerotic cardiovascular disease. Cholesterol homeostasis in the body is controlled mainly by endogenous synthesis, intestinal absorption, and hepatic excretion. Niemann-Pick C1-Like 1 (NPC1L1) is a polytopic transmembrane protein localized at the apical membrane of enterocytes and the canalicular membrane of hepatocytes. It functions as a sterol transporter to mediate intestinal cholesterol absorption and counter-balances hepatobiliary cholesterol excretion. NPC1L1 is the molecular target of ezetimibe, a potent cholesterol absorption inhibitor that is widely used in treating hypercholesterolemia. Recent findings suggest that NPC1L1 deficiency or ezetimibe treatment also prevents diet-induced hepatic steatosis and obesity in addition to reducing blood cholesterol. Future studies should focus on molecular mechanisms underlying NPC1L1-dependent cholesterol transport and elucidation of how a cholesterol transporter modulates the pathogenesis of metabolic diseases.