Ezetimibe's effect on platelet aggregation and LDL tendency to peroxidation in hypercholesterolaemia as monotherapy or in addition to simvastatin

Lipid-Lowering Therapy after Acute Coronary Syndrome

Achieving guideline-recommended low-density lipoprotein cholesterol (LDL-C) targets remains a significant challenge in clinical practice. This review assesses the barriers to reaching LDL-C goals and explores the potential solutions to these issues. When aiming for the recommended LDL-C goal, strategies like "lower is better" and "strike early and strong" should be used. The evidence supports the safety and efficacy of intensive lipid-lowering therapy post-acute coronary syndrome (ACS), leading to improved long-term cardiovascular health and atherosclerotic plaque stabilization. Despite the availability of effective lipid-lowering therapies, such as high-intensity statins, ezetimibe, the combination of both, bempedoic acid, and proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, a substantial proportion of patients do not meet their LDL-C targets. Contributing factors include systemic healthcare barriers, healthcare provider inertia, patient non-adherence, and statin intolerance. Statin intolerance, often rather statin reluctance, is a notable obstacle due to perceived or expected side effects, which can lead to discontinuation of therapy. In conclusion, while there are obstacles to achieving optimal LDL-C levels post-ACS, these can be overcome with a combination of patient-centric approaches, clinical vigilance, and the judicious use of available therapies. The safety and necessity of reaching lower LDL-C goals to improve outcomes in patients post-ACS are well-supported by current evidence.

Expanding the therapeutic landscape: ezetimibe as non-statin therapy for dyslipidemia

Dyslipidemia is a significant risk factor for atherosclerotic cardiovascular disease (ASCVD), and statins are the primary therapeutic options for reducing low-density lipoprotein cholesterol (LDL-C) levels. However, it can be challenging to achieve optimal LDL-C goals with statin monotherapy. Ezetimibe, a cholesterol absorption inhibitor, offers a potential non-statin therapy to optimize LDL-C management. Key clinical trials, such as IMPROVE-IT and RACING, have demonstrated that the addition of ezetimibe to statin therapy leads to further decreases in LDL-C or significant decreases in major adverse cardiovascular events (MACEs), particularly in patients with high ASCVD risk. Subsequent meta-analyses and clinical trials have further supported the beneficial effect of ezetimibe, suggesting additive decreases in LDL-C and MACEs, as well as pleiotropic effects. This review provides a comprehensive analysis of the clinical implications of ezetimibe for managing dyslipidemia; it also evaluates the available evidence that supports the role of ezetimibe as an adjunct non-statin therapy for long-term use. However, the long-term pleiotropic effects of ezetimibe remain controversial because of limited clinical data. Therefore, additional research is needed to clarify its potential benefits beyond LDL-C reduction. Nonetheless, an understanding of the role of ezetimibe in dyslipidemia management will help clinicians to develop effective treatment strategies.

The Effects of Statins, Ezetimibe, PCSK9-Inhibitors, Inclisiran, and Icosapent Ethyl on Platelet Function

This review aims to examine the complex interaction between dyslipidemia, platelet function, and related drug treatments. In particular, the manuscript provides an overview of the effects of major hypolipidemic drugs on platelet function. Indeed, growing evidence supports the view that statins, ezetimibe, PCSK9 inhibitors, inclisiran, and icosapent ethyl also act as antithrombotics. It is known that platelets play a key role not only in the acute phase of coronary syndromes but also in the early phase of atherosclerotic plaque formation. The goal of cholesterol-lowering therapy is to reduce cardiovascular events. The direct effects of cholesterol-lowering drugs are widely described in the literature. Lowering LDL-c (low-density lipoprotein cholesterol) by 1 mmol/L results in a 22-23% reduction in cardiovascular risk. Numerous studies have examined the direct antithrombotic effects of these drugs on platelets, endothelium, monocytes, and smooth muscle cells, and thus, potentially independent of blood LDL-cholesterol reduction. We reviewed in vitro and in vivo studies evaluating the complex interaction between hypercholesterolemia, hypertriglyceridemia, platelet function, and related drug treatments. First, we discussed the role of statins in modulating platelet activation. Discontinuation of statin therapy was associated with increased cardiovascular events with increased ox-LDL, P-selectin, and platelet aggregation. The effect of PCSK9-I (inhibitors of proprotein convertase subtilisin/kexin type 9, PCSK9 involved in the degradation of LDL receptors in the liver) was associated with a statistically significant reduction in platelet reactivity, calculated in P2Y12 reaction units (PRU), in the first 14 days and no difference at 30 days compared to placebo. Finally, in patients with hypertriglyceridemia, the REDUCE-IT study showed that icosapent ethyl (an ethyl ester of eicosapentaenoic acid that reduces triglyceride synthesis and improves triglyceride clearance) resulted in a 25% reduction in ischemic events and cardiovascular death. However, to date, there is not yet clear clinical evidence that the direct antithrombotic effects of the drugs may have a beneficial impact on outcomes independently from the reduction in LDL-C or triglycerides.

Moderate-Intensity Statins Plus Ezetimibe vs. High-Intensity Statins After Coronary Revascularization: A Cohort Study

PURPOSE

Whether moderate-intensity statins plus ezetimibe could be an alternative to high-intensity statins in patients with atherosclerotic cardiovascular disease is unclear. We compared the risk of adverse cardiovascular events in patients receiving moderate-intensity statins plus ezetimibe vs. high-intensity statins after a coronary revascularization procedure using data from a large cohort study.

METHOD

Population-based cohort study using nationwide medical insurance data from Korea. Study participants (n = 20,070) underwent percutaneous coronary intervention or coronary artery bypass graft surgery between January 1, 2015, and December 31, 2016, and received moderate-intensity statins (atorvastatin 10-20 mg or rosuvastatin 5-10 mg) plus ezetimibe (n = 922) or high-intensity statins (atorvastatin 40-80 mg or rosuvastatin 20 mg; n = 19,148). The primary outcome was a composite of cardiovascular mortality, hospitalization for myocardial infarction (MI), hospitalization for stroke, or revascularization.

RESULTS

At 12 months, the incidence rates of the primary outcome were 138.0 vs. 154.0 per 1000 person-years in the moderate-intensity stains plus ezetimibe and the high-intensity statins group, respectively. The fully adjusted hazard ratio [HR] for the primary outcome was 1.11 (95% confidence interval [CI] 0.86-1.42; p = 0.43). The multivariable-adjusted HR for a composite of cardiovascular mortality, hospitalization for MI, or hospitalization for stroke was 1.05 (95% CI 0.74-1.47; p = 0.80). During follow-up, the proportion of patients maintaining their initial lipid-lowering therapy was significantly higher in the moderate-intensity statins plus ezetimibe group than in the high-intensity statins group.

CONCLUSIONS

Patients undergoing a coronary revascularization procedure who received moderate-intensity statins plus ezetimibe showed similar rates of major adverse cardiovascular events as patients who received high-intensity statins.

Pleiotropic Effects of PCSK9: Focus on Thrombosis and Haemostasis

The proprotein convertase subtilisin/keying 9 (PCSK9) is a serine protease that has gained importance in recent years as a drug target, mainly due to its effect on cholesterol metabolism in promoting the degradation of the low-density lipoprotein receptor (LDLR). However, this protease may also play an important role in lipid-independent reactions, including the process of thrombogenesis. Considering this, we reviewed the effects and implications of PCSK9 on platelet function and blood coagulation. PCSK9 knockout mice exhibited reduced platelet activity and developed less agonist-induced arterial thrombi compared to the respective control animals. This is in line with known research that elevated blood levels of PCSK9 are associated with an increased platelet reactivity and total number of circulating platelets in humans. Moreover, PCSK9 also has an effect on crucial factors of the coagulation cascade, such as increasing factor VIII plasma levels, since the degradation of this blood clotting factor is promoted by the LDLR. The aforementioned pleiotropic effects of the PCSK9 are important to take into account when evaluating the clinical benefit of PCSK9 inhibitors.

Three Musketeers for Lowering Cholesterol: Statins, Ezetimibe and Evolocumab

Coronary heart disease (CHD) is closely related to hypercholesterolemia, and lowering serum cholesterol is currently the most important strategy in reducing CHD. In humans, the serum cholesterol level is determined mainly by three metabolic pathways, namely, dietary cholesterol intake, cholesterol synthesis, and cholesterol degradation in vivo. An intervention that targets the key molecules in the three pathways is an important strategy in lowering serum lipids. Statins inhibit 3-hydroxyl-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) to reduce low-density lipoprotein (LDL) by about 20% to 45%. However, up to 15% of patients cannot tolerate the potential side effects of high statin dosages, and several patients also still do not reach their optimal LDL goals after being treated with statins. Ezetimibe inhibits cholesterol absorption by targeting the Niemann-Pick C1-like 1 protein (NPC1L1), which is related to cholesterol absorption in the intestines. Ezetimibe lowers LDL by about 18% when used alone and by an additional 25% when combined with statin therapy. The proprotein convertase subtilisin/kexin type 9 (PCSK9) increases hepatic LDLR degradation, thereby reducing the liver's ability to remove LDL, which can lead to hypercholesterolemia. Evolocumab, which is a PCSK9 monoclonal antibody, can reduce LDL from baseline by 53% to 56%. The three drugs exert lipid-lowering effects by regulating the three key pathways in lipid metabolism. Combining any with the two other drugs on the basis of statin treatment has improved the lipid-lowering effect. Whether the combination of the three musketeers will reduce the side effects of monotherapy and achieve the lipid-lowering effect should be studied further in the future.

Management of dyslipidaemia in patients with chronic kidney disease: a position paper endorsed by the Italian Society of Nephrology

Chronic kidney disease (CKD) represents a major public health issue worldwide and entails a high burden of cardiovascular events and mortality. Dyslipidaemia is common in patients with CKD and it is characterized by a highly atherogenic profile with relatively low levels of HDL-cholesterol and high levels of triglyceride and oxidized LDL-cholesterol. Overall, current literature indicates that lowering LDL-cholesterol is beneficial for preventing major atherosclerotic events in patients with CKD and in kidney transplant recipients while the evidence is less clear in patients on dialysis. Lipid lowering treatment is recommended in all patients with stage 3 CKD or worse, independently of baseline LDL-cholesterol levels. Statin and ezetimibe are the cornerstones in the management of dyslipidaemia in patients with CKD, however alternative and emerging lipid-lowering therapies may acquire a central role in near future. This position paper endorsed by the Italian Society of Nephrology aims at providing useful information on the topic of dyslipidaemia in CKD and at assisting decision making in the management of these patients.

Statins, haemostatic factors and thrombotic risk

PURPOSE OF REVIEW

Statins reduce cholesterol synthesis and promote low-density lipoprotein clearance from circulation. Beyond their cholesterol-lowering action, statins may interfere with haemostasis. This review aims to provide an update on the impact of statin treatment on markers of haemostasis and platelet function and on thrombosis-related outcomes.

RECENT FINDINGS

Different coagulation factors are modulated by statins, leading to inhibition of coagulation and increased fibrinolysis. Also, an impact of statins on platelet function has been documented. From a clinical perspective, several observational studies have revealed a reduced incidence of venous thromboembolism in patients receiving statins, which has been argued in some available studies and meta-analyses. Furthermore, a beneficial effect of early statin initiation following acute coronary syndrome for short-term prevention of thrombosis-related events has been documented, but the available data are still not consistent.

SUMMARY

Although statins influence the levels of a multitude of haemostatic factors in an antithrombotic direction, data supporting their use for venous thromboembolism prevention are not consistent, and the impact of statins on early vascular events following acute coronary syndrome is still debated. Whether the robust long-term beneficial effects of statins in reducing cardiovascular risk may be also explained by persistent changes in haemostatic factors needs further exploration.

Comparison of the Effects of Ezetimibe-Statin Combination Therapy on Major Adverse Cardiovascular Events in Patients with and without Diabetes: A Meta-Analysis

BACKGROUND

Ezetimibe-statin combination therapy has been found to reduce low density lipoprotein cholesterol levels and the risk of major adverse cardiovascular events (MACEs) in large trials. We sought to examine the differential effect of ezetimibe on MACEs when added to statins according to the presence of diabetes.

METHODS

Randomized clinical trials with a sample size of at least 50 participants and at least 24 weeks of follow-up that compared ezetimibe-statin combination therapy with a statin- or placebo-controlled arm and reported at least one MACE, stratified by diabetes status, were included in the meta-analysis and meta-regression.

RESULTS

A total of seven trials with 28,191 enrolled patients (mean age, 63.6 years; 75.1% men; 7,298 with diabetes [25.9%]; mean follow-up, 5 years) were analysed. MACEs stratified by diabetes were obtained from the published data (two trials) or through direct contact (five trials). No significant heterogeneity was observed among studies (I²=14.7%, P=0.293). Ezetimibe was associated with a greater reduction of MACE risk in subjects with diabetes than in those without diabetes (pooled relative risk, 0.84 vs. 0.93; P(heterogeneity)=0.012). In the meta-regression analysis, the presence of diabetes was associated with a greater reduction of MACE risk when ezetimibe was added to statins (β=0.87, P=0.038).

CONCLUSION

Ezetimibe-statin combination therapy was associated with greater cardiovascular benefits in patients with diabetes than in those without diabetes. Our findings suggest that ezetimibe-statin combination therapy might be a useful strategy in patients with diabetes at a residual risk of MACEs.

Role of dual lipid-lowering therapy in coronary atherosclerosis regression: Evidence from recent studies

Despite recent therapeutic advances, there is an unmet need in cardiovascular disease prevention. Clinical trials and meta-analyses have established that LDL-C lowering, particularly by statin therapy, reduces the progression of coronary atherosclerosis and the risk of coronary events. Insufficient LDL-C reduction and high residual risk in a significant proportion of statin-treated patients signify that additional therapies are required to deliver more effective coronary care. Pharmacological inhibition of cholesterol absorption (with ezetimibe) and PCSK9 activity (with evolocumab or alirocumab) provides potentially useful approaches for the therapeutic modulation of LDL-C metabolism in statin-treated patients. In recent trials, combination strategies involving a statin and non-statin agent (ezetimibe or evolocumab) have been shown to promote coronary atherosclerosis regression and improve cardiovascular outcomes in patients with moderate-to-high cardiovascular risk. This review summarizes recent evidence on the effects of dual lipid-lowering therapy on coronary atherosclerosis.

Benefit of Adding Ezetimibe to Statin Therapy on Cardiovascular Outcomes and Safety in Patients With Versus Without Diabetes Mellitus: Results From IMPROVE-IT (Improved Reduction of Outcomes: Vytorin Efficacy International Trial)

BACKGROUND

Ezetimibe, when added to simvastatin, reduces cardiovascular events after acute coronary syndrome. We explored outcomes stratified by diabetes mellitus (DM).

METHODS

In IMPROVE-IT (Improved Reduction of Outcomes: Vytorin Efficacy International Trial), 18 144 patients after acute coronary syndrome with low-density lipoprotein cholesterol 50 to 125 mg/dL were randomized to 40 mg ezetimibe/simvastatin (E/S) or 40 mg placebo/simvastatin. The primary composite end point was cardiovascular death, major coronary events, and stroke. DM was a prespecified subgroup.

RESULTS

The 4933 (27%) patients with DM were more often older and female, had had a prior myocardial infarction and revascularization, and presented more frequently with non-ST segment elevation acute coronary syndrome compared with patients without DM (each P<0.001). The median admission low-density lipoprotein cholesterol was lower among patients with DM (89 versus 97 mg/dL, P<0.001). E/S achieved a significantly lower median time-weighted average low-density lipoprotein cholesterol compared with placebo/simvastatin, irrespective of DM (DM: 49 versus 67 mg/dL; no DM: 55 versus 71 mg/dL; both P<0.001). In patients with DM, E/S reduced the 7-year Kaplan-Meier primary end point event rate by 5.5% absolute (hazard ratio, 0.85; 95% confidence interval, 0.78-0.94); in patients without DM, the absolute difference was 0.7% (hazard ratio, 0.98; 95% confidence interval, 0.91-1.04; P_int=0.02). The largest relative reductions in patients with DM were in myocardial infarction (24%) and ischemic stroke (39%). No differences in safety outcomes by treatment were present regardless of DM. When stratified further by age, patients ≥75 years of age had a 20% relative reduction in the primary end point regardless of DM (P_int=0.91), whereas patients <75 years of age with DM had greater benefit than those without (P_int=0.011). When stratified by the TIMI (Thrombolysis in Myocardial Infarction) Risk Score for Secondary Prevention, all patients with DM demonstrated benefit with E/S regardless of risk. In contrast, among patients without DM, those with a high risk score experienced a significant (18%) relative reduction in the composite of cardiovascular death, myocardial infarction, and ischemic stroke with E/S compared with placebo/simvastatin, whereas patients without DM at low or moderate risk demonstrated no benefit with the addition of ezetimibe to simvastatin (P_int =0.034).

CONCLUSIONS

In IMPROVE-IT, the benefit of adding ezetimibe to statin was enhanced in patients with DM and in high-risk patients without DM.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT00202878.

Modulation of Hypercholesterolemia-Induced Oxidative/Nitrative Stress in the Heart

Hypercholesterolemia is a frequent metabolic disorder associated with increased risk for cardiovascular morbidity and mortality. In addition to its well-known proatherogenic effect, hypercholesterolemia may exert direct effects on the myocardium resulting in contractile dysfunction, aggravated ischemia/reperfusion injury, and diminished stress adaptation. Both preclinical and clinical studies suggested that elevated oxidative and/or nitrative stress plays a key role in cardiac complications induced by hypercholesterolemia. Therefore, modulation of hypercholesterolemia-induced myocardial oxidative/nitrative stress is a feasible approach to prevent or treat deleterious cardiac consequences. In this review, we discuss the effects of various pharmaceuticals, nutraceuticals, some novel potential pharmacological approaches, and physical exercise on hypercholesterolemia-induced oxidative/nitrative stress and subsequent cardiac dysfunction as well as impaired ischemic stress adaptation of the heart in hypercholesterolemia.

Longxuetongluo Capsule Improves Erythrocyte Function against Lipid Peroxidation and Abnormal Hemorheological Parameters in High Fat Diet-Induced ApoE-/- Mice

Chinese dragon's blood, the red resin of Dracaena cochinchinensis, one of the renowned traditional medicines, has been used to facilitate blood circulation and disperse blood stasis for thousands of years. Phenolic compounds are considered to be responsible for its main biological activities. In this study, total phenolic compounds of Chinese dragon's blood were made into capsule (Longxuetongluo Capsule, LTC) and their effects on the abnormal hemorheological properties were examined by high fat diet (HFD) induced ApoE−/− mice. Compared to the model group, LTC recovered the abnormal hemorheological parameters in HFD-induced ApoE−/− mice by reducing whole blood viscosity (WBV) at high rate and improving erythrocyte function. In conclusion, LTC could ameliorate erythrocyte deformability and osmotic fragility through the reduction of lipid peroxidation on plasma and erythrocyte membranes in HFD-induced ApoE−/− mice, which supported the traditional uses of Chinese dragon's blood as an effective agent for improving blood microcirculation in hypercholesterolemia.

Influence of ezetimibe on selected parameters of oxidative stress in rat liver subjected to ischemia/reperfusion

INTRODUCTION

Ischemia/reperfusion (I/R) is considered to be one of the main causes of liver damage after transplantation. The authors evaluated the effect of ezetimibe on selected oxidative stress parameters in ischemic/reperfused (I/R) rat liver.

MATERIAL AND METHODS

Rats were administered ezetimibe (5 mg/kg) (groups E and E-I/R) or saline solution (groups C and C-I/R) intragastrically for 21 days. Livers of animals in groups C-I/R and E-I/R were subjected to 60 min of partial ischemia (left lateral and median lobes) followed by 4 h of reperfusion. Alanine and asparagine aminotransferase (ALT, AST) activity was determined in blood before I/R and during reperfusion (at 15 and 240 min). After the reperfusion period, malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH) and glutathione peroxidase (GPx) were determined in liver homogenates using colorimetric methods.

RESULTS

Ezetimibe caused a significant increase in GSH level in groups subjected to I/R (E-I/R (99.91 ±9.01) vs. C-I/R (90.51 ±8.87), p < 0.05). Additionally, under I/R the decrease of GPx activity in the drug-treated group was lower compared to the non-treated group (E-I/R (3.88 ±1.11) vs. E (5.31 ±1.83), p = 0.076). Neither ezetimibe nor I/R affected SOD or MDA levels. I/R produced a significant increase in aminotransferase levels (ALT240-0: C-I/R (42.23 ±43.56) vs. C (9.75 ±11.09), and E-I/R (39.85 ±26.53) vs. E (4.38 ±1.36), p < 0.05 in both cases; AST 240-0: E-I/R (53.87 ±17.23) vs. E (24.10 ±9.66), p < 0.05) but no effect of ezetimibe on those enzymes was found.

CONCLUSIONS

Ezetimibe demonstrates antioxidant properties in rat livers subjected to I/R. However, neither a hepatoprotective nor a hepatotoxic effect of ezetimibe was demonstrated, regardless of I/R.

Effect of statins on platelet function in patients with hyperlipidemia

INTRODUCTION

It is generally assumed that cholesterol reduction by statins is the predominant therapeutic result underlying their beneficial effects in cardiovascular disease. However, the action of statins may be partially independent of their effects on plasma cholesterol levels, as they combine lipid lowering with positive effects on hemorheological conditions and endothelial function. We evaluated the impact of statin treatment on platelet adhesion to fibrinogen (spontaneous and ADP-activated), along with ADP, collagen or ristocetin-induced aggregation in type II hyperlipidemic patients.

MATERIAL AND METHODS

The study group included 70 persons: 50 patients affected by type II hyperlipidemia without concomitant diseases and 20 healthy volunteers. The effects of 8-week statin treatment (atorvastatin 10 mg/day, simvastatin 20 mg/day, or pravastatin 20 mg/day) on platelet activation were evaluated.

RESULTS

Regardless of the type of statin, a significant decrease in ADP-induced platelet aggregation was observed: for atorvastatin 50.6 ±12.8% vs. 41.1 ±15.8% (p < 0.05), for simvastatin 57.2 ±18.0% vs. 44.7 ±22.1% (p = 0.05), and for pravastatin 55.8 ±19.5% vs. 38.8 ±23.3% (p < 0.05). There was no significant effect of statins on collagen or ristocetin-induced platelet aggregation and adhesion.

CONCLUSIONS

Therapy with statins beneficially modifies ADP-induced platelet aggregation in patients with hyperlipidemia and does not affect spontaneous or ADP-induced platelet adhesion to fibrinogen and platelet aggregation induced by collagen or ristocetin.

Paraoxonase activity and expression is modulated by therapeutics in experimental rat nonalcoholic Fatty liver disease

Objective. The objective of the present study is to investigate the effect of rosiglitazone, metformin, ezetimibe, and valsartan (alone or in combinations) on paraoxonase (PON) activity and PON-mRNA expression in nonalcoholic fatty liver disease (NAFLD). Methods. 54 Male Sprague-Dawley rats were divided to 9 groups: chow diet group (15 weeks); methionine-choline-deficient diet (MCDD) group (15 weeks); MCDD-treated groups for the last 6 weeks with either metformin (M), rosiglitazone (R), metformin plus rosiglitazone (M+R), ezetimibe (E), valsartan (V), or a combination of R+M+V or of R+M+V+E for a total period of 15 weeks. Results. PON activities in serum and liver were decreased in MCDD rats. PON activity in serum increased significantly in all treatment groups. PON activity in liver was also increased significantly, except only in groups R, E, V, R+M+V, and R+M+V+E. Liver PON3 mRNA expression increased significantly in groups R+M, E, V, R+M+V, and R+M+V+E whereas liver PON2 mRNA expression increased significantly in MCDD, R+M, E, V, R+M+V, and R+M+V+E. Conclusions. PON activities in serum and liver were decreased in NAFLD. Treatment with insulin sensitizers, ezetimibe, and valsartan increased PON activity and reduced oxidative stress both in serum and liver.

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.

Impact of hypertriglyceridemia on endothelial dysfunction during statin ± ezetimibe therapy in patients with coronary heart disease

Despite the use of statin therapy and achieving the target for low-density lipoprotein cholesterol, a substantial number of coronary events are not prevented, and residual risk factors remain unsettled. Recently, ezetimibe has been shown to reduce not only low-density lipoprotein cholesterol but also triglyceride (TG) levels. The aim of this study was to investigate the associations of residual risk factors, mainly hypertriglyceridemia, with endothelial function during statin therapy in patients with coronary heart disease and examine the effect of ezetimibe add-on therapy. A total of 109 consecutive patients with coronary heart disease during statin therapy were enrolled. Lipid profile was measured and endothelial function was assessed by flow-mediated dilation (FMD) of the brachial artery in a fasting state. Next, 32 patients with high TG levels (≥150 mg/dl) were prospectively assigned to the ezetimibe add-on group or the no-ezetimibe group, and endothelial function was assessed after 3 months. Multivariate linear regression analysis demonstrated that serum TG and high-density lipoprotein cholesterol levels were independent determinants of percentage FMD (β = -0.210 and 0.208, respectively, p <0.05). In patients with high TG levels, ezetimibe add-on therapy significantly improved percentage FMD (from 3.3 ± 1.1% to 4.0 ± 1.1%, p <0.005), whereas no significant change was observed in the no-ezetimibe group. Moreover, the improvement in percentage FMD was significantly associated with reduction in serum TG levels (β = -0.387, p <0.05) independent of the change in serum low-density lipoprotein cholesterol levels. In conclusion, hypertriglyceridemia is independently associated with endothelial dysfunction in patients with coronary heart disease during statin therapy. Ezetimibe add-on therapy improves endothelial function in these high-risk populations.

Pleiotropic effects of ezetimibe/simvastatin vs. high dose simvastatin

BACKGROUND

In the setting of stable coronary artery disease (CAD), it is not known if the pleiotropic effects of cholesterol reduction differ between combined ezetimibe/simvastatin and high-dose simvastatin alone.

OBJECTIVE

We sought to compare the anti-inflammatory and antiplatelet effects of ezetimibe 10mg/simvastatin 20mg (E10/S20) with simvastatin 80 mg (S80).

METHODS AND RESULTS

CAD patients (n=83, 63 ± 9 years, 57% men) receiving S20, were randomly allocated to receive E10/S20 or S80, for 6 weeks. Lipids, inflammatory markers (C-reactive protein, interleukin-6, monocyte chemoattractant protein-1, soluble CD40 ligand and oxidized LDL), and platelet aggregation (platelet function analyzer [PFA]-100) changes were determined. Baseline lipids, inflammatory markers and PFA-100 were similar between groups. After treatment, E10/S20 and S80 patients presented, respectively: (1) similar reduction in LDL-C (29 ± 13% vs. 28 ± 30%, p=0.46), apo-B (18 ± 17% vs. 22 ± 15%, p=0.22) and oxidized LDL (15 ± 33% vs. 18 ± 47%, p=0.30); (2) no changes in inflammatory markers; and, (3) a higher increase of the PFA-100 with E10/S20 than with S80 (27 ± 43% vs. 8 ± 33%, p=0.02).

CONCLUSIONS

These data suggest that among stable CAD patients treated with S20, (1) both E10/S20 and S80 were equally effective in further reducing LDL-C; (2) neither treatment had any further significant anti-inflammatory effects; and (3) E10/S20 was more effective than S80 in inhibiting platelet aggregation. Thus, despite similar lipid lowering and doses 4× less of simvastatin, E10/S20 induced a greater platelet inhibitory effect than S80.

Variability and persistence of aspirin response in lower extremity peripheral arterial disease patients

OBJECTIVE

To determine the prevalence of poor response to aspirin (ASA) therapy over 12-month follow-up in patients with lower extremity peripheral arterial disease (PAD), and to compare the classification agreement among different ASA response assays.

METHODS

Patients with PAD on ASA therapy at baseline were included from the ongoing Effect of Lipid Modification on Peripheral Arterial Disease after Endovascular Intervention Trial (ELIMIT), which is a randomized trial testing whether combination treatment with ezetimibe, niacin, and a statin will halt/regress atherosclerosis compared with statin monotherapy. Patients who had baseline platelet testing and repeat testing at 6-month or 12-month follow-up were included. ASA responsiveness was tested using three different assays: Optical aggregation with 0.5 mg/mL of arachidonic acid (AA), optical aggregation with 10 μM of adenosine diphosphate (ADP), and platelet function analyzer-100 (PFA-100) testing with collagen/epinephrine (Epi) loaded cartridges. ASA response was defined as AA aggregation <30%, ADP aggregation <70%, or PFA-100 Epi >164 seconds. Patients who showed response to ASA at baseline were classified as Responders. Poor response to ASA was defined as AA aggregation ≥ 30%, ADP aggregation ≥ 70%, or PFA-100 Epi ≤ 164 seconds. Patients who showed poor response (PR) to an assay at baseline, but then were responsive at follow-up visits were classified as Initial PRs. Patients who showed poor response at baseline and all follow-up visits were classified as Persistent PRs. The classification agreement between assays was tested using the kappa statistic.

RESULTS

Of 102 patients randomized in ELIMIT, 80 patients satisfied inclusion criteria. There were no significant baseline demographic differences between Responders, Initial PRs, and Persistent PRs. The prevalence of persistent poor response varied by the assay used; 5% of subjects (4/80) were Persistent PRs by AA aggregation, compared with 27.5% (22/80) of subjects by ADP aggregation and 9.9% (7/71) of patients by PFA-100 Epi. Regarding the agreement of the assays, only AA aggregation and PFA-100 Epi agreed significantly (K = 0.3223; 95% confidence interval [CI] 0.15-0.493; P = .0001), and though statistically significant, the magnitude of this agreement is small. AA aggregation and ADP aggregation did not agree (K = 0.1161; 95% CI -0.004-0.236; P = .029), nor did ADP aggregation and PFA-100 Epi (K = 0.0044; 95% CI -0.151-0.160; P = .48).

CONCLUSIONS

Between 5% and 27.5% of PAD patients were Persistent PRs to ASA over 6- to 12-month follow-up using different platelet assays. Further, these commonly used platelet assays show weak agreement in determining poor response to aspirin.

Hypercholesterolemia and microvascular dysfunction: interventional strategies

Hypercholesterolemia is defined as excessively high plasma cholesterol levels, and is a strong risk factor for many negative cardiovascular events. Total cholesterol levels above 200 mg/dl have repeatedly been correlated as an independent risk factor for development of peripheral vascular (PVD) and coronary artery disease (CAD), and considerable attention has been directed toward evaluating mechanisms by which hypercholesterolemia may impact vascular outcomes; these include both results of direct cholesterol lowering therapies and alternative interventions for improving vascular function. With specific relevance to the microcirculation, it has been clearly demonstrated that evolution of hypercholesterolemia is associated with endothelial cell dysfunction, a near-complete abrogation in vascular nitric oxide bioavailability, elevated oxidant stress, and the creation of a strongly pro-inflammatory condition; symptoms which can culminate in profound impairments/alterations to vascular reactivity. Effective interventional treatments can be challenging as certain genetic risk factors simply cannot be ignored. However, some hypercholesterolemia treatment options that have become widely used, including pharmaceutical therapies which can decrease circulating cholesterol by preventing either its formation in the liver or its absorption in the intestine, also have pleiotropic effects with can directly improve peripheral vascular outcomes. While physical activity is known to decrease PVD/CAD risk factors, including obesity, psychological stress, impaired glycemic control, and hypertension, this will also increase circulating levels of high density lipoprotein and improving both cardiac and vascular function. This review will provide an overview of the mechanistic consequences of the predominant pharmaceutical interventions and chronic exercise to treat hypercholesterolemia through their impacts on chronic sub-acute inflammation, oxidative stress, and microvascular structure/function relationships.

Potential therapeutic uses for ezetimibe beyond lowering LDL-c to decrease cardiovascular events

Ezetimibe is a relatively new drug that inhibits the absorption of dietary cholesterol in the small intestine. It is a low density lipoprotein-cholesterol (LDL-C) lowering medication that acts directly on the intestine by inhibiting Niemann-Pick C1 Like1 (NPC1L1). Recently, results of the ARBITER 6-HALTS trial (Arterial Biology for the Investigation of the Treatment Effects of Reducing Cholesterol 6-HDL and LDL Treatment Strategies) and the ENHANCE trial (Ezetimibe and Simvastatin in Hypercholesterolemia Enhances Atherosclerosis Regression) showed that ezetimibe had no effect on atherosclerosis despite producing a marked decrease in LDL-C. Recent studies show a potential benefit of ezetimibe in treating insulin resistance, non-alcoholic fatty liver disease (NAFLD), gallstones and dyslipidaemia associated with chronic renal failure and organ transplantation. All of these conditions are known to be associated with an increase in risk of cardiovascular disease (CVD) and further studies are needed to assess the potential benefits of ezetimibe in these therapeutics areas.

Effect of ezetimibe/atorvastatin combination on oxidized low density lipoprotein cholesterol in patients with coronary artery disease or coronary artery disease equivalent

Ezetimibe is effective in providing additional low-density lipoprotein (LDL) cholesterol lowering when coadministered with statins, but its effect beyond LDL cholesterol lowering is unknown. Oxidized LDL (ox-LDL) is a better predictor of adverse cardiovascular events than standard lipid parameters. The objective of this study was to investigate the effect of ezetimibe on ox-LDL. A total of 100 patients with coronary artery disease or coronary artery disease equivalent were randomized to atorvastatin 40 mg/day and ezetimibe 10 mg/day or to atorvastatin 40 mg/day and placebo. LDL cholesterol, LDL cholesterol subfractions, and ox-LDL were measured at baseline and after 8 weeks of therapy. The ezetimibe group had a larger reduction in total LDL cholesterol compared to placebo. This was due mainly to a larger reduction in large buoyant LDL (24% vs 10%, p = 0.008). Ox-LDL level did not change in the placebo group (50 +/- 13 vs 51 +/- 13 U/L), while it decreased in the ezetimibe group, from 51 +/- 13 to 46 +/- 10 U/L (p = 0.01 vs baseline and p = 0.02 vs final level in placebo). The change in ox-LDL correlated significantly with those in total LDL and in large buoyant LDL (r = 0.6 and r = 0.5, respectively, p <0.01 for both), but not with that of small dense LDL, high-density lipoprotein, or very low density lipoprotein. In conclusion, this study demonstrates that ezetimibe decreases ox-LDL cholesterol through reductions in total LDL cholesterol and in large buoyant LDL cholesterol.

Pleiotropic effects of ezetimibe: do they really exist?

Ezetimibe represents a new lipid lowering agent which inhibits cholesterol absorption. It effectively reduces low-density lipoprotein cholesterol when administered either alone or in combination with statins. However, its effect on cardiovascular mortality remains under question since it failed to demonstrate any significant changes in the primary endpoints of the recently published ENHANCE and SEAS studies. A possible explanation for this unsuccessful outcome is that ezetimibe lacks pleiotropic effects. This article aims to review the potential pleiotropic effects of the drug mainly on inflammation markers, lipoprotein subfractions and endothelial function.

The impact of ezetimibe on endothelial function and other markers of cardiovascular risk

OBJECTIVE

To review the published literature characterizing the impact of ezetimibe-containing lipid-lowering regimens on endothelial function and other markers of cardiovascular risk and discuss the potential relevance of these effects to the clinical benefit of ezetimibe.

DATA SOURCES

A MEDLINE search (2000-August 2009) was completed using the key words ezetimibe, statins, endothelial function, flow-mediated dilation, pleiotropic, and inflammation to identify relevant literature. Bibliographies of identified literature were reviewed for additional references.

STUDY SELECTION AND DATA EXTRACTION

All clinical studies published in English that evaluated the effect of ezetimibe on ancillary endpoints of cardiovascular disease risk, including endothelial function, inflammation, thrombosis, and oxidative stress, were evaluated.

DATA SYNTHESIS

Recent studies in patients with coronary artery disease (CAD), heart failure, and hypercholesterolemia have demonstrated that treatment with ezetimibe for 4-12 weeks elicits no improvement of endothelial function or other measures of cardiovascular disease risk. In contrast, other studies have reported that ezetimibe improves endothelial function in certain patient populations, including those with rheumatoid arthritis, CAD with type 2 diabetes, and metabolic syndrome. However, the statin monotherapy comparator groups in these studies that yielded equivalent reductions in cholesterol were superior, or at least equivalent to, ezetimibe-containing regimens in the improvement of these ancillary endpoints.

CONCLUSIONS

Overall, the evidence to date suggests that administration of ezetimibe, either as monotherapy or in combination with a statin, exerts minimal beneficial effects on endothelial function and other ancillary measures of cardiovascular disease risk beyond those conferred by its cholesterol-lowering effects. Studies with larger sample sizes and follow-up beyond 12 weeks remain necessary to further define the impact of ezetimibe on the processes integral to the pathogenesis and progression of cardiovascular disease.

Effects of ezetimibe add-on therapy for high-risk patients with dyslipidemia

Background

Ezetimibe (Zetia^®) is a potent inhibitor of cholesterol absorption that has been approved for the treatment of hypercholesterolemia. Statin, an inhibitor of cholesterol synthesis, is the first-choice drug to reduce low-density lipoprotein-cholesterol (LDL-C) for patients with hypercholesterolemia, due to its strong effect to lower the circulating LDL-C levels. Because a high dose of statins cause concern about rhabdomyolysis, it is sometimes difficult to achieve the guideline-recommended levels of LDL-C in high-risk patients with hypercholesterolemia treated with statin monotherapy. Ezetimibe has been reported to reduce LDL-C safely with both monotherapy and combination therapy with statins.

Results

To investigate the effect of ezetimibe as "add-on" therapy to statin on hypercholesterolemia, we examined biomarkers and vascular endothelial function in 14 patients with hypercholesterolemia before and after the 22-week ezetimibe add-on therapy. Ezetimibe add-on therapy reduced LDL-C by 24% compared with baseline (p < 0.005), with 13 patients (93%) reaching their LDL cholesterol goals. Of the Ezetimibe add-on therapy significantly improved not only LDL-C, high-density lipoprotein-cholesterol (HDL-C), and apolipoprotein (apo)B levels, but also reduced levels of triglyceride (TG), the ratio of LDL/HDL-C, the ratio of apoB/apoA-I, and a biomarker for oxidative stress (d-ROMs). Furthermore, ezetimibe add-on therapy improved vascular endothelial function in high-risk patients with hypercholesterolemia.

Conclusion

In conclusion, ezetimibe as add-on therapy to statin might be a therapeutic good option for high-risk patients with atherosclerosis.

Impact of ezetimibe on atherosclerosis: is the jury still out?

Ezetimibe is a new lipid-lowering agent that inhibits intestinal absorption of dietary cholesterol. It substantially lowers low-density lipoprotein cholesterol levels when used alone or in combination with statins. However, its effect on cardiovascular mortality remains unknown. We reviewed peer-reviewed published literature on the effect of ezetimibe on different phases of atherosclerosis. MEDLINE, EMBASE, BIOSIS, and other Web of Knowledge databases were searched for relevant abstracts and articles published in the English language that compared ezetimibe and statins as modulators of atherosclerosis. On the basis of the available evidence, ezetimibe appears to reduce inflammation when used in combination with statins, but its effect on endothelial function is mixed and less clear. The effect of ezetimibe on coronary disease progression or prevention of cardiovascular events is currently unknown. Use of ezetimibe as a second- or third-line agent to achieve low-density lipoprotein cholesterol treatment goals seems appropriate on the basis of the available evidence.