Ezetimibe/Simvastatin: a review of its use in the management of hypercholesterolemia

A Review of Progress on Targeting LDL Receptor-Dependent and -Independent Pathways for the Treatment of Hypercholesterolemia, a Major Risk Factor of ASCVD

Since the discovery of the LDL receptor in 1973 by Brown and Goldstein as a causative protein in hypercholesterolemia, tremendous amounts of effort have gone into finding ways to manage high LDL cholesterol in familial hypercholesterolemic (HoFH and HeFH) individuals with loss-of-function mutations in the LDL receptor (LDLR) gene. Statins proved to be the first blockbuster drug, helping both HoFH and HeFH individuals by inhibiting the cholesterol synthesis pathway rate-limiting enzyme HMG-CoA reductase and inducing the LDL receptor. However, statins could not achieve the therapeutic goal of LDL. Other therapies targeting LDLR include PCSK9, which lowers LDLR by promoting LDLR degradation. Inducible degrader of LDLR (IDOL) also controls the LDLR protein, but an IDOL-based therapy is yet to be developed. Among the LDLR-independent pathways, such as angiopoietin-like 3 (ANGPTL3), apolipoprotein (apo) B, apoC-III and CETP, only ANGPTL3 offers the advantage of treating both HoFH and HeFH patients and showing relatively better preclinical and clinical efficacy in animal models and hypercholesterolemic individuals, respectively. While loss-of-LDLR-function mutations have been known for decades, gain-of-LDLR-function mutations have recently been identified in some individuals. The new information on gain of LDLR function, together with CRISPR-Cas9 genome/base editing technology to target LDLR and ANGPTL3, offers promise to HoFH and HeFH individuals who are at a higher risk of developing atherosclerotic cardiovascular disease (ASCVD).

Co-Amorphous Formation of Simvastatin-Ezetimibe: Enhanced Physical Stability, Bioavailability and Cholesterol-Lowering Effects in LDLr-/-Mice

Hypercholesterolemia is one of the independent risk factors for the development of cardiovascular diseases such as atherosclerosis. The treatment of hypercholesterolemia is of great significance to reduce clinical cardiovascular events and patient mortality. Simvastatin (SIM) and ezetimibe (EZE) are commonly used clinically as cholesterol-lowering drugs; however, their treatment efficacy is severely affected by their poor water solubility and low bioavailability. In this study, SIM and EZE were made into a co-amorphous system to improve their dissolution, oral bioavailability, storage stability, and cholesterol-lowering effects. The SIM-EZE co-amorphous solids (CO) were prepared successfully using the melt-quenched technique, and the physicochemical properties of CO were characterized accordingly, which exhibited improved physical stability and faster dissolution release profiles than their physical mixture (PM). In the pharmacokinetic study, the SIM-EZE CO or PM was given once by oral gavage, and mouse blood samples were collected retro-orbitally at multiple time points to determine the plasma drug concentrations. In the pharmacodynamic study, low-density lipoprotein receptor-deficient (LDLr−/−) mice were fed with a high-fat diet (HFD) for two weeks to establish a mouse model of hypercholesterolemia. Using PM as a control, we investigated the regulation of CO on plasma lipid levels in mice. Furthermore, the mice feces were collected to determine the cholesterol contents. Besides, the effect of EZE on the NPC1L1 mRNA expression level in the mouse intestines was also investigated. The pharmacokinetics results showed that the SIM-EZE CO has improved bioavailability compared to the PM. The pharmacodynamic studies showed that SIM-EZE CO significantly increased the cholesterol-lowering effects of the drugs compared to their PM. The total cholesterol excretion in the mouse feces and inhibitory effect on NCP1L1 gene expression in the mouse intestines after being given the SIM-EZE CO were more dramatic than the PM. Our study shows that the SIM-EZE CO prepared by the melt-quenched method can significantly improve the stability, bioavailability, and cholesterol-lowering efficacy with excellent development potential as a new drug formulation.

Rosuvastatin/Ezetimibe: A Review in Hypercholesterolemia

Rosuvastatin/ezetimibe combines two lipid-lowering agents: rosuvastatin, an HMG-CoA reductase inhibitor (i.e. statin) with particularly strong inhibitory effects on hepatic cholesterol synthesis, and ezetimibe, which inhibits the intestinal absorption of cholesterol. A fixed-dose combination (FDC) of rosuvastatin/ezetimibe is indicated as an adjunctive therapy to diet for the management of primary hypercholesterolemia in adults in numerous countries worldwide. In well-designed clinical trials evaluating the therapeutic efficacy of rosuvastatin/ezetimibe administered as either separate agents or as an FDC, rosuvastatin/ezetimibe was significantly more effective than rosuvastatin monotherapy (including at double the dose of rosuvastatin) or simvastatin/ezetimibe in reducing low-density lipoprotein cholesterol (LDL-C) and total cholesterol in adults with hypercholesterolemia. Furthermore, rosuvastatin/ezetimibe enabled significantly higher proportions of patients to achieve recommended LDL-C levels than rosuvastatin monotherapy or simvastatin/ezetimibe. Rosuvastatin/ezetimibe did not significantly differ from rosuvastatin monotherapy with respect to incidences of treatment-related or serious adverse events in these short-term trials and displayed a similar safety profile to simvastatin/ezetimibe. While additional cardiovascular outcomes data and head-to-head comparisons with atorvastatin/ezetimibe would be of interest, rosuvastatin/ezetimibe is a potent and generally well-tolerated drug combination that extends the range of options available for the pharmacological management of primary hypercholesterolemia in adults.

Selective Compensatory Induction of Hepatic HMG-CoA Reductase in Response to Inhibition of Cholesterol Absorption

The effect of the potent inhibitor of cholesterol absorption, ezetimibe, on serum cholesterol levels was tested in diabetic and thyroidectomized male Sprague-Dawley rats. Feeding diets supplemented with 1% cholesterol to the diabetic rats raised serum cholesterol levels from 132 to 514 mg/dl while decreasing hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase protein and mRNA levels. Addition of 10 mg/kg/day of ezetimibe to the diets of these animals lowered the serum cholesterol level to 90 mg/dl and produced a large compensatory increase in hepatic HMG-CoA reductase protein without significantly increasing mRNA levels, indicating a post-transcriptional effect. Hepatic LDL receptor protein levels in these diabetic rats were unaffected by ezetimibe treatment. In contrast, ezetimibe treatment of these young normal Sprague-Dawley rats, known to express high levels of hepatic HMG-CoA reductase, did not lower serum cholesterol levels. In thyroidectomized rats, dietary cholesterol increased serum cholesterol levels from 116 to 135 mg/dl and ezetimibe treatment lowered these elevated cholesterol levels to 85 mg/dl. Cholesterol feeding of thyroidectomized rats severely reduced hepatic HMG-CoA reductase protein, while ezetimibe treatment restored reductase protein to normal levels. Again, hepatic LDL receptor protein levels were unaffected by ezetimibe treatment of cholesterol-fed thyroidectomized rats. The data demonstrate that the cholesterol absorption inhibitor ezetimibe profoundly lowers serum cholesterol levels in animals expressing very low rates of hepatic cholesterol synthesis and produces large compensatory increases in hepatic HMG-CoA reductase expression without significantly affecting expression of hepatic LDL receptors. This indicates that ezetimibe should be most effective in lowering serum cholesterol levels in people with low rates of cholesterol synthesis/high rates of cholesterol absorption.

Lactobacillus acidophilus ATCC 4356 prevents atherosclerosis via inhibition of intestinal cholesterol absorption in apolipoprotein E-knockout mice

The objective of this study was to investigate the effect of Lactobacillus acidophilus ATCC 4356 on the development of atherosclerosis in apolipoprotein E-knockout (ApoE(-/-)) mice. Eight-week-old ApoE(-/-) mice were fed a Western diet with or without L. acidophilus ATCC 4356 daily for 16 weeks. L. acidophilus ATCC 4356 protected ApoE(-/-) mice from atherosclerosis by reducing their plasma cholesterol levels from 923 ± 44 to 581 ± 18 mg/dl, likely via a marked decrease in cholesterol absorption caused by modulation of Niemann-Pick C1-like 1 (NPC1L1). In addition, suppression of cholesterol absorption induced reverse cholesterol transport (RCT) in macrophages through the peroxisome proliferator-activated receptor/liver X receptor (PPAR/LXR) pathway. Fecal lactobacillus and bifidobacterium counts were significantly (P < 0.05) higher in the L. acidophilus ATCC 4356 treatment groups than in the control groups. Furthermore, L. acidophilus ATCC 4356 was detected in the rat small intestine, colon, and feces during the feeding trial. The bacterial levels remained high even after the administration of lactic acid bacteria had been stopped for 2 weeks. These results suggest that administration of L. acidophilus ATCC 4356 can protect against atherosclerosis through the inhibition of intestinal cholesterol absorption. Therefore, L. acidophilus ATCC 4356 may be a potential therapeutic material for preventing the progression of atherosclerosis.

Comparative efficacy of the addition of ezetimibe to statin vs statin titration in patients with hypercholesterolaemia: systematic review and meta-analysis

OBJECTIVE

To systematically review and analyse evidence for cholesterol-lowering efficacy of at least 4 weeks of add-on ezetimibe vs doubling statin dose, in adults with primary hypercholesterolaemia.

RESEARCH DESIGN AND METHODS

MEDLINE, EMBASE and Cochrane databases were searched to identify randomised controlled trials of ezetimibe-statin combination vs statin titration (January 1993 - March 2010). Studies were selected using predefined criteria. Two reviewers conducted screening of articles, critical appraisal and data extraction; a third reviewer resolved disagreements. The difference between treatments was analysed for four co-primary outcomes: mean percentage change from baseline in low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and total cholesterol (TC); and proportion of patients achieving LDL-C treatment goal. Data were combined by two sets of direct comparison fixed and random effects meta-analysis: (1) compared data in the same treatment period between groups; (2) compared the incremental change in lipid levels of add-on ezetimibe vs doubling statin dose. Heterogeneity was assessed using the I(2) statistic.

RESULTS

Thirteen studies including 5080 patients were included in the meta-analyses. Data on simvastatin, atorvastatin and rosuvastatin were analysed. Results for primary and secondary outcomes were in favour of the ezetimibe-statin combination. A significantly greater percentage reduction in LDL-C levels was achieved in patients treated with ezetimibe-statin vs statin monotherapy (weighted mean difference [WMD]: -14.1% [-16.1, -12.1], p < 0.001). Reduction in LDL-C levels attributed to add-on ezetimibe was significantly greater than that for statin dose doubling (WMD: -15.3% [-19.1, -11.4], p < 0.001). Achievement of LDL-C goal favoured add-on ezetimibe over statin titration and was statistically significant (odds ratio: LDL-C treatment goal 2.45 [1.95, 3.08], p = 0.007).

CONCLUSIONS

Meta-analyses were restricted by the limited number of studies with similar trial design and method of statin titration. Results indicate that add-on ezetimibe is significantly more effective in reducing LDL-C levels than doubling statin dose, enabling more patients to achieve LDL-C goal.

Isocoumarin-based inhibitors of pancreatic cholesterol esterase

Pancreatic cholesterol esterase (CEase), which is secreted from the exocrine pancreas, is a serine hydrolase that aids in the bile salt-dependent hydrolysis of dietary cholesteryl esters and contributes to the hydrolysis of triglycerides and phospholipids. Additional roles for CEase in intestinal micelle formation and in transport of free cholesterol to the enterocyte have been suggested. There also are studies that point to a pathological role(s) for CEase in the circulation where CEase accumulates in atherosclerotic lesions and triggers proliferation of smooth muscle cells. Thus, there is interest in CEase as a potential drug target. 4-Chloro-3-alkoxyisocoumarins are a class of haloenol lactones that inhibit serine hydrolases and serine proteases and have the potential to be suicide inhibitors. In the present study, we have developed 3-alkoxychloroisocoumarins that are potent inhibitors of CEase. These inhibitors were designed to have a saturated cycloalkane ring incorporated into a 3-alkoxy substituent. The size of the ring as well as the length of the tether holding the ring was found to be important contributors to binding to CEase. 4-Chloro-3-(4-cyclohexylbutoxy)isocoumarin and 4-chloro-3-(3-cyclopentylpropoxy)isocoumarin were demonstrated to be potent reversible inhibitors of CEase, with dissociation constants of 11nM and 19nM, respectively. The kinetic results are consistent with predictions from molecular modeling.

Cardiovascular disease posttransplant

Renal transplantation is currently the preferred treatment modality for virtually all suitable candidates with end-stage renal disease. Compared with dialysis, kidney transplantation improves both patient survival and quality of life. Nonetheless, posttransplant cardiac complications are associated with increased morbidity and mortality after renal transplantation. When compared with the general population, cardiovascular mortality in transplant recipients is increased by nearly 10-fold among patients within the age range of 35 and 44 and at least doubled among those between the ages of 55 and 64. Although renal transplantation ameliorates cardiovascular disease risk factors by restoring renal function, it introduces new cardiovascular risks derived, in part, from immunosuppressive medications. We provide an overview of the literature on conventional and unconventional cardiovascular disease risk factors after renal transplantation, and discuss an approach to their medical management.

The RXR agonist bexarotene improves cholesterol homeostasis and inhibits atherosclerosis progression in a mouse model of mixed dyslipidemia

OBJECTIVE

The activity of the antitumoral agent bexarotene (Targretin, Bexarotene) depends on its binding to the nuclear retinoid-X receptor (RXR) and subsequent transcriptional regulation of target genes. Through RXR activation, bexarotene may modulate numerous metabolic pathways involved in atherosclerosis. Here, we investigated the effect of bexarotene on atherosclerosis progression in a dyslipidemic murine model, the human apolipoprotein E2 knockin mouse, that develops essentially macrophage-laden lesions.

METHODS AND RESULTS

Atherosclerotic lesions together with different metabolic pathways involved in atherosclerosis were investigated in mice treated or not with bexarotene. Bexarotene protects from atherosclerosis development in mice, at least in part by improving the circulating cholesterol distribution profile likely via a marked decrease of dietary cholesterol absorption caused by modulation of intestinal expression of genes recently identified as major players in this process, Niemann-Pick-C1-Like1 (NPC1L1) and CD13. This atheroprotection appears despite a strong hypertriglyceridemia. Moreover, bexarotene treatment only modestly modulates inflammatory gene expression in the vascular wall, but markedly enhanced the capacity of macrophages to efflux cellular lipids.

CONCLUSIONS

These data provide evidence of a favorable pharmacological effect of bexarotene on atherosclerosis despite the induction of hypertriglyceridemia, likely via a beneficial action on intestinal absorption and macrophage efflux.

The Nurse Practitioner's Role in Helping Patients Achieve Lipid Goals with Statin Therapy

PURPOSE

To discuss the merits of statins in achieving lipid goals and the role of nurse practitioners (NPs) in improving adherence to medical regimens with the goals of improving patient outcomes, reducing cardiovascular disease (CVD) risk within the population at large, and enhancing patients' ability to reach their individual goals.

DATA SOURCES

Original research articles, journal articles, professional association practice guidelines.

CONCLUSIONS

Despite extensive research clearly documenting the relation between lowering low-density lipoprotein cholesterol (LDL-C) and decreasing rates of cardiovascular events and deaths, lipid-lowering therapy is not being aggressively managed to achieve optimal lipid levels and CVDs remain the leading cause of death among adults in the United States. Contributing factors include lack of patient adherence with prescribed therapy, absence of dose titration when needed, and suboptimal follow-up. Two pathways to improving compliance are the following: first, use of a starting dose of a more efficacious statin to allow more patients to reach their LDL-C goal and, second, more effective primary care programs with NPs as team leaders who can assess and diagnose patients, then develop individual treatment plans and follow-up with patients to ensure that their lipid goals are met.

IMPLICATIONS FOR PRACTICE

NPs are well suited to manage patients with hypercholesterolemia. The NP can bridge all aspects of care for the patient by overseeing assessment and treatment of cardiovascular risk factors, including elevated levels of LDL-C, initiating pharmacotherapy when needed, and establishing for each patient an individualized program that features education, support, and follow-up.