Effect of ezetimibe on serum concentrations of lipid-soluble vitamins

Studies of the Formation and Stability of Ezetimibe-Cyclodextrin Inclusion Complexes

In the presented studies, the interactions between ezetimibe (EZE) and selected cyclodextrins were investigated. α-Cyclodextrin (αCD), β-cyclodextrin (βCD) and its modified derivatives, hydroxypropyl-β-cyclodextrin (HPβCD) and sulfobutylether-β-cyclodextrin (SBEβCD), were selected for the research. Measurements were carried out using calorimetric and spectroscopic methods. Additionally, the Hirshfeld surface and biochemical analysis were achieved. As a result of the study, the inclusion complexes with 1:1 stoichiometry were obtained. The most stable are the complexes of β-cyclodextrin and its derivatives. The comparison of βCD with its derivatives shows that the modifications have an affect on the formation of more durable and stable complexes.

Squalene monooxygenase – a target for hypercholesterolemic therapy

Squalene monooxygenase catalyzes the epoxidation of C-C double bond of squalene to yield 2,3-oxidosqualene, the key step of sterol biosynthesis pathways in eukaryotes. Sterols are essential compounds of these organisms and squalene epoxidation is an important regulatory point in their synthesis. Squalene monooxygenase downregulation in vertebrates and fungi decreases synthesis of cholesterol and ergosterol, respectively, which makes squalene monooxygenase a potent and attractive target of hypercholesterolemia and antifungal therapies. Currently some fungal squalene monooxygenase inhibitors (terbinafine, naftifine, butenafine) are in clinical use, whereas mammalian enzymes’ inhibitors are still under investigation. Research on new squalene monooxygenase inhibitors is important due to the prevalence of hypercholesterolemia and the lack of both sufficient and safe remedies. In this paper we (i) review data on activity and the structure of squalene monooxygenase, (ii) present its inhibitors, (iii) compare current strategies of lowering cholesterol level in blood with some of the most promising strategies, (iv) underline advantages of squalene monooxygenase as a target for hypercholesterolemia therapy, and (v) discuss safety concerns about hypercholesterolemia therapy based on inhibition of cellular cholesterol biosynthesis and potential usage of squalene monooxygenase inhibitors in clinical practice. After many years of use of statins there is some clinical evidence for their adverse effects and only partial effectiveness. Currently they are drugs of choice but are used with many restrictions, especially in case of children, elderly patients and women of childbearing potential. Certainly, for the next few years, statins will continue to be a suitable tool for cost-effective cardiovascular prevention; however research on new hypolipidemic drugs is highly desirable. We suggest that squalene monooxygenase inhibitors could become the hypocholesterolemic agents of the future.

Squalene monooxygenase - a target for hypercholesterolemic therapy

Squalene monooxygenase catalyzes the epoxidation of C-C double bond of squalene to yield 2,3-oxidosqualene, the key step of sterol biosynthesis pathways in eukaryotes. Sterols are essential compounds of these organisms and squalene epoxidation is an important regulatory point in their synthesis. Squalene monooxygenase downregulation in vertebrates and fungi decreases synthesis of cholesterol and ergosterol, respectively, which makes squalene monooxygenase a potent and attractive target of hypercholesterolemia and antifungal therapies. Currently some fungal squalene monooxygenase inhibitors (terbinafine, naftifine, butenafine) are in clinical use, whereas mammalian enzymes' inhibitors are still under investigation. Research on new squalene monooxygenase inhibitors is important due to the prevalence of hypercholesterolemia and the lack of both sufficient and safe remedies. In this paper we (i) review data on activity and the structure of squalene monooxygenase, (ii) present its inhibitors, (iii) compare current strategies of lowering cholesterol level in blood with some of the most promising strategies, (iv) underline advantages of squalene monooxygenase as a target for hypercholesterolemia therapy, and (v) discuss safety concerns about hypercholesterolemia therapy based on inhibition of cellular cholesterol biosynthesis and potential usage of squalene monooxygenase inhibitors in clinical practice. After many years of use of statins there is some clinical evidence for their adverse effects and only partial effectiveness. Currently they are drugs of choice but are used with many restrictions, especially in case of children, elderly patients and women of childbearing potential. Certainly, for the next few years, statins will continue to be a suitable tool for cost-effective cardiovascular prevention; however research on new hypolipidemic drugs is highly desirable. We suggest that squalene monooxygenase inhibitors could become the hypocholesterolemic agents of the future.

Efficacy and safety of ezetimibe 40 mg vs. ezetimibe 10 mg in the treatment of patients with homozygous sitosterolaemia

OBJECTIVE

To assess the effect of ezetimibe (EZE) 40 mg/day on non-cholesterol sterol plasma concentrations in patients with homozygous sitosterolaemia (HoS).

METHODS

This was a multi-centre, randomised, double-blind, placebo-controlled parallel group study. Twenty-seven patients (> or = 18 years) with HoS and plasma sitosterol levels > 5 mg/dl who had been taking EZE 10 mg/day for > or = 6 months prior to enrolment received open-label EZE 10 mg/day for the duration of the study and were randomised 1 : 1 to blinded EZE 30 mg/day (4 x EZE 10 mg tablets; n = 13) or placebo (1 x EZE 10 mg tablet and 3 x matching placebo tablets; n = 14) for 26 weeks. Patients were permitted to remain on other ongoing treatments (e.g. bile salt-binding resin, statin and/or low sterol diet). End-points included median per cent between-group changes from baseline in plasma sitosterol, campesterol, lathosterol, low-density lipoprotein (LDL) sterols, LDL cholesterol (LDL-C) measured by gas-liquid chromatography, and Achilles tendon thickness size measured radiographically.

RESULTS

Ezetimibe 40 mg/day resulted in median per cent changes from baseline in plasma sitosterol levels of 3.3% vs. -10% in the EZE 10 mg/day group, in plasma campesterol of -0.5% vs. -9.7% in the EZE 10 mg/day group, and in plasma lathosterol of 0.8% vs. 1.1% in the EZE 10 mg/day group (p = ns for all between-group differences). Median per cent changes in the EZE 40 mg/day and EZE 10 mg/day groups, respectively, were 1.3% and 0% for LDL sterols and 2.5% and 4.4% for LDL-C (p = ns for both between-group differences). At study end-point, Achilles tendon thickness remained unchanged in the EZE 40 mg/day group and increased slightly in the EZE 10 mg/day group (2.2%), yielding a non-significant between-group difference of -2.2%. EZE 40 mg/day was generally well tolerated.

CONCLUSIONS

In patients with HoS, treatment with EZE 40 mg/day for 26 weeks was no more effective at reducing plasma plant sterol concentrations vs. EZE 10 mg/day. EZE 40 mg/day had a safety and tolerability profile similar to EZE 10 mg/day.

The effect of famotidine, esomeprazole, and ezetimibe on levothyroxine absorption

BACKGROUND

Recent literature describing the effect of gastric acid suppression on levothyroxine absorption has been inconsistent. Also, ezetimibe, a lipid-lowering compound that inhibits intestinal absorption of cholesterol, may interfere with levothyroxine absorption. The objective of this study was to measure changes in levothyroxine absorption before and after famotidine, esomeprazole or single-dose ezetimibe."

METHODS

We conducted levothyroxine absorption testing on 30 healthy volunteers, excluding those with thyroid disease. Subjects were randomized to receive one of three regimens: 1 week of either famotidine or esomeprazole, or a single dose of ezetimibe administered simultaneously with levothyroxine (n = 10 in each group). Baseline levothyroxine absorption testing was performed on all subjects using 600 mcg of Synthroid with thyroid hormone levels checked at 0, 2, 4, 6, and 8 hours after administration, and then repeated 6 weeks later, after administration of one of the three study drug regimens. The area under the curve (AUC) over 8 hours for serum thyroxine (T4), triiodothyronine (T3), and free T4 index, and the mean peak hormone levels achieved during levothyroxine absorption testing at baseline and following administration of one of the three study medications were compared using paired t-tests.

RESULTS

Peak mean hormone levels and AUCs of T4, T3, and free T4 index during absorption testing before and after each of three study medications did not differ. Results for differences before and after study medication did not reach significance even when using the subtractive correction method of AUC calculation.

CONCLUSIONS

No differences were noted in levothyroxine absorption after gastric acid suppression with 1 week of famotidine or esomeprazole. A simultaneously administered dose of ezetimibe did not significantly change levothyroxine absorption.

Ezetimibe: rationale and role in the management of hypercholesterolemia

Elevated low-density lipoprotein (LDL) cholesterol plays an important role in the development of atherosclerosis. In part, plasma LDL levels are dependent on cholesterol absorption in the intestine and the rate of intrinsic cholesterol synthesis. Therapy with 3-hydroxy-3-methylglutaryl coenzyme A-reductase inhibitors has often proven to be successful in reducing plasma LDL levels. However, a significant number of patients do not reach their target LDL levels despite statin therapy. As is reviewed, drugs that inhibit cholesterol absorption are a useful adjunct to lipid-lowering therapy by statins. This review discusses the mechanisms involved in intestinal absorption of cholesterol and its transport as potential targets of newer agents that affect cholesterol absorption. The use of bile acid sequestrants and esters of plant stanols, as well as other intestinally active agents for reducing plasma LDL levels, has been limited by side effects and difficulties in patient compliance. In contrast, the new selective cholesterol transporter inhibitor ezetimibe has been demonstrated to reduce plasma LDL alone or in combination with statins without significant adverse effects. In spite of the robust lipid-lowering data with ezetimibe, questions about clinical outcomes, safety, and efficacy in various combinations remain.

Comparative effects of lipid-lowering therapies

The pharmacologic regulation of lipid metabolism in patients with dyslipidemia is unequivocally associated with significant reductions in risk for cardiovascular morbidity and mortality. A number of therapeutic drug classes have been developed in an effort to ever more precisely and intensively modulate lipid metabolism. Statins, fibrates, ezetimibe, and niacin exert their effects via different mechanisms and afford physicians the opportunity to beneficially impact multiple pathways in patients. When used alone or in combination, these drugs decrease risk for the development and progression of atherosclerotic disease. There are strong clinical trial data to support of the use of lipid-lowering therapies in the settings of both primary and secondary prevention. This article (1) discusses the mechanisms of action of antilipidemic medications, (2) reviews dosing regimens and the pharmacokinetic differences among drugs of the same class, (3) assesses risk for drug interactions, and (4) reviews the clinical trial evidence used to support the use of particular antilipidemic medications in specific physiologic settings. The incidence of dyslipidemia is rising worldwide. This trend portends an ever-growing need for the aggressive and judicious use of different antilipidemic medication(s) in patients at risk for all forms of atherosclerotic vascular disease.

Efficacy and safety of ezetimibe co-administered with simvastatin compared with atorvastatin in adults with hypercholesterolemia

This study compared the efficacy and safety of co-administered ezetimibe + simvastatin with atorvastatin monotherapy in adults with hypercholesterolemia. Seven hundred eighty-eight patients were randomized 1:1:1 to 3 treatment groups; each group was force-titrated over four 6-week treatment periods: (1) 10 mg of atorvastatin as the initial dose was titrated to 20, 40, and 80 mg; (2) co-administration of 10 mg of ezetimibe and 10 mg of simvastatin (10/10 mg) was titrated to 10/20, 10/40, and 10/80 mg of ezetimibe + simvastatin; and (3) co-administration of 10/20 mg of ezetimibe + simvastatin was titrated to 10/40 mg (for 2 treatment periods) and 10/80 mg of ezetimibe + simvastatin. Key efficacy measures included percent changes in low-density lipoprotein cholesterol (LDL) and high-density lipoprotein cholesterol (HDL) from baseline to the ends of (1) treatment periods 1 and 2 (for LDL cholesterol) comparing co-administration of 10/20 mg and 10/10 mg of ezetimibe + simvastatin with 10 mg of atorvastatin and (2) treatment period 4 (for LDL cholesterol and HDL cholesterol) comparing co-administration of 10/80 mg of ezetimibe + simvastatin with 80 mg of atorvastatin. Baseline LDL and HDL cholesterol levels were comparable between treatment groups. At the end of treatment period 1, the mean decrease of LDL cholesterol was significantly (p </=0.001) greater for co-administration of 10/10 mg and 10/20 mg of ezetimibe + simvastatin than for 10 mg of atorvastatin. At the end of treatment period 4 and after comparing maximum doses, co-administration of 10/80 mg of ezetimibe + simvastatin was superior to 80 mg of atorvastatin in the percent LDL cholesterol decrease (-59.4% vs -52.5%, p <0.001) and HDL cholesterol increase (12.3% vs 6.5%; p <0.001). All treatments were well tolerated. Thus, a greater LDL cholesterol decrease and HDL cholesterol increase were attained by treating patients with co-administration of ezetimibe and simvastatin than with atorvastatin.

Ezetimibe: A Selective Cholesterol Absorption Inhibitor

Ezetimibe is the first agent of a novel class of selective cholesterol absorption inhibitors recently approved by the Food and Drug Administration for treatment in the United States. Ezetimibe inhibits the absorption of biliary and dietary cholesterol from the small intestine without affecting the absorption of fat-soluble vitamins, triglycerides, or bile acids. Ezetimibe localizes at the brush border of the small intestine and decreases cholesterol uptake into the enterocytes. Preclinical studies demonstrated lipid-lowering properties of ezetimibe as monotherapy and showed a synergistic effect in combination with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins). The efficacy and safety of ezetimibe 10 mg/day have been established in phase III clinical trials. In these trials, ezetimibe was investigated as monotherapy, as an add-on to ongoing statin therapy, and as combination therapy with statins in patients with primary hypercholesterolemia. In addition, ezetimibe has been evaluated in patients with homozygous and heterozygous familial hypercholesterolemia and in those with sitosterolemia. When given as monotherapy or in combination with statins or fenofibrate, ezetimibe reduces low-density lipoprotein cholesterol (LDL) by 15-20% while increasing high-density lipoprotein cholesterol by 2.5-5%. Unlike other intestinally acting lipid-lowering agents, ezetimibe does not adversely affect triglyceride levels and, due to its minimal systemic absorption, drug interactions are few. Ezetimibe's side-effect profile resembles that of placebo when given as monotherapy or in combination with statins. In clinical practice, ezetimibe has a role as monotherapy for patients who require modest LDL reductions or cannot tolerate other lipid-lowering agents. In combination therapy with a statin, ezetimibe is used in patients who cannot tolerate high statin doses or in those who need additional LDL reductions despite maximum statin doses.

Newer pharmaceutical agents to treat lipid disorders

The National Cholesterol Education Program Adult Treatment Panel III guidelines and the results of the Heart Protection Study have provided a stronger rationale to more aggressively treat high-risk patients to a low-density (LDL) cholesterol goal of less than 100 mL/dL. Two new therapies, ezetimibe and rosuvastatin, have recently been added to the lipid-lowering armamentarium to improve guideline adherence. Ezetimibe, a novel cholesterol absorption inhibitor, lowers LDL by 18% to 20% and can be used safely in combination with statins. Adding ezetimibe to a statin is comparable with the LDL-lowering efficacy of tripling the dose of the statin. Rosuvastatin is a highly efficacious statin providing 8% greater LDL reduction than equivalent doses of atorvastatin, and the starting dose of 10 mg/d provides nearly a 50% reduction in LDL cholesterol. There are several investigational drugs in development for the prevention and treatment of atherosclerosis. Of these investigational drugs, the most promising are the cholesterol ester transfer protein inhibitors, which have the potential to significantly raise high-density lipoprotein cholesterol and acetyl-coenzyme A: cholesterol acyltransferase inhibitors, which may directly inhibit the progression of atherosclerosis.

Achievement of low-density lipoprotein cholesterol goals: new strategies to address new guidelines

Evidence that CHD morbidity and mortality can be reduced with reduction of LDL-C to less than 100 mg/dL (2.6 mmol/L) is rapidly accumulating. NCEP-ATP III guidelines should be considered minimal goals of therapy. Regarding the prevention and treatment of CHD, health care providers need to recognize the wide therapeutic gap between evidence-based medicine and customary clinical practice. Aggressive pharmacologic therapy is probably required to achieve optimal LDL-C levels in many hyperlipidemic patients. Novel agents, including selective cholesterol absorption inhibitors, will provide clinicians with a tool to safely and effectively target the exogenous pathway of cholesterol metabolism. Combination therapy with cholesterol-lowering agents that have complementary mechanisms of action and can be safely co-administered may be a new option to achieve broader lipid control.

Ezetimibe for management of hypercholesterolemia

OBJECTIVE

To review the primary literature describing the pharmacology of ezetimibe and clinical trials investigating its use in the management of hypercholesterolemia.

DATA SOURCES

A MEDLINE search (1966-December 2002) was performed using SCH 48461, SCH 58235, ezetimibe, and 2-azetidinone as key words. English-language articles were identified and the references of these articles were used to further identify pertinent articles and abstracts. Given the paucity of published articles available on ezetimibe, many of the references cited are abstracts.

STUDY SELECTION

All acquired articles that discussed the pharmacology, pharmacokinetics, chemistry, and clinical efficacy of ezetimibe were reviewed.

DATA EXTRACTION

Articles were selected based on content regarding the medicinal chemistry, pharmacology, and clinical use of ezetimibe.

DATA SYNTHESIS

Ezetimibe, approved for use in October 2002, belongs to a new class of antihyperlipidemic agents that uniquely inhibit the absorption of cholesterol by inhibiting the cholesterol transport system located within intestinal cell walls. In humans, ezetimibe reduced cholesterol absorption by >50%. In clinical trials, ezetimibe 10 mg/d reduced low-density lipoprotein cholesterol (LDL-C) by approximately 18% and further enhanced the LDL-C-lowering effect of statin medications by an additional 15-20%. In addition, ezetimibe lowered triglycerides about 5% and increased high-density lipoprotein cholesterol (HDL-C) approximately 3%. Ezetimibe is well tolerated. At present, no serious adverse effects have been directly attributable to ezetimibe.

CONCLUSIONS

Based on the data currently available, it appears that ezetimibe has a potential role in the treatment of primary hypercholesterolemia; however further data are needed to determine its long-term tolerability and efficacy. The potential roles for ezetimibe include its concurrent use with a statin to further enhance the lowering of LDL-C. Other possible roles for ezetimibe include its concurrent use with a statin to permit a lowering of statin dosage to avoid statin-related complications or its use as monotherapy to treat hypercholesterolemia when statin use cannot be tolerated or is contraindicated. Outcome data demonstrating that cardiovascular morbidity and/or mortality are reduced by ezetimibe therapy have yet to be generated.

Efficacy and safety of ezetimibe coadministered with lovastatin in primary hypercholesterolemia

This multicenter, randomized, double-blind, placebo-controlled clinical study assessed the efficacy and safety of ezetimibe administered with lovastatin in primary hypercholesterolemia. After dietary stabilization, a 2- to 12-week washout period, and a 4-week single-blind placebo lead-in period, 548 patients with low-density lipoprotein (LDL) cholesterol > or =145 mg/dl (3.75 mmol/L) and < or =250 mg/dl (6.47 mmol/L) and triglycerides < or =350 mg/dl (3.99 mmol/L) were randomized to one of the following, administered daily for 12 weeks: ezetimibe 10 mg; lovastatin 10, 20, or 40 mg; ezetimibe 10 mg plus lovastatin 10, 20, or 40 mg; or placebo. The primary efficacy variable was percentage decrease in direct LDL cholesterol from baseline to end point for pooled ezetimibe plus lovastatin versus pooled lovastatin alone. Ezetimibe plus lovastatin significantly improved concentrations of LDL cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides compared with lovastatin alone (p <0.01). The coadministration of ezetimibe provided an incremental 14% LDL cholesterol decrease, a 5% HDL cholesterol increase, and a 10% decrease in triglycerides compared with pooled lovastatin alone. Ezetimibe plus lovastatin provided mean LDL cholesterol decreases of 33% to 45%, median triglyceride decreases of 19% to 27%, and mean HDL cholesterol increases of 8% to 9%, depending on the statin dose. The coadministration of ezetimibe 10 mg plus the starting dose of lovastatin (10 mg) provided comparable efficacy to high-dose lovastatin (40 mg) across the lipid profile (LDL cholesterol, HDL cholesterol, and triglycerides). Ezetimibe plus lovastatin was well tolerated, with a safety profile similar to both lovastatin alone and placebo. The coadministration of ezetimibe and lovastatin may offer a new treatment option in lipid management of patients with hypercholesterolemia.

Ezetimibe coadministered with simvastatin in patients with primary hypercholesterolemia

OBJECTIVES

The purpose of this study was to assess the efficacy and safety of ezetimibe administered with simvastatin in patients with primary hypercholesterolemia.

BACKGROUND

Despite the availability of statins, many patients do not achieve lipid targets. Combination therapy with lipid-lowering agents that act via a complementary pathway may allow additional patients to achieve recommended cholesterol goals.

METHODS

After dietary stabilization, a 2- to 12-week washout period, and a 4-week, single-blind, placebo lead-in period, patients with baseline low-density lipoprotein cholesterol (LDL-C) > or =145 mg/dl to < or =250 mg/dl and triglycerides (TG) < or =350 mg/dl were randomized to one of the following 10 groups administered daily for 12 consecutive weeks: ezetimibe 10 mg; simvastatin 10, 20, 40, or 80 mg; ezetimibe 10 mg plus simvastatin 10, 20, 40, or 80 mg; or placebo. The primary efficacy variable was percentage reduction from baseline to end point in direct LDL-C for the pooled ezetimibe plus simvastatin groups versus pooled simvastatin groups.

RESULTS

Ezetimibe plus simvastatin significantly improved LDL-C (p < 0.01), high-density lipoprotein cholesterol (HDL-C) (p = 0.03), and TG (p < 0.01) compared with simvastatin alone. Ezetimibe plus simvastatin (pooled doses) provided an incremental 13.8% LDL-C reduction, 2.4% HDL-C increase, and 7.5% TG reduction compared with pooled simvastatin alone. Coadministration of ezetimibe and simvastatin provided LDL-C reductions of 44% to 57%, TG reductions of 20% to 28%, and HDL-C increases of 8% to 11%, depending on the simvastatin dose. Ezetimibe 10 mg plus simvastatin 10 mg and simvastatin 80 mg alone each provided a 44% LDL-C reduction. The coadministration of ezetimibe with simvastatin was well tolerated, with a safety profile similar to those of simvastatin and of placebo.

CONCLUSIONS

When coadministered with simvastatin, ezetimibe provided significant incremental reductions in LDL-C and TG, as well as increases in HDL-C. Coadministration of ezetimibe with simvastatin was well tolerated and comparable to statin alone.

Efficacy and safety of a potent new selective cholesterol absorption inhibitor, ezetimibe, in patients with primary hypercholesterolemia

The efficacy and safety of ezetimibe, a new cholesterol absorption inhibitor, was evaluated in this randomized, double-blind, placebo-controlled trial of 892 patients with primary hypercholesterolemia. After > or =2 weeks on the National Cholesterol Education Program (NCEP) Step I or a stricter diet and a 4- to 8-week single-blind placebo lead-in, patients with low-density lipoprotein (LDL) cholesterol 130 to 250 mg/dl and triglycerides < or =350 mg/dl were randomized 3:1 to receive ezetimibe 10 mg or placebo orally each morning for 12 weeks. The primary efficacy end point was the percent reduction in direct plasma LDL cholesterol from baseline to end point. A total of 434 men and 458 women (ages 18 to 85 years) received randomized treatment (666 ezetimibe 10 mg, 226 placebo). Demographics and baseline characteristics were similar between treatment groups. Ezetimibe significantly reduced direct LDL cholesterol by a mean of 16.9%, compared with an increase of 0.4% with placebo (p <0.01). Subgroup analysis indicated that response to ezetimibe was generally consistent across all subgroups, regardless of risk-factor status, gender, age, race, or baseline lipid profile. Ezetimibe effects on LDL cholesterol occurred early (2 weeks) and persisted throughout the 12-week treatment period. Compared with placebo, ezetimibe 10 mg also significantly improved calculated LDL cholesterol, apolipoprotein B, total cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, and HDL(3) cholesterol (p <0.01). Ezetimibe was well tolerated. There were no differences in laboratory or clinical safety parameters, or gastrointestinal, liver, or muscle side effects from that of placebo. Ezetimibe 10 mg/day is well tolerated, reduces LDL cholesterol approximately 17%, and improves other key lipid parameters.

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

Ezetimibe is a lipid-lowering drug that inhibits the intestinal absorption of dietary and biliary cholesterol by blocking passage across the intestinal wall. The efficacy and safety of adding ezetimibe to ongoing statin therapy in patients with primary hypercholesterolemia was evaluated in a randomized, double-blind, placebo-controlled study. The study group included 769 adults (aged > or =18 years) with primary hypercholesterolemia who had not achieved National Cholesterol Education Program (NCEP) Adult Treatment Panel II goals with dietary alteration and statin monotherapy. Patients receiving a stable dose of a statin for > or =6 weeks were randomized to receive concurrent treatment with placebo (n = 390) or ezetimibe (n = 379), 10 mg/day, in addition to continuing their open-label statin for 8 weeks. The primary efficacy variable was the percent change in low-density lipoprotein (LDL) cholesterol from baseline with statin monotherapy to end point after intervention (secondary variables: high-density lipoprotein [HDL] cholesterol and triglycerides). Ongoing statin therapy plus ezetimibe led to changes of -25.1% for LDL cholesterol (HDL cholesterol +2.7%; triglycerides -14.0%) compared with LDL cholesterol -3.7% (p <0.001), HDL cholesterol +1.0% (p <0.05), and triglycerides -2.9% (p <0.001) for placebo added to ongoing statin therapy. Among patients not at LDL cholesterol goal at on-statin baseline, 71.5% receiving statin plus ezetimibe versus 18.9% receiving statin plus placebo reached goal at end point (odds ratio 23.7; p <0.001). The co-administration of statin and ezetimibe was generally well tolerated. Adding ezetimibe to ongoing statin therapy led to substantial additional reduction in LDL cholesterol levels, facilitating attainment of NCEP goals. Ezetimibe offers a new therapeutic option for patients receiving statins who require further reduction in LDL cholesterol.

Ezetimibe: the first in a novel class of selective cholesterol-absorption inhibitors

Zetia (ezetimibe) is the first medication in the novel class of selective cholesterol-absorption inhibitors to be released in the United States. Ezetimibe selectively inhibits the uptake of cholesterol from the intestinal lumen at the level of the enterocyte in the intestinal brush border while having no effect on other sterols or lipid-soluble vitamins. Ezetimibe 10 mg daily produces a consistent reduction in low-density lipoprotein cholesterol (LDL-C) by approximately 15 to 20% when used as monotherapy or in combination with 3-hydroxy-3-methylglutaryl coenzyme A inhibitors (statins) or fenofibrate and a 4 to 9% increase in high-density lipoprotein cholesterol. Unlike other lipid-lowering medications that act in the gastrointestinal tract, ezetimibe does not appear to worsen hypertriglyceridemia. Ezetimibe also has an adverse-event profile that is similar to placebo when used as monotherapy or in combination with statins and fenofibrate. Studies of longer duration and with niacin, bile acid sequestrants, and gemfibrozil are warranted to more completely assess the safety of ezetimibe in combination therapy. To date, no clinically significant drug-drug interactions have been noted with the use of ezetimibe; however, further studies are warranted. Ezetimibe will be useful as monotherapy in patients who need modest reductions in LDL-C or are intolerant to other lipid-lowering medication, and in combination with a statin in patients who are unable to tolerate large doses of statins or need further reductions in LDL-C despite maximum doses of a statin. The long-term safety and the effect on cardiovascular morbidity and mortality of ezetimibe are unknown.

Management of dyslipidemia

The 2 principal approaches to management of dyslipidemias are lifestyle intervention and lipid-modifying drug therapy. Recent revisions to the American Heart Association's dietary guidelines for reducing cardiovascular disease emphasize an overall healthy eating pattern and maintenance of appropriate body weight, together with achieving a desirable blood pressure and a desirable lipoprotein profile. New National Cholesterol Education Program treatment guidelines include a scoring system for calculating coronary heart disease (CHD) risk that is adapted from the Framingham Heart Study, as well as a category of CHD risk equivalents (e.g., diabetes) that will encourage more aggressive therapeutic intervention for individuals at high short-term risk for CHD, even in the absence of clinically evident coronary disease. Classes of lipid-modifying drugs include bile acid sequestrants (resins), fibrates, and statins, with each class exerting different effects on the lipid profile. Nicotinic acid (niacin) is also an approved lipid-modifying agent. The armamentarium for treating lipid disorders and atherosclerosis now includes statins that can decrease low-density lipoprotein (LDL) cholesterol levels by up to 55%, as well as a resin with improved tolerability. In patients with high levels of LDL cholesterol and triglycerides, together with low concentrations of high-density lipoprotein cholesterol, combination therapy may be effective. Moreover, researchers are currently investigating the development of drugs directed at molecular targets, including cholesterol esterification and accumulation in macrophage foam cells (e.g., inhibiting acyl-coenzyme A : cholesterol acyltransferase), degradation of atherosclerotic plaque (e.g., decreasing the expression of matrix metalloproteinases), and reverse cholesterol transport (e.g., stimulating ATP-binding cassette transporter A1).

Ezetimibe selectively inhibits intestinal cholesterol absorption in rodents in the presence and absence of exocrine pancreatic function

1. Ezetimibe potently inhibits the transport of cholesterol across the intestinal wall, thereby reducing plasma cholesterol in preclinical animal models of hypercholesterolemia. The effect of ezetimibe on known absorptive processes was determined in the present studies. 2. Experiments were conducted in the hamster and/or rat to determine whether ezetimibe would affect the absorption of molecules other than free cholesterol, namely cholesteryl ester, triglyceride, ethinylestradiol, progesterone, vitamins A and D, and taurocholic acid. In addition, to determine whether exocrine pancreatic function is involved in the mechanism of action of ezetimibe, a biliary anastomosis model, which eliminates exocrine pancreatic function from the intestine while maintaining bile flow, was established in the rat. 3. Ezetimibe reduced plasma cholesterol and hepatic cholesterol accumulation in cholesterol-fed hamsters with an ED(50) of 0.04 mg kg(-1). Utilizing cholesteryl esters labelled on either the cholesterol or the fatty acid moiety, we demonstrated that ezetimibe did not affect cholesteryl ester hydrolysis and the absorption of fatty acid thus generated in both hamsters and rats. The free cholesterol from this hydrolysis, however, was not absorbed (92 - 96% inhibition) in the presence of ezetimibe. Eliminating pancreatic function in rats abolished hydrolysis of cholesteryl esters, but did not affect the ability of ezetimibe to block absorption of free cholesterol (-94%). Ezetimibe did not affect the absorption of triglyceride, ethinylestradiol, progesterone, vitamins A and D, and taurocholic acid in rats. 4. Ezetimibe is a potent inhibitor of intestinal free cholesterol absorption that does not require exocrine pancreatic function for activity. Ezetimibe does not affect the absorption of triglyceride as a pancreatic lipase inhibitor (Orlistat) would, nor does it affect the absorption of vitamin A, D or taurocholate, as a bile acid sequestrant (cholestyramine) would.

Effectiveness and tolerability of ezetimibe in patients with primary hypercholesterolemia: pooled analysis of two phase II studies

BACKGROUND

Ezetimibe (SCH 58235) is a novel cholesterol absorption inhibitor that selectively and potently blocks intestinal absorption of dietary and biliary cholesterol.

OBJECTIVE

Data from 2 multicenter, placebo-controlled, double-blind, randomized, parallel-group, 12-week studies of ezetimibe were pooled to evaluate the drug's effect on lipid parameters in patients with primary hypercholesterolemia.

METHODS

After dietary stabilization (National Cholesterol Education Program Step I diet or a stricter diet), washout of lipid-altering drugs, and a 6-week placebo lead-in period, patients with baseline plasma low-density lipoprotein cholesterol (LDL-C) levels > or = 130 and < or = 250 mg/dL and plasma triglyceride (TG) levels < or = 300 mg/dL were randomized to receive either ezetimibe 0.25, 1, 5, or 10 mg, or placebo administered once daily before the morning meal in study A (dose-response study) or ezetimibe 5 or 10 mg or placebo administered once daily before the morning meal or at bedtime in study B (dose-regimen study).

RESULTS

A total of 432 patients were included in this pooled analysis, 243 in study A and 189 in study B. The 5- and 10-mg doses of ezetimibe significantly reduced LDL-C levels by 15.7% and 18.5%, respectively (P < 0.01 vs placebo) and significantly increased high-density lipoprotein cholesterol (hDL-C) levels by 2.9% and 3.5%, respectively (P < 0.05 vs placebo). A reduction in plasma TG levels was observed (P = NS). With the 10-mg dose of ezetimibe, 67.8% of patients achieved > or = 15% reduction in plasma LDL-C levels, and 22.0% achieved > or = 25% reduction. With the 5-mg dose, 54.0% of patients achieved > or = 15% reduction in plasma LDL-C levels, and 15.3% achieved > or = 25% reduction. The decrease in plasma LDL-C levels was significantly greater with ezetimibe 10 mg compared with ezetimibe 5 mg (P < 0.05). Ezetimibe was well tolerated, with an adverse event profile similar to that of placebo.

CONCLUSIONS

In these two 12-week studies, ezetimibe significantly decreased plasma LDL-C levels and increased plasma HDL-C levels, with a tolerability profile similar to that of placebo.