Effectiveness and tolerability of ezetimibe add-on therapy to a bile acid resin-based regimen for hypercholesterolemia

Colesevelam - a bile acid sequestrant for treating hypercholesterolemia and improving hyperglycemia

INTRODUCTION

Low density Lipoprotein cholesterol)LDL-C) levels show a clear relationship with cardiovascular disease (CVD). Statins are first line agents to reduce LDL-C and CVD risk. However, combination lipid-lowering therapy is often required to achieve large reductions in LDL-C.

AREA COVERED

Colesevelam HCl is a bile acid sequestrant (BAS), which reduces LDL-C by 16-22% in monotherapy and adds a further 12-14% reduction in LDL-C when combined with other lipid-lowering drugs. Like statins, colesevelam reduces C-reactive protein levels by 16% in monotherapy and additional 6% when added to statins. Colesevelam also reduced HbA_1c by 4mmol/mol (0.5%) when used alone and added to other hypoglycaemic drugs in studies of patients with diabetes .

EXPERT OPINION

Bile acid sequestrants reduce LDL-C and HbA_1c and have some CVD outcome evidence. The uses of these agents are limited in patients with gastrointestinal disease or high triglycerides due to adverse effects on gut function and raising triglycerides and they interfere with the absorption of lipid-soluble drugs. Colesevelam has a higher bile acid binding capacity, and fewer adverse effects than other BAS. Colesevelam may be useful as a third line agent for treatment of hypercholesterolemia with some additional specific benefits on glycemic control.

Resistance and intolerance to statins

BACKGROUND AND AIMS

Many patients treated with statins are considered statin-resistant because they fail to achieve adequate reduction of low density lipoprotein cholesterol (LDL-C) levels. Some patients are statin-intolerant because they are unable to tolerate statin therapy at all or to tolerate a full therapeutic statin dose because of adverse effects, particularly myopathy and increased activity of liver enzymes.

RESULTS

The resistance to statins has been associated with polymorphisms in the 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA-R), P-glycoprotein (Pg-P/ABCB1), breast cancer resistance protein (BCRP/ABCG2), multidrug resistance-associated proteins (MRP1/ABCC1 and MRP2/ABCC2), organic anion transporting polypeptides (OATP), RHOA, Nieman-Pick C1-like1 protein (NPC1L1), farnesoid X receptor (FXR), cholesterol 7alpha-hydroxylase (CYP7A1), Apolipoprotein E (ApoE), proprotein convertase subtilisin/kexin type 9 (PCSK9), low density lipoprotein receptor (LDLR), lipoprotein (a) (LPA), cholesteryl ester transfer protein (CETP), and tumor necrosis factor α (TNF-α) genes. However, currently, there is still not enough evidence to advocate pharmacogenetic testing before initiating statin therapy. Patients with inflammatory states and HIV infection also have diminished LDL-C lowering as a response to statin treatment. Pseudo-resistance due to nonadherence or non-persistence in real-life circumstances is probably the main cause of insufficient LDL-C response to statin treatment.

CONCLUSIONS

If a patient is really statin-resistant or statin-intolerant, several other treatment possibilities are nowadays available: ezetimibe alone or in combination with bile acid sequestrants, and possibly in the near future mipomersen, lomitapide, or monoclonal antibodies against PCSK9.

Colesevelam hydrochloride in the management of dyslipidemia

Dyslipidemia is a highly heterogeneous group of disorders strongly influenced by both genetic and environmental factors. Dyslipidemia significantly increases risk for atherosclerotic disease and all of its various clinical manifestations. Identifying patients with dyslipidemia and initiating therapies aimed at normalizing the lipid profile has been demonstrated to significantly reduce the risk for myocardial infarction, stroke and cardiovascular mortality in both the primary and secondary prevention settings. Guidelines in Europe, Canada and the USA emphasize the need to reduce the burden of atherogenic lipoproteins in serum and to raise levels of high-density lipoproteins in patients at risk for cardiovascular events. Statins have emerged as front-line therapy for managing dyslipidemia, especially in patients with elevated serum levels of low-density lipoprotein cholesterol. As guidelines emphasize the need to reduce serum low-density lipoprotein cholesterol to lower levels, goal attainment can be challenging. The use of combination therapy increases the likelihood of therapeutic success for many patients. Furthermore, a significant percentage of patients with dyslipidemia either cannot achieve goals on statin monotherapy, choose not to take a statin or do not tolerate these drugs due to adverse side effects, such as myalgias, weakness or hepatotoxicity. This article summarizes the pharmacology, clinical efficacy and safety of colesevelam hydrochloride, a bile acid-binding resin. Bile acid-binding resins are orally administered anion-exchange resins that are not absorbed systemically. These agents bind bile acids and reduce their reabsorption at the level of the terminal ileum and prevent their enterohepatic recirculation. Colesevelam has a favorable side effect and toxicity profile and significantly impacts serum levels of lipoproteins when used as monotherapy or when used in combination with either statins or ezetimibe.

Toward individualized cholesterol-lowering treatment in end-stage renal disease

There is broad evidence that lowering low-density lipoprotein (LDL) cholesterol will reduce cardiovascular risk. However, in patients on maintenance hemodialysis treatment, lowering LDL cholesterol is not as effective in preventing cardiovascular complications as in the general population. Cholesterol is either endogenously synthesized or absorbed from the intestine. It has been suggested that the benefit of using statins to prevent atherosclerotic complications is less pronounced in people with high absorption of cholesterol. Recent data indicate that patients on hemodialysis have high absorption of cholesterol. Therefore, these patients may benefit from dietary counseling to reduce cholesterol intake, from functional foods containing plant sterols and stanols, and from drugs that interfere with intestinal absorption of sterols (i.e., ezetimibe, bile acid resins, and sevelamer). This review discusses cholesterol homeostasis and the perspective of personalized treatment of hypercholesterolemia in hemodialysis.

Colesevelam hydrochloride: evidence for its use in the treatment of hypercholesterolemia and type 2 diabetes mellitus with insights into mechanism of action

Colesevelam hydrochloride is a molecularly engineered, second-generation bile acid sequestrant demonstrating enhanced specificity for bile acids which has been approved for use as adjunctive therapy to diet and exercise as monotherapy or in combination with a β-hydroxymethylglutaryl-coenzyme A reductase inhibitor for the reduction of elevated low-density lipoprotein cholesterol in patients with primary hypercholesterolemia. It is also the only lipid-lowering agent currently available in the United States which has been approved for use as adjunctive therapy in patients with type 2 diabetes mellitus whose glycemia remains inadequately controlled on therapy with metformin, sulfonylurea, or insulin. With the recent emphasis upon drug safety by the Food and Drug Administration and various consumer agencies, it is fitting that the role of nonsystemic lipid-lowering therapies such as bile acid sequestrants – with nearly 90 years of in-class, clinically safe experience – should be reexamined. This paper presents information on the major pharmacologic effects of colesevelam, including a discussion of recent data derived from both in vitro and in vivo rodent and human studies, which shed light on the putative mechanisms involved.

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.

Combinations of ezetimibe with nonstatin drug regimens affecting lipid metabolism

In this article we discuss the available data on the effects of combined therapy of ezetimibe with agents affecting lipid metabolism other than statins. We consider studies evaluating the effects of combined therapy of ezetimibe with bile acid sequestrants, fenofibrate, niacin, n-3 fatty acids, plant sterols, orlistat, metformin, acarbose and glitazones. Combination of ezetimibe with bile acid sequestrants (especially colesevelam) was shown to have additional effects on lipid parameters in patients with hyperlipidemia. Combination of ezetimibe with fenofibrate may be a good approach to improve the overall lipid profile of patients with mixed hyperlipidemia. The addition of ezetimibe to niacin-based therapy can be useful for high-risk patients with dyslipidemia who are not achieving their assigned treatment goals. For patients who cannot tolerate statins there are useful combinations of ezetimibe with other drugs affecting lipid metabolism. These combinations improve many metabolic parameters, but more trials should be carried out to reach more robust conclusions about their effects on cardiovascular disease prevention.

Combination therapy of statin and ezetimibe for the treatment of familial hypercholesterolemia

High-dose potent statin therapy in combination with ezetimibe is now standard practice for the treatment of adult patients with heterozygous familial hypercholesterolemia (heFH), as the result of numerous studies in patients with primary hypercholesterolemia or heFH. These studies have shown the combination to be both effective and safe in the short to medium term. Recently, short-term ezetimibe therapy has also been shown to be effective and safe in combination with statin therapy for children and adolescents with heFH. Effective statin–ezetimibe combination therapy is capable of achieving near-normal lipid profiles in heFH patients, with expected improvement in risk for cardiovascular disease (CVD) and improved life expectancy resulting predominantly from reduction in levels of low-density lipoprotein cholesterol. There are few data to support a pleiotropic action of ezetimibe with regard to CVD benefit, unlike therapy with statins. No serious and unexpected clinical adverse effects of combination statin–ezetimibe therapy have emerged till date, although data are limited in children and adolescents, for whom longer-term studies are required. Recent data suggesting possible proatherogenic effects of ezetimibe require confirmation. One large long-term randomized controlled clinical outcomes trial is in progress in non-FH patients to determine the efficacy and safety of ezetimibe therapy; it is unlikely that such a trial will ever be performed in patients with FH.

Colesevelam: an improved bile acid sequestrant for treating hypercholesterolemia and improving diabetes

There is a well-established association between serum cholesterol and coronary heart disease. Statins are the first-line agents for the treatment of hypercholesterolemia, yet combination therapy is required to achieve the desired reduction in low-density lipoprotein cholesterol (LDL-C). Niacin and bile acid sequestrants were among the first lipid-lowering drugs developed to lower LDL-C and have been established to be effective both in monotherapy and in combination therapy. However, tolerability and compliance issues have limited their use. Colesevelam HCl is the newest bile acid sequestrant and reduces LDL-C by 16-22% in monotherapy and adds 12-14% in combination dual therapy with statins, fibrates and ezetimibe or in triple therapy with statin and ezetimibe. It reduces C-reactive protein levels by 16-19% in monotherapy or by 23% in combination with statins and other lipid-lowering therapies. In addition, it consistently reduces hemoglobin A_1c by 0.5% in addition to other hypoglycemic drugs in studies of patients with diabetes. Compared with other bile acid sequestrants it has a higher bile acid-binding capacity, reduced adverse effects and, therefore, has better compliance. Colesevelam HCl is thus a useful addition to the lipid-lowering formulary as a second-line agent, particularly for patients with metabolic syndrome requiring extra reduction in LDL-C.

Improving glycemic and cholesterol control through an integrated approach incorporating colesevelam - a clinical perspective

Bile sequestrants have been used for almost 50 years to lower low density lipoprotein cholesterol (LDL-C). The advent of colesevelam in 2000 provided a more tolerable add-on LDL-C-lowering agent with an excellent safety record and with likely benefit for coronary heart disease events. Colesevelam lowers LDL-C approximately 15%, and has an additive effect when combined with statin or non-statin lipid-modifying agents. It also tends to increase triglyceride levels. The discovery that bile sequestrants also lower glucose levels led to definitive large-scale clinical trials testing the effect of colesevelam as a dual antihyperglycemic agent with LDL-C-lowering properties in type 2 diabetic subjects on metformin-, sulfonylurea- or insulin-based therapy with inadequate glycemic control. Colesevelam was found to lower hemoglobin A1c (HbA1c) by approximately 0.5% compared to placebo over the 16- to 26-week period, and had similar effects on the lipid profile in these diabetic subjects, as had previously been demonstrated in non-diabetic individuals. Colesevelam was well tolerated, with constipation being the most common adverse effect, and did not cause weight gain or excessive hypoglycemia. Colesevelam thus combines antihyperglycemic action with LDL-C-lowering properties, and should be useful in the management of type 2 diabetes.

Tolerability and effects on lipids of ezetimibe coadministered with pravastatin or simvastatin for twelve months: results from two open-label extension studies in hypercholesterolemic patients

OBJECTIVE

The aim of these studies was to assess the long-term tolerability and effects on lipids of ezetimibe coadministered with pravastatin or simvastatin during treatment of hypercholesterolemic patients.

METHODS

Two separate 12-month, open-label extension studies enrolled patients who had successfully completed one of three 12-week, double-blind, placebo-controlled trials of ezetimibe coadministered with pravastatin, lovastatin, or simvastatin. In the extensions, the initial dose of each drug administered was 10 mg/d, with the option to up-titrate the statins if low-density lipoprotein cholesterol (LDL-C) goals were not met. Tolerability was assessed using monitoring of clinical and laboratory adverse events (AEs). Changes from baseline in LDL-C, total cholesterol, high-density lipoprotein cholesterol, and triglyceride levels were calculated.

RESULTS

Overall, 436 patients received ezetimibe + pravastatin 10 to 40 mg/d, including patients from the parent studies who received coadministration treatment but did not continue in the extension studies; 359 patients received ezetimibe + simvastatin 10 to 80 mg/d in the extension study. The majority of patients in both studies were white (ezetimibe + pravastatin, 374 [86%]; ezetimibe + simvastatin, 314 [87%]) and female (ezetimibe + pravastatin, 246 [56%]; ezetimibe + simvastatin, 210 [58%]). The mean ages were 55.7 and 57.7 years and the mean body mass indexes were 29.4 and 28.8 kg/m2 in the ezetimibe + pravastatin and ezetimibe + simvastatin studies, respectively. The most commonly reported AEs with ezetimibe + pravastatin were upper respiratory tract infection (78 [18%]), headache (47 [11%]), musculoskeletal pain (45 [10%]), arthralgia (43 [10%]), and sinusitis (42 [10%]); with ezetimibe + simvastatin, they were upper respiratory tract infection (67 [19%]), arthralgia (39 [11%]), and musculoskeletal pain (37 [10%]). AEs considered treatment related were reported in 98 (22%) and 80 (22%) patients in the ezetimibe + pravastatin and ezetimibe + simvastatin studies, respectively. Serious AEs were reported in 29 patients (7%) who received ezetimibe + pravastatin and 36 patients (10%) who received ezetimibe + simvastatin; <1% were considered treatment related in either study. Forty-one (9%) and 29 patients (8%), respectively, were withdrawn due to AEs. One death occurred due to cardiopulmonary arrest in the ezetimibe + simvastatin study and was not considered treatment related. Percentage changes from baseline in LDL-C were -36.5% and -40.4% in patients who received ezetimibe + pravastatin and ezetimibe + simvastatin.

CONCLUSION

In these 12-month, open-label extension studies in these patients with hypercholesterolemia, ezetimibe + pravastatin or simvastatin was generally well tolerated. Both treatments were associated with maintaining improvements in lipid parameters throughout the studies in these patients.

Long-term safety and tolerability of ezetimibe coadministered with simvastatin in hypercholesterolemic patients: a randomized, 12-month double-blind extension study

OBJECTIVES

To assess the long-term safety and tolerability and to further evaluate the effect of ezetimibe plus simvastatin on LDL-C, HDL-C, and triglyceride levels in subjects with primary hypercholesterolemia.

METHODS

This was a 12-month, double-blind, placebo-controlled extension study that enrolled patients with primary hypercholesterolemia who had successfully completed the 12-week, double-blind, placebo-controlled trial of ezetimibe coadministered with simvastatin. The initial dose administered to patients in the extension was ezetimibe 10 mg coadministered with simvastatin 10 mg with the option to up-titrate statin dosage if LDL-C goals were not met. Safety and tolerability were assessed through clinical and laboratory adverse experiences (AEs). Changes from baseline in low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and triglyceride levels were measured.

RESULTS

Overall, 87 patients were randomized to receive ezetimibe + simvastatin and 22 were randomized to receive simvastatin and placebo. Treatment-emergent AEs were reported for 72/87 (83%) ezetimibe + simvastatin-treated patients and for 17/22 (77%) simvastatin-treated patients. The most commonly reported AEs in the simvastatin treatment group were hypertension, gastro-esophageal reflux, and musculoskeletal pain (each reported by 3/22 [14%] patients); and in the ezetimibe + simvastatin group were upper respiratory tract infection (16/87 [18%]), arthralgia and musculoskeletal pain (both reported by 10/87 [11%] patients). Drug-related AEs were reported for 3/22 (14%) simvastatin-treated patients and 21/87 (24%) patients in the coadministration group. AEs considered serious by the investigator were reported by 2/22 (9%) patients taking simvastatin monotherapy and by 20/87 (23%) patients taking ezetimibe + simvastatin. Discontinuations due to AEs occurred in no patients taking simvastatin monotherapy and in 7/87 (8%) patients taking ezetimibe + simvastatin. Percent change ± standard deviation from baseline in LDL-C was -29% ± 15.4 and -44% ± 14.2 in subjects taking simvastatin monotherapy and ezetimibe + simvastatin, respectively.

CONCLUSIONS

Ezetimibe coadministered with simvastatin was generally well-tolerated and no new safety concerns were raised. Both treatments effectively maintained improvements in lipid parameters throughout the course of the studies. Interpretation of these results was limited by the small convenience sample included in the trial.

Colesevelam hydrochloride in clinical practice: a new approach in the treatment of hypercholesterolaemia

OBJECTIVE

Hypercholesterolaemia is a major risk factor for atherosclerosis and coronary heart disease. Treatment with lipid lowering agents reduces the risk of vascular events. Colesevelam is a novel bile acid sequestrant (BAS) indicated for the treatment of hypercholesterolaemia, either as monotherapy or in combination with statins.

SCOPE

This article reviews the efficacy, tolerability and safety of colesevelam in clinical practice. The literature search was based on a PubMed search up to January 2008.

FINDINGS

Colesevelam, used alone or in combination with other hypolipidaemic agents (statins, ezetimibe and fenofibrate), has an overall favourable effect on lipid profile. Specifically, colesevelam reduces total and low-density lipoprotein cholesterol (LDL-C) and apolipoprotein B levels and increases high-density lipoprotein cholesterol and apolipoprotein AI. However, colesevelam may slightly raise triglyceride levels. Colesevelam can improve glycaemic control in diabetic patients. Moreover, it may have anti-inflammatory properties, as it can reduce high sensitivity C-reactive protein concentration. Colesevelam almost lacks the intense side effects of previously used BASs, thus resulting in better patient compliance. However, the dose regimen consisting of up to 7 tablets/day and high cost may limit its use.

CONCLUSIONS

Colesevelam is a safe alternative for those intolerant to other lipid lowering medication. This BAS also provides an option for patients who do not reach their LDL-C goal despite treatment with a statin.

The role of Niemann-Pick C1 - Like 1 (NPC1L1) in intestinal sterol absorption

The absorption of cholesterol by the proximal small intestine represents a major pathway for the entry of cholesterol into the body pools. This cholesterol is derived primarily from the bile and the diet. In adult humans, typically several hundred milligrams of cholesterol reach the liver from the intestine daily, with the potential to impact the plasma low density lipoprotein-cholesterol (LDL-C) concentration. There are three main phases involved in cholesterol absorption. The first occurs intraluminally and culminates in micellar solubilization of unesterified cholesterol which facilitates its movement up to the brush border membrane (BBM) of the enterocyte. The second phase involves the transport of cholesterol across the BBM by Niemann-Pick C1 Like-1 (NPC1L1), while the third phase entails a series of steps within the enterocyte involving the esterification of cholesterol and its incorporation, along with other lipids and apolipoprotein B48 (apo B48), into nascent chylomicrons (CM). The discovery of the role of NPC1L1 in intestinal sterol transport occurred directly as a consequence of efforts to identify the molecular target of ezetimibe, a novel, potent, and specific inhibitor of sterol absorption that is now widely used in combination therapy with statins for the management of hypercholesterolemia in the general population. Some aspects of the role of NPC1L1 in cholesterol absorption nevertheless remain controversial and are the subject of ongoing research. For example, one report suggests that NPC1L1 is located not in the plasma membrane but intracellularly where it is thought to be involved in cytosolic trafficking of cholesterol, while another concludes that a protein other than NPC1L1 is responsible for the high affinity binding of cholesterol on intestinal BBM. However, other new studies which show that the in vivo responsiveness of different species to ezetimibe correlates with NPC1L1 binding affinity further support the widely held belief that NPC1L1 does facilitate sterol uptake by the enterocyte and is the target of ezetimibe. Added to this is the unequivocal finding that deletion of the gene for NPC1L1 in mice results in a near complete prevention of cholesterol absorption and an accelerated rate of fecal neutral sterol excretion. In summary, the development of ezetimibe and the identification of NPC1L1 as a key player in sterol absorption have taken research on the molecular control of this pathway to an exciting new level. From this it is hoped that we will now be able to determine more precisely what effect, if any, other classes of lipid lowering agents, particularly the statins, might exert on the amount of intestinal cholesterol reaching the liver.

Cholesterol goal attainment in patients with coronary heart disease and elevated coronary risk: results of the Hong Kong hospital audit study

OBJECTIVE

We sought to determine 1) long-term lipid-lowering treatment patterns; 2) cholesterol goal attainment rates and possible determinants of goal achievement; and 3) effects of cholesterol goal attainment on coronary events in hospitalized Hong Kong patients.

METHODS

In this retrospective cohort analysis, records of two public Hong Kong hospitals were reviewed for 196 adults (69% with coronary heart disease (CHD) or CHD-risk equivalent) who received at least one lipid-lowering therapy during hospitalization. Low-density lipoprotein cholesterol (LDL-C) targets were <2.6 mmol/l (<100 mg/dL) for patients with CHD or CHD risk equivalents and <3.37 mmol/l (<130 mg/dL) for those without.

RESULTS

Most participants were initiated on regimens of low to midequipotency doses and never had their regimens adjusted to higher potency. Approximately 44% of patients not at LDL-C at baseline failed to achieve goal during a median follow-up of 1.9 years. Patients with higher coronary risk and/or LDL-C levels at baseline were less likely than their lower-risk counterparts to achieve goal; for each 1-mmol/l (38.7-mg/dL) increase in LDL-C at baseline, the likelihood of attaining goal declined by 64%. Patients achieving cholesterol goal had significantly longer cardiovascular event-free times.

CONCLUSIONS

A total of 44% of Hong Kong patients not at LDL-C goals at baseline did not achieve them over 1.9 years. More effective and well-tolerated therapies, including adjunctive regimens (e.g., ezetimibe-statin, niacin-statin), may be necessary to enhance LDL-C goal achievement and increase event-free time.

Ezetimibe: an update on the mechanism of action, pharmacokinetics and recent clinical trials

Elevated serum cholesterol is a known risk factor for the development of coronary artery disease. Circulating cholesterol is a product of both cholesterol absorption from the gut and cellular cholesterol production. Ezetimibe is a novel cholesterol-lowering drug that acts at the brush border of the small intestine. Recent studies have further identified the molecular target as the Niemann-Pick C1-like transporter. Ezetimibe blocks the absorption of dietary and biliary cholesterol and plant sterols resulting in intracellular cholesterol depletion. Clinical studies have demonstrated beneficial improvements in the lipid profile with ezetimibe as monotherapy, but dramatic effects are seen when ezetimibe is combined with other lipid-lowering drugs, particularly 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins). Combination studies of ezetimibe with statins, bile acid sequestrants, fenofibrate and niacin all demonstrate significant total and low density lipoprotein cholesterol lowering. An excellent safety and tolerability profile combined with once-daily dosing make this attractive adjunct therapy for the treatment of hypercholesterolemia.

Colesevelam Hydrochloride-Ezetimibe Combination Lipid-Lowering Therapy in Patients with Diabetes or Metabolic Syndrome and a History of Statin Intolerance

OBJECTIVE

To determine the effectiveness and safety of colesevelam hydrochloride (HCl) and ezetimibe combination therapy in statin-intolerant patients with dyslipidemia and diabetes mellitus (DM) or metabolic syndrome (MS).

METHODS

We identified potential study subjects through a computerized text search of patient electronic medical records using the terms colesevelam, WelChol, ezetimibe, and Zetia. Medical records were subsequently reviewed to identify all patients with DM or MS. Baseline total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), non-HDL-C, and triglyceride levels immediately before the initiation of therapy with colesevelam HCl (1.875 g twice a day) or ezetimibe (10 mg daily) were compared with those after a minimum of 3 months of single drug therapy and after a minimum of 3 months of combination therapy. Drug safety was evaluated by review of transaminase levels and reports of side effects or drug discontinuation.

RESULTS

The computerized search initially identified 91 electronic medical records; 16 patients fulfilled all study criteria. Baseline patient demographics included a mean age of 62.5 (+/-11.8) years and a mean body mass index of 31.4 (+/-5.2) kg/m2; 50% of patients were female, 75% had type 2 DM, and 25% had MS. In comparison with baseline, colesevelam HCl-ezetimibe combination therapy was associated with significant reductions in mean levels of total cholesterol (27.5%), LDL-C (42.2%), and non-HDL-C (37.1%). In addition, 50% of patients achieved the National Cholesterol Education Program Adult Treatment Panel III LDL-C target of less than 100 mg/dL. Therapy was well tolerated, with no significant changes in mean transaminase levels, no reports of myalgia, and no discontinuation of therapy.

CONCLUSION

Colesevelam HCl-ezetimibe combination therapy was associated with improved TC, LDL-C, and non-HDL-C lipid profiles and was well tolerated. Such therapy may be a reasonable consideration for statin-intolerant patients with DM or MS who have elevated cholesterol levels.

Lipoprotein effects of combined ezetimibe and colesevelam hydrochloride versus ezetimibe alone in hypercholesterolemic subjects: a pilot study

Two drug classes act in the intestine to lower cholesterol. Ezetimibe inhibits cholesterol absorption, whereas bile acid-binding resins enhance cholesterol excretion via enhanced conversion to bile acids. Combining these 2 classes may be beneficial, but cholestyramine binds ezetimibe, and the combined effect of colesevelam hydrochloride and ezetimibe was little studied. The aim of the study was to determine if adding colesevelam HCl to ezetimibe provides additional lowering of low-density lipoprotein- and apolipoprotein B-containing lipoproteins or alters ezetimibe levels. Twenty subjects with low-density lipoprotein cholesterol (LDL-C) levels of 130 mg/dL or higher were enrolled and taught a National Cholesterol Education Program Step I diet. At a second baseline visit, lipoproteins were measured and subjects were randomly allocated to (1) ezetimibe 10 mg daily with placebo colesevelam HCl twice daily (E) or (2) ezetimibe 10 mg daily with 1.875 g colesevelam HCl twice daily (E + C). Lipoproteins were measured 6 and 12 weeks after initiating treatment. Baseline characteristics (mean +/- SD) were statistically indistinguishable in E vs E + C: LDL-C (mg/dL), 167 +/- 26 and 158 +/- 27; triglyceride, 134 +/- 75 and 140 +/- 67; and BMI, 29.4 +/- 4.9 and 27.8 +/- 6.6 kg/m(2), respectively. Percent changes after 12 weeks in E vs E + C were as follows: LDL-C, -24 +/- 12 vs -30 +/- 11 (P = .102); triglyceride, -19 +/- 34 vs 36 +/- 85 (P = .054; at 6 weeks, P = .009); total cholesterol, -19 +/- 9 vs -15 +/- 8 (P = .50); non-high-density lipoprotein cholesterol, -25 +/- 10 vs -21 +/- 11 (P = .70); apolipoprotein B, -31 +/- 14 vs -22 +/- 14 (P = .41). Plasma ezetimibe levels at 12 weeks were 21% lower in E + C vs E, a nonsignificant difference (P = .54). In conclusion, in the short term, colesevelam HCl may not consistently add cholesterol-lowering benefit to ezetimibe. This observation requires confirmation.

Non-low-density lipoprotein cholesterol-associated actions of ezetimibe: an overview

Ezetimibe, an intestinal cholesterol absorption inhibitor, lowers circulating low-density lipoprotein cholesterol (LDL-C) levels both when administered as monotherapy and in combination with other hypolipidaemic drugs, mostly statins. This review focuses on the effects of ezetimibe on non-LDL-C-associated variables. In most studies, ezetimibe effectively reduced triglyceride and increased high density lipoprotein cholesterol levels. The authors also consider the effect of ezetimibe on other variables such as C-reactive protein levels, insulin sensitivity and endothelial function. Ezetimibe is useful in patients with sitosterolaemia (a rare inherited disorder) as it significantly reduces plasma phytosterol concentrations. Ezetimibe fulfils two of the three essential characteristics of any drug (efficacy and safety). However, clinical studies are required to provide evidence of its ability to reduce vascular events.

Lipid-lowering effects of colesevelam HCl in combination with ezetimibe

OBJECTIVE

The primary aim of this study was to compare the effect of colesevelam HCl in combination with ezetimibe to ezetimibe monotherapy on low-density lipoprotein cholesterol (LDL-C) levels in subjects with primary hypercholesterolemia.

METHODS

Subjects with primary hypercholesterolemia (N = 86) were enrolled in a multicenter, randomized, double-blind, placebo-controlled, parallel-group study. After a 4- to 8-week washout period, subjects received colesevelam HCl 3.8 g/day plus ezetimibe 10 mg/day or colesevelam HCl placebo plus ezetimibe 10 mg/day for 6 weeks. The primary efficacy endpoint was the mean percent change in LDL-C during randomized treatment. Secondary endpoints included mean absolute change in LDL-C, mean absolute and mean percent change in levels of high-density lipoprotein cholesterol (HDL-C), non-HDL-C, total cholesterol (TC), apolipoprotein (apo) A-I and apo B, and median absolute and percent changes in triglycerides (TG) and high-sensitivity C-reactive protein from baseline to end of treatment. Of the 86 subjects randomized to treatment, 85 were included in the intent-to-treat analysis.

RESULTS

After 6 weeks of treatment, colesevelam HCl plus ezetimibe produced a mean percent change in LDL-C of -32.3% versus -21.4% with ezetimibe monotherapy (p < 0.0001). Colesevelam HCl plus ezetimibe was significantly more effective than ezetimibe alone at producing mean percent reductions in TC, non-HDL-C, and apo B and increases in apo A-I (p < 0.005 for all). Neither treatment regimen resulted in significant changes in median TG levels compared with baseline (p = NS). Both treatments were safe and generally well tolerated.

CONCLUSIONS

Colesevelam HCl plus ezetimibe combination therapy significantly reduced mean LDL-C, TC, non-HDL-C, and apo B levels and increased apo A-I levels (p < 0.005 for all) without significantly increasing median TG levels in hypercholesterolemic subjects compared with ezetimibe alone. Although limited in that atherosclerotic coronary heart disease outcomes were not evaluated, this study demonstrated that combining colesevelam HCl with ezetimibe is a therapeutic option in hypercholesterolemic patients, such as those in whom statins are contraindicated and/or who may have intolerances to statin therapy.

Type of Preexisting Lipid Therapy Predicts LDL-C Response to Ezetimibe

Background:

Ezetimibe as monotherapy or in combination with statins effectively lowers low-density lipoprotein cholesterol (LDL-C). However, there are few reports of ezetimibe's effect when added to ongoing non-statin lipid-lowering drugs or combination lipid-lowering therapy.

Objective:

To evaluate the impact of preexisting lipid therapy on LDL-C response to ezetimibe.

Methods:

We performed a retrospective review of all patients started on ezetimibe therapy at the Veterans Affairs Long Beach Healthcare System between March 1, 2003, and March 1, 2005. We calculated the ezetimibe-induced percent change in LDL-C in patients without concomitant changes in other lipid-lowering medications. We then stratified the population according to the type and number of preexisting lipid therapies and compared the LDL-C–lowering efficacy of ezetimibe among these groups.

Results:

Overall, ezetimibe was associated with a 23.0% reduction in LDL-C. Patients with preexisting statin monotherapy had significantly greater LDL-C reduction with ezetimibe than did those with preexisting non-statin drugs (–26.1% vs –9.3%; p = 0.0138). In patients with no preexisting lipid therapy (n = 58), monotherapy (n = 115), double therapy (n = 36), or triple therapy (n = 9), ezetimibe decreased LDL-C by 17.3%, 21.4%, 33.5%, and 38.1%, respectively. This stepwise trend in increased ezetimibe efficacy was statistically significant, even with adjustments for baseline LDL-C.

Conclusions:

Ezetimibe's LDL-C–lowering effects are most pronounced when added to preexisting combination lipid therapy. It appears to be more effective when added to statin therapy compared with other lipid-lowering therapies.

Clinical utility of bile acid sequestrants in the treatment of dyslipidemia: a scientific review

Bile acid sequestrants (BAS) continue to command a position in the treatment of dyslipidemias 25 years after their introduction. Partial diversion of the enterohepatic circulation using BAS depletes the endogenous bile acid pool by approximately 40%, thus stimulating an increase in bile acid synthesis from cholesterol, which lowers low-density lipoprotein cholesterol (LDL-C) by 15 to 26%. Three BAS are currently used for treating hypercholesterolemia in the United States: the conventional sequestrants, cholestyramine and colestipol, and the specifically engineered BAS, colesevelam hydrochloride (HCl). Compared with conventional BAS, colesevelam HCl has enhanced specificity, greater affinity, and higher capacity for binding bile acids, due to its polymer structure engineered for bile acid sequestration. BAS are not absorbed by the intestine and thus have no systemic drug-drug interactions, but may interfere with the absorption of some drugs. Although BAS monotherapy effectively lowers LDL-C, combination therapy, especially with BAS and statins, is becoming increasingly common due to complementary mechanisms of action. Low-dose statin plus BAS combinations lead to greater or similar LDL-C reductions compared with high-dose statin monotherapy and may have a better safety profile. Combinations of BAS with nonstatin lipid-lowering agents, including niacin, fibrates, and cholesterol absorption inhibitors, may be useful in those patients who require intensive lipid-lowering, but are statin intolerant. BAS treatment can significantly reduce coronary artery disease (CAD) progression and the risk of CAD-associated outcomes. It is also becoming clear that BAS and other therapies that manipulate the bile acid synthetic pathway may have clinically useful therapeutic effects on other metabolic disorders including type 2 diabetes.

Effectiveness and Tolerability of Adding Ezetimibe to Niacin-Based Regimens for Treatment of Primary Hyperlipidemia

OBJECTIVE

To determine the effectiveness and tolerability of adding ezetimibe, 10 mg daily, to niacin-based regimens for dyslipidemia.

METHODS

We conducted a retrospective review of medical records of 53 patients in 2 lipid clinics who received ezetimibe as add-on therapy to stable doses of niacin and other lipid medications. Mean percentage changes of lipoprotein cholesterol and triglyceride levels were determined. Safety and tolerability measures included adverse events, serum hepatic transaminases, and hemoglobin A1c (in patients with diabetes).

RESULTS

Most study subjects (81%) had established atherosclerotic disease. The niacin formulation was extended-release in 31 patients (58%), immediate-release in 17 (32%), and slow-release in 5 (9%). Most patients (75%) were also taking a statin. Add-on ezetimibe therapy yielded mean reductions of 18% for total cholesterol (P<0.001), 25% for low-density lipoprotein (LDL) cholesterol (P<0.001), and 17% for triglycerides (P<0.001). High-density lipoprotein (HDL) cholesterol did not change significantly (+2%). Only 7 patients (13%) met Adult Treatment Panel III (ATP III) LDL cholesterol goals before the addition of ezetimibe, but 24 (45%; P<0.001 compared with baseline) attained these goals after addition of ezetimibe to the therapeutic regimen. Ezetimibe effectiveness did not correlate with the baseline dose of niacin or the dose/efficacy of the statin used. The addition of ezetimibe to niacin-based therapy for dyslipidemia was well tolerated. No patient had clinically significant elevations in hepatic enzyme or hemoglobin A1c levels or discontinued the ezetimibe therapy permanently.

CONCLUSION

In our study, the addition of ezetimibe to niacin-based regimens lowered the LDL cholesterol level by 25% and did not change the level of HDL cholesterol. This combination can be useful in multidrug regimens for high-risk patients with dyslipidemia who are not achieving ATP III treatment goals.

Reaching goal in hypercholesterolaemia: dual inhibition of cholesterol synthesis and absorption with simvastatin plus ezetimibe

Lowering serum cholesterol levels reduces the risk of coronary heart disease (CHD)-related events. Statins are commonly prescribed as first-line treatment but many patients at high-risk for CHD still fail to reach their cholesterol or low-density lipoprotein cholesterol (LDL-C) goals with statin monotherapy. National and international guidelines for the prevention of CHD recommend the modification of lipid profiles and particularly LDL-C [e.g. the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III; 2001) and Third Joint Task Force of European and other Societies on Cardiovascular Disease Prevention in Clinical Practice (2003) Guidelines]. Several recent clinical trials indicated an added benefit from aggressive lowering of LDL-C levels. Based on these findings, the NCEP ATP III revised the LDL-C target from < 100 mg/dL (2.6 mmol/L) to < 70 mg/dL (1.8 mmol/L) (optional target) for very high-risk patients and < 130 mg/dL (3.4 mmol/L) to < 100 mg/dL (2.6 mmol/L) for moderately high-risk patients. For patients who fail to achieve their LDL-C target, inhibiting the two main sources of cholesterol - synthesis and uptake - can produce more effective lipid lowering, allowing more patients to reach their LDL-C goal. Ezetimibe is a highly-selective inhibitor of cholesterol absorption and simvastatin is an evidence-based inhibitor of cholesterol synthesis. The LDL-C-lowering efficacy of targeting both major sources of cholesterol with ezetimibe plus simvastatin was demonstrated in several multicentre, double-blind, placebo-controlled trials in patients with hypercholesterolaemia. For patients who do not reach their cholesterol goal with a statin, adding ezetimibe 10 mg significantly reduces LDL-C compared with statin monotherapy. Thus, this treatment option may help patients reach the new 'stricter' cholesterol goals. This review, based on a Medline database search from January 2000 to August 2005, considers the LDL-C-lowering efficacy of ezetimibe and discusses the role of this agent for patients who fail to achieve guideline cholesterol goals with statin monotherapy.

Cholestanol: A serum marker to guide LDL cholesterol-lowering therapy

Statins have been the mainstay of lipid-lowering therapy since their introduction. However, as lower LDL cholesterol targets are sought, adjunct therapies are becoming increasingly important. Few patients reach new targets with statin monotherapy. We propose that the cholestanol:cholesterol ratio can be used to guide lipid-lowering therapy and result in greater numbers of patients reaching target LDL cholesterol. By determining whether a patient is mainly a synthesizer or absorber of cholesterol, customized regimens can be used and are expected to improve patient outcomes and minimize costs of treatment.

Rationale for targeting multiple lipid pathways for optimal cardiovascular risk reduction

Clinical trials of statin therapy have consistently demonstrated significant reductions in coronary artery disease (CAD) events, yet statin-treated patients remain at risk for CAD despite substantial reductions in low-density lipoprotein (LDL) cholesterol. Recent evidence from clinical trials supports reduction of LDL cholesterol to lower targets, and the updated treatment guidelines include optional, more aggressive LDL cholesterol goals for patients at very high and moderately high risk. Achievement of these lower goals will require enhanced treatment strategies. Targeting multiple lipid pathways can provide greater reductions in LDL cholesterol as well as improvements in other lipid parameters. Clinical trials are needed to determine which treatment strategies provide optimal cardiovascular risk reduction.

The use of ezetimibe in achieving low density lipoprotein lowering goals in clinical practice: position statement of a United Kingdom consensus panel

There is no doubt that lowering serum cholesterol levels reduces the risk of major coronary events. This evidence has led treatment guidelines to set progressively lower targets for low density lipoprotein cholesterol (LDL-C). However, despite widespread use of statins, substantial numbers of patients do not achieve the LDL-C goals. Using higher doses of statins in an attempt to achieve these targets may increase the risk of serious adverse effects. Furthermore, the use of combination therapy with agents such as bile acid sequestrants, niacin and fibrates has been limited by increased potential for side effects, drug interactions and poor compliance. Ezetimibe, a selective cholesterol transport inhibitor, reduces the intestinal uptake of cholesterol without affecting absorption of triglycerides or fat-soluble vitamins. In clinical studies, ezetimibe 10 mg, in combination with statins or as monotherapy, was well tolerated and reduced LDL-C by 34-53% and 17-18%, respectively. The available evidence for ezetimibe is reviewed. The role of ezetimibe in increasing the proportion of patients attaining LDL-C treatment goals is discussed.