Choosing the right lipid-regulating agent. A guide to selection

Bioactive Compounds for the Management of Hypertriglyceridemia: Evidence From Clinical Trials and Putative Action Targets

Hypertriglyceridemia refers to the presence of elevated concentrations of triglycerides (TG) in the bloodstream (TG >200 mg/dL). This lipid alteration is known to be associated with an increased risk of atherosclerosis, contributing overall to the onset of atherosclerotic cardiovascular disease (CVD). Guidelines for the management of hypertriglyceridemia are based on both lifestyle intervention and pharmacological treatment, but poor adherence, medication-related costs and side effects can limit the success of these interventions. For this reason, the search for natural alternative approaches to reduce plasma TG levels currently represents a hot research field. This review article summarizes the most relevant clinical trials reporting the TG-reducing effect of different food-derived bioactive compounds. Furthermore, based on the evidence obtained from in vitro studies, we provide a description and classification of putative targets of action through which several bioactive compounds can exert a TG-lowering effect. Future research may lead to investigations of the efficacy of novel nutraceutical formulations consisting in a combination of bioactive compounds which contribute to the management of plasma TG levels through different action targets.

Dietary fat content modulates the hypolipidemic effect of dietary inulin in rats

SCOPE

Dietary fat content (low versus high fat) may modulate the serum lipid-lowering effect of high-performance (HP)-inulin. This study investigated the effect of dietary HP-inulin on metabolism in rats fed a low- or high-fat diet.

METHODS AND RESULTS

Rats were fed a diet of 5% fat with 5% cellulose or 5% HP-inulin (average degree of polymerization = 24) (low-fat diet) or of 20% fat with 5% cellulose or 5% HP-inulin (high-fat diet) for 28 days. Total, HDL, and non-HDL cholesterols, and triglyceride concentrations in the serum were measured along with total lipid content of liver and feces. Hepatic triglyceride and cholesterol, and fecal neutral and acidic sterol concentrations in total lipid were assessed. In addition, cecum SCFA levels and bacterial profiles were determined. The hypolipidemic effect of HP-inulin differed depending on dietary fat content (5% versus 20%). Specifically, 5% inulin instead of cellulose in a semi-purified diet significantly reduced serum lipid levels in rats fed a high-fat diet, which was strongly associated with increased total lipid and neutral sterol excretion.

CONCLUSION

Dietary fat content modulates the hypolipidemic effect of dietary inulin.

Effect of extended-release niacin on hormone-sensitive lipase and lipoprotein lipase in patients with HIV-associated lipodystrophy syndrome

BACKGROUND

HIV-associated lipodystrophy syndrome is strongly associated with antiretroviral treatment in patients with human immunodeficiency virus (HIV). Niacin is thought to affect hormone-sensitive lipase (HSL) and lipoprotein lipase (LPL) expression in peripheral and intra-abdominal fat (IAF).

OBJECTIVE

This study investigated the effect of extended-release niacin (ERN) on adipose HSL and LPL expression in patients with HIV-associated lipodystrophy syndrome.

METHODS

Changes in IAF and peripheral fat content and HSL and LPL expression were examined in 4 HIV-infected patients recruited from a prospective study treated with ERN. Patients underwent limited 8 slice computerized tomography abdominal scans, dual-energy X-ray absorptiometry scans, and skin punch biopsies of the mid-thigh at baseline and after 12 weeks of ERN. All subjects were on stable highly active antiretroviral therapy prior to and during the study. Changes in body habitus were self-reported.

RESULTS

Normalized HSL expression decreased in 3 patients and normalized LPL expression increased in all 4 patients when comparing pre- and post-ERN treated samples. All subjects showed a decrease in total cholesterol (TC) and triglyceride (TG) levels.

CONCLUSIONS

Preliminary analysis suggests ERN may induce changes in HSL and LPL expression. This method is a feasible approach to identify changes in adipose RNA expression involved with lipolysis.

The functional changes of the perivascular adipose tissue in spontaneously hypertensive rats and the effects of atorvastatin therapy

The aim of this study was to examine the function of perivascular adiposa tissue (PVAT) on vascular relaxation response in spontaneously hypertensive rats (SHR) and the modulatory effects of the atorvastatin therapy on the PVAT functions. We investigated the mechanisms of the perivascular adipocyte-derived relaxation factor (PVRF) by using isolated rat's aortic rings and isometric contraction measurements. We found that contraction of the thoracic aorta induced by phenylephrine was significantly attenuated in the presence of PVAT from normotensive Wistar-Kyoto rats (WKY group) or the spontaneously hypertensive rats treated with atorvastatin (SHR-A group, atorvastatin 50mg/kg/day), whereas this effect was not observed in the thoracic aortic rings from the control SHR (SHR group). Transferring the solution incubated with PVAT-intact thoracic aorta to PVAT-free thoracic aorta, it induced a remarkable relaxation response in the WKY but not in the control SHR. Tetraethylammoniumchloride (TEA) could block the above relaxation. It was also shown that the PVRF function was likely, depending on the extracellular [Ca(2+)]; the anti-contractile effect of PVAT could be reduced by the inhibitor of the adenosine triphosphate (ATP)-dependent potassium channels, glibenclamide, and could be reduced by the inhibitor of cyclooxygenase by indomethacin. We thus infer that the PVAT function was distorted in hypertension rats, and the lipid-lowering treatment with atorvastatin could restore the PVAT function. The function of the PVRF may involve the Ca(2+)-activated potassium channels, the ATP-dependent potassium channels in vascular smooth muscle cell (SMC), and the release of PVRF from PVAT may involve prostaglandins (PGs) and the calcium metabolism. These results provide an insight into the pathological mechanisms of hypertension development, and indicate that the PVAT may be a potential new target for the hypertensive therapy.

Bile acid sequestrants and the treatment of type 2 diabetes mellitus

Bile acids promote bile formation and facilitate dietary lipid absorption. Animal and human studies showing disturbed bile acid metabolism in diabetes mellitus suggest a link between bile acids and glucose control. Bile acids are activating ligands of the farnesoid X receptor (FXR), a nuclear receptor with an established role in bile acid and lipid metabolism. Evidence suggests a role for FXR also in maintenance of glucose homeostasis. Animal and human studies employing bile acid sequestrants (bile acid binding agents), which interrupt the enterohepatic circulation of bile acids and effectively reduce plasma cholesterol, support a link between bile acid and glucose metabolism. In lipid-lowering trials, bile acid sequestrants, such as colesevelam hydrochloride, colestyramine (cholestyramine) and colestilan (colestimide), have also been shown to lower plasma glucose and glycosylated haemoglobin levels, suggesting the utility of these agents as a potential therapy for type 2 diabetes. In this article, we review the relationship between bile acid metabolism and glucose homeostasis, and present data demonstrating the utility of bile acid sequestrants in the management of diabetes.

Colesevelam: Potential Uses for the Newest Bile Resin

Colesevelam is the newest bile resin with a unique chemical structure. It binds to bile acids with higher affinity than traditional bile acid sequestrants and has fewer gastrointestinal side effects and drug interactions. Colesevelam is safe and efficacious alone or in combination with HMG-CoA reductase inhibitors (statins) in reducing low-density lipoprotein cholesterol (LDL-C) levels. Despite this, the role of colesevelam in the treatment of hyperlipidemia remains limited, particularly in the face of new lipid lowering agents. As guidelines for cholesterol control become more stringent, the need to maximize therapeutic benefit through combination therapy will become increasingly more important. Colesevelam has a dose-sparing effect on statin therapy, potentially decreasing the risk of unwanted side effects or drug-drug interactions associated with statin use. This makes colesevelam a viable option for addition to a statin regimen when goal LDL-C levels cannot be achieved with a statin alone. Additionally, anecdotal reports indicate that colesevelam may have potential benefits in certain patient populations that cannot tolerate other lipid lowering therapies, including organ transplant recipients, cholestatic liver disesase, and end-stage renal disease. By recognizing the potential utility of colesevelam, clinicians can better manage those patients who are not able to tolerate first-line therapies.

Lack of protective effect of D-003, a mixture of high-molecular-weight primary acids from sugar cane wax, on liver damage induced by galactosamine in rats

D-003 is a mixture of very-high-molecular-weight aliphatic primary acids purified from sugar cane wax, wherein octacosanoic acid is the most abundant. Experimental and clinical studies have shown that D-003 lowers cholesterol and prevents plasma lipoprotein peroxidation (LP). D-003 has protected against the histological changes characteristic of CCl4- and paracetamol-induced hepatic injury in rats, in which LP plays a pivotal role for explaining the resulting hepatotoxicity. Galactosamine induces hepatotoxicity associated with depressed RNA and protein synthesis, not with LP. The aim of this study was to evaluate whether D-003 could prevent hepatoxicity induced by mechanisms others than increased LP. We investigated the effects on galactosamine hepatotoxicity in rats distributed into five groups: a negative control group, a positive control group, and three groups treated with galactosamine and D-003 (5, 25, and 100 mg/kg). To induce liver damage, galactosamine (800 mg/kg) was injected intraperitoneally 30 minutes after dosing with vehicle or D-003. Twenty-four hours later, rats were sacrificed, and livers were immediately removed for histopathological studies. Livers from positive controls showed the characteristic pattern of galactosamine-induced damage. Galactosamine significantly reduced the percentage of normal hepatocytes, increasing both necrotic or lipid-rich hepatocytes compared with negative controls. D-003, however, did not increase the percentage of normal hepatocytes compared with positive controls, indicating that treatment was not effective for preventing the hepatic injury induced with galactosamine. Likewise, D-003 failed to change the content of necrotic and lipid-rich hepatocytes relative to positive controls. It is concluded that D-003 did not protect against the histological changes of galactosamine-induced hepatotoxicity.

Role of the Pharmacist in Establishing Lipid Intervention Programs

Despite the availability of the National Cholesterol Education Program Adult Treatment Panel (ATP) guidelines for the management of hyperlipidemia since 1988, most patients do not achieve their target low-density lipoprotein cholesterol (LDL) goals. With the publication of the most recent guidelines (ATP III), which contain more aggressive treatment recommendations, the cholesterol treatment gap is likely to widen further. Factors responsible for patients not receiving adequate treatment include a lack of focus on asymptomatic diseases, time and reimbursement constraints, inadequate training, a reluctance to prescribe aggressive treatment regimens, and poor communication among health care professionals. Results of several studies evaluating intervention programs indicate that pharmacists can play a key role in improving cholesterol management whether in lipid clinics, community pharmacies, or hospitals. In these intervention programs, pharmacists provided a wide range of functions that included reviewing the medical history, monitoring laboratory values, selecting lipid-lowering therapies, and educating patients regarding drug therapies and the importance of compliance. These interventions produced significant improvements in lipid parameters and in the number of patients who achieved LDL treatment goals. Most important, these interventions were associated with decreases in clinical events. Pharmacist intervention also was highly cost-effective and time efficient. These results suggest that pharmacists are in a unique position and possess the requisite skills to improve the treatment of patients with hyperlipidemia.

What’s New in Lipid Management?

Statins are the principal agents for managing hyperlipidemia because of their ability to reduce low-density lipoprotein cholesterol (LDL) and triglyceride levels, increase high-density lipoprotein cholesterol (HDL) levels slightly, and decrease clinical events. Nevertheless, not all patients can tolerate the statins or achieve their treatment goals with these drugs. In addition, available statins have only modest effects on HDL, and clinical events still occur despite the best current lipid-lowering agents. Thus, new lipid-lowering agents are required to improve clinical outcomes. These recently or soon to be released agents are stanol esters, which can be incorporated into spreads and other foods and reduce LDL levels up to 15%; colesevelam, a new bile acid sequestrant with a higher potency, fewer adverse effects, and less drug interactions than those of older agents in this class; rosuvastatin, a new statin that reduces LDL levels and increases HDL levels at least more effectively than atorvastatin; and a new class of agents that inhibit cholesterol absorption and are likely to be used in combination with statins. Low-density lipoprotein cholesterol apheresis is another, nonpharmacologic option for patients with severe hyperlipidemia despite maximal medical therapy.

Update on fenofibrate

Fenofibrate is a fibric acid derivative that has been marketed since the mid-1970's (1998 in the United States). Its active metabolite, fenofibric acid, is responsible for the primary pharmacodynamic effects of the drug: reductions in total plasma cholesterol, low density lipoprotein cholesterol, triglycerides, and very low-density lipoprotein concentrations and increases in high-density lipoprotein cholesterol and apolipoproteins AI and AII concentrations. These effects are mediated by activation of peroxisome proliferator-activated receptor-alpha (PPAR(alpha)). The drug has broad spectrum utility, with documented efficacy in Fredrickson types IIa, IIb, III, IV, and V hyperlipidemias. Fenofibrate is well tolerated, with digestive and musculoskeletal side effects similar to those of other fibrates. Results of the initial cardiovascular morbidity/mortality outcomes study with fenofibrate (known as DAIS [Diabetes Atherosclerosis Intervention Study]) were encouraging vis-à-vis slowing of atherosclerotic progression in the coronary vasculature of type II diabetics. The results of other ongoing outcome trials are eagerly awaited. These results will help to establish the overall place of fenofibrate in the hypolipidemic armamentarium.

Effects of policosanol and lovastatin in patients with intermittent claudication: a double-blind comparative pilot study

Policosanol is a cholesterol-lowering drug with concomitant antiplatelet effects. The present study was undertaken to compare the effects of policosanol and lovastatin on patients with moderately severe intermittent claudication. The study had a 4-week baseline step, followed by a 20-week double blinded, randomized treatment period. Twenty-eight patients who met study entry criteria were randomized to policosanol 10 mg or lovastatin 20 mg tablets once daily. Walking distances in a treadmill (constant speed 3.2 km/hr, slope 10 degrees, temperature 25 degrees C) were assessed before and after 20 weeks of treatment. Both groups were similar at randomization. Compared with baseline, policosanol increased significantly (p < 0.01) the initial claudication distance (ICD) from 160.39 +/- 15.82 m to 211.31 +/- 21.48 m (+33.7%) and the absolute claudication distance (ACD) (p < 0.001) from 236.39 +/- 25.44 m to 288.09 +/- 28.47 m (+24.3%); meanwhile both variables remained unchanged after lovastatin therapy. Changes in ICD and ACD were significantly larger in the policosanol than in the lovastatin group (p < 0.01). Policosanol, but not lovastatin, significantly increased (p < 0.05) the ankle/arm index, although between-group differences were not significant. The frequency of patients reporting improvement on quality of life domains was greater in the policosanol than in the lovastatin group. Policosanol significantly (p < 0.001) lowered total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C) by 17.5% and 31.0%, respectively, and meanwhile increased (p < 0.01) high-density lipoprotein-cholesterol (HDL-C) levels by 31.5%. Lovastatin reduced (p < 0.01) TC (18.0%), LDL-C (22.6%), and (p < 0.05) triglycerides (9.8%). In addition, policosanol, but not lovastatin, moderately, but significantly, reduced (p < 0.05) fibrinogen levels, so that final values and percent changes in both groups were different (p < 0.01). Treatments were well tolerated. Only 1 lovastatin patient withdrew from the study because of a nonfatal myocardial infarction. Five lovastatin patients, but none from the policosanol group, experienced 6 adverse events (AE) (p < 0.01). The present results indicate that policosanol, but not lovastatin, is a suitable alternative to manage patients with intermittent claudication because of pleiotropic properties beyond its cholesterol-lowering effects.

Micronised fenofibrate: an updated review of its clinical efficacy in the management of dyslipidaemia

Micronised fenofibrate is a synthetic phenoxy-isobutyric acid derivative (fibric acid derivative) indicated for the treatment of dyslipidaemia. Recently, a new tablet formulation of micronised fenofibrate has become available with greater bioavailability than the older capsule formulation. The micronised fenofibrate 160mg tablet is bioequivalent to the 200mg capsule. The lipid-modifying profile of micronised fenofibrate 160mg (tablet) or 200mg (capsule) once daily is characterised by a decrease in low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TC) levels, a marked reduction in plasma triglyceride (TG) levels and an increase in high-density lipoprotein cholesterol (HDL-C) levels. Micronised fenofibrate 200mg (capsule) once daily produced greater improvements in TG and, generally, in HDL-C levels than the hydroxymethylglutaryl coenzyme A reductase inhibitors simvastatin 10 or 20 mg/day, pravastatin 20 mg/day or atorvastatin 10 or 40 mg/day. Combination therapy with micronised fenofibrate 200mg (capsule) once daily plus fluvastatin 20 or 40 mg/day or atorvastatin 40 mg/day was associated with greater reductions from baseline than micronised fenofibrate alone in TC and LDL-C levels. Similar or greater changes in HDL-C and TG levels were seen in combination therapy, compared with monotherapy, recipients. Micronised fenofibrate 200mg (capsule) once daily was associated with significantly greater improvements from baseline in TC, LDL-C, HDL-C and TG levels than placebo in patients with type 2 diabetes mellitus enrolled in the double-blind, randomised Diabetes Atherosclerosis Intervention Study (DAIS) [> or =3 years follow-up]. Moreover, angiography showed micronised fenofibrate was associated with significantly less progression of coronary atherosclerosis than placebo. Micronised fenofibrate has also shown efficacy in patients with metabolic syndrome, patients with HIV infection and protease inhibitor-induced hypertriglyceridaemia and patients with dyslipidaemia secondary to heart transplantation. Micronised fenofibrate was generally well tolerated in clinical trials. The results of a large (n = 9884) 12-week study indicated that gastrointestinal disorders are the most frequent adverse events associated with micronised fenofibrate therapy. Elevations in serum transaminase and creatine phosphokinase levels have been reported rarely with micronised fenofibrate. In conclusion, micronised fenofibrate improves lipid levels in patients with primary dyslipidaemia; the drug has particular efficacy with regards to reducing TG levels and raising HDL-C levels. Micronised fenofibrate is also effective in diabetic dyslipidaemia; as well as improving lipid levels, the drug reduced progression of coronary atherosclerosis in patients with type 2 diabetes mellitus. The results of large ongoing studies (e.g. FIELD with approximately 10 000 patients) will clarify whether the beneficial lipid-modifying effects of micronised fenofibrate result in a reduction in cardiovascular morbidity and mortality.

Pharmacokinetic-pharmacodynamic drug interactions with HMG-CoA reductase inhibitors

The HMG-CoA reductase inhibitors (statins) are effective in both the primary and secondary prevention of ischaemic heart disease. As a group, these drugs are well tolerated apart from two uncommon but potentially serious adverse effects: elevation of liver enzymes and skeletal muscle abnormalities, which range from benign myalgias to life-threatening rhabdomyolysis. Adverse effects with statins are frequently associated with drug interactions because of their long-term use in older patients who are likely to be exposed to polypharmacy. The recent withdrawal of cerivastatin as a result of deaths from rhabdomyolysis illustrates the clinical importance of such interactions. Drug interactions involving the statins may have either a pharmacodynamic or pharmacokinetic basis, or both. As these drugs are highly extracted by the liver, displacement interactions are of limited importance. The cytochrome P450 (CYP) enzyme system plays an important part in the metabolism of the statins, leading to clinically relevant interactions with other agents, particularly cyclosporin, erythromycin, itraconazole, ketoconazole and HIV protease inhibitors, that are also metabolised by this enzyme system. An additional complicating feature is that individual statins are metabolised to differing degrees, in some cases producing active metabolites. The CYP3A family metabolises lovastatin, simvastatin, atorvastatin and cerivastatin, whereas CYP2C9 metabolises fluvastatin. Cerivastatin is also metabolised by CYP2C8. Pravastatin is not significantly metabolised by the CYP system. In addition, the statins are substrates for P-glycoprotein, a drug transporter present in the small intestine that may influence their oral bioavailability. In clinical practice, the risk of a serious interaction causing myopathy is enhanced when statin metabolism is markedly inhibited. Thus, rhabdomyolysis has occurred following the coadministration of cyclosporin, a potent CYP3A4 and P-glycoprotein inhibitor, and lovastatin. Itraconazole has been shown to increase exposure to simvastatin and its active metabolite by at least 10-fold. Pharmacodynamically, there is an increased risk of myopathy when statins are coprescribed with fibrates or nicotinic acid. This occurs relatively infrequently, but is particularly associated with the combination of cerivastatin and gemfibrozil. Statins may also alter the concentrations of other drugs, such as warfarin or digoxin, leading to alterations in effect or a requirement for clinical monitoring. Knowledge of the pharmacokinetic properties of the statins should allow the avoidance of the majority of drug interactions. If concurrent therapy with known inhibitors of statin metabolism is necessary, the patient should be monitored for signs and symptoms of myopathy or rhabdomyolysis and the statin should be discontinued if necessary.

Involvement of oxidation-sensitive mechanisms in the cardiovascular effects of hypercholesterolemia

Hypercholesterolemia is a common clinical metabolic and/or genetic disorder that promotes functional and structural vascular wall injury. The underlying mechanisms for these deleterious effects involve a local inflammatory response and release of cytokines and growth factors. Consequent activation of oxidation-sensitive mechanisms in the arterial wall, modulation of intracellular signaling pathways, increased oxidation of low-density lipoprotein cholesterol, and quenching of nitric oxide can all impair the functions controlled by the vascular wall and lead to the development of atherosclerosis. This cascade represents a common pathological mechanism activated by various cardiovascular risk factors and may partly underlie synergism among them as well as the early pathogenesis of atherosclerosis. Antioxidant intervention and restoration of the bioavailability of nitric oxide have been shown to mitigate functional and structural arterial alterations and improve cardiovascular outcomes. Elucidation of the precise nature and role of early transductional signaling pathways and transcriptional events activated in hypercholesterolemia in children and adults, including mothers during pregnancy, and understanding their downstream effects responsible for atherogenesis may help in directing preventive and interventional measures against atherogenesis and vascular dysfunction.

Colesevelam: a new bile acid sequestrant

Coronary heart disease is the most prevalent form of cardiovascular disease in the United States. Hyperlipidemia--specifically, increased total and low-density lipoprotein cholesterol levels--positively correlates with the development of coronary heart disease. Colesevelam, a nonabsorbed, water-insoluble polymer, is a new bile acid sequestrant that is effective in lowering total and low-density lipoprotein cholesterol levels. In several short-term, placebo-controlled studies, colesevelam has decreased total cholesterol levels by approximately 6 to 10% and low-density lipoprotein cholesterol levels by approximately 9 to 20%. When given in combination with atorvastatin, lovastatin, or simvastatin, low-density lipoprotein cholesterol levels were decreased more than with colesevelam alone. Its unique hydrogel formulation may also minimize the potential for gastrointestinal adverse effects, which are common with other bile acid sequestrants. There have been few published studies available concerning this drug; no long-term studies and few large-scale studies have been published.

Colesevelam hydrochloride: a non-absorbed, polymeric cholesterol-lowering agent

Colesevelam hydrochloride (formerly known as Cholestagel((R)) and re-named WelCholtrade mark, GelTex Pharmaceuticals, Inc. and Sankyo Parke-Davis) is a new, polymeric, high potency, water-absorbing hydrogel. It has been shown to be a safe and effective cholesterol-lowering agent with a non-systemic mechanism of action, good tolerability and minimal side effects. To date, the lipid-lowering activity of colesevelam has been evaluated in approximately 1400 subjects. Colesevelam reduces low density lipoprotein (LDL)-cholesterol levels, in a dose-dependent manner, by as much as 20% (median) in patients with hypercholesterolaemia. Dosing regimen evaluations indicate that colesevelam is effective at both once per day and twice daily dosing and that concurrent administration of colesevelam with hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins), specifically lovastatin, does not alter the absorption of the statin. Combination therapy with HMG-CoA reductase inhibitors, including lovastatin, simvastatin and atorvastatin, produces an additional reduction (8 - 16%) in LDL-cholesterol levels above that seen with the statin alone. The overall incidence of adverse effects with colesevelam alone and in combination with statins is comparable with that seen with placebo. Colesevelam lacks the constipating effect seen with typical bile acid sequestrants, a trait that would be expected to improve compliance with lipid-lowering therapy. Colesevelam, recently approved by the US FDA, represents a valuable non-absorbed alternative in the armamentarium against hypercholesterolaemia, both for monotherapy and combination therapy, as an adjunct to diet and exercise.

Debate: at what level of coronary heart disease risk should a statin be prescribed?

3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) are effective treatments for the primary and secondary prevention of coronary heart disease, but an outstanding issue is determining who should have such treatment. The benefit from treatment with statins appears to be proportional to the underlying risk of coronary heart disease and independent of the factors increasing risk. Most benefit will therefore be achieved by treating people at increased risk of coronary heart disease. Statins reduce coronary morbidity even when the risk of coronary heart disease is relatively low (6% over 10 years), but reduction in all-cause mortality, the true measure of safety has been shown only when the risk of a major coronary heart disease event is 15% over 10 years or greater. At this level of risk patients appear willing to take treatment to gain the benefit expected from statin treatment, and the cost effectiveness of statin treatment is within the range accepted for other treatments. The major impediments to the systematic introduction of statin treatment at this level of risk are the very high overall cost and the large workload in countries like Britain, where the population risk of coronary heart disease is high. For this reason, recent British guidelines correctly advise statin treatment for secondary prevention and primary prevention when the 10 year coronary heart disease risk is 30% or greater as the first priority, moving to a lower coronary heart disease threshold for primary prevention only when resources permit.

Micronized fenofibrate: a new fibric acid hypolipidemic agent

OBJECTIVE

To review the efficacy and safety of fenofibrate in the management of hyperlipidemias.

DATA SOURCES

A MEDLINE search (1974-October 1998), Current Contents search, additional references from article bibliographies, and the package insert from the manufacturer were used to identify data for evaluation. Studies evaluating fenofibrate (peer-reviewed publications, package insert data) were considered for inclusion. Abstracts and data on file with the manufacturer were not considered for inclusion.

STUDY SELECTION

English-language literature was reviewed to evaluate the pharmacology, pharmacokinetics, clinical use, and tolerability of fenofibrate. Data from animals and in vitro systems were included only when necessary to explain the drug's pharmacology.

DATA SYNTHESIS

Micronized fenofibrate is a fibric acid derivative approved by the Food and Drug Administration (FDA) in February 1998 for the treatment of types IV and V hyperlipidemia. Data from the peer-reviewed literature also support the use of fenofibrate in types IIa, IIb, and III hyperlipidemias. Micronized fenofibrate 67-201 mg/d is useful as monotherapy or as an adjunct to other hypolipidemics and dietary therapy. In placebo-controlled clinical trials, regular formulation fenofibrate 300-400 mg/d lowered serum triglyceride (TG) concentrations by 24-55%, total cholesterol by 9-25%, low-density lipoprotein cholesterol (LDL-C) concentrations by 6-35%, and raised high-density lipoprotein cholesterol (HDL-C) concentrations by 8-38%. Few comparative data exist regarding fenofibrate versus clofibrate and gemfibrozil. In noncomparative and comparative clinical trials, fenofibrate appeared to be well tolerated. The most common causally related adverse events were digestive, musculoskeletal, and dermatologic in nature. Concurrent use of fenofibrate and a hydroxymethylglutaryl-coenzyme A inhibitor may increase the risk of myopathy and/or rhabdomyolysis, although recent data suggest that concurrent use of fenofibrate with low-dose simvastatin or pravastatin is safe. Fenofibrate may enhance the effect of oral anticoagulants.

CONCLUSIONS

Fenofibrate reduces serum TG, total cholesterol, and LDL-C, and raises HDL-C to clinically relevant degrees. Its spectrum of activity appears to exceed that recommended for types IV and V hyperlipidemia to encompass types IIa, IIb, and III hyperlipidemias as well. To this extent, it may be considered a broader-spectrum fibrate than is indicated by its FDA approval. Adverse effects of fenofibrate appear to be similar to those of other fibrates and require routine monitoring (clinical, liver function). Long-term safety data are readily available from drug registries in many countries where the product has been available for nearly two decades. Cost-effectiveness studies comparing fenofibrate with other hypolipidemics demonstrate benefits of fenofibrate over simvastatin in types IIa and IIb hyperlipidemia. The need for dosage titration of the micronized preparation from 67 mg/d upward to a final dose of 200 mg/d is also not supported by peer-reviewed literature (except in the case of renal impairment). Although preliminary data on plaque regression are encouraging, published clinical studies evaluating the impact of fenofibrate on cardiovascular morbidity and mortality are awaited. Micronized fenofibrate is worthy of formulary inclusion.

Micronised fenofibrate: a review of its pharmacodynamic properties and clinical efficacy in the management of dyslipidaemia

Micronised fenofibrate is a new formulation of the fibric acid derivative fenofibrate. It is indicated for the treatment of patients with type IIa, IIb, III or IV dyslipidaemia who have failed to respond to dietary control or other nonpharmacological interventions. Micronised fenofibrate has improved absorption characteristics compared with the standard preparation, allowing a lower daily dosage and once-daily administration. The lipid-modifying profile of micronised fenofibrate is characterised by a decrease in low density lipoprotein (LDL) and total cholesterol levels, a marked reduction in elevated plasma triglyceride levels and an increase in high density lipoprotein (HDL) cholesterol levels. Consistent with the standard formulation, which is administered as 300mg daily in divided doses, the micronised preparation has demonstrated efficacy in the treatment of type IIa, IIb and IV primary dyslipidaemias but at a lower daily dosage of 200mg once daily. Because of its significant triglyceride-lowering effect, micronised fenofibrate appears to be of greatest benefit in patients with hypertriglyceridaemia (with or without hypercholesterolaemia), including patients with type 2 (non-insulin-dependent) diabetes mellitus and dyslipidaemia. In the comparisons available, micronised fenofibrate 200mg once daily was of similar efficacy to or less effective than the HMG-CoA reductase inhibitors simvastatin 20mg daily and pravastatin 20mg daily at reducing LDL and total cholesterol levels. However micronised fenofibrate produced greater improvements in triglyceride and, generally, HDL cholesterol levels than both simvastatin and pravastatin. Data on the long term tolerability of micronised fenofibrate are limited. However, data from a large short term (3-month) study have indicated that gastrointestinal disorders are the most frequent adverse events associated with therapy. Elevations in serum transaminase and creatine phosphokinase levels have been reported rarely with micronised fenofibrate. In conclusion, available data suggest that the more convenient lower once-daily dosage of micronisedfeno fibrate retains the beneficial lipid-modifying effects of the standard formulation. Further studies are required to determine whether the lipid changes achieved with micronised fenofibrate result in a reduction in cardiovascular morbidity and mortality.