Effect of fenofibrate treatment on type III hyperlipoproteinemia

Influence of trimetazidine and ranolazine on endothelial function in patients with ischemic heart disease

OBJECTIVE

Endothelial dysfunction is an independent predictor of atherosclerosis progression and cardiovascular events in patients with ischemic heart disease. Ranolazine and trimetazidine are novel drugs that reduce angina symptoms in the above-mentioned patients. The aim of this study was to compare the effects of ranolazine and trimetazidine on flow-mediated (FMD) and nitroglycerine-induced (GTN) dilation of the brachial artery.

METHODS

In a prospective, double-blind study, 56 men between 32 and 65 years of age with chronic ischemic heart disease were randomized and subjected to 12 weeks of treatment with either trimetazidine (35 mg twice daily) or ranolazine. Ranolazine was administered at a dose of 375 mg twice daily for 4 weeks and was increased to 500 mg twice daily for the rest of the study. FMD and GTN were measured using high-resolution ultrasound before and after treatment.

RESULTS

FMD increased from 3.5±7.4 to 13.8±9.4% (P<0.013; 294%) in the trimetazidine group and from 2.4±4.3 to 9.5±7.7% (P<0.037; 296%) in the ranolazine group, with no difference between the groups (P=0.444). GTN increased from 16.1±9.2 to 21.2±19.3% (P<0.022; 32%) in the trimetazidine group and from 13.8±9.6 to 21.7±13.7% (P<0.006; 57%) in the ranolazine group, with no difference between the groups (P=0.309).

CONCLUSION

Both trimetazidine and ranolazine led to an improvement in FMD and GTN of the brachial artery in patients with ischemic heart disease, with no statistically significant difference between the groups.

Type III Hyperlipoproteinemia: Still Worth Considering?

Familial type III hyperlipoproteinemia (HLP) was first recognized as a distinct entity over 60 years ago. Since then, it has proven to be instructive in identifying the key role of apolipoprotein E (apoE) in removal of the remnants of very low density lipoproteins and chylomicrons produced by the action of lipoprotein lipase on these triglyceride-transporting lipoproteins. It has additionally shed light on the potent atherogenicity of the remnant lipoproteins. This review describes the history of development of our understanding of type III HLP, discusses the several genetic variants of apoE that play roles in the genesis of type III HLP, and describes the remarkable responsiveness of this fascinating disorder to lifestyle modification, especially carbohydrate restriction and calorie restriction, and, when required, the addition of pharmacotherapy.

Selective peroxisome proliferator-activated receptor α modulators (SPPARMα): the next generation of peroxisome proliferator-activated receptor α-agonists

Dyslipidemia is a major risk factor for cardiovascular (CV) disease – the primary cause of death, worldwide. Although reducing levels of low-density lipoprotein-cholesterol can significantly reduce CV risk, a high level of residual risk persists, especially in people with obesity-related conditions, such as metabolic syndrome and type 2 diabetes mellitus. Peroxisome proliferator-activated receptor alpha- (PPARα-) agonists (e.g. fibrates), play a central role in the reduction of macro- and microvascular risk in these patients. However, the currently available fibrates are weak (PPARα-agonists) with limited efficacy due to dose-related adverse effects. To address this problem, a new generation of highly potent and selective PPARα-modulators (SPPARMα) is being developed that separate the benefits of the PPARα-agonists from their unwanted side effects. Among these, aleglitazar (a dual PPARα/γ agonist) and GFT505 (a dual PPAR α/δ agonist) have recently entered late-phase development. Although both compounds are more potent PPARα-activators than fenofibrate in vitro, only aleglitezar is more effective in lowering triglycerides and raising high-density lipoprotein-cholesterol (HDL-C) in humans. However, it is also associated with a potential risk of adverse effects. More recently, a highly potent, specific PPARα-agonist (K-877) has emerged with SPPARMα characteristics. Compared to fenofibrate, K-877 has more potent PPARα-activating efficacy in vitro, greater effects on triglycerides- and HDL-C levels in humans, and a reduced risk of adverse effects. If successful, K-877 has the potential to supersede the fibrates as the treatment of choice for patients with residual CV risk associated with metabolic syndrome and type 2 diabetes.

A review of the role of apolipoprotein C-II in lipoprotein metabolism and cardiovascular disease

The focus of this review is on the role of apolipoprotein C-II (apoC-II) in lipoprotein metabolism and the potential effects on the risk of cardiovascular disease (CVD). We searched PubMed/Scopus for articles regarding apoC-II and its role in lipoprotein metabolism and the risk of CVD. Apolipoprotein C-II is a constituent of chylomicrons, very low-density lipoprotein, low-density lipoprotein, and high-density lipoprotein (HDL). Apolipoprotein C-II contains 3 amphipathic α-helices. The lipid-binding domain of apoC-II is located in the N-terminal, whereas the C-terminal helix of apoC-II is responsible for the interaction with lipoprotein lipase (LPL). At intermediate concentrations (approximately 4 mg/dL) and in normolipidemic subjects, apoC-II activates LPL. In contrast, both an excess and a deficiency of apoC-II are associated with reduced LPL activity and hypertriglyceridemia. Furthermore, excess apoC-II has been associated with increased triglyceride-rich particles and alterations in HDL particle distribution, factors that may increase the risk of CVD. However, there is not enough current evidence to clarify whether increased apoC-II causes hypertriglyceridemia or is an epiphenomenon reflecting hypertriglyceridemia. A number of pharmaceutical interventions, including statins, fibrates, ezetimibe, nicotinic acid, and orlistat, have been shown to reduce the increased apoC-II concentrations. An excess of apoC-II is associated with increased triglyceride-rich particles and alterations in HDL particle distribution. However, prospective trials are needed to assess if apoC-II is a CVD marker or a risk factor in high-risk patients.

Peroxisome proliferator-activated receptor-α activation promotes macrophage reverse cholesterol transport through a liver X receptor-dependent pathway

OBJECTIVE

Peroxisome proliferator-activated receptor-α (PPARα) activation has been shown in vitro to increase macrophage cholesterol efflux, the initial step in reverse cholesterol transport (RCT). However, it remains unclear whether PPARα activation promotes macrophage RCT in vivo.

METHODS AND RESULTS

We demonstrated that a specific potent PPARα agonist GW7647 inhibited atherosclerosis and promoted macrophage RCT in hypercholesterolemic mice expressing the human apolipoprotein A-I (apoA-I) gene. We compared the effect of GW7647 on RCT in human apoA-I transgenic (hA-ITg) mice with wild-type mice and showed that the PPARα agonist promoted RCT in hA-ITg mice to a much greater extent than in wild-type mice, indicating that human apoA-I expression is important for PPARα-induced RCT. We further investigated the dependence of the macrophage PPARα-liver X receptor (LXR) pathway on the promotion of RCT by GW7647. Primary murine macrophages lacking PPARα or LXR abolished the ability of GW7647 to promote RCT in hA-ITg mice. In concert, the PPARα agonist promoted cholesterol efflux and ATP binding cassette transporter A1/G1 expression in primary macrophages, and this was also by the PPARα-LXR pathway.

CONCLUSION

Our observations demonstrate that a potent PPARα agonist promotes macrophage RCT in vivo in a manner that is enhanced by human apoA-I expression and dependent on both macrophage PPARα and LXR expression.

Micronized fenofibrate: a useful choice for the correction of dyslipidemia in metabolic syndrome and Type 2 diabetes

Cardiovascular disease is the principal cause of illness and disability in patients with diabetes, and is also the most common cause of death worldwide in adults. Fenofibrate, a member of the fibrate class of lipid-modifying drugs, is a potent triglyceride-lowering and high-density lipoprotein cholesterol-raising agent and has a variable effect on low-density lipoprotein cholesterol. Fenofibrate administration also leads to a modified, less atherogenic low-density lipoprotein profile, with a consistent effect toward increased low-density lipoprotein particle size and a reduction in the low-density lipoprotein particle density. Maximal clinical efficacy in fibrates has been demonstrated in subjects with dyslipidemia, particularly in populations with features of the metabolic syndrome and in patients with Type 2 diabetes. Angiographic data from the Diabetes Atherosclerosis Intervention Study (DAIS) support a similar effect of fenofibrate. However, in the recent Fenofibrate Intervention and Event Lowering in Diabetes trial (FIELD; 9795 patients with Type 2 diabetes), the rate of nonfatal macrovascular events, after adjustment for the use of other lipid-lowering agents and significant reductions in microvascular complications, was lower for the fenofibrate treatment group. These results and those from a current large trial, ACtion to COntrol cardiovascular Risk in Diabetes (ACCORD), will provide valuable evidence for the likely future use of this drug in combination with statins for reducing cardiovascular disease risk in the metabolic syndrome and in Type 2 diabetes.

Fenofibrate Induces a Novel Degradation Pathway for Scavenger Receptor B-I Independent of PDZK1

Fibrate drugs improve cardiovascular health by lowering plasma triglycerides, normalize low density lipoprotein levels, and raise high density lipoprotein (HDL) levels in patients with dyslipidemias. The HDL-raising effect of fibrates has been shown to be due in part to an increase in human apolipoprotein AI gene expression. However, it has recently been shown that fibrates can affect HDL metabolism in mouse by significantly decreasing hepatic levels of the HDL receptor scavenger receptor B-I (SR-BI) and the PDZ domain containing protein PDZK1. PDZK1 is essential for maintaining hepatic SR-BI levels. Therefore, decreased SR-BI might be secondary to decreased PDZK1, but the mechanism by which fibrates lower SR-BI has not been elucidated. Here we show that feeding PDZK1-deficient mice fenofibrate resulted in the near absence of SR-BI in liver, definitively demonstrating that the effect of fenofibrate on SR-BI is PDZK1-independent. Metabolic labeling experiments in primary hepatocytes from fenofibrate-fed mice demonstrated that fenofibrate enhanced the degradation of SR-BI in a post-endoplasmic reticulum compartment. Moreover, fenofibrate-induced degradation of SR-BI was independent of the proteasome, calpain protease, or the lysosome, and antioxidants did not inhibit fenofibrate-induced degradation of SR-BI. Using metabolic labeling coupled with cell surface biotinylation assays, fenofibrate did not inhibit SR-BI trafficking to the plasma membrane. Together, the data support a model in which fenofibrate enhances the degradation of SR-BI in a post-ER, post-plasma membrane compartment. The further elucidation of this novel degradation pathway may provide new insights into the physiological and pathophysiological regulation of hepatic SR-BI.

Regulation of human apoA-I by gemfibrozil and fenofibrate through selective peroxisome proliferator-activated receptor alpha modulation

OBJECTIVE

The objective of this trial was to study the effects of fenofibrate (FF) and gemfibrozil (GF), the most commonly used fibrates, on high-density lipoprotein (HDL) and apolipoprotein (apo) A-I.

METHODS AND RESULTS

In a head-to-head double-blind clinical trial, both FF and GF decreased triglycerides and increased HDL cholesterol levels to a similar extent, whereas plasma apoA-I only increased after FF but not GF. Results in human (h) apoA-Itransgenic (hA-ITg) peroxisome proliferator-activated receptor (PPAR) alpha-/- mice demonstrated that PPARalpha mediates the effects of FF and GF on HDL in vivo. Although plasma and hepatic mRNA levels of hapoA-I increased more pronouncedly after FF than GF in hA-ITgPPARalpha+/+ mice, both fibrates induced acylCoAoxidase mRNA similarly. FF and GF transactivated PPARalpha with similar activity and affinity on a DR-1 PPAR response element, but maximal activation on the hapoA-I DR-2 PPAR response element was significantly lower for GF than for FF. Moreover, GF induced recruitment of the coactivator DRIP205 on the DR-2 site less efficiently than did FF.

CONCLUSIONS

Both GF and FF exert their effects on HDL through PPARalpha. Whereas FF behaves as a full agonist, GF appears to act as a partial agonist due to a differential recruitment of coactivators to the promoter. These observations provide an explanation for the differences in the activity of these fibrates on apoA-I.

Fenofibrate in the treatment of dyslipidemia: a review of the data as they relate to the new suprabioavailable tablet formulation

BACKGROUND

The fibric acid derivative fenofibrate is indicated as an adjunct to dietary modification in adults with primary hypercholesterolemia or mixed dyslipidemia (types IIa and IIb hyperlipidemia, Fredrickson classification) to reduce levels of low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), triglycerides (TG), and apolipoprotein (apo) B, and to increase levels of high-density lipoprotein cholesterol (HDL-C) and apo A. It is also indicated as adjunctive therapy to diet for the treatment of hypertriglyceridemia (types IV and V hyperlipidemia). Initially approved in the United States in a micronized capsule formulation, fenofibrate is now available in a new "suprabioavailable" tablet formulation that has increased bioavailability, achieving equivalent plasma concentrations at lower doses. The 67- and 200-mg micronized capsules can be considered equivalent to the 54- and 160-mg suprabioavailable tablets, respectively.

OBJECTIVE

This paper reviews the pharmacologic properties, clinical usefulness, and safety profile of fenofibrate in the management of dyslipidemias.

METHODS

Recent studies, abstracts, reviews, and consensus statements published in the English-language literature were identified through searches of MEDLINE (1966-January 2002), International Pharmaceutical Abstracts (1970-January 2002), and PharmaProjects (1990-January 2002) using the search terms fenofibrate, fibrates, hyperlipidemia, hypertriglyceridemia, and dyslipidemia.

RESULTS

Fenofibrate is well absorbed after oral administration, with peak plasma levels attained in 6 to 8 hours. The absolute bioavailability of fenofibrate cannot be determined due to its being virtually insoluble in aqueous media suitable for injection; however, after oral administration of a single dose of radiolabeled fenofibrate, approximately 60% of the dose appeared in urine, primarily as fenofibric acid and its glucuronated conjugate, and approximately 25% was excreted in the feces. The apparent volume of distribution is 0.89 L/kg in healthy volunteers, and protein binding is approximately 99% in healthy and hyperlipidemic patients. Neither fenofibrate nor fenofibric acid appears to undergo significant oxidative metabolism in vivo. Fenofibric acid has a half-life of 20 hours. Fenofibrate is effective in lowering TG levels and increasing HDL-C levels. Its LDL-C-lowering effect is greater than that of gemfibrozil. Adverse effects of fenofibrate appear to be similar to those of other fibrates, including gastrointestinal symptoms, cholelithiasis, hepatitis, myositis, and rash. Fenofibrate therapy has been associated with increases in serum aminotransferase levels, and clinical monitoring of these markers of liver function should be performed regularly.

CONCLUSIONS

Fenofibrate is effective in reducing levels of TG, TC, and LDL-C, and increasing levels of HDL-C in patients with dyslipidemias. Its efficacy and tolerability in the treatment of hypertriglyceridemia and combined hyperlipidemia have been demonstrated in numerous clinical trials. Its use is accompanied by a low incidence of adverse effects and laboratory abnormalities. Fenofibrate protects against coronary heart disease not only through its effects on lipid parameters but also by producing alterations in LDL structure and, possibly, alterations in the various hemostatic parameters. Its uricosuric property may prove to be a useful adjunctive attribute.

Long term efficacy and safety of atorvastatin in the treatment of severe type III and combined dyslipidaemia

BACKGROUND

Fibric acid derivatives and HMG-CoA reductase inhibitors are effective in combination for treating patients with familial dysbetalipoproteinaemia and severe combined dyslipidaemia, but combination therapy affects compliance and increases the risk of side effects.

AIM

To evaluate the efficacy and safety of monotherapy with atorvastatin, an HMG-CoA reductase inhibitor with superior efficacy in lowering low density lipoprotein cholesterol and triglyceride concentrations, in patients with dysbetalipoproteinaemia and severe combined dyslipidaemia.

METHODS

Atorvastatin was tested as single drug treatment in 36 patients with familial dysbetalipoproteinaemia and 23 patients with severe combined dyslipidaemia.

RESULTS

After 40 weeks of 40 mg atorvastatin treatment decreases in total cholesterol, triglycerides, and apolipoprotein B of 40%, 43%, and 41%, respectively, were observed in the combined dyslipidaemia group, and of 46%, 40%, and 43% in the dysbetalipoproteinaemic patients. Target concentrations of total cholesterol (< 5 mmol/l) were reached by 63% of the patients, and target concentrations of triglycerides (< 3.0 mmol/l) by 66%. Treatment with atorvastatin was well tolerated and no serious side effects were reported.

CONCLUSIONS

Atorvastatin is very effective as monotherapy in the treatment of familial dysbetalipoproteinaemia and severe combined dyslipidaemia.

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.

Comparison of the hypolipidemic effect of gemfibrozil versus simvastatin in patients with type III hyperlipoproteinemia

BACKGROUND

Type III hyperlipoproteinemia is characterized by the accumulation of chylomicron and very low density lipoprotein (VLDL) remnants. Individuals with this disorder have a high risk of premature atherosclerosis, and hypolipidemic drugs are useful in their management.

METHODS

We compared, in a double-blind, placebo-controlled, randomized crossed study, the effects of gemfibrozil (1200 mg/day) and simvastatin (20 mg/day) on lipids, apolipoprotein AI, apolipoprotein B, and apolipoprotein E and on lipids and apolipoprotein B content in VLDL, intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) in 10 patients with type III hyperlipoproteinemia.

RESULTS

Levels of total cholesterol, VLDL cholesterol, IDL cholesterol, and apolipoprotein B decreased with both drugs. Larger reductions in triglycerides (109 +/- 28.2 mg/dL, P =.005), VLDL cholesterol (24.7 +/- 10.9 mg/dL, P =.05), and VLDL triglycerides (86.3 +/- 20.2 mg/dL, P =.003) were obtained with gemfibrozil compared with simvastatin. LDL cholesterol reduction was more effective with simvastatin than with gemfibrozil (44.3 +/- 17.1 mg/dL, P =.03). HDL cholesterol after gemfibrozil was 5.71 +/- 2.37 mg/dL higher than after simvastatin.

CONCLUSIONS

In patients with type III hyperlipoproteinemia gemfibrozil is more effective in reducing total triglyceride and VLDL lipid levels than simvastatin, and simvastatin is better in reducing LDL cholesterol than gemfibrozil is. IDL and apolipoprotein E levels were reduced similarly with both drugs.

Severe xanthomatosis associated with familial apolipoprotein E deficiency

AIM

To present the clinical, dermatological, and histological features of a patient with generalised xanthomatosis, familial apolipoprotein (apo) E deficiency, and unusual type III hyperlipoproteinaemia (HLP).

METHODS

The underlying molecular defect was disclosed using molecular biological techniques. The unusual xanthomas were histologically analysed and the morphology of the abnormal lipoprotein particles examined using electron microscopy.

RESULTS

A 10 base pair deletion in exon 4 of the proband's apo epsilon gene (base pairs 4037-4046 coding for amino acids 209-212 of the mature protein) was identified. This is predictive for a reading frameshift encoding a premature stop (TGA) in codon 229. The mutation is responsible for delayed catabolism of atherogenic lipoprotein remnants, lipid storage in monocyte/macrophages, and phenotypic expression of xanthomatosis early in life.

CONCLUSIONS

Familial apo E deficiency is a rare genetic disease which offers the unique opportunity to study the impact of apo E on lipoprotein metabolism and development of atherosclerosis in humans.

Role of Lp A-I and Lp A-I/A-II in cholesteryl ester transfer protein-mediated neutral lipid transfer. Studies in normal subjects and in hypertriglyceridemic patients before and after fenofibrate therapy

The two major subclasses of HDL contain apo A-I only (Lp A-I) or both apo A-I and apo A-II (Lp A-I/A-II). We have carried out experiments to quantify the participation of Lp A-I and Lp A-I/A-II in the neutral lipid transfer reaction in normal and hypertriglyceridemic subjects. Thirteen hypertriglyceridemic subjects were studied before and after fenofibrate therapy. Fenofibrate treatment resulted in decreases in total cholesterol, triglycerides (TG), and VLDL cholesterol of 19%, 48%, and 70%, respectively, and a 28% increase in HDL cholesterol, with no significant change in the proportion of Lp A-I and Lp A-I/A-II particles. The abundance of cholesteryl ester transfer protein (CETP) mRNA in peripheral adipose tissue decreased with treatment in four of five patients studied; however, no change occurred in plasma CETP mass. Using an isotopic transfer assay, we demonstrated that both Lp A-I and Lp A-I/A-II participated in the CE transfer reaction, with no change after fenofibrate therapy. This finding suggests that the marked increase in HDL cholesterol during fenofibrate therapy is due to normalization of plasma TG and hence decreased opportunity for mass transfer of lipid between HDL and TG-rich proteins in vivo. In this population of hypertriglyceridemic subjects, CETP was distributed in both the Lp A-I and Lp A-I/A-II subfractions of HDL, with preferential association with the smaller Lp A-I poor. In contrast, in nine normal subjects studied, negligible amounts of CETP were associated with Lp A-I/A-II. Nonetheless, the Lp A-I/A-II fraction of HDL contributed significantly to total CE mass transfer in normolipidemic plasma. Lp A-I/A-II is an efficient donor for CE transfer to TG-rich lipoproteins, and its low affinity for CETP may in fact facilitate neutral lipid transfer either by a shuttle mechanism or by formation of a ternary complex.

The effects of fibrates on lipoprotein and hemostatic coronary risk factors

The effects of fibrates on lipoprotein profiles and lipoprotein physiology, as well as on selected coagulation and fibrinolytic factors are reviewed. It is concluded that the action of fibrates on these systems is such as to render the fibrates beneficial in atherosclerosis prevention.

Comparative effects of gemfibrozil and clofibrate in type III hyperlipoproteinemia

Type III hyperlipoproteinemia (dysbetalipoproteinemia) is characterized by elevated concentrations of plasma cholesterol and triglycerides due to an increase in very low density lipoprotein (VLDL) remnant lipoproteins. In a retrospective analysis we observed that in 12 patients with this disorder, gemfibrozil reduced concentrations of total cholesterol, VLDL cholesterol and triglycerides by 48%, 72% and 68%, respectively. These changes were greater than those reported in a similar number of patients treated with clofibrate. Comparative data on the efficacy of different fibrates in this disorder are very limited; to assess this further we have compared the hypolipidemic effects of gemfibrozil (600 mg twice daily) and clofibrate (1 g twice daily) in six patients with well-characterized type III hyperlipoproteinemia. Baseline values were obtained after at least 8 weeks on diet and treatment values were obtained after 6 and 8 weeks of treatment with each drug. Treatment with clofibrate and gemfibrozil both resulted in significant reductions in the plasma concentrations of total cholesterol (40% and 54%), VLDL cholesterol (59% and 79%) and total triglycerides (48% and 70%), as well as a significant increase in HDL cholesterol (9% and 7%). Gemfibrozil was, however, significantly (P < 0.05) more effective in reducing plasma concentrations of total cholesterol, VLDL cholesterol and triglycerides than was clofibrate, in the same patients.

Rare apolipoprotein E variant identified in a patient with type III hyperlipidaemia

We report a rare apolipoprotein E variant in an Irish female with Type III hyperlipidaemia who has the phenotype E2E1 as determined by isoelectric focusing. Sequence analysis of the apolipoprotein E gene from the proband and from four other family members, using DNA amplified by the polymerase chain reaction, demonstrated the presence of a point mutation in the common epsilon 2 allele with a G-->A transition at nucleotide 3791. This was confirmed by digestion with the restriction endonuclease TaqI, which cuts at a new site within the apolipoprotein E gene, created by the base change. This mutation results in a substitution of aspartic acid for glycine at position 127 of the mature protein. We believe this to be the first description of this apolipoprotein E variant in a family from the British Isles. The mutation appears to be 'recessive' with respect to the expression of Type III hyperlipidaemia, although it may be somewhat more potent in this regard than the parent epsilon 2 allele. The Type III hyperlipidaemia is responsive to treatment with diet and gemfibrozil.

Relation of arteriographically defined coronary artery disease to serum lipoprotein particles mapped with monoclonal antibodies

BACKGROUND

This study was designed to investigate the relation of a molecular analysis of apolipoprotein B (apoB)-containing atherogenic lipoprotein particles to coronary artery disease (CAD) in middle-aged men.

METHODS AND RESULTS

Two groups of men were studied. The first consisted of 97 patients with angiographically documented CAD (greater than 50% stenosis of at least one coronary artery). The second group consisted of 145 subjects without symptomatic CAD, who served as controls. In both groups, measurements were obtained for total cholesterol level, triglyceride level, cholesterol contents in apoB- and nonapoB-containing particles (LpB, LpnonB), total apoB and apolipoprotein AI (apoAI levels), lipoprotein particles recognized by monoclonal antibodies anti-apoB (LpBL3, LpBL5, LpBL7) and anti-apoAI (LpAI-2GII). Taking into account age, body mass index, hypertension, diabetes, smoking habits, and drug consumption, the analysis showed that the mean levels of cholesterol were identical in both groups but differed when cholesterol content in LpB and LpnonB subfractions were assessed, thus reflecting an increase in the low density fraction and a decrease in the high density fraction, respectively. This was confirmed by an increase in total apoB and a decrease in total apoAI. Measurements of LpBL3, LpBL5, LpBL7, and LpAI-2GII particles also discriminated between the two groups. After adjustment for cholesterol content in LpnonB particles, a difference in total apoB was no longer significant between groups, whereas LpBL3, LpBL5, and LpBL7 levels remained significantly higher in CAD patients.

CONCLUSIONS

The measurement of separate concentrations of apoB in different particles may permit a more-accurate assessment of CAD risk than measurements of total apoB levels.

Type III hyperlipoproteinemia in a child with hemolytic uremic syndrome

The case of a 6-year-old girl with severe hyperlipoproteinemia and chronic renal failure that developed after hemolytic uremic syndrome (HUS) is reported. The patient was homozygous for apolipoprotein (apo) E2, and her very-low-density lipoprotein (VLDL)-cholesterol/serum-triglyceride (TG) ratio of 0.63 was unusually high. She was consistently diagnosed to have type III hyperlipoproteinemia (HLP). This is the first report of type III HLP in a child with chronic renal disease.

Fenofibrate. A review of its pharmacodynamic and pharmacokinetic properties and therapeutic use in dyslipidaemia

Fenofibrate is a lipid-regulating drug which is structurally related to other fibric acid derivatives, such as clofibrate. At the recommended dosage of 200 to 400 mg daily, it produces substantial reductions in plasma triglyceride levels in hypertriglyceridaemic patients and in plasma total cholesterol levels in hypercholesterolaemic patients. High density lipoprotein (HDL)-cholesterol levels are generally increased in patients with low pretreatment values. Fenofibrate appears to be equally effective in diabetic patients with hyperlipoproteinaemia without adversely affecting glycaemic control. The influence of fenofibrate on the plasma lipid profile is sustained during long term (2 to 7 years) treatment. Comparative studies conducted to date have involved only small groups of patients--in overall terms fenofibrate was at least as effective as other fibrates, but larger comparative studies are needed before valid conclusions on its relative efficacy compared with nonfibrate lipid-lowering drugs can be drawn. The influence of fenofibrate on morbidity and mortality from cardiovascular disease has not been studied. Clinical adverse reactions to fenofibrate have mainly consisted of gastrointestinal disturbances, headache and muscle cramps. Transient elevations in transaminase and creatine phosphokinase levels commonly occur. Isolated cases of hepatitis with substantially elevated transaminase levels have been reported. Fenofibrate induces hepatomegaly, peroxisome proliferation and hepatic carcinomas in rodents, but this type of hepatotoxicity has not been observed in humans. The biliary lithogenic index is increased by fenofibrate, but this has not been shown to have increased the incidence of gallstones in treated patients. Thus, fenofibrate offers an effective and well tolerated alternative to clofibrate or other fibric acid derivatives, but its relative efficacy and tolerability compared with other types of lipid-lowering drugs, and its effect on cardiovascular morbidity and mortality, remain to be clarified.

The hypolipidemic effects of lovastatin and clofibrate alone and in combination in patients with type III hyperlipoproteinemia

The hypolipidemic effects of lovastatin and clofibrate have been evaluated in 12 patients with type III hyperlipoproteinemia. In these patients plasma concentrations of total cholesterol decreased from 500 +/- 56 mg/dL (mean +/- SEM) at baseline to 278 +/- 23 mg/dL on lovastatin (20 mg twice daily), and were 299 +/- 15 mg/dL during treatment with clofibrate (1 g twice daily). Nine patients were treated sequentially with lovastatin at doses of 20 and 40 mg twice daily and clofibrate; in these patients total plasma cholesterol concentrations decreased from 549 +/- 67 mg/dL at baseline to 291 +/- 24 mg/dL on lovastatin (20 mg twice daily), 247 +/- 20 mg/dL (40 mg twice daily) and were 297 +/- 18 mg/dL on monotherapy with clofibrate. Concentrations of very-low-density lipoprotein (VLDL) cholesterol were similar on clofibrate and the higher dose of lovastatin, whereas concentrations of low-density lipoprotein (LDL) cholesterol were significantly lower on lovastatin. In six patients who remained hyperlipidemic on monotherapy with either drug, combination drug therapy with lovastatin (20 mg twice daily) plus clofibrate reduced plasma concentrations of total cholesterol from 635 +/- 79 mg/dL to 205 +/- 11 mg/dL. No patients were discontinued from single or combined drug therapy and no significant biochemical abnormalities were observed. The results of this study demonstrate the potential usefulness of lovastatin in the therapy of type III hyperlipoproteinemia and indicate that, in selected patients who remain hypercholesterolemic on monotherapy with either clofibrate or lovastatin, combination drug therapy with both of these drugs is effective in further reducing plasma concentrations of total, VLDL, and LDL cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipoprotein composition changes induced by fenofibrate in dysbetalipoproteinemia type III

Fenofibrate (300 mg daily) was given to 9 subjects (7 men, 2 women) with dysbetalipoproteinemia type III. The treatment brought about important plasma level reductions in cholesterol (-35%), triglycerides (-56%), VLDL-cholesterol (-63%) and VLDL-triglycerides (-59%). The VLDL-C/TG ratio, which was 0.40 before treatment, was 0.30 after 4 weeks of fenofibrate, still suggestive of type III. LDL-C, when measured by conventional methods, was unchanged but isolation of the IDL (1.006-1.019 g/ml) fraction from the 1.006 g/ml infranatant revealed that true LDL-C levels actually increased in 6 individuals while IDL-C decreased considerably. The total HDL-C increase was mostly due to a 33% HDL3-C change. Apolipoprotein levels were considerably modified, notably apo B, C-III and E which were decreased, as well as the lipoprotein particles containing combinations of these apolipoproteins, namely LpE:B and LpC-III:B. Apo A-I was slightly modified as LpA-I: A-II particle levels increased and LpA-I decreased. There were marked compositional modifications of apo B-containing lipoproteins which corresponded to changes of the whole lipoprotein profile. Some abnormal classes of lipoproteins (e.g., beta-VLDL, dense LDL), characteristic of this disease, tended to disappear and were in some cases replaced by material of different size and density.

Potential use of fenofibrate and other fibric acid derivatives in the clinic

The fibric acid derivatives continue to have a place in the treatment of hyperlipidemia. The third generation of these drugs, including fenofibrate, appears to offer some advantages over those currently available in the United States. These drugs should be prescribed only after dietary and lifestyle changes have been offered as the preferable treatment. In severe hypertriglyceridemia, clofibrate, gemfibrozil, or fenofibrate may reduce the very low-density lipoprotein and chylomicron levels adequately. Dysbetalipoproteinemia may also be completely controlled by a combination of diet and any one of these drugs. When the low-density lipoprotein level is elevated, the newer fibric acid derivatives, such as fenofibrate, may be more effective in lowering the plasma cholesterol levels. This is true for those patients with elevated low-density lipoprotein and normal very low-density lipoprotein triglyceride levels, as well as those with elevated very low-density lipoprotein triglyceride levels. A 20 percent reduction in low-density lipoprotein cholesterol levels is expected when the triglyceride levels are not elevated. When the very low-density lipoprotein triglyceride levels are elevated, the low-density lipoprotein response is more variable, and on occasion the low-density lipoprotein cholesterol level may rise as the very low-density lipoprotein level is reduced. The average reduction in low-density lipoprotein cholesterol levels (about 6 percent) caused by fenofibrate may be greater in patients with elevated very low-density lipoprotein triglyceride levels than by other fibrates. In combination with other agents that lower low-density lipoprotein levels more specifically, such as the bile acid sequestrants and hydroxymethylglutaryl coenzyme A reductase inhibitors, fenofibrate may act to effect control of the triglycerides allowing management of those patients with disorders producing elevated very low-density lipoprotein and low-density lipoprotein levels. Extensive European experience with fenofibrate (six million patient-years) indicates that severe side effects are unlikely. However, the physician should monitor patients for skin rash, liver and renal function abnormalities, gastrointestinal dysfunction, and generalized muscle tenderness. All of these usually appear very early in the course of treatment and are reversible. Of greater concern is the possibility of an increased incidence of cholelithiasis, since the bile becomes relatively enriched in cholesterol during therapy with any fibric acid derivative.(ABSTRACT TRUNCATED AT 400 WORDS)