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, hyper-lipidernia, 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, similar to60% of the dose appeared in urine, primarily as fenofibric acid and its glucuronated conjugate, and similar to25% was excreted in the feces. The apparent volume of distribution is 0.89 L/kg in healthy volunteers, and protein binding is similar to99% 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 hyper-triglyceridemia 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.