A review of clinical trials comparing HMG-CoA reductase inhibitors

Abstract

Four drugs that act as specific inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase--lovastatin, pravastatin, simvastatin, and, most recently, fluvastatin--have been approved by regulatory authorities throughout the world. In the present review, we have critically assessed the comparative hypocholesterolemic effects of these four drugs based on direct comparative studies, which were randomized, double-blind, and included more than 25 patients per treatment group. All studies were conducted in patients with primary hypercholesterolemia and the major end point of efficacy was reduction in the plasma concentrations of low-density lipoprotein (LDL)-cholesterol. Eight comparative trials have evaluated the efficacy and safety of lovastatin, simvastatin, or pravastatin, and one recently completed trial has compared lovastatin and fluvastatin. These trials confirm the log-linear dose response curves for all four of these drugs but indicate that on a milligram-for-milligram basis, lovastatin and pravastatin are approximately equipotent, whereas simvastatin is at least twice as effective per milligram of drug administered as lovastatin and pravastatin. Lovastatin at doses of 20 and 40 mg/d was of similar efficacy to fluvastatin at doses of 40 and 80 mg/d and would suggest that on a milligram-for-milligram basis, fluvastatin is half as potent as lovastatin. The side-effect profiles of all four drugs appeared similar, and earlier reports that suggested a higher incidence of sleep disorders in patients treated with the more lipophilic drugs, lovastatin and simvastatin, as compared with pravastatin, are not supported by more recent, controlled clinical trials. We conclude that although the currently available HMG-CoA reductase inhibitors differ in their relative hypolipidemic effects, as a class they constitute the most effective agents available to maximally reduce elevated concentrations of LDL-cholesterol.