Effects of HR780, a novel 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, in Watanabe heritable hyperlipidemic rabbits and cholesterol-fed rabbits

The aim of this study was to evaluate the effects of (+)-(E)-6S-(2-(4-(4-fluorophenyl)-2-(1-methylethyl)-6-phenylpyridin-3-yl)ethenyl)-4R-hydroxy-3,4,5,6-tetrahydro-2H-pyran-2-one (HR780), a novel 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, on hypercholesterolemia in Watanabe heritable hyperlipidemic (WHHL) rabbits and rabbits fed a diet with 1% Cholesterol, in comparison with the effects of simvastatin. Each drug was administered orally to WHHL rabbits for 24 weeks and to 1% cholesterol-fed rabbits for 10 weeks. In WHHL rabbits, HR780 at doses of 1, 2.5 and 5 mg/kg/day reduced the plasma total Cholesterol level by 15, 24 and 20%, respectively. In contrast, simvastatin at 5 mg/kg/day lowered the level by 23%. In 1% cholesterol-fed rabbits, HR780 (1 and 2.5 mg/kg/day) was found to inhibit the increases in the plasma total Cholesterol and phospholipid levels and liver Cholesterol contents in a dose-dependent manner. Simvastatin (5 mg/kg/day) also inhibited their increase. Neither HR780 nor simvastatin increased the contents of Cholesterol and total bile acid in the gallbladder bile. In conclusion, long-term treatment with HR780 reduced the plasma Cholesterol level in WHHL rabbits and 1% cholesterol-fed rabbits, and decreased the liver Cholesterol contents in 1% cholesterol-fed rabbits.