In the plasma of rats, YM-53601 inhibits cholesterol biosynthesis from acetate in a dose-dependent manner. YM-53601 inhibits both FFA and triglyceride biosynthesis in rats treated with cholestyramine over the same dose range at which it inhibits cholesterol biosynthesis. Through a single oral administration, YM-53601 reduces the increase in plasma triglyceride levels of hamsters induced by protamine sulfate injection, thereby inhibiting lipoprotein lipase (LPL), thereby increasing plasma very low density lipoprotein (VLDL) Triglyceride levels. YM-53601 can also reduce plasma triglyceride and cholesterol levels in hamsters treated with Triton WR1339, which also inhibits the degradation of VLDL. Plasma cholesterol was significantly decreased as soon as 1 h after single administration of YM-53601 in hamsters fed a normal diet.