Fenofibrate treatment inhibits HMG-CoA reductase activity in mononuclear cells from hyperlipoproteinemic patients

The effect of fenofibrate treatment on serum cholesterol levels was studied in relation to the activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase in mononuclear cells from patients with hyperlipoproteinemia type IIa and IIb. When patients who had received fenofibrate (300 mg/day) for at least 8 weeks were given placebo during a subsequent 2-months period, both serum cholesterol concentration and mononuclear cell HMGR increased significantly in both types IIa and IIb. After reinstitution of fenofibrate treatment both parameters gradually declined and returned close to the initial level after another 28 weeks. It is concluded that a part of the lipid-lowering action of fenofibrate may be due to an inhibition of cholesterol synthesis.