THE EFFECT OF TWO CHOLESTEROL-LOWERING AGENTS ON PLATELETS IN PATIENTS WITH HYPERCHOLESTEROLEMIA

Twenty-one subjects with type Ila hyperlipoproteinemia, receiving dietary treatment were given Synvinolin (MK-733), a HMG-CoA reductase inhibitor, 40 mg or Cholestyramin (Questran) 24 g daily for a period of 12 weeks.Serum lipids, platelet cholesterol, phospholipids and fatty acid composition and platelet function were measured before and after the intake of the two drugs.

Both drugs reduced serum total cholesterol with approximately 50%. No significant changes were observed in platelet lipid concentrations or in the primary bleeding time. Collagen induced aggregation and thromboxane (TXA₂) production were reduced, whereas thrombin induced aggregation and TXA₂ production were unaffected. This study shows that both a cholesterol synthetase inhibitor and Cholestyramin reduce the total serum cholesterol concentration and also reduce platelet aggregation and thromboxane synthesis without changing the platelet cholesterol content or the cholesterol/phospholipid ratio. The effect on serum lipids and platelet function may indicate a beneficial effect of both drugs on arterial disease in patients with hypercholesterolemia.