Hemostatic effects of atorvastatin versus simvastatin

OBJECTIVE: To compare the effects of simvastatin and atorvastatin on hemostatic parameters. METHODS: Sixty-one patients with primary hypercholesterolemia without coronary heart disease were treated with atorvastatin 10-20 mg/d or simvastatin 10-20 mg/d. At baseline, 4, 12, and 24 weeks, lipid levels such as low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), very-low-density lipoprotein cholesterol (VLDL-C), triglycerides (TGs), and hemostatic parameters such as platelet counts, partial thromboplastin time (PTT) prothrombin time (PT), and fibrinogen levels were measured. RESULTS: At 12 weeks, the doses of the statins were increased to 20 mg/d in 10 of 35 (28.5%) patients treated with atorvastatin and 18 of 26 (69.2%) patients treated with simvastatin when the target level of LDL-C (130 mg/dL) was not reached. Mean doses were atorvastatin 12.8 mg/d and simvastatin 16.9 mg/d. After 24 weeks, 5 patients (14.3%) in the atorvastatin group and 4 patients (15.3%) in the simvastatin group had not reached the goal. In patients with diabetes, target level (LDL-C <100 mg/dL) was not reached in 35.7% of patients in the atorvastatin group and 44.4% of patients in the simvastatin group. Both simvastatin and atorvastatin were effective in lowering TC and LDL-C levels (p < 0.001). Atorvastatin lowered TGs significantly (p < 0.01). Neither atorvastatin nor simvastatin significantly reduced VLDL-C levels. HDL-C levels increased with atorvastatin, but there was no significant difference between the 2 groups. Platelet counts decreased with both statins nonsignificantly. Moreover, fibrinogen levels decreased with simvastatin and atorvastatin, but these reductions were significant only for simvastatin (p < 0.05). We detected prolongation of the PT with both drugs (p < 0.05); however, prolongation of the PTT was significant only with simvastatin (p < 0.001). Effectiveness of both statins on lipid and hemostatic parameters was dose related. Adverse effects were seen in 5 patients (14.2%) treated with atorvastatin and 3 patients (11.5%) treated with simvastatin. Elevations in serum transaminase levels >3 times the upper limit of normal and in creatine phosphokinase >5 times the upper limit of normal were not observed in any group. CONCLUSIONS: Atorvastatin was more effective than simvastatin on lipid parameters, although statistically insignificantly, while simvastatin produced more significant changes than atorvastatin on hemostatic parameters. The mean dose of simvastatin was greater than that of atorvastatin. Both statins had increased effects on lipid and hemostatic parameters when doses were increased. Atorvastatin and simvastatin were well tolerated. Different effects of statins on lipid levels and on coagulation parameters should be considered in patients with hypercholesterolemia and tendency to coagulation, especially in preventing thrombotic events. Further studies in larger trials are needed to confirm these observations.