Antioxidant effects of simvastatin in primary and secondary prevention of coronary heart disease

Objective: The aim of the present study was to determine the effect of simvastatin on the levels of oxidized low-density lipoprotein (ox-LDL) and free radicals in hypercholesterolemic subjects undergoing primary and secondary prevention of coronary heart disease (CHD). Methods: Fifteen subjects with hypercholesterolemia and no obvious CHD and 29 subjects with hypercholesterolemia and stable angina received 40 mg of simvastatin daily for 12 weeks. Serum total cholesterol, HDL-cholesterol and triglyceride concentrations were determined by automated enzymatic assays whereas LDL-cholesterol was calculated using the Friedwald formula. The ox-LDL levels were determined by a commercially available ELISA kit. Free radicals were assessed by the Free Radical Analytical System (FRAS). Results: Both in primary and secondary prevention, subjects had borderline levels of free radicals but in neither group there was a significant reduction of free radicals after simvastatin treatment. In subjects undergoing primary prevention of CHD, ox-LDL levels were reduced by 31.1 +/- 5.0% (P < 0.001) whereas in secondary prevention were reduced by 6.5 +/- 5.2% (P < 0.02) after simvastatin treatment. The reduction of ox-LDL levels did not correlate with the reduction of total cholesterol levels in either group studied. In both groups, ox-LDL levels were not associated with free radical levels either before or after simvastatin treatment. Conclusion: This study demonstrates that simvastatin can significantly reduce circulating ox-LDL levels both in subjects undergoing primary and secondary prevention of CHD. These results could partly explain the slowing down of the progression of atherosclerosis caused by HMG-CoA reductase inhibitors.