Lochol Drug Interactions

Simvastatin may interact with: CYP3A4: Simvastatin has no CYP3A4 inhibitory activity; therefore it is no expected to affect plasma levels of other drugs metabolized by CYP3A4. However, simvastatin itself is a substrate for CYP3A4. Potent inhibitors of CYP3A4 may increase the risk of myopathy by increasing the plasma level of HMG-CoA reductase inhibitory activity during simvastatin therapy. These include cyclosporin, itraconazole, ketoconazole, erythromycin, clarithromycin, HIV protease inhibitors and nefazodone.
Gemfibrozil and other fibrates, niacin (lipid-lowering dose ≥1 gram/day: These drugs increase the risk of myopathy when given concomitantly with simvastatin, probably because they can produce myopathy when given alone.
Propranolol: Decrease in antihyperlipidemic activity may occur.
Warfarin: Anticoagulant effect of warfarin may be increased; therefore, prothrombin time should be determined before starting simvastatin and frequently enough during early therapy to ensure that no significant alteration of prothrombin time occurs.