The most serious consequence of drug interactions with Atorvastatin and other statins is the development of myopathy and rhabdomyolysis. Drugs that can cause myopathy when given alone increase the risk of myopathy with all statins: These drugs include fibric acid derivatives (fibrates or gemfibrozil), and nicotinic acid. Atorvastatin is metabolized by cytochrome P450 isoenzyme CYP3A4, as are simvastatin and lovastatin, and interactions may occur with drugs that inhibit this enzyme, including ciclosporin, itraconazole, ketoconazole, erythromycin, clarithromycin, HIV-protease inhibitors, nefazodone, amiodarone, and verapamil; there may also be similar interaction with grapefruit juice.