Statins and Grapefruit
Grapefruit juice consumption may interfere with statin metabolism in the body, therefore dramatically increasing side effects. Taking simvastatin (Zocor) and even modest quantities of grapefruit juice may significantly increase exposure to this statin drug and cause serious myopathy. Patients taking lovastatin (Mevacor) or atorvastatin (Lipitor) should also avoid drinking grapefruit juice. Fluvastatin (Lescol) and grapefruit consumption, does not seem to be affected by the same problem, because it is metabolized by a different cytochrome P450 enzyme. Pravastatin (Pravachol) and rosuvastatin (Crestor) are also are not substantially metabolised by cytochrome P450, and therefore, their metabolism is not affected by grapefruit juice. In summary, you should avoid consuming grapefruit products if you are taking simvastatin (Zocor), atorvastatin (Lipitor), or lovastatin (Mevacor). On the other hand, if you are taking Fluvastatin (Lescol), (Pravachol) or rosuvastatin (Crestor) it is probably safe to consume grapefruit products but it is recommended to avoid it a few hours before or after taking your medication, just to be safe.
Other Statin Drug Interactions
Statins interact with a number of drugs. The risk of muscle toxicity increases when statins are used in conjunction with immunosuppressants such as ciclosporin, fibrates such as gemfibrozil or nicotinic acid such as niacin. Using statins concomitantly with any lipid lowering drug should be undertaken with caution and supervised by a specialist.
Some statins, particularly atorvastatin (Lipitor) and simvastatin (Zocor), are metabolized by an enzyme called CYP3A4. Using statins concomitantly with potent inhibitors of this type enzyme, (e.g. azole antifungal agents and HIV protease inhibitors), may cause an increase in plasma levels of those statins, thus increasing the risk of side-effects such as rhabdomyolysis (muscle damage). The risk of serious myopathy (muscular disease) is increased, when high doses of simvastatin (Zocor) are used, with less potent inhibitors of the CYP3A4 enzyme. Examples of those less potent inhibitors include amiodarone, verapamil and diltiazem.
Statin Contraindications
In medicine, a contraindication (pronounced as contra-indication) is a condition or factor that increases the risks involved in using a particular drug, carrying out a medical procedure, or engaging in a particular activity.
Statins are contraindicated in individuals with active liver disease or abnormal liver function tests, because statins affect the liver function. Statins should also be used with caution in patients with a history of high alcohol intake or liver disease. In these situations, liver function tests should be carried out before prescribing the medications and every 1-3 months after starting the treatment. Follow up liver function tests are recommended every 6 months to 1 year. Tests should be carried out sooner, if signs or symptoms suggestive of liver toxicity are noted.
Statins are also contraindicated in pregnant and breast-feeding females. Consultation with a qualified licensed physician or local treatment center before pursuing any course of treatment is advised.
Untreated hypothyroidism may also increase the risk of myositis (inflammation of skeletal muscles) when used with lipid-regulating drugs. Again, consultation with a physician is advised for this scenario.
