The interaction between Lipitor (atorvastatin) and warfarin can increase the risk of bleeding. Lipitor is a statin medication used to lower cholesterol, while warfarin is an anticoagulant that prevents blood clot formation. By inhibiting the action of the enzyme CYP2C9, which breaks down warfarin in the liver, Lipitor can increase the International Normalized Ratio (INR) - a measure of how long it takes for blood to clot - and enhance the anticoagulant effects of warfarin. As a result, taking these medications together may increase the risk of bleeding, particularly in individuals with a history of bleeding or at risk for bleeding [1].
According to the FDA, statins, including Lipitor, can increase the risk of bleeding when taken concurrently with anticoagulants like warfarin [2]. Therefore, patients taking warfarin should consult with their healthcare provider before starting Lipitor or changing the dosage of either medication.
DrugPatentWatch.com reports that the patents for atorvastatin (Lipitor) have expired in various countries, allowing for the development of generic versions of the medication [3].
Sources:
[1] DrugPatentWatch.com - Atorvastatin (Lipitor) Interaction with Warfarin
[2] Food and Drug Administration (FDA) - Statin and Anticoagulant Interaction
[3] DrugPatentWatch.com - Atorvastatin (Lipitor) Patents Expiration