Drug General Information (ID: DDI02Y3TOK)
Drug Name			Warfarin		Drug Info		Gemfibrozil		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Anticoagulants				Antihyperammonia Agents
Structure

Mechanism of Warfarin-Gemfibrozil Interaction (Severity Level: Major)
Competitive binding of plasma proteins Click to Show/Hide Mechanism Graph
Drug Name		Warfarin				Gemfibrozil
Mechanism		Competition for plasma protein binding sites				Competition for plasma protein binding sites
Key Mechanism Factor 1
		Factor Name		Plasma protein binding
		Factor Description		Plasma protein binding refers to the degree of binding of a drug to proteins in the blood, and the lower the degree of binding, the more efficiently the drug can cross cell membranes or diffuse. Plasma protein binding alters the distribution and therapeutic characteristics of the drugs.
Mechanism Description		Increased plasma concentration of Gemfibrozil and Warfarin due to competitive binding of plasma proteins

Recommended Action
Management		Caution should be exercised when fibrates are prescribed to patients receiving oral anticoagulant therapy. Frequent prothrombin determinations are advisable until prothrombin level has stabilized. Patients should be advised to notify their physician if they experience potential signs of excessive anticoagulation such as unusual or prolonged bleeding, bruising, vomiting, change in stool or urine color, headache, dizziness, or weakness.

References
1	Adkins JC, Faulds D "Micronised fenofibrate: a review of its pharmacodynamic properties and clinical efficacy in the management of dyslipidaemia." Drugs 54 (1997): 615-33. [PMID: 9339964]
2	Ascah KJ, Rock GA, Wells PS "Interaction between fenofibrate and warfarin." Ann Pharmacother 32 (1998): 765-8. [PMID: 9681093]
3	Canadian Pharmacists Association.
4	Cerner Multum, Inc. "UK Summary of Product Characteristics.".
5	Harvengt C, Heller F, Desager JP "Hypolipidemic and hypouricemic action of fenofibrate in various types of hyperlipoproteinemias." Artery 7 (1980): 73-82. [PMID: 7247733]
6	Pharmaceutical Society of Australia "APPGuide online. Australian prescription products guide online.".
7	Product Information. Lopid (gemfibrozil). Parke-Davis, Morris Plains, NJ.
8	Product Information. Tricor (fenofibrate). Abbott Pharmaceutical, Abbott Park, IL.
9	Product Information. Trilipix (fenofibric acid). Abbott Pharmaceutical, Abbott Park, IL.