Drug General Information (ID: DDIVHTC0NG)
Drug Name			Dicoumarol		Drug Info		Ribavirin		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Anticoagulants				Antiviral Agents
Structure

Mechanism of Dicoumarol-Ribavirin Interaction (Severity Level: Moderate)
Antagonize the effect of antithrombotic agents Click to Show/Hide Mechanism Graph
Drug Name		Dicoumarol				Ribavirin
Mechanism		Vitamin K antagonist				Decrease the hypoprothrombinemic effect of vitamin K antagonist
Key Mechanism Factor 1
		Factor Name		Antithrombotic agents
		Factor Description		The beneficial effects of antithrombotic agents are reduced, leading to an increased risk of thromboembolism, stroke and/or myocardial infarction.
Mechanism Description		Antagonize the effect of Dicoumarol when combined with Ribavirin

Recommended Action
Management		Patients treated with warfarin should be closely monitored during concomitant therapy with ribavirin. The INR should be checked frequently (e.g., weekly) during the 4 weeks following initiation or discontinuation of ribavirin therapy in patients who are stabilized on their warfarin regimen, and the warfarin dosage adjusted accordingly. The same precaution may be applicable during therapy with other oral anticoagulants, although clinical data are lacking. Patients should be advised to promptly report any signs of bleeding to their physician, including pain, swelling, headache, dizziness, weakness, prolonged bleeding from cuts, increased menstrual flow, vaginal bleeding, nosebleeds, bleeding of gums from brushing, unusual bleeding or bruising, red or brown urine, or red or black stools.

References
1	Product Information. Copegus (ribavirin). Roche Laboratories, Nutley, NJ.
2	Product Information. Rebetol (ribavirin). Schering-Plough Corporation, Kenilworth, NJ.
3	Schulman S "Inhibition of warfarin activity by ribavirin." Ann Pharmacother 36 (2002): 72-4