Drug General Information (ID: DDIL58C2MS)
Drug Name			Sildenafil		Drug Info		Warfarin		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Impotence Agents/Agents For Pulmonary Hypertension				Anticoagulants
Structure

Mechanism of Sildenafil-Warfarin Interaction (Severity Level: Moderate)
Increased risk of bleeding Click to Show/Hide Mechanism Graph
Drug Name		Sildenafil				Warfarin
Mechanism		Risk of bleeding				Risk of bleeding Anticoagulant
Key Mechanism Factor 1
		Factor Name		Bleeding
		Factor Description		Patients may be at risk for bleeding when the outcome of a disease or disease treatment confounds the standard mechanisms for maintaining hemostasis. Signs or symptoms of abnormal bleeding include: bleeding that takes a long time to stop (including nosebleeds, bleeding gums, bleeding from cuts and abrasions, and menstrual bleeding); severe unexplained bruising, or bruising that becomes larger; blood in the urine or stool, etc.
Mechanism Description		Increased risk of bleeding by the combination of Sildenafil and Warfarin

Recommended Action
Management		Caution is advised in patients with pulmonary arterial hypertension receiving sildenafil and oral vitamin K antagonists. The INR should be checked frequently and 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	Cerner Multum, Inc. "UK Summary of Product Characteristics.".
2	Product Information. Revatio (sildenafil). Pfizer U.S. Pharmaceuticals Group, New York, NY.