Drug General Information (ID: DDIJMVF0P5)
Drug Name			Azithromycin		Drug Info		Anisindione		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Macrolides				Anticoagulants
Structure

Mechanism of Azithromycin-Anisindione Interaction (Severity Level: Moderate)
Increased risk of bleeding Click to Show/Hide Mechanism Graph
Drug Name		Azithromycin				Anisindione
Mechanism		Potentiate the hypoprothrombinemic effect of vitamin K antagonist				Vitamin K antagonist
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 Azithromycin and Anisindione

Recommended Action
Management		Given the potential for clinically significant interaction in the occasional, susceptible patient, close monitoring is recommended if azithromycin is prescribed during warfarin therapy. The INR should be checked frequently and warfarin dosage adjusted accordingly, particularly following initiation or discontinuation of azithromycin therapy in patients who are stabilized on their anticoagulant regimen. 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. The same precaution may be applicable during therapy with other oral anticoagulants, although clinical data are lacking.

References
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