Drug General Information (ID: DDIO9XH1UJ)
Drug Name			Aztreonam		Drug Info		Warfarin		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Antibiotics				Anticoagulants
Structure

Mechanism of Aztreonam-Warfarin Interaction (Severity Level: Moderate)
Increased risk of bleeding Click to Show/Hide Mechanism Graph
Drug Name		Aztreonam				Warfarin
Mechanism		Inhibition of vitamin K-producing intestinal bacteria				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 Warfarin and Aztreonam

Recommended Action
Management		Given the potential for clinically significant interaction and even fatality in the occasional, susceptible patient, monitoring is recommended during concomitant therapy. The INR should be checked frequently and coumarin dosage adjusted accordingly, particularly following initiation or discontinuation of the antibacterial 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.

References
1	Agencia Espaola de Medicamentos y Productos Sanitarios Healthcare "Centro de informacion online de medicamentos de la AEMPS - CIMA.".
2	Cerner Multum, Inc. "UK Summary of Product Characteristics.".