Details of Drug-Drug Interaction
| Drug General Information (ID: DDIEGNFJPD) | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Drug Name | Warfarin | Drug Info | Nalidixic acid | Drug Info | |||||
| Drug Type | Small molecule | Small molecule | |||||||
| Therapeutic Class | Anticoagulants | Antibiotics | |||||||
| Structure | |||||||||
| Mechanism of Warfarin-Nalidixic acid Interaction (Severity Level: Major) | |||||||||
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| Increased risk of bleeding Click to Show/Hide Mechanism Graph | |||||||||
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| Drug Name | Warfarin | Nalidixic acid | |||||||
| Mechanism | Vitamin K antagonist | Potentiate the hypoprothrombinemic effect of 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 |
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| Recommended Action | |||||||||
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| Management | Given the potential for clinically significant interaction and even fatality in the occasional, susceptible patient, close monitoring is recommended if a quinolone antibiotic is prescribed during coumarin anticoagulant therapy. The INR should be checked frequently and coumarin dosage adjusted accordingly, particularly following initiation or discontinuation of quinolone 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 (e.g., indandiones), although clinical data are lacking. | ||||||||