Drug interactions between Coumadin and dronedarone
| Results for the following 2 drugs: |
|---|
| Coumadin (warfarin) |
| dronedarone |
Interactions between your selected drugs
warfarin ↔ dronedarone
Applies to:Coumadin (warfarin) and dronedarone
MONITOR: Coadministration with dronedarone may occasionally increase the hypoprothrombinemic effects of warfarin. The exact mechanism of interaction is unknown. When healthy subjects were administered warfarin in combination with dronedarone 600 mg twice daily, systemic exposure to the more active S(-) enantiomer of warfarin, which is primarily metabolized by CYP450 2C9, increased by 1.2-fold compared to warfarin administered alone. Systemic exposure to R(+) warfarin, which is metabolized by CYP450 1A2 and 3A4, was unchanged. No clinically significant increases in INR were observed. Interestingly, dronedarone is a moderate inhibitor of CYP450 3A4, but has not been shown to inhibit CYP450 2C9. In one clinical trial (ATHENA), more patients taking oral anticoagulants experienced clinically significant INR elevations (>= 5) usually within 1 week after starting dronedarone as opposed to placebo, although no excess risk of bleeding was observed in the dronedarone group. Pooled data from six clinical trials including ATHENA also revealed no major differences in frequency of bleeding complications between patients treated with dronedarone versus placebo. However, postmarketing cases of INR elevations, with or without bleeding events, have been reported in warfarin-treated patients initiated on dronedarone.
MANAGEMENT: Caution is advisable if dronedarone is used in combination with warfarin. The INR should be checked frequently and warfarin dosage adjusted accordingly, particularly following initiation or discontinuation of dronedarone in patients who are stabilized on their warfarin regimen. 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.
See also...
Drug Interaction Classification
The classifications below are a guideline only. The relevance of a particular drug interaction to a specific patient is difficult to determine using this tool alone given the large number of variables that may apply.
| Major | Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. |
| Moderate | Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. |
| Minor | Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan. |
Do not stop taking any medications without consulting your healthcare provider.
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