Warfarin with Dronedarone Interaction Details
Brand Names Associated with Warfarin
- Coumadin®
- Jantoven®
- Warfarin
Brand Names Associated with Dronedarone
- Dronedarone
- Multaq®
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 07, 2023
Interaction Effect
Increased INR
Interaction Summary
In pharmacokinetic studies, exposure to s-warfarin was slightly increased when warfarin was coadministered with dronedarone, but no significant increase in INR was observed. In a clinical study, more patients had INR elevations to 5 or greater usually within 1 week of starting dronedarone versus placebo. No excess risk of bleeding was observed in the dronedarone group. Increased INR with or without bleeding events have been reported postmarketing including a case report of increased INR without bleeding following dronedarone initiation in a woman with a stable INR over the previous year . When coadministration is necessary, closely monitor INR , especially for the first week after initiating dronedarone . If INR increases or bleeding occurs, decrease the warfarin dose and monitor within 2 weeks to determine if further dose adjustment is warranted .
Severity
Major
Onset
Unspecified
Evidence
Probable
How To Manage Interaction
Concomitant use of warfarin with a CYP3A4 inhibitor, such as dronedarone, has to potential to increase the effect (ie, INR) of warfarin by increasing exposure to warfarin. When coadministration is necessary, closely monitor INR, especially within the first week after initiating dronedarone . If INR increases or bleeding occurs, decrease the warfarin dose and monitor within 2 weeks to determine if further dose adjustment is warranted .
Mechanism Of Interaction
Unknown
Literature Reports
A) Increased INR without bleeding was reported approximately 10 days following initiation of dronedarone in a 72-year-old woman who had a stable INR for 1 year prior with warfarin 25 mg/wk. The patient, who had a history of hyperlipidemia, osteopenia, tinnitus, GERD, and permanent pacemaker implantation, was switched from sotalol to dronedarone 400 mg twice daily for persistent episodes of atrial fibrillation. Concomitant medications included risedronate 35 mg/wk and atorvastatin 10 mg at bedtime for over 6 years. Approximately 10 days after dronedarone initiation, INR was 4.8 and the patient reported persistent diarrhea but no bleeding events. The patient was instructed to reduce warfarin by 5 mg/wk. Three weeks later, INR was 2.7 and the diarrhea had resolved. The patient continued with dronedarone 400 mg twice daily and warfarin 20 mg/wk and INR remained in target range over the next 11 months. During this time, the patient denied any change in diet, other medications, or health. The Drug Interaction Probably Scale (DIPS) indicated a probably interaction between dronedarone and warfarin .
Warfarin Overview
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Warfarin is used to prevent blood clots from forming or growing larger in your blood and blood vessels. It is prescribed for people with certain types of irregular heartbeat, people with prosthetic (replacement or mechanical) heart valves, and people who have suffered a heart attack. Warfarin is also used to treat or prevent venous thrombosis (swelling and blood clot in a vein) and pulmonary embolism (a blood clot in the lung). Warfarin is in a class of medications called anticoagulants ('blood thinners'). It works by decreasing the clotting ability of the blood.
Dronedarone Overview
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Dronedarone is used to treat people who currently have normal heart rhythm, but have had atrial fibrillation in the past. Dronedarone decreases the risk that people who have this condition will need to be hospitalized to treat atrial fibrillation. Dronedarone is in a class of medications called antiarrhythmics. It works by helping the heart to beat normally.
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Definitions
Severity Categories
Contraindicated
These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.
Major
This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.
Moderate
This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.
Minor
While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.
Onset
Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.
Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.
Evidence
Level of documentation of the interaction.
Established: The interaction is documented and substantiated in peer-reviewed medical literature.
Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.
How To Manage The Interaction
Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.
It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.
Mechanism Of Interaction
The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.
Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.
Where Does Our Information Come From?
Information for our drug interactions is compiled from several drug compendia, including:
The prescribing information for each drug, as published on DailyMED, is also used.
Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.
The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.