Amoxicillin; Clavulanate with Acenocoumarol Interaction Details
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 15, 2023
Interaction Effect
Increased INR and an increased risk of bleeding
Interaction Summary
Concomitant use of amoxicillin with oral anticoagulants, including acenocoumarol, has resulted in rare cases of abnormal prolongation of bleeding time (increased INR). A case of elevated INR was described in a patient who received a course of amoxicillin while receiving acenocoumarol . Therefore, when amoxicillin and acenocoumarol are coadministered, the patient should be appropriately monitored. It may be necessary to adjust the acenocoumarol dose in order to maintain the desired anticoagulation level .
Severity
Moderate
Onset
Unspecified
Evidence
Probable
How To Manage Interaction
Concomitant use of amoxicillin with oral anticoagulant, such as acenocoumarol, has resulted in abnormal prolongation of bleeding time (increased INR). If concurrent use is necessary, appropriately monitor the patient and adjust the acenocoumarol dose, as needed, to maintain the desired anticoagulation level .
Mechanism Of Interaction
Unknown
Literature Reports
A) A case of increased INR is described in a patient maintained on acenocoumarol who was prescribed a course of amoxicillin. An 81-year-old female was hospitalized for treatment of osteoarthritis and a hip prosthesis was inserted. The patient developed DVT in both legs for which anticoagulation was performed. The patient received a continuous IV infusion of sodium heparin, and 5 days later oral anticoagulant therapy with acenocoumarol. The dose of acenocoumarol was titrated to maintain an INR of between 2.5 and 4. Other medications included terbutaline, amiloride, and hydrochlorothiazide. The patient was discharged on 3 mg/day of acenocoumarol with an INR of 3.8. Five weeks later, the patient experienced coughing and increased expectoration for which amoxicillin was prescribed. A week later, bruising on both buttocks was observed. Although there was no evidence of bleeding, her INR at this point was 7.1. Treatment with acenocoumarol was stopped for 2 days and amoxicillin was discontinued. Acenocoumarol was resumed at 2 mg/day. Six days later her INR was 1.6 and the dose of acenocoumarol was increased to 3 mg/day. The author concluded that the interaction between amoxicillin and acenocoumarol was produced either by an alteration in the intestinal microflora by amoxicillin, or by inhibition by amoxicillin of the hepatic metabolism of acenocoumarol .
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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.
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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.
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