Clarithromycin with Acenocoumarol Interaction Details
Brand Names Associated with Clarithromycin
- Biaxin® Filmtab®
- Biaxin® Granules
- Biaxin® XL Filmtab
- Biaxin® XL Pac
- Clarithromycin
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 08, 2023
Interaction Effect
Increased prothrombin time ratio or international normalized ratio (INR) and an increased risk of bleeding
Interaction Summary
Five case reports have described patients stabilized on acenocoumarol therapy who experienced a significant increase in their international normalized ratio (INR) values when clarithromycin was coadministered. In four of these cases, acenocoumarol therapy had to be temporarily suspended until the course of clarithromycin was finished. Although clarithromycin may have a lower affinity for cytochrome P450 hepatic enzymes than erythromycin, clarithromycin may have inhibited acenocoumarol metabolism by this mechanism.
Severity
Moderate
Onset
Delayed
Evidence
Probable
How To Manage Interaction
In patients receiving oral anticoagulant therapy with acenocoumarol, the prothrombin time ratio or international normalized ratio (INR) should be closely monitored with the addition and withdrawal of treatment with clarithromycin, and should be reassessed periodically during concurrent therapy. Adjustments of the acenocoumarol dose may be necessary in order to maintain the desired level of anticoagulation.
Mechanism Of Interaction
Inhibition of acenocoumarol metabolism
Literature Reports
A) A 67-year-old obese male patient with a history of chronic obstructive lung disease and a pulmonary embolism was stabilized on acenocoumarol with international normalized ratios (INR) between 1.5 and 2.2. He was admitted to the hospital for respiratory decompensation and was started on clarithromycin 500 mg twice daily for a respiratory infection. His INR was 1.95 on admission. Following three days of clarithromycin therapy, the INR reached 7.01, although no signs of bleeding were present. Acenocoumarol therapy was temporarily discontinued for two days while the INR decreased to a therapeutic level. Acenocoumarol was restarted at 7 mg weekly until the end of clarithromycin therapy and then was increased to 11 mg to 16 mg weekly with INR values ranging from 1.41 to 2.05 .
B) Four other cases of an interaction between clarithromycin and acenocoumarol have been reported. In all of these cases, clarithromycin had been prescribed for an acute respiratory infection. Three to eight days elapsed after the start of treatment before an increase in the prothrombin time was detected. International normalized ratio (INR) values for these four patients averaged 2.46 prior to clarithromycin treatment and increased to 5.51 during clarithromycin therapy .
Clarithromycin Overview
-
Clarithromycin is used to treat certain bacterial infections, such as pneumonia (a lung infection), bronchitis (infection of the tubes leading to the lungs), and infections of the ears, sinuses, skin, and throat. It also is used to treat and prevent disseminated Mycobacterium avium complex (MAC) infection [a type of lung infection that often affects people with human immunodeficiency virus (HIV)]. It is used in combination with other medications to eliminate H. pylori, a bacterium that causes ulcers. Clarithromycin is in a class of medications called macrolide antibiotics. It works by stopping the growth of bacteria.
-
Antibiotics such as clarithromycin will not work for colds, flu, or other viral infections. Taking antibiotics when they are not needed increases your risk of getting an infection later that resists antibiotic treatment.
Return To Our Drug Interaction Homepage
Feedback, Question Or Comment About This Information?
Ask Dr. Brian Staiger, PharmD, our medical editor, directly! He's always more than happy to assist.
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.