Clarithromycin with Astemizole 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
Cardiotoxicity (QT prolongation, torsades de pointes, cardiac arrest)
Interaction Summary
Enzyme inhibiting drugs such as clarithromycin may lead to high levels of astemizole if used concurrently. Astemizole overdoses have led to prolonged QT intervals and severe ventricular arrhythmias. Due to the potential for an interaction which could lead to increased astemizole concentrations which may result in adverse cardiac reactions, astemizole use is contraindicated with clarithromycin .
Severity
Contraindicated
Onset
Delayed
Evidence
Probable
How To Manage Interaction
The concurrent use of astemizole and clarithromycin is contraindicated.
Mechanism Of Interaction
Decreased hepatic metabolism of astemizole
Literature Reports
A) The cytochrome P450 enzyme system is involved in astemizole metabolism. Erythromycin, another macrolide antibiotic, is known to impair this system; therefore, concurrent administration of erythromycin with astemizole may result in increased serum astemizole levels. There have been cases of syncope with torsades de pointes in patients receiving astemizole 10 mg daily with erythromycin. In two cases, the QT intervals were prolonged beyond 650 milliseconds .
B) Drug interactions associated with terfenadine and astemizole have been described . It is reported that recent research suggests that the incidence of prescribing these drugs with ketoconazole or erythromycin is increasing. Cases of adverse cardiovascular events have been reported when astemizole is given concurrently with erythromycin, ketoconazole, or itraconazole. These same adverse cardiovascular effects have also been seen when astemizole is taken at higher than recommended doses. The use of astemizole should be avoided in patients with hepatic dysfunction and in patients who are also receiving drugs which may inhibit the metabolism of astemizole or prolong the QT interval. Recommended doses of astemizole should not be exceeded.
C) An 87-year-old female was being treated concurrently with erythromycin twice daily (unknown strength) and astemizole (10 mg daily) for an upper respiratory infection . Four days after the initiation of treatment, she collapsed suddenly. The initial electrocardiogram noted multiple episodes of torsades de pointes and a QTc of 720 msec. Lab results showed a potassium level of 3.1 mEq/L. A ventricular pacemaker was placed and the remainder of the hospitalization was uneventful.
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.