Verapamil with Telithromycin Interaction Details

Brand Names Associated with Verapamil

Brand Names Associated with Telithromycin

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Dec 03, 2023

Interaction Effect

Increased verapamil plasma concentrations, thereby increasing the risk of verapamil toxicity (hypotension, bradyarrhythmia, lactic acidosis)

Interaction Summary

The concomitant use of telithromycin (a strong CYP3A4 inhibitor) with verapamil (a CYP3A4 substrate) has resulted in hypotension, bradyarrhythmia, and lactic acidosis . A case report of a patient who received telithromycin and verapamil concurrently illustrates the potential for an interaction manifested by profound hypotension and bradycardia. Caution is warranted with the concomitant use of telithromycin and verapamil . If concomitant use is required, dose adjustment of verapamil may be warranted .

Severity

Moderate

Onset

Delayed

Evidence

Probable

How To Manage Interaction

The concomitant use of telithromycin and verapamil may result in increased verapamil plasma concentrations, thereby increasing the risk for verapamil toxicity (hypotension, bradyarrhythmia, lactic acidosis). If concomitant use is required, dose adjustment of verapamil may be warranted .

Mechanism Of Interaction

Inhibition of CYP3A4-mediated verapamil metabolism by telithromycin

Literature Reports

A) Competitive inhibition by telithromycin of verapamil metabolism was the probable cause of the verapamil toxicity presented in this case report. A 76-year-old woman presented to the emergency department with shortness of breath and weakness 2 days after the initiation of a regimen of telithromycin 800 mg per day. The patient was profoundly hypotensive and bradycardic with a systolic blood pressure of 50 to 60 mmHg and a heart rate of 30 beats per minute. An ECG indicated the patient was in a junctional rhythm. Treatment included dopamine and norepinephrine infusions and the placement of a transvenous pacemaker. The patient's maintenance medications prior to hospitalization included sustained-release verapamil 180 mg daily along with esomeprazole, telmisartan, furosemide, montelukast, colesevelam, oxaprozin, fluticasone, albuterol/ipratropium, and budesonide. Investigators suspected verapamil toxicity which was substantiated by the patient's relatively rapid recovery upon discontinuation of telithromycin. Fifty percent of telithromycin is metabolized via the CYP3A4 isozyme. Verapamil is metabolized via several CYP isoenzyme systems including CYP3A4. Telithromycin may displace verapamil from the CYP3A4 pathway causing an increased exposure to verapamil resulting in verapamil toxicity .

Verapamil Overview

• Verapamil is used to treat high blood pressure and to control angina (chest pain). The immediate-release tablets are also used alone or with other medications to prevent and treat irregular heartbeats. Verapamil is in a class of medications called calcium-channel blockers. It works by relaxing the blood vessels so the heart does not have to pump as hard. It also increases the supply of blood and oxygen to the heart and slows electrical activity in the heart to control the heart rate.

• High blood pressure is a common condition and when not treated, can cause damage to the brain, heart, blood vessels, kidneys and other parts of the body. Damage to these organs may cause heart disease, a heart attack, heart failure, stroke, kidney failure, loss of vision, and other problems. In addition to taking medication, making lifestyle changes will also help to control your blood pressure. These changes include eating a diet that is low in fat and salt, maintaining a healthy weight, exercising at least 30 minutes most days, not smoking, and using alcohol in moderation.

Telithromycin Overview

• Telithromycin is used to treat certain types of pneumonia (an infection of the lungs) that is caused by bacteria. Telithromycin is in a class of medications called ketolide antibiotics. It works by killing bacteria.

• Antibiotics such as telithromycin 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.

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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:

• Gold Standard Drug Database
• Micromedex
• Lexicomp
• DrugBank

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.