Metoprolol with Terbinafine Interaction Details
Brand Names Associated with Metoprolol
- Dutoprol® (as a combination product containing Metoprolol, Hydrochlorothiazide)
- Kapspargo Sprinkle®
- Lopressidone® (as a combination product containing Chlorthalidone, Metoprolol)
- Lopressor®
- Lopressor® HCT (as a combination product containing Metoprolol, Hydrochlorothiazide)
- Metoprolol
- Toprol®
- Toprol® XL
Brand Names Associated with Terbinafine
- Lamisil®
- Terbinafine
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Jan 04, 2024
Interaction Effect
Increased metoprolol exposure and an increased risk of bradycardia
Interaction Summary
Terbinafine may inhibit CYP2D6-mediated metoprolol metabolism, increasing serum concentrations of metoprolol which may lead to a risk of bradycardia and may decrease the cardioselectivity of metoprolol . The interaction may have a delayed effect due to the long half-life and large volume of distribution of terbinafine. If use of both agents is necessary, consider close monitoring of heart rate and blood pressure. A dosage reduction or usage of an alternate beta-blocker or antifungal may be necessary .
Severity
Major
Onset
Delayed
Evidence
Probable
How To Manage Interaction
Use of metoprolol with terbinafine may increase serum concentrations of metoprolol, which may increase the risk of bradycardia and may decrease the cardioselectivity of metoprolol . If use is necessary, close monitoring of heart rate and blood pressure may be advisable. A dosage reduction of metoprolol or usage of an alternate beta-blocker may also be necessary .
Mechanism Of Interaction
Inhibition of CYP2D6-mediated metoprolol metabolism by terbinafine
Literature Reports
A) A 63-year-old man presented with altered mental status and bradycardia (heart rate 37 beats per minute) after 49 days of terbinafine 250 mg orally daily. The subject had been on a stable dose of metoprolol 200 mg daily for acute coronary syndrome with residual heart failure. Upon tapering of metoprolol, discontinuation of terbinafine, and eventual transition to bisoprolol, the bradycardia resolved. The patient had also been receiving rivastigmine, but had discontinued therapy 27 days prior to the bradycardia event. This interaction was rated a 7 on the Naranjo adverse event probability scale. The observed delay in interaction effect may be due to the long half-life and gradual accumulation of terbinafine .
B) In healthy subjects with CYP2D6 extensive metabolizer phenotype, coadministration of quiNIDine 100 mg, a potent CYP2D6 inhibitor, and immediate-release metoprolol 200 mg tripled the concentration of S-metoprolol and doubled the metoprolol elimination half-life. In four patients with cardiovascular disease, coadministration of propafenone 150 mg thrice daily with immediate-release metoprolol 50 mg thrice daily increased the steady-state metoprolol concentration 2- to 5-fold compared to metoprolol alone. Extensive metabolizers who concomitantly use CYP2D6 inhibiting drugs will have increased (several-fold) metoprolol blood levels, decreasing metoprolol's cardioselectivity .
Metoprolol Overview
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Metoprolol is used alone or in combination with other medications to treat high blood pressure. It also is used to treat chronic (long-term) angina (chest pain). Metoprolol is also used to improve survival after a heart attack. Metoprolol also is used in combination with other medications to treat heart failure. Metoprolol is in a class of medications called beta blockers. It works by relaxing blood vessels and slowing heart rate to improve blood flow and decrease blood pressure.
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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.
Terbinafine Overview
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Terbinafine granules are used to treat fungal infections of the scalp. Terbinafine tablets are used to treat fungal infections of the toenails and fingernails. Terbinafine is in a class of medications called antifungals. It works by stopping the growth of fungi.
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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.