Verapamil with St John's Wort Interaction Details

Brand Names Associated with Verapamil

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

Interaction Effect

Reduced bioavailability of verapamil

Interaction Summary

Concomitant administration of verapamil with St. John's Wort significantly reduced the bioavailability of verapamil, in a controlled jejunal perfusion study of healthy subjects. Whereas St. John's Wort did not alter jejunal permeability or drug absorption of verapamil, the coadministration with verapamil significantly reduced the maximal plasma concentrations for R-and S-verapamil (by 76% and 78%, respectively), and area under the concentration-time curve was similarly reduced for R- and S- verapamil (78% and 80%, respectively). The risk of interactions cannot be excluded even for low-dose hyperforin St. John’s wort products, however the use of St. John’s wort products that result in a dose of not more than 1 mg hyperforin per day may minimize the risk of interactions .

Severity

Moderate

Onset

Delayed

Evidence

Probable

How To Manage Interaction

Concomitant administration of verapamil with St. John's Wort significantly reduced the bioavailability of verapamil. The risk of interactions cannot be excluded even for low-dose hyperforin St. John’s wort products, however the use of St. John’s wort products that result in a dose of not more than 1 mg hyperforin per day may minimize the risk of interactions .

Mechanism Of Interaction

Induction of cytochrome P450 3A4-mediated verapamil metabolism

Literature Reports

A) Concomitant administration of verapamil with St. John's Wort significantly reduced the bioavailability of verapamil. In a controlled jejunal perfusion study, healthy subjects (n=8) were subjected to 2 100-minute sessions of single-pass perfusion of the proximal jejunum via a Loc-I-Gut perfusion tube. Subjects were first perfused with racemic verapamil hydrochloride (cumulative dose of 24 mg), after which serial blood samples were analyzed over the next 12 hours. Following a 4-week washout, each subject received a 14-day oral regimen of St. John's Wort 300 mg 3 times daily (27 to 54 mg/day of hyperforin) prior to undergoing the second jejunal perfusion and pharmacokinetic blood analysis using the same dose of verapamil. St. John's Wort did not alter jejunal permeability or drug absorption. The coadministration of St. John's Wort significantly reduced the maximal plasma concentrations for R-and S-verapamil (by 76% and 78%, respectively) and area under the concentration-time curve was similarly reduced for R- and S- verapamil (78% and 80%, respectively). Areas under the concentration-time curve for the R- and S-enantiomers of norverapamil were also decreased with concomitant exposure to St. John's Wort (by 51% and 63%, respectively), whereas no change was observed in peak plasma concentrations for either metabolite. Neither time-to-peak concentrations nor plasma half-lives of verapamil and its active metabolite norverapamil were changed by exposure to St. John's Wort .

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.

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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.