Verapamil with Flecainide Interaction Details

Brand Names Associated with Verapamil

Brand Names Associated with Flecainide

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

Interaction Effect

Excessive negative inotropic effects and prolongation of atrioventricular conduction

Interaction Summary

Concomitant administration of flecainide and verapamil may result in additive negative inotropic effects and prolongation of atrioventricular conduction. Asystole and cardiogenic shock have also been reported in two patients taking these agents concurrently .

Severity

Moderate

Onset

Rapid

Evidence

Probable

How To Manage Interaction

Use caution when coadministering verapamil and flecainide. Monitor patients for signs and symptoms of additive effects on myocardial contractility, AV conduction, and repolarization.

Mechanism Of Interaction

Additive effects

Literature Reports

A) In a placebo-controlled, randomized study of eight healthy male volunteers, the pharmacokinetic and pharmacodynamic interactions between flecainide and verapamil were examined. Each subject received four separate treatments seven to ten days apart. Each treatment consisted of a two drug combination consisting of flecainide 200 mg or flecainide placebo in addition to verapamil 120 mg or verapamil placebo. Noninvasive cardiac measurements and blood samples were obtained throughout the day of treatment. Concurrent therapy with flecainide and verapamil was shown to produce additive effects on myocardial contractility and atrioventricular conduction. Verapamil also decreased the plasma clearance of flecainide from 7.78 +/- 0.60 ml/kg/min to 7.34 +/- 0.48 ml/kg/min (P less than 0.05). Flecainide had no effect on the plasma clearance of verapamil .

B) A study reported two cases in which a possible interaction between verapamil with flecainide occurred. The first patient, a 67-year old man, had been taking flecainide 200 mg daily when his dose was increased to 300 mg daily for control of tachycardia. Two days after the increase in flecainide dose, verapamil 80 mg three times daily was started. One day later, the patient developed severe cardiogenic shock with idioventricular rhythm of 88/min and a blood pressure of 60/40 mm Hg. After discontinuation of the anti-arrhythmic drugs and catecholamine administration, blood pressure and sinus rhythm improved. The patient's condition was later successfully managed with amiodarone and flecainide. The second patient, a 67-year old male, had been taking verapamil 120 mg three times daily and digitalis for three weeks for atrial fibrillation. Flecainide 150 mg per day was started and later increased to 200 mg. Three days after the dosage increase, the patient fainted. Two hours later, the patient developed severe bradycardia and periods of asystole which led to refractory systole and eventual death. In both of the cases, cardiogenic shock and asystole was presumed to be induced by additive inotropic and chronotropic effects of both drugs .

C) A study reported the successful treatment of 14 patients with combined flecainide and verapamil therapy. The patients were being treated for ventricular tachycardia, atrial fibrillation, or both. Dosage ranges for the drugs were unavailable. During coadministration, no significant changes were noted in heart rate, blood pressure, ejection fraction, or functional class .

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.

Flecainide Overview

• Flecainide is used to prevent certain types of life-threatening irregular heartbeats. Flecainide is in a class of medications called antiarrhythmics. It works by slowing electrical signals in the heart to stabilize the heart rhythm.

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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.