Nifedipine with Efavirenz Interaction Details

Brand Names Associated with Nifedipine

Brand Names Associated with Efavirenz

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Nov 20, 2023

Interaction Effect

Decreased NIFEdipine exposure

Interaction Summary

NIFEdipine is metabolized by CYP3A4. Concomitant administration of NIFEdipine and CYP3A4 inducers reduced the AUC and Cmax of NIFEdipine by approximately 70%. Using NIFEdipine together with any known CYP3A4 inducer may significantly reduce the effectiveness of NIFEdipine, and should be avoided. Alternate antihypertensive treatment should be considered. Case reports and studies suggest concomitant administration of NIFEdipine and CYP3A4 inducers may result in reduced effectiveness of NIFEdipine .

Severity

Major

Onset

Unspecified

Evidence

Probable

How To Manage Interaction

Coadministration of NIFEdipine and CYP3A4 inducers may significantly reduce the effectiveness of NIFEdipine. Avoid concomitant use of NIFEdipine and any known CYP3A4 inducer. Alternate antihypertensive treatment should be considered.

Mechanism Of Interaction

Induction of CYP3A4-mediated NIFEdipine metabolism

Literature Reports

A) St John's wort, a CYP3A4 inducer, reduced the mean plasma concentration of NIFEdipine, a CYP3A4 substrate, by 53% at 30 minutes in an open trial of 22 healthy subjects. Subjects received oral St John's wort 900 mg/day for 18 days and then received a single oral dose of NIFEdipine 10 mg. The mean plasma concentration of NIFEdipine at 30 minutes was reduced by 53% compared with NIFEdipine alone (statistical significance not stated) .

B) A 75-year-old hypertensive woman had been well controlled with NIFEdipine, a CYP3A4 substrate. After she developed tuberculosis and was treated with rifampin, a CYP3A4 inducer, both peak plasma concentration and AUC of NIFEdipine decreased to about 40% of previous levels; control of the hypertension was significantly affected. Another calcium channel blocker, nisoldipine, was administered concurrently with rifampin, but it also was unable to lower her blood pressure .

C) Eight healthy subjects were administered NIFEdipine, a CYP3A4 substrate, sparteine, and phenytoin, a CYP3A4 inducer, separately and as a "cocktail" on separate occasions. There were no significant differences in clearance of any of the substrates after separate or "cocktail" administration .

D) Concomitant administration of NIFEdipine, a CYP3A4 substrate, and rifampin, a CYP3A4 inducer, resulted in exacerbation of variant angina in one case, presumably due to enhanced NIFEdipine elimination from rifampin-induced enzyme induction .

Nifedipine Overview

• Nifedipine is used to treat high blood pressure and to control angina (chest pain). Nifedipine is in a class of medications called calcium-channel blockers. It lowers blood pressure by relaxing the blood vessels so the heart does not have to pump as hard. It controls chest pain by increasing the supply of blood and oxygen to the heart.

• 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.

Efavirenz Overview

• Efavirenz is used along with other medications to treat human immunodeficiency virus (HIV) infection. Efavirenz is in a class of medications called non-nucleoside reverse transcriptase inhibitors (NNRTIs). It works by decreasing the amount of HIV in the blood. Although efavirenz does not cure HIV, it may decrease your chance of developing acquired immunodeficiency syndrome (AIDS) and HIV-related illnesses such as serious infections or cancer. Taking these medications along with practicing safer sex and making other life-style changes may decrease the risk of transmitting (spreading) the HIV virus to other people.

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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.