Verapamil with Indinavir Interaction Details

Brand Names Associated with Verapamil

Brand Names Associated with Indinavir

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

Interaction Effect

Increased plasma concentrations of calcium channel blockers

Interaction Summary

Calcium channel blockers are metabolized by CYP3A4, which is inhibited by indinavir. Increased plasma calcium channel blocker concentrations may result with coadministration of indinavir. This may result in prolonged therapeutic and adverse effects of the calcium channel blocker. In a patient receiving indinavir treatment, calcium channel blockers should be initiated at low doses and titrated based on response and development of toxicity . Monitor patients for signs and symptoms of hypotension and/or edema .

Severity

Moderate

Onset

Unspecified

Evidence

Probable

How To Manage Interaction

Coadministration of indinavir and a calcium channel blocker, such as amlodipine, diltiazem, or NIFEdipine, may result in increased concentrations of the calcium channel blocker. If coadministration cannot be avoided, monitor for signs and symptoms of edema and/or hypotension. Observe patient for prolonged therapeutic and adverse effects of the calcium channel blocker . Patients on indinavir treatment, initiate calcium channel blockers at low doses and titrate based on response and development of toxicity .

Mechanism Of Interaction

Inhibition of CYP3A4-mediated metabolism of calcium channel blockers by indinavir

Literature Reports

A) The coadministration of indinavir and ritonavir with amlodipine or diltiazem significantly increased exposure to amlodipine and to a lesser extent, diltiazem. In this study, healthy HIV-seronegative subjects participated in an open-label, randomized, 2-arm pharmacokinetic drug interaction study to evaluate the effects of ritonavir and indinavir on diltiazem and amlodipine. Subjects received either amlodipine (5 mg once daily; n=18) or diltiazem (120 mg once daily; n=13) alone for 7 days, followed by indinavir/ritonavir (800/100 mg twice daily) alone through day 19, followed by initiation of the calcium channel blocker in combination with indinavir/ritonavir through day 26. The amlodipine AUC was increased by 89.8% (p less than 0.0001), while the diltiazem AUC increased by 26.5% but was not statistically significant (p=0.06). The AUCs of the active desacetyldiltiazem metabolites doubled, however, this was considered not to be clinically significant, due to the lower activity of the metabolites in comparison with diltiazem. There were no significant changes in heart rate, blood pressure or ECG parameters detected during the study. No change in the AUC or Cmax of either indinavir or ritonavir was seen when coadministered with amlodipine or diltiazem .

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.

Indinavir Overview

• Indinavir is used along with other medications to treat human immunodeficiency virus (HIV) infection. Indinavir is in a class of medications called protease inhibitors. It works by decreasing the amount of HIV in the blood. Although indinavir 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 lifestyle changes may decrease the risk of transmitting 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.