Ketoconazole with Nelfinavir Interaction Details
Brand Names Associated with Ketoconazole
- Ketoconazole
- Nizoral®
Brand Names Associated with Nelfinavir
- Nelfinavir
- Viracept®
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Dec 02, 2023
Interaction Effect
Increased serum concentrations of ketoconazole and/or nelfinavir
Interaction Summary
Caution is advised when using ketoconazole, a strong CYP3A4 inhibitor and substrate, together with nelfinavir, also a strong CYP3A4 inhibitor and substrate, as concomitant use may result in elevated plasma concentrations of either agent. Coadministration of ketoconazole and nelfinavir resulted in increased nelfinavir Cmax and AUC by 25% and 35%, respectively . If concomitant use is required, monitor patient for signs and symptoms of increased or prolonged pharmacologic effects of ketoconazole or nelfinavir.
Severity
Major
Onset
Unspecified
Evidence
Theoretical
How To Manage Interaction
Caution is advised when using ketoconazole, a strong CYP3A4 inhibitor and substrate, together with nelfinavir also a strong CYP3A4 inhibitor and substrate as concomitant use may result in elevated plasma concentrations of either agent. If concomitant use is required, monitor patient for signs and symptoms of increased or prolonged pharmacologic effects of ketoconazole or nelfinavir.
Mechanism Of Interaction
Inhibition of CYP3A4-mediated metabolism of ketoconazole by nelfinavir; inhibition of CYP3A4-mediated metabolism of nelfinavir by ketoconazole
Literature Reports
A) In a pharmacokinetic study (n=12), the coadministration of ketoconazole 400 mg once daily for 7 days and nelfinavir 500 mg every 8 hours for 5 to 6 days resulted in increased nelfinavir maximum serum concentrations and area under the concentration-time curve by 25% (95% CI, 11% to 40%) and 35% (95% CI, 24% to 46%), respectively .
Ketoconazole Overview
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Ketoconazole is used to treat fungal infections when other medications are not available or cannot be tolerated. Ketoconazole should not be used to treat fungal meningitis (infection of the membranes surrounding the brain and spinal cord caused by a fungus) or fungal nail infections. Ketoconazole is in a class of antifungals called imidazoles. It works by slowing the growth of fungi that cause infection.
Nelfinavir Overview
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Nelfinavir is used along with other medications to treat human immunodeficiency virus (HIV) infection. Nelfinavir is in a class of medications called protease inhibitors. It works by decreasing the amount of HIV in the blood. Although nelfinavir 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:
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.