Raltegravir with Fosamprenavir Interaction Details
Brand Names Associated with Raltegravir
- Isentress®
- Isentress® HD
- Raltegravir
Brand Names Associated with Fosamprenavir
- Fosamprenavir
- Lexiva®
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Jan 04, 2024
Interaction Effect
Decreased amprenavir and decreased raltegravir serum concentrations
Interaction Summary
Concomitant use of fosamprenavir and raltegravir has resulted in decreased amprenavir exposure (active fosamprenavir metabolite) and may also decrease raltegravir plasma concentrations. In pharmacokinetic studies, concomitant use resulted in decreases in amprenavir Cmax, AUC, and Cmin. Appropriate doses of the combination have not been established with regard to safety or efficacy.
Severity
Major
Onset
Unspecified
Evidence
Established
How To Manage Interaction
Concomitant use of fosamprenavir and raltegravir has resulted in decreased amprenavir exposure (active fosamprenavir metabolite) and may also decrease raltegravir plasma concentrations. Appropriate doses of the combination have not been established with regard to safety or efficacy.
Mechanism Of Interaction
Unknown
Literature Reports
A) In a pharmacokinetic study, subjects (n=14) who received 14 days of treatment with raltegravir 400 mg twice daily concomitantly with fosamprenavir 1400 mg twice daily under fasting conditions experienced decreases in amprenavir (active fosamprenavir metabolite) Cmax, AUC, and Cmin. The Cmax decreased by 27% (90% confidence interval (CI), -46% to +/- 10% or less), AUC decreased by 36% (90% CI, -53% to -13%), and the last concentration tested (C12-hour or C24-hour) decreased by 43% (90% CI, -59% to -21%). When subjects (n=14) received treatment without regard to food, except for the doses given with food on the day of pharmacokinetic blood sampling, the Cmax decreased by 15% (90% CI, -27% to -1%), AUC decreased by 17% (90% CI, -27% to -6%), and the last concentration tested (C12-hour or C24-hour) decreased by 32% (90% CI, -53% to -1%). The effect on raltegravir plasma concentrations when coadministered with fosamprenavir was not reported .
B) In a pharmacokinetic study, subjects (n=14) who received 14 days of treatment with raltegravir 400 mg twice daily concomitantly with fosamprenavir 700 mg plus ritonavir 100 mg twice daily under fasting conditions experienced decreases in amprenavir (active fosamprenavir metabolite) Cmax, AUC, and Cmin. The Cmax decreased by 14% (90% confidence interval (CI), -39% to +20%), AUC decreased by 17% (90% CI, -38% to +12%), and the last concentration tested (C12-hour or C24-hour) decreased by 20% (90% CI, -45% to +17%). When subjects (n=12) received treatment without regard to food, except for the doses given with food on the day of pharmacokinetic blood sampling, the Cmax decreased by 25% (90% CI, -42% to -2%), AUC decreased by 25% (90% CI, -44% to +/- 10% or less), and the last concentration tested (C12-hour or C24-hour) decreased by 33% (90% CI, -52% to -7%). The effect on raltegravir plasma concentrations when coadministered with fosamprenavir was not reported .
C) In a pharmacokinetic study, subjects (n=13) who received 14 days of treatment with raltegravir 400 mg twice daily concomitantly with fosamprenavir 1400 mg plus ritonavir 100 mg once daily under fasting conditions experienced decreases in amprenavir (active fosamprenavir metabolite) Cmax, AUC, and Cmin. The Cmax decreased by 18% (90% confidence interval (CI), -34% to +/- 10% or less), AUC decreased by 24% (90% CI, -41% to +/- 10% or less), and the last concentration tested (C12-hour or C24-hour) decreased by 50% (90% CI, -64% to -31%). When subjects (n=14) received treatment without regard to food, except for the doses given with food on the day of pharmacokinetic blood sampling, the Cmax increased by 27% (90% CI, -1% to +62%) , AUC increased by 13% (90% CI, -7% to +38%), and the last concentration tested (C12-hour or C24-hour) decreased by 17% (90% CI, -45% to +26%). The effect on raltegravir plasma concentrations when coadministered with fosamprenavir was not reported .
Raltegravir Overview
-
Raltegravir is used along with other medications to treat human immunodeficiency virus (HIV) infection in adults and children who weigh at least 4.5 lbs (2 kg). Raltegravir is in a class of medications called HIV integrase inhibitors. It works by decreasing the amount of HIV in the blood. Although raltegravir 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.
Fosamprenavir Overview
-
Fosamprenavir is used along with other medications to treat human immunodeficiency virus (HIV) infection. Fosamprenavir is in a class of medications called protease inhibitors. It works by decreasing the amount of HIV in the blood. Although fosamprenavir 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 the HIV virus to other people.
Return To Our Drug Interaction Homepage
Feedback, Question Or Comment About This Information?
Ask Dr. Brian Staiger, PharmD, our medical editor, directly! He's always more than happy to assist.
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.