Sildenafil with Indinavir Interaction Details
Brand Names Associated with Sildenafil
- Revatio®
- Sildenafil
- Viagra®
Brand Names Associated with Indinavir
- Crixivan®
- IDV
- Indinavir
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 12, 2023
Interaction Effect
Increased sildenafil plasma levels, thereby increasing the risk for sildenafil adverse effects (hypotension, visual changes, priapism)
Interaction Summary
In a small study conducted with six HIV-positive males stabilized on indinavir therapy, the coadministration of sildenafil 25 mg resulted in sildenafil plasma levels which were in excess of those reached when sildenafil was administered alone. Average AUC of sildenafil was increased by 340% . For erectile dysfunction, a maximum dose of sildenafil 25 mg every 48 hours should be used in patients also receiving indinavir. Patients should also be monitored for an increase in sildenafil adverse effects . Due to lack of a safe and effective dose recommendation, concurrent use of sildenafil (as Revatio(R)) and protease inhibitors is contraindicated in patients being treated for pulmonary arterial hypertension.
Severity
Contraindicated
Onset
Unspecified
Evidence
Probable
How To Manage Interaction
Coadministration of indinavir and sildenafil (as Revatio(R)) for the treatment of pulmonary arterial hypertension is contraindicated as a safe and effective dose for treatment of pulmonary arterial hypertension has not been established. For erectile dysfunction, use sildenafil with caution at a reduced dose not exceeding 25 mg every 48 hours, and monitor for increased incidence of sildenafil adverse effects such as headache, flushing, visual disturbance, hypotension, and priapism.
Mechanism Of Interaction
Inhibition of CYP3A4-mediated sildenafil metabolism by indinavir
Literature Reports
A) Six HIV-positive males with erectile dysfunction participated in a two-day pharmacokinetic study to determine the effect of indinavir on sildenafil plasma concentrations. All patients were receiving triple antiretroviral therapy with zidovudine/lamivudine or stavudine/didanosine plus indinavir 800 mg 3 times daily. A single dose of sildenafil 25 mg was administered on the second day of the study. In the presence of sildenafil, there was an 11% increase in the indinavir AUC from 0 to 8 hours and a 48% increase in the indinavir Cmax. Sildenafil AUC was increased by 340% following coadministration of sildenafil and indinavir . Data from historical controls for doses of sildenafil 50 mg and 100 mg were dose normalized to 25 mg and were compared with the results from this study. Results showed that the coadministration of sildenafil 25 mg with indinavir caused plasma sildenafil concentrations which exceeded those reached when sildenafil was administered at 100 mg in the absence of indinavir. All 6 subjects experienced sildenafil-related adverse effects, including headache, flushing, dyspepsia, and rhinitis. Additionally, the mean maximal decrease in blood pressure was 14/10 mm Hg, which is larger than the maximum decrease seen following sildenafil 100 mg in other clinical studies. The marked increase in sildenafil plasma levels in the presence of indinavir suggests that a starting sildenafil dose of 12.5 mg would be appropriate to minimize dose-related toxicities .
Sildenafil Overview
-
Sildenafil (Viagra) is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. Sildenafil (Revatio) is used to improve the ability to exercise in adults and children 1 year of age and older with pulmonary arterial hypertension (PAH; high blood pressure in the vessels carrying blood to the lungs, causing shortness of breath, dizziness, and tiredness). Sildenafil is in a class of medications called phosphodiesterase (PDE) inhibitors. Sildenafil treats erectile dysfunction by increasing blood flow to the penis during sexual stimulation. This increased blood flow can cause an erection. Sildenafil treats PAH by relaxing the blood vessels in the lungs to allow blood to flow easily.
-
If you are taking sildenafil to treat erectile dysfunction, you should know that it does not cure erectile dysfunction or increase sexual desire. Sildenafil does not prevent pregnancy or the spread of sexually transmitted diseases such as human immunodeficiency virus (HIV).
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.
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.