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Database of Antiretroviral Drug Interactions

Interactions with Sildenafil (Viagra) and Antiretrovirals

Antiretroviral (ARV)Dose of ARVDose of SildenafilEffect on ARV LevelsEffect on Sildenafil LevelsPotential Clinical EffectsMechanism of InteractionManagement
Amprenavir739, 60, 727
(APV)(Agenerase)
---Not studied; may increase sildenafil levelsPotentially increased sildenafil effects (eg, hypotension, priapism)Inhibition of CYP450 3A4 by amprenavir

For erectile dysfunction, initiate sildenafil 25 mg every 48 hours and monitor for adverse effects. Manufacturer recommends not to exceed dose of 25 mg every 48 hours. Do not coadminister if using sildenafil for pulmonary arterial hypertension.

Atazanavir739, 727
(ATV)(Reyataz)
----Potentially increased sildenafil effects (eg, hypotension, priapism)-

For erectile dysfunction, initiate sildenafil 25 mg every 48 hours and monitor for adverse effects. Manufacturer recommends not to exceed dose of 25 mg every 48 hours. Do not coadminister if using sildenafil for pulmonary arterial hypertension.

Darunavir739, 297, 727, 161
(DRV)(Prezista)
400 mg BID with ritonavir 100 mg BID25 mg x 1Not studiedSildenafil Cmax: decreased 38%; Cmin: no significant change; AUC: no significant change (compared to sildenafil 100 mg x 1 without darunavir/ritonavir)Increased sildenafil effects (eg, hypotension, priapism)Inhibition of CYP450 3A4 by darunavir/ritonavir

For erectile dysfunction, initiate sildenafil 25 mg every 48 hours and monitor for adverse effects. Manufacturer recommends not to exceed dose of 25 mg every 48 hours. Do not coadminister if using sildenafil for pulmonary arterial hypertension.

Elvitegravir/cobicistat727, 623
(Genvoya, Stribild)
--No effect expectedNot studied; may increase sildenafil levelsPotentially increased sildenafil effects (eg, hypotension, priapism)-

For erectile dysfunction, initiate sildenafil 25 mg every 48 hours and monitor for adverse effects. Manufacturer recommends not to exceed dose of 25 mg every 48 hours. Do not coadminister if using sildenafil for pulmonary arterial hypertension.

Elvitegravir/ritonavir-boosted protease inhibitor727
--No effect expectedSildenafil levels increased when co-administered with boosted protease inhibitorsIncreased sildenafil effects (eg, hypotension, priapism)Inhibition of CYP450 3A4 by ritonavir

For erectile dysfunction, initiate sildenafil 25 mg every 48 hours and monitor for adverse effects. Manufacturer recommends not to exceed dose of 25 mg every 48 hours. Do not coadminister if using sildenafil for pulmonary arterial hypertension.

Antiretroviral (ARV)Dose of ARVDose of SildenafilEffect on ARV LevelsEffect on Sildenafil LevelsPotential Clinical EffectsMechanism of InteractionManagement
Etravirine405
(ETR)(Intelence)
-50 mg x 1- Sildenafil AUC: decreased 57%; Cmax: decreased 45%Decreased sildenafil effectsInduction of CYP450 3A4 by etravirine

No dose adjustment necessary

Indinavir254, 16, 299
(IDV)(Crixivan)
800 mg TID25 mg x 1 doseIndinavir AUC: increased 11%; Cmax: increased 48%Sildenafil AUC: increased 340%; Cmax: increased 300% (Levels exceeded those achieved by a 100 mg single dose)Increased sildenafil effects (eg, hypotension, priapism)Inhibition of CYP450 3A4 by indinavir

For erectile dysfunction, initiate sildenafil 25 mg every 48 hours and monitor for adverse effects. Manufacturer recommends not to exceed dose of 25 mg every 48 hours. Do not coadminister if using sildenafil for pulmonary arterial hypertension.

Lopinavir/ritonavir78
(LPV/r)(Kaletra)
---Not studied; may increase sildenafil levelsIncreased sildenafil effects (eg, hypotension, priapism)Inhibition of CYP450 3A4 by lopinavir/ritonavir

Initiate sildenafil at 25 mg QOD-QD; adjust dose as indicated; not recommended to exceed 25 mg in a 48 hour period

Nelfinavir24
(NFV)(Viracept)
---Not studied; may increase sildenafil levelsIncreased sildenafil effects (eg, hypotension, priapism)Inhibition of CYP450 3A4 by nelfinavir

Initiate sildenafil at 25 mg QOD-QD; adjust dose as indicated; not recommended to exceed 25 mg in a 48 hour period

Nelfinavir298
(NFV)(Viracept)
1250 mg Q12H25 mg x 1Not studiedNo significant change--

No dose adjustment necessary

Rilpivirine567
(RPV)(Edurant)
75 mg QD50 mg x 1No significant changeNo significant change--

No dose adjustment necessary

Ritonavir55, 301
(RTV)(Norvir)
300 mg, 400 mg and 500 mg BID on days 2, 3 and 4-8100 mg x 1 dose-Sildenafil AUC: increased 1000%; Cmax: increased 290%; Tmax: delayed 3 hoursIncreased sildenafil effects (eg, hypotension, priapism)Inhibition of CYP450 3A4 by ritonavir

For erectile dysfunction, initiate sildenafil 25 mg every 48 hours and monitor for adverse effects. Manufacturer recommends not to exceed dose of 25 mg every 48 hours. Do not coadminister if using sildenafil for pulmonary arterial hypertension.

Saquinavir75
(SQV)(Fortovase, Invirase)
1200 mg TID x 8 days100 mg x 1-Sildenafil AUC: increased 210%; Cmax: increased 140%Increased sildenafil effects (eg, headache, flushing, priapism)Inhibition of CYP450 3A4 by saquinavir

For erectile dysfunction, initiate sildenafil 25 mg every 48 hours and monitor for adverse effects. Manufacturer recommends not to exceed dose of 25 mg every 48 hours. Do not coadminister if using sildenafil for pulmonary arterial hypertension.

"-" indicates that there are no data available
 16:Crixivan [package insert]. Whitehouse Station, NJ: Merck & Co., Inc.; Oct 2005.
 24:Viracept [package insert]. La Jolla, CA: Agouron Pharmaceuticals, Inc.; Sept 2004.
 55:Norvir [package insert]. North Chicago, IL: Abbott Laboratories, 2008.
 60:Agenerase [package insert]. Research Triangle Park, NC: Glaxo Wellcome Inc; 2004.
 75:Invirase [package insert]. Roche Laboratories Inc, Nutley, NJ, 2007.
 78:Kaletra [package insert]. North Chicago, IL: Abbott Laboratories; Oct 2005.
 161:Prezista [package insert]. Raritan, NJ: Tibotec Therapeutics Inc.; April 2010.
 254:CDC. Guidelines for the use of antiretroviral agents in HIV-infected adults and adolescents. Jan 28, 2000. [AIDS Treatment Information Service: Current Treatment] Available at: http://www.hivatis.org/trtgdlns.html.
 297:Sekar V, Lefebvre E, De Marez T, et al. Effect of repeated doses of darunavir plus low-dose ritonavir on the pharmacokinetics of sildenafil in healthy male subjects: phase I, randomized, open-label, two-way crossover study. Clin Drug Investig 2008; 28: 479-85.
 298:Bratt G, Stahle L. Silfenavil does not alter nelfinavir pharmacokinetics. Ther Drug Monit 2003;25:240-2.
 299:Merry C, Barry MG, Ryan M, et al. Interaction of sildenafil and indinavir when co-administered to HIV-positive patients. AIDS. 1999;13:F101-107.
 301:Muirhead GJ, Wulff MB, Fielding A, et al. Pharmocokinetic interactions between sildenafil and saquinavir/ritonavir. J Clin Pharmacol 2000;50:99-107.
 405:Intelence [package insert]. Raritan, NJ: Tibotec Therapeutics; 2010.
 567:Edurant [package insert]. Raritan, NJ: Tibotec Therapeutics Inc.; May 2011.
 623:Stribild [package insert]. Foster City, CA: Gilead Sciences, Inc.; August 2012.
 727:Panel on Antiretroviral Guidelines for Adults and Adolescents. Guidelines for the use of antiretroviral agents in HIV-1-infected adults and adolescents. Department of Health and Human Services. Available at http://aidsinfo.nih.gov/contentfiles/lvguidelines/AdultandAdolescentGL.pdf.
 739:Viagra [package insert]. Pfizer Inc, Mission, KS, 2016.