Avanafil and Fosamprenavir interaction
Avanafil and Fosamprenavir: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Avanafil label · effective 2025-12-17
Do not use avanafil in patients taking strong CYP3A4 inhibitors [see Warnings and Precautions ( 5.2 ) and Dosage and Administration ( 2.3 )].
Inhibitors of CYP3A4 may reduce avanafil clearance and increase plasma concentrations of avanafil.
For patients taking concomitant moderate CYP3A4 inhibitors (including erythromycin, amprenavir, aprepitant, diltiazem, fluconazole, fosamprenavir, and verapamil), the maximum recommended dose of avanafil is 50 mg, not to exceed once every 24 hours [see Drug Interactions ( 7.2 )].
• CYP3A4 inhibitors (e.g., ketoconazole, ritonavir, erythromycin) increase avanafil exposure ( 7.2 )
Studies have shown that drugs that inhibit CYP3A4 can increase avanafil exposure.
From the Fosamprenavir (Fosamprenavir Calcium) label · effective 2026-06-30
John’s wort ( Hypericum perforatum ) Lipid modifying agents: Lomitapide, lovastatin, simvastatin Non-nucleoside reverse transcriptase inhibitor: Delavirdine PDE5 inhibitor: Sildenafil (Revatio) (for treatment of pulmonary arterial hypertension) Sedative/hypnotics: Midazolam, triazolam Hypersensitivity to fosamprenavir calcium or amprenavir (e.g., Stevens-Johnson…
Use of PDE5 inhibitors for pulmonary arterial hypertension (PAH): •Use of sildenafil (REVATIO) is contraindicated when used for the treatment of PAH.
PDE5 inhibitors: Sildenafil, tadalafil, vardenafil ↑ Sildenafil ↑ Tadalafil ↑ Vardenafil May result in an increase in PDE5 inhibitor-associated adverse events, including hypotension, syncope, visual disturbances, and priapism.
Use of PDE5 inhibitors for erectile dysfunction: Fosamprenavir calcium: Sildenafil: 25 mg every 48 hours.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.