Coadministration of avanafil and ritonavir is contraindicated due to increased concentrations of avanafil. Coadministration of avanafil (50 mg single dose) and ritonavir (600 mg twice daily) increased avanafil AUC and Cmax by 13-fold and 2.4-fold.

Do not use ritonavir with avanafil because a safe and effective avanafil dosage regimen has not been established. Coadministration of avanafil (50 mg single dose) and ritonavir (600 mg twice daily) was studied in 14 subjects. Avanafil AUC increased by 13-fold (n=4) and Cmax increased by 2.4-fold (n=13).