No pharmaceutical opinion available for this interaction.
Atazanavir / cobicistat can inhibit the metabolism (CYP 3A4) and increase the plasma concentration of Vardenafil.
Atazanavir : 3A4 and UGT1A1, 2C8 (weak to moderate) / Cobicistat : 3A4 (potent) and 2D6 (weak), P-gp, BCRP, OATP1B1 and OATP1B3
Possible increase of adverse effects.
Use this combination with caution.
Use a single maximum dose of vardenafil of 2.5 mg every 72 hours according to the US product monograph.
Monitor closely for adverse effects.
The canadian monograph contraindicates this combination.
Sildenafil or tadalafil.
Vardenafil toxicity: hypotension, tachycardia, headache, dizziness, flushing, visual changes (difficulty distinguishing blue and green) and syncope.
The monographs of vardenafil and ritonavir contraindicate the coadministration with potent CYP 3A4 inhibitors.
Ref #1384 : Indeed, vardenafil AUC has increased by 49-fold when using a 5 mg vardenafil dose associated with ritonavir 600 mg BID, a potent inhibitor of cytochrome 3A4.
- Liver impairment (Child Pugh B) : increases AUC to 160% and
- kidney failure (Clcr < 30 ml/min) : increases AUC to 20-30% and
- age > 65 years old : increases 52% of AUC.
See ritonavir and vardenafil.