 Coadministration of a protease inhibitor with a PDE5 inhibitor is expected to substantially increase the PDE5 inhibitor concentration and may result in an increase in PDE5 inhibitor-associated adverse events, including hypotension, visual changes, and priapism.PDE5-inhibiting drugs are very effective.PDE5 inhibitor drugs appear to work in men regardless of why they have erectile dysfunction — including vascular disease, nerve problems, and even psychological causes.