Combination therapy with topical alprostadil and phosphodiesterase-5 inhibitors after failure of oral therapy in patients with erectile dysfunction: a prospective, two-arm, open-label, non-randomized study.

Phosphodiesterase type 5 inhibitors (PDE5Is) are the first-line therapeutic option for erectile dysfunction (ED), while second-line therapy includes the alprostadil. Due to the different pharmacodynamic mechanism of PDE5Is and alprostadil, a synergistic action is conceivable when they are administered in combination.