A new era in the treatment of erectile dysfunction: chronic phosphodiesterase type 5 inhibition.

Historically, oral phosphodiesterase type 5 inhibitors (PDE5-i) have been prescribed with an 'as-necessary' regimen for treating erectile dysfunction (ED), thus addressing primarily symptom relief. However, approximately 30% of patients are unresponsive to on-demand PDE5-i regimens due to both psychogenic and organic factors and, although it is difficult to estimate the proportion, discontinuation rates remain high. In recent years, a 2.5-5 mg daily dose of tadalafil has been proposed and was recently approved for treating ED. Chronic PDE-5 inhibition has the advantage of potentially 'curing' ED, on a daily basis, by interfering with pathophysiological factors of both psychogenic (anxiety related to planning sexual activity) and organic (endothelial dysfunction, penile structural homeostasis) origin, although further research is needed to better address these hypotheses. Clinical studies showed that chronic PDE5-i regimens are a safe and effective alternative to the classical on-demand dosage, and might improve the outcomes in a selected group of patients.