SOURCE: Hatzimouratidis K, et al. Psychosocial outcomes after initial treatment of erectile dysfunction with tadalafil once daily, tadalafil on demand or sildenafil citrate on demand: Results from a randomized open-label study. Int J Impotence Research 2014;26:223-229.

The currently available PDE5 inhibitors — avanafil (Stendra), sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra) — all function by the same basic mechanism and have similar efficacy. Thus, the choice of which agent to prescribe depends more on specific patient-related factors and preferences.

The primary focus of this study by Hatzimouratidis et al was to evaluate the psychosocial outcomes of patients with erectile dysfunction when treated with an on-demand PDE5 inhibitor (sildenafil 50 mg or tadalafil 10 mg) vs daily tadalafil 5 mg. After the first 8 weeks of treatment, patients (n = 770) were informed about the option to try the other two treatments and decide which one they preferred, using their preferred PDE5 inhibitor for the next 16 weeks.

At the conclusion of the trial, there were no statistically significant differences among the three treatment options for most of the study metrics. There was a greater improvement in sexual self-confidence and spontaneity in patients who receive tadalafil (daily or on-demand) than sildenafil, perhaps related to the longer half-life of tadalafil, which allows a substantially greater window of efficacy than sildenafil.

Patients may benefit from an opportunity to try more than one PDE5 inhibitor, but the differences between them are generally quite modest.