BACKGROUND: Phosphodiesterase (type) 5 (PDE5) inhibitors are currently administered on demand for treatment of erectile dysfunction (ED). Once-daily dosing has been suggested to benefit patients. OBJECTIVE: To determine whether daily vardenafil use provides added clinical benefits to patients compared with on-demand dosing. DESIGN, SETTING, AND PARTICIPANTS: In this placebo-controlled, double-blind, multicentre parallel-group study, men with mild-to-moderate ED were randomised to 24 wk of treatment, followed by a 4-wk washout. INTERVENTION: Patients were randomised to receive once-daily vardenafil 10mg plus on-demand placebo for 12 or 24 wk, or once-daily placebo plus on-demand vardenafil 10mg for 24 wk. MEASUREMENTS: Primary efficacy variable was the between-group difference in change in International Index of Erectile Function-Erectile Function domain (IIEF-EF) score from baseline to end of washout. Secondary variables included change from baseline in proportion of positive respondents to Sexual Encounter Profile questions and in satisfaction with treatment as assessed with the Treatment Satisfaction Scale (TSS). RESULTS AND LIMITATIONS: LS mean changes from baseline in IIEF-EF scores were 2.02, 2.29, and 2.63 for vardenafil 12 wk once daily, 24 wk once daily, and 24 wk on demand, respectively. After washout, the trend was towards improved IIEF-EF scores in the on-demand group (20.58 [+/-0.96]) versus both once-daily groups (12 wk, 19.88 [+/-0.93]; 24 wk, 20.11 [+/-0.94]). Furthermore, there were no significant between-group differences in the percentage of patients with "normal" erectile function. TSS analyses demonstrated no significant differences between treatment groups. This study recruited patients with mild-to-moderate ED; therefore, the results may not be the same as in patients with severe ED. CONCLUSIONS: Once-daily vardenafil did not produce greater sustained effects on EF than on-demand vardenafil in men with mild-to-moderate ED, suggesting that daily dosing of PDE5 inhibitors does not produce sustained clinical benefits beyond cessation of treatment above those observed with on-demand administration.
