Patients with erectile dysfunction (ED), are equally satisfied with on-demand and once daily doses of PDE5 inhibitors.
A total of 236 patients with mild to moderate ED were recruited in a placebo-controlled double-blind parallel group study. Patients were randomized to once daily verdenafil 10mg for 12 or 24 weeks and on-demand placebo or on-demand verdenafil 10mg and once daily placebo for 24 weeks.
The primary efficacy variable was the difference between scores on the International Index of Erectile Function (IIEF), an established symptoms score for ED.
No statistically significant differences in IIEF scores were observed between treatment groups during the study, although some trends in favor of on-demand dosing were seen. No differences were seen in any secondary outcome measures.
Adverse event rates did not suggest a difference in tolerability between daily and on-demand dosing and were consistent with the usual side effect profile of PDE5 inhibitors, ie headache, flushing and dyspepsia.
After the cessation of treatment, erectile function decreased in all three treatment group, once daily treatment offered no prolonged advantage compared with on-demand therapy. Patients were equally satisfied with on-demand daily dosing.
Pre-clinical studies have suggested that daily dosing of PDE5 inhibitors may improve endothelial function and thus prevent further detoriation of existing ED. It is also possible that this dosing regimen may help patients re-establish sexual spontaneity. However, daily dosing increase the burden to patients, side effects and cost of therapy.
It remains to be seen whether daily dosing in severe ED is of benefit, but for now on-demand dosing remains the most appropriate regimen for patients with ED.
