The study involved 87 centers across Europe, the United States, Canada and South Africa between December 2004 and September 2007.

A total of 423 patients completed the study. The inclusion of the on-demand dosing regimen enabled comparison of the currently recommended guidelines for the use of PDE5 inhibitors with a proposed nightly dosing regimen. The results clearly show that nightly dosing with vardenafil does not have any effect beyond that of on-demand use.

The study, published in European Urology, shows that on-demand use of vardenafil during the treatment period was associated with significantly greater erectile function and sexual intercourse completion rates compared to placebo. The success rates for the vardenafil on-demand group were also higher than for the nightly group.