Agent shows benefit in PDE-5 incomplete responders

A greater percentage of men who had an incomplete response to as-needed phosphodiesterase type-5 inhibitor treatment returned to normal erectile function when given tadalafil (Cialis) once daily, compared to placebo, researchers reported.

"PDE-5 inhibitors are highly effective for most men when taken as needed, but responses can range from minimal change to a return to normal erectile function," said lead study author Edward D. Kim, MD, of the University of Tennessee Graduate School of Medicine, Knoxville. "We believe the study outcome will help prescribers make better informed decisions when treating their patients."

The randomized, double-blind, parallel, placebo-controlled trial was conducted in 51 sites in the United States and Canada. The study enrolled men with ED aged 18 years and older who had some response but were unable to reach normal erectile function while on a maximum dose of an as-needed PDE5 inhibitor treatment. The study assessed whether tadalafil for once-daily use is superior to placebo in returning these men to normal erectile function. A total of 623 subjects were randomly assigned to receive treatment with tadalafil for once-daily use or placebo.

The primary objective was to determine whether a significantly greater percentage of incomplete responders had a return to normal erectile function when treated with tadalafil, 2.5 mg titrated to 5 mg and 5 mg once daily compared to placebo. The key secondary objective was evaluation of the efficacy of tadalafil, 2.5 titrated to 5 mg and 5 mg once daily compared to placebo, as measured by change from baseline to endpoint in the International Index of Erectile Function-Erectile Function Domain (IIEF-EF).

Treatment with tadalafil, 2.5 mg to 5 mg and 5 mg met the primary endpoint, resulting in significantly higher percentages of men (38.7% and 39.6%, respectively) with IIEF-EF domain scores in the normal range (≥26) through 12 weeks versus placebo (12.1%; both, p<.001). At week 4, significantly greater percentages of men being treated with tadalafil, 2.5 to 5 mg and 5 mg (33.5% and 41.1%, respectively) had experienced a return to normal erectile function (placebo, 8.5%; both, p<.001), as reported online in the Journal of Sexual Medicine (July 10, 2013).

For the key secondary objective, improvements in the IIEF-EF domain score were statistically significant for the tadalafil, 2.5- to 5-mg group (8.1) and the tadalafil 5-mg group (8.0), compared to the placebo group (1.9; both, p<.001).

Dr. Kim is a speaker for Watson, Astellas, Eli Lilly, and Auxilium, and serves as an investigator and adviser for Eli Lilly. One co-author is a consultant for Eli Lilly, Endo, Abbott, Actient, and Auxilium, and an investigator for Eli Lilly and Auxilium. Another co-author is a speaker/consultant for Astellas, Eli Lilly, Ferring, Janssen, and Watson and a clinical trial investigator for Astellas, Allergan, and Janssen.

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