Durability of response following cessation of tadalafil taken once daily as treatment for erectile dysfunction.

Introduction: Research has focused on improvement of erectile function during treatment with phosphodiesterase type 5 (PDE5) inhibitors, but less is known about what occurs after treatment cessation.

Aim: The aim of this retrospective analysis was to examine durability of response, defined as sustainability of erectogenic benefits following treatment cessation, in men with erectile dysfunction (ED) following long-term treatment with daily tadalafil.

Methods: The subjects (N=160) had participated in a 12-week double-blind trial followed by a one-year, open-label extension of tadalafil 5mg once daily. The extension was followed by a 4-week, treatment-free follow-up period. A total of 158 subjects completed International Index of Erectile Function-Erectile Function (IIEF-EF) domain score and were included in this analysis.

Main Outcome Measures: The primary measures for this analysis were changes in ED severity category as captured by the IIEF-EF domain score.

Results: At the end of the 1-year open-label treatment period, a majority (86.1%, n=136) of subjects had either improved by at least one ED severity category (e.g., Severe to Moderate) (n=128), or maintained Normal erectile function (EF domain score ≥26) (n=8), compared to baseline. Following the 4-week, treatment-free period, 63 of those subjects (46.3% of the 136 subjects) had continued improvement of at least one ED severity category (n=61) or maintained scores in the Normal category (n=2) compared with baseline. Subjects who showed a sustained benefit of treatment were considered to have demonstrated a "durable response." Seventy-three subjects (53.7%) did not have a durable response following treatment cessation. A few patient characteristics were associated with durability of response.

Conclusions: Of those men who demonstrated improved erectile function while taking tadalafil 5mg once daily for 1 year, 46.3% continued to show improvement compared with baseline following a 4-week treatment free period. Durability of response should be a focus of future research.