Durability of Response Following Cessation of Tadalafil Taken Once Daily as Treatment for Erectile Dysfunction

Abstract

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