Ejaculation disorder is associated with increased efficacy of silodosin for benign prostatic hyperplasia

To provide clinical evidence that ejaculation disorder caused by selective alpha(1A)-blockers may be associated with larger symptomatic improvements in patients with benign prostatic hyperplasia.

Post hoc analyses of data from a randomized, double-blind, placebo-controlled clinical trial of silodosin in Japan were performed. Subjects were randomized into 3 treatments: silodosin (4 mg twice daily), tamsulosin (0.2 mg once daily), or placebo. For statistical analysis, subjects receiving silodosin were stratified by the presence or absence of ejaculation disorder. Efficacy was assessed using total International Prostate Symptom Score (IPSS), IPSS subscores, 25% reduction in total IPSS, and quality of life score. Safety was assessed by frequency of adverse drug reactions (ADRs) and silodosin discontinuation.

The silodosin subgroup with ejaculation disorder (SIL+EjD) showed larger change in total IPSS than the silodosin subgroup without ejaculation disorder (SIL-EjD) (difference: -4.36 [95% CI: -6.44 to -2.27]) and the placebo group (difference: -6.29 [95% CI: -8.44--4.14]). Remarkable improvement was observed at all time points. The success rate in SIL+EjD was higher than in SIL-EjD and placebo when measured using a 25% reduction in the total IPSS category. There were no significant differences in ADR rates other than ejaculation disorder. Discontinuation rates between SIL+EjD and SIL-EjD were similar.

Our results suggest that ejaculation disorder caused by selective alpha(1A)-blockers is associated with very large improvements in lower urinary tract symptoms. Patients with ejaculation disorder may have larger symptomatic improvements without incremental risk for adverse events.