Silodosin in the treatment of the signs and symptoms of benign prostatic hyperplasia: a 9-month, open-label extension study.

Objectives: To evaluate long-term safety of the highly selective alpha(1A)-adrenoceptor antagonist silodosin in men with signs and symptoms of benign prostatic hyperplasia (BPH).

Methods: Patients enrolled in this open-label extension study had completed 1 of 2 identical double-blind, placebo-controlled 12-week studies of silodosin treatment for symptomatic BPH. For 40 weeks, patients received silodosin 8 mg once daily with breakfast. Adverse events (AEs) were recorded to evaluate safety. Change in International Prostate Symptom Score was a secondary variable.

Results: Of the 661 participants, 435 (65.8%) completed the study; 431 patients (65.2%) experienced 924 AEs. No serious AEs that were considered drug-related by investigators occurred. AEs reported most often (percentage of patients) were retrograde ejaculation (20.9%), diarrhea (4.1%), and nasopharyngitis (3.6%). Orthostatic hypotension and dizziness occurred in 2.6% and 2.9% of patients, respectively. The percentage of patients with treatment-emergent AEs, stratified by preceding double-blind treatment (placebo or silodosin), was higher for de novo (previous treatment with placebo, 71.5%) than for continuing silodosin treatment (58.3%). More patients receiving de novo (7.5%) vs continuing treatment (1.9%) discontinued study participation because of retrograde ejaculation. Mean International Prostate Symptom Score change (standard deviation) from baseline to week 40 (observed cases) was -4.5 (6.7) for de novo treatment (P <.0001) and -1.6 (6.0) for continuing treatment (P <.01).

Conclusions: Silodosin was well tolerated by men with BPH-related symptoms and was associated with low incidences of dizziness and orthostatic hypotension. Discontinuation because of retrograde ejaculation was more common among patients receiving silodosin de novo than in those who continued silodosin treatment.