Silodosin for Men With Chronic Prostatitis/Chronic Pelvic Pain Syndrome: Results of a Phase II Multicenter, Double-Blind, Placebo Controlled Study

Purpose: We evaluated the efficacy and safety of 2 doses of silodosin vs placebo in men with moderate to severe abacterial chronic prostatitis/chronic pelvic pain syndrome who had not been treated previously with alpha-blockers for chronic prostatitis/chronic pelvic pain syndrome. Materials and Methods: In this multicenter, randomized, double-blind, phase II study, men 18 years old or older with chronic prostatitis/chronic pelvic pain syndrome, a total National Institutes of Health Chronic Prostatitis Symptom Index score of 15 or greater and a National Institutes of Health Chronic Prostatitis Symptom Index pain score of 8 or greater received 4 or 8 mg silodosin, or placebo once daily for 12 weeks. The primary efficacy end point was change from baseline to week 12 in National Institutes of Health Chronic Prostatitis Symptom Index total score. Results: Of 151 patients (mean age 48 years) 52 received 4 mg silodosin, 45 received 8 mg silodosin and 54 received placebo. Silodosin 4 mg was associated with a significant decrease in total National Institutes of Health Chronic Prostatitis Symptom Index score (mean +/- SD change-12.1 +/- 9.3) vs placebo (-8.5 +/- 7.2, p = 0.0224), including a decrease in urinary symptom (- 2.2 +/- 2.7, placebo -1.3 +/- 3.0, p = 0.0102) and quality of life (-4.1 + 3.1, placebo -2.7 +/- 2.5, p = 0.0099) subscores. The 4 mg dose of silodosin also significantly increased Medical Outcomes Study Short Form 12 physical component scores (4.2 +/- 8.1, placebo 1.7 +/- 9.0, p = 0.0492). During global response assessment 56% of patients receiving 4 mg silodosin vs 29% receiving placebo reported moderate or marked improvement (p = 0.0069). Increasing the dose of silodosin to 8 mg resulted in no incremental treatment effects. Conclusions: Silodosin 4 mg relieved symptoms and improved quality of life in men with chronic prostatitis/chronic pelvic pain syndrome but its efficacy requires confirmation in additional studies.