Safety and efficacy of 8-mg once-daily vs 4-mg twice-daily silodosin in patients with lower urinary tract symptoms suggestive of benign prostatic hyperplasia (SILVER Study): a 12-week, double-blind, randomized, parallel, multicenter study.

Objective: To show the noninferiority of silodosin 8-mg once-daily (QD) to 4-mg twice-daily (BID) in efficacy and safety in patients with lower urinary tract symptoms or benign prostatic hyperplasia in the Korean population.

Methods: A prospective, multicenter, double-blind, randomized, comparative study was conducted. A total of 532 male patients aged ≥50 years with lower urinary tract symptoms or benign prostatic hyperplasia were included. All patients received silodosin QD or BID for 12 weeks. The primary end point was the change from baseline in total International Prostate Symptom Score (IPSS) at 12 weeks. Adverse drug reactions, vital signs, and laboratory tests were recorded.

Results: A total of 424 patients were randomized to the silodosin QD or BID groups. These groups were not significantly different in baseline characteristics. The mean total IPSS change in QD group was not inferior to that in BID group (-6.70 and -6.94, respectively; 95% confidence interval, -0.88 to 1.36). The QD and BID groups did not significantly differ in the following: percentages of patients with ≥25% (63.41% and 67.82%, respectively; P = .349) or ≥4-point improvement in total IPSS (65.85% and 69.31%, respectively; P = .457), maximum urinary flow rate improvement ≥30% (47.32% and 40.59%, respectively; P = .172), changes in IPSS voiding subscore (-4.42 ± 4.93 and -4.65 ± 4.77; P = .641), IPSS storage subscore (-2.05 ± 3.07 and -2.52 ± 2.97; P = .117), quality of life (-1.19 ± 1.49 and -1.40 ± 1.42; P = .136), maximum urinary flow rate (3.55 ± 5.93 and 3.74 ± 6.79 mL/s; P = .768), International Continence Society male questionnaire score, Patient Goal Achievement Score, or Treatment Satisfaction Question. The 2 groups had similar frequencies of adverse drug reactions.

Conclusion: QD administration of silodosin was not inferior to BID in efficacy. The 2 groups had similar adverse drug reaction profiles.