NEW YORK (Reuters Health) – A comparison trial conducted in Taiwan indicates that silodosin improves lower urinary tract symptoms associated with benign prostatic hyperplasia at least as well as tamsulosin, and with less hypotensive side effect.
Like tamsulosin, silodosin is a selective alpha-1A-adrenoreceptor blocker, but it has an even higher preferential selectivity, explain Dr. Hong-Jeng Yu, with the National Taiwan University Hospital in Taipei, and colleagues in BJU International online May 18.
To see if the high receptor subtype selectivity of silodosin confers a clinical advantage, the team conducted a randomized double-blind study comparing it to tamsulosin in 209 BPH patients. They were randomized to silodosin 4 mg BID or tamsulosin 0.2 mg/daily (the recommended dose in Asian men) for 12 weeks.
The primary endpoint was the change from baseline in International Prostate Symptom Score. A decrease of 25% or greater was achieved by 86.2% of patients in the silodosin group compared with 81.9% of those in the tamsulosin group (p=0.53), according to the report.
The difference in IPSS score change between the two groups was 0.60, within the pre-specified non-inferiority margin of 1.0, the researchers report. Secondary measures of maximal urinary flow rate and health-related quality of life were similar in both groups.
Mean systolic blood pressure dropped by 4.2 mm Hg with tamsulosin, but by only 0.1 mm Hg with silodosin. As the authors note, “A hypotensive effect may pose a significant problem among the older population because it may lead to serious morbidity, e.g. falls and fractures.”
The two most common adverse effects were abnormal ejaculation (silodosin 9.7% vs tamsulosin 1.0%) and dizziness (silodosin 7.8% vs tamsulosin 2.9%). Still, only two patients discontinued silodosin treatment, Dr. Yu and colleagues note.
Given these results, they conclude, “Silodosin can be considered an effective and safe treatment for BPH.”
BJU Int 2011.