Silodosin is a novel alpha(1)-adrenoceptor antagonist with high uroselectivity. The company licensed silodosin from Kissei Pharmaceuticals Co., of Japan in April 2004, to develop and market silodosin in the US, Canada and Mexico.
Watson has begun to enroll patients for two large silodosin phase III studies, which will further evaluate the efficacy and safety of 8mg once-daily silodosin in patients with signs and symptoms of Benign Prostatic Hyperplasia (BPH).
These multi-center (approximately 90 sites), double-blind, placebo- controlled trials, which will run for 12 weeks, will evaluate a total of 1,200 patients with signs and symptoms of BPH, in the US. Watson plans to submit a New Drug Application for silodosin in 2008.
The primary objective of the trials is to demonstrate that the effectiveness of 8mg silodosin given once daily for 12 weeks is superior to placebo for the relief of BPH symptoms, as measured by a baseline-to-endpoint change in the total score of the International Prostate Symptom Score-1.
Meanwhile, silodosin licensor, Kissei Pharmaceuticals has completed phase III studies in Japan under different protocols and dosage levels and has filed a marketing application with the Pharmaceutical and Medical Device Agency in Japan.