An orally available, alpha-1 adrenoreceptor (alpha-1a) selective antagonist that can be used to relieve symptoms of benign prostate hyperplasia (BPH). Upon administration, silodosin selectively binds alpha-1a receptors located in the human prostate and bladder with high affinity and blocks signaling pathways mediated by alpha-1a. Blockade of these receptors causes smooth muscle relaxation, lowers intraurethral pressure, and results in improved urine flow and a reduction in the symptoms of BPH, such as difficulty with urinating, painful urination, urinary frequency and incomplete bladder emptying. In addition, silodosin may be used to improve lower urinary tract symptoms, which can occur after receiving radiation therapy for prostate cancer.