Efficacy of Silodosin for Relieving Benign Prostatic Obstruction: Prospective Pressure Flow Study

Purpose: We investigated the effect of the new sympathetic alpha 1A-adrenoceptor antagonist silodosin for relieving benign prostatic obstruction by pressure flow study. Materials and Methods: In this open, nonblinded, prospective study we administered 8 mg silodosin daily for 4 weeks in 60 patients with lower urinary tract symptoms associated with benign prostatic enlargement. As a primary outcome measure, we assessed changes in bladder function and benign prostatic obstruction using pressure flow study. As secondary outcome measures, changes in subjective symptoms and quality of life were assessed. by the International Prostate Symptom Score. Objective changes in urination status were also assessed by free uroflowmetry in terms of maximum flow rate and post-void residual urine volume. Results: A total of 57 patients were enrolled for analysis. In the storage phase of the pressure flow study bladder capacity at first desire to void increased significantly with no significant change in maximum cystometric capacity. Of 24 patients 14 (58.3%) with uninhibited detrusor contractions before administration showed apparent improvement in detrusor overactivity after administration, including 6 in whom uninhibited contractions disappeared. In the voiding phase mean detrusor pressure at maximum flow significantly decreased from 72.5 to 51.4 cm H2O. The mean bladder outlet obstruction index decreased significantly from 60.6 to 33.8. Obstruction grade assessed by the Schaefer nomogram improved in all except 1 patient. Total symptom and quality of life scores, maximum flow rate and post-void residual urine volume on free uroflowmetry significantly improved. Conclusions: Silodosin improved lower urinary tract symptoms by improving bladder storage function and relieving benign prostatic obstruction.