Improvement of pressure flow parameters with finasteride is greater in menwith large prostates

Purpose: We assess the effect of finasteride, a 5 alpha-reductase inhibitor , on objective voiding parameters in men with lower urinary tract symptoms and benign prostatic enlargement on digital rectal examination (known as cl inical benign prostatic enlargement) in a double-blind placebo controlled m ulticenter study using strict standard:pressure flow study techniques. Materials and Methods: A modification of the Abrams-Griffiths nomogram was used by 1 reader to ensure that all patients met objective criteria for bla dder outlet obstruction at, baseline. After performing a pressure flow stud y patients with obstruction were randomized 2:1 to receive 5 mg. finasterid e (81) or placebo (40) daily. A second pressure flow study was performed at month 12. At baseline and month 12 free urinary flow studies and transrect al ultrasound were performed, and International Prostate Symptom Score ques tionnaires were completed. Patients were treated between May 1994 and July 1996. Results: Finasteride caused a significant decrease (-8.1. cm. water) in det rusor pressure at maximum flow (p <0.05 versus placebo p = 0.02), increase (+1.1 ml. per second) in maximum flow rate (p <0.05 versus placebo p 0.02) and decrease (-22.8%) in prostate volume (p <0.05 versus placebo p <0.001). Men with prostates larger than 40 cc had greater improvement in detrusor p ressure at maximum flow (between group difference - 14.5 cm. water, 95% con fidence interval -26.2 to -2.6, p = 0.02) and maximum flow rate (mean treat ment effect +1.6 mi. per second, 95% confidence interval -0.2 to 3.0, p = 0 .02) compared to those with prostates 40 cc or less (between group differen ces not significant). Conclusions: Finasteride treatment resulted in improvements in urodynamic p arameters, which were greater in men with large prostates.