Finasteride (MK-906) in the treatment of benign prostatic hyperplasia. The Finasteride Study Group.

The effects of finasteride, a potent 5 alpha-reductase inhibitor, were assessed in 750 patients with benign prostatic hyperplasia (BPH) in a multicenter, double-blind, placebo-controlled study. Patients were randomized to finasteride, 1 or 5 mg, or placebo, daily for 12 months. The following changes were seen with finasteride 5 mg after 12 months: (1) Serum dihydrotestosterone decreased by 62% compared to no change with placebo (P < 0.001); (2) serum prostate-specific antigen (PSA) decreased by 46% compared to no change with placebo (P < 0.001); (3) prostate volume was reduced by 22% compared to a 5% decrease with placebo (P < 0.001); (4) maximum urinary flow rate increased by 1.7 ml/sec compared to a 0.4 ml/sec increase with placebo (P < 0.025); (5) total urinary symptom scores decreased by 3.3 points compared to a 2.0 point decrease with placebo (P = 0.005), and (6) obstructive symptom scores decreased by 2.1 points compared to a 1.4 point decrease with placebo (P = 0.017). The effects of finasteride 1 mg were similar to 5 mg, except in urinary symptoms, where no significant differences between 1 mg and placebo were seen. Patients treated with 5 mg finasteride demonstrated significantly greater improvements in urological status (assessed by the investigator) and the troublesome symptom score, compared to placebo. Treatment with finasteride was well tolerated. We conclude that finasteride is an effective medical therapy for a significant proportion of patients with BPH.