Efficacy and safety of dutasteride in the four-year treatment of men with benign prostatic hyperplasia

Objectives To assess the long-term safety and efficacy of dutasteride, a dual type 1 and type 2 5-α-reductase inhibitor, in the treatment of symptomatic benign prostatic hyperplasia and associated lower urinary tract symptoms. Methods Data from two Phase IIIa multicenter, randomized, placebo-controlled trials of 2-year duration plus a 2-year open-label extension were pooled and analyzed. The entry criteria included age 50 years old or older, clinical diagnosis of benign prostatic hyperplasia, prostate volume of 30 cm³ or greater, American Urological Association symptom score of 12 or greater, peak urinary flow rate of 15 mL/s or less, and prostate-specific antigen level of 1.5 ng/mL or greater but less than 10 ng/mL. Results A total of 2802 men were randomized into the double-blind phase of the two studies with 1908 patients (68%) completing the study. Of these, 1570 subjects were enrolled in the open-label phase, and 569 subjects received dutasteride for 48 months. Changes at the 48-month visit for dutasteride/dutasteride-treated subjects included improvement in prostate volume (-26.2%), American Urological Association Symptom Index (-6.1 points), and peak urinary flow rate (+2.8 mL/s). Changes for the placebo/dutasteride group included prostate volume (-20.7%), American Urological Association Symptom Index (-5.3 points), and peak urinary flow rate (+1.8 mL/s). Acute urinary retention and surgery occurred in a small percentage of subjects (less than 2% and less than 1%) in the open-label extension phase. Dutasteride was well tolerated with no statistically significant increase in drug-related adverse events during the open-label extension and no adverse laboratory trends. Conclusions Dual inhibition of 5-α-reductase with dutasteride provided sustained efficacy in subjects with symptomatic benign prostatic hyperplasia treated for 48 months. Near-complete, long-term suppression of dihydrotestosterone (93% at 48 months) with dutasteride did not lead to an increase in adverse events compared with that reported in the 2-year period.