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January 10, 1994

Maintenance of Clinical Efficacy With Finasteride Therapy for 24 Months in Patients With Benign Prostatic Hyperplasia

Author Affiliations

From Merck Research Laboratories, Rahway, NJ.

Arch Intern Med. 1994;154(1):83-88. doi:10.1001/archinte.1994.00420010111013

Background:  Finasteride, a 5α-reductase inhibitor, has been shown to have beneficial effects in the treatment of benign prostatic hyperplasia. The long-term safety and efficacy of finasteride in the treatment of benign prostatic hyperplasia was assessed.

Methods:  In two multicenter, double-blind, placebo-controlled studies (North American and international), patients with symptomatic benign prostatic hyperplasia were randomly assigned to receive finasteride, 1 or 5 mg, or placebo for 1 year followed by an open-extension study in which all patients were treated with finasteride, 5 mg, regardless of original therapy. Men aged 40 to 80 years, in good physical and mental health, were eligible to enter the study. All patients were to have a maximum urinary flow rate of 15 mL/s or less with a voided volume of 150 mL or more, an enlarged prostate, and symptoms of urinary obstruction. Patients with a prostate-specific antigen level of 40 mg/mL or more or any finding suggestive of prostate cancer were excluded.

Results:  Two hundred ninety-eight patients received finasteride, 5 mg, continuously for 24 months. At the end of 24 months of finasteride therapy, the median prostate volume was reduced by 25%, and 60% of patients had a 20% or greater reduction in prostate volume. Maximum urinary flow rate was improved by at least 2 mL/s, and symptoms were improved by approximately 3.5 points. Decreased libido and ejaculation disorders were the only drug-related adverse experiences reported in more than 1% of patients.

Conclusion:  These studies support the long-term safety and tolerability of finasteride, while demonstrating its continuing clinical efficacy in the treatment of patients with symptomatic benign prostatic hyperplasia.(Arch Intern Med. 1994;154:83-88)