We evaluated the effect of long-term administration of finasteride (MK-906), a potent inhibitor of 5 alpha-reductase in patients with benign prostatic hyperplasia (BPH). The effect of an increase in dose was also assessed. Finasteride was administered to 61 patients with BPH at the dose of 1 mg/day for 48 weeks. Thirty three of these patients subsequently received finasteride at the dose of 5 mg/day for further 24 weeks in an open extension study. Urinary symptoms, urinary flow rate, residual urinary volume, prostatic volume and serum concentrations of dihydrotestosterone and prostate-specific antigen were examined periodically during the treatment. The size of the prostate and total urinary symptom scores decreased progressively during the first 16 weeks of treatment. The patients who received finasteride had a significant increase in the maximal urinary flow rate and a significant decrease in residual urinary volume. After 72 weeks of treatment, finasteride at an increased dose of 5 mg did not provide additional benefit to patients, although the effects of the drug at a dose of 1 mg were well maintained. Treatment with finasteride was well tolerated at both doses. In conclusion, the treatment of BPH with 1 mg of finasteride per day for 48 weeks results in a significant increase in maximal urinary flow rate, and a decrease in prostatic volume, symptoms of obstruction and residual urinary volume, with minimal toxicity.
5-alpha Reductase Inhibitors Aged