Urodynamic effects of finasteride in the treatment of bladder outlet obstruction due to benign prostatic hyperplasia.

Urodynamic effects of the 5-alpha-reductase inhibitor, finasteride, were studied in the treatment of patients with bladder outlet obstruction due to benign prostatic hyperplasia (BPH). A total of 36 patients was randomly assigned in a double-bind manner to receive either 5 mg. finasteride daily (19) or placebo (17) for 6 months. The possible relief of bladder outlet obstruction was monitored with uroflowmetry and repeated urodynamics. The mean flow rate, detrusor opening pressure, detrusor pressure at maximum flow and maximum detrusor pressure improved significantly in the patients treated with finasteride. There were no significant differences in the improvement of symptom score or peak flow rate, or in the reduction of residual urine between the finasteride and placebo groups. The treatment resulted in 30% average decrease in prostatic size and 46% decrease in prostate specific antigen concentration. The efficacy of finasteride in relief of bladder outlet obstruction caused by BPH seems to be of the same degree as that achieved by chemical castration therapy but without any significant side effects. There were wide variations among BPH patient response to finasteride treatment. Further studies are needed to define the responders who benefit from this treatment.