To evaluate the efficacy and tolerability of the selective alpha₁-adrenergic antagonist doxazosin and the 5-alpha-reductase inhibitor finasteride, alone and in combination, for the symptomatic treatment of benign prostatic hyperplasia.

In a prospective, double-blind, placebo-controlled trial, 1095 men aged 50 to 80 years were randomized to treatment for 52 weeks with doxazosin, finasteride, the combination of doxazosin and finasteride, or placebo. The dose of finasteride (or its matched placebo) was 5 mg/day. Doxazosin (or its matched placebo) was initiated at 1 mg/day, and titrated up to a maximum of 8 mg/day over approximately 10 weeks according to the response of the maximal urinary flow rate (Qmax) and International Prostate Symptom Score (IPSS). The IPSS and Qmax were assessed at baseline and at weeks 10, 14, 26, 39, and 52 or at the endpoint.

An intent-to-treat analysis of 1007 men showed doxazosin and doxazosin plus finasteride combination therapy produced statistically significant improvements in total IPSS and Qmax compared with placebo and finasteride alone (P <0.05). Finasteride alone was not significantly different statistically from placebo with respect to total IPSS and Qmax. All treatments were generally well tolerated.

Doxazosin was effective in improving urinary symptoms and urinary flow rate in men with benign prostatic hyperplasia, and was more effective than finasteride alone or placebo. The addition of finasteride did not provide further benefit to that achieved with doxazosin alone.