A second phase III multicenter placebo controlled study of 2 dosages of modified release tamsulosin in patients with symptoms of benign prostatic hyperplasia. United States 93-01 Study Group

Abstract

Purpose: In a double-blind, phase III clinical trial we evaluate the safety and efficacy of 0.4 and 0.8 mg. tamsulosin daily for the treatment of patients with symptoms of moderate to severe benign prostatic hyperplasia.

Materials and methods: Patients meeting the basic requirements of the study underwent a 4-week single-blind placebo evaluation period. A total of 735 patients were randomized to double-blind therapy with tamsulosin or placebo. Treatment duration was 13 weeks. Efficacy and safety were evaluated at 5 visits during the double-blind treatment period.

Results: When efficacy data between baseline and end point were compared there was a significant reduction in total American Urological Association symptom score (25%) in each tamsulosin group compared with placebo (p = 0.01) and the percentage of patients with a 30% or more reduction in peak urinary flow rate was significantly greater in the tamsulosin versus placebo group (p <0.05). Improvements in American Urological Association symptom scores and maximum flow rate occurred at 1 week of treatment. None of the patients experienced a first dose effect. There were no significant changes in blood pressure on standing at any visit during the study except for a decrease in systolic blood pressure of 20 mm. Hg or more between the 0.8 mg. dose and placebo groups at visit 4 (p = 0.036). Positive orthostatic tests were significantly more frequent in the 0.8 mg. group compared with placebo at visit 4 (p = 0.012). The treatment groups did not differ significantly in incidence of electrocardiogram abnormalities at each post-baseline visit and at end point.

Conclusions: Tamsulosin was safe and effective, and clinically and statistically superior to placebo in relieving symptoms of benign prostatic hyperplasia in men with moderate to severe symptoms at baseline. There was no evidence of a first dose effect and no clinically significant orthostatic hypertension. In addition, response to treatment was rapid.