Long-term, open-label, phase III multicenter study of tamsulosin in benign prostatic hyperplasia

Abstract

Objectives. To investigate the long-term efficacy and safety of tamsulosin in patients with benign prostatic hyperplasia and to monitor the increases and decreases in therapeutic response over time. Tamsulosin, a uroselective alpha-adrenergic receptor antagonist for the treatment of lower urinary tract symptoms due to benign prostatic hyperplasia, targets alpha 1A-adrenergic receptors of prostatic smooth muscle with greater affinity than the vascular alpha 1B receptors. Since the alpha 1A-adrenoceptor subtype mediates prostatic smooth muscle tension, alpha 1A-adrenoceptor antagonists may diminish toxicity, with few unwanted effects on blood pressure, while still providing efficacious treatment. Methods. This study extended two 13-week trials and one 40-week extension trial for an additional 64 weeks. On study entry, all patients (n = 949) received 0.4 mg/day tamsulosin. Baseline values were taken from either those of the previous trials for patients who had been treated with tamsulosin or the first visit of this study for patients not previously exposed to the drug. The primary efficacy parameters were the changes in the total American Urological Association (AUA) symptom score, mean peak urinary flow rate (Qmax), and percentage of patients having 25% or greater improvement in the total AUA symptom score and 30% or more improvement in the Qmax. Safety was assessed primarily on the incidence and severity of adverse events and discontinuations due to adverse events. Results. Improvements from baseline were seen in all primary efficacy parameters and were maintained throughout the study. The changes from baseline for the total AUA symptom score and Qmax were statistically significant ( P <0.001) at all 3-month intervals. Tamsulosin was well tolerated, and the incidence of adverse events did not increase over time. The mean sitting vital signs did not vary from baseline or relative to the treatment duration. Conclusions. Tamsulosin was safe and effective in long-term treatment (longer than 1 year) of benign prostatic hyperplasia.