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

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 tr act symptoms due to benign prostatic hyperplasia, targets alpha(1A)-adrener gic receptors of prostatic smooth muscle with greater affinity than the vas cular alpha,, receptors. Since the alpha(1A)-adrenoceptor subtype mediates prostatic smooth muscle tension, alpha(1A)-adrenoceptor antagonists may dim inish toxicity, with few unwanted effects on blood pressure, while still pr oviding efficacious treatment. Methods. This study extended two 13-week trials and one 40-week extension t rial for an additional 64 weeks. On study entry, all patients (n = 949) rec eived 0.4 mg/day tamsulosin. Baseline values were taken from either those o f 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 dr ug. The primary efficacy parameters were the changes in the total American Urological Association (AUA) symptom score, mean peak urinary flow rate (Qm ax), and percentage of patients having 25% or greater improvement in the to tal AUA symptom score and 30% or more improvement in the Qmax. Safety was a ssessed primarily on the incidence and severity of adverse events and disco ntinuations due to adverse events. Results. Improvements from baseline were seen in all primary efficacy param eters and were maintained throughout the study. The changes from baseline f or the total AUA symptom score and Qmax were statistically significant (P < 0.001) at all 3-month intervals. Tamsulosin was well tolerated, and the in cidence of adverse events did not increase over time. The mean sitting vita l signs did not vary from baseline or relative to the treatment duration. Conclusions. Tamsulosin was safe and effective in long-term treatment (long er than 1 year) of benign prostatic hyperpasia. UROLOGY 57: 466-470, 2001, (C) 2001, Elsevier Science Inc.