A randomized, double-blind crossover study of tamsulosin and controlled-release doxazosin in patients with benign prostatic hyperplasia

OBJECTIVE To compare the effects of the doxazosin gastrointestinal therapeutic system, extended-release (doxazosin-GITS) formulation, and tamsulosin, another alpha(1)-antagonist, on total International Prostate Symptom Score (IPSS) and maximum urinary flow rate (Q(max)) in treating patients with benign prostatic hyperplasia (BPH). PATIENTS AND METHODS Data were analysed from a prospective, randomized, double-blind, crossover study of men aged 50-80 years with concomitant BPH and hypertension as inclusion criteria. Fifty-two men were treated in four phases: phase I, placebo run-in for 2 weeks; phase II, first study drug doxazosin-GITS or tamsulosin for 8 weeks; phase III, washout with placebo for 2 weeks; and phase IV, second study drug tamsulosin or doxazosin-GITS for 8 weeks. Doxazosin-GITS was started at 4 mg/day and tamsulosin at 0.4 mg/day, and then titrated to 8 mg/day and 0.8 mg/day, respectively, after 4 weeks of therapy if the increase in Q(max) was < 3 mL/s or the reduction in total IPSS was < 30%. Efficacy assessments included the IPSS and Q(max). Changes in blood pressure were not analysed, as most patients were actually not hypertensive. Endpoint efficacy data were analysed using an analysis of covariance model, with terms for sequence, phase, patients and sequence within patients, in addition to the baseline as covariate. Forty-seven men were treated in both efficacy arms of the study and were evaluable for analysis. RESULTS Doxazosin-GITS and tamsulosin significantly relieved lower urinary tract symptoms and significantly increased Q(max) from baseline (P = 0.001). Doxazosin-GITS produced significantly greater improvements than tamsulosin in total IPSS (P = 0.019) and obstructive subscores (P = 0.004) at the last treatment visit. The difference between doxazosin-GITS and tamsulosin in improving Q(max) approached significance in favour of the former (mean change from baseline 2.6 vs 1.7 mL/s, respectively; between-group difference P = 0.089). Both treatments were well tolerated. CONCLUSIONS Treatment with doxazosin-GITS was significantly more effective than tamsulosin in relieving lower urinary tract symptoms.