A three month double-blind study of doxazosin as treatment for benign prostatic bladder outlet obstruction.

Objective: To evaluate the efficacy and tolerability of doxazosin in the treatment of bladder outflow obstruction resulting from benign prostatic hyperplasia (BPH).

Patients And Methods: One-hundred and thirty-five patients with symptomatic urodynamically confirmed obstructive BPH were treated for 12 weeks with either doxazosin (67 patients) or placebo (68 patients) after an initial 2 week baseline evaluation. The main outcome measures were urodynamic and symptomatic evaluation for efficacy. Blood pressure and adverse events were monitored.

Results: Data were obtained in 122 patients (60 doxazosin, 62 placebo). Doxazosin produced increases in both mean and maximum urinary flow rates of 1.01 ml/s and 3.2 ml/s respectively, compared with 0.21 ml/s and 2.2 ml/s on placebo. The increase in mean flow rate was statistically significant (P = 0.04), while that for maximum flow rate approached significance (P = 0.09). The maximum subtracted voiding pressure was substantially reduced (P = 0.007) and 19 of 53 (36%) patients had an increase in maximum flow rate of 50% or more compared with 9 of 54 (17%) on placebo (P = 0.024). Twelve weeks' therapy with doxazosin resulted in significant improvements (compared with placebo) in: hesitancy (doxazosin 26 of 46, placebo 11 of 43; P = 0.003), impaired urinary stream (doxazosin 31 of 55, placebo 16 of 48; P = 0.019) nocturia (doxazosin 22 of 56, placebo 10 of 54; P = 0.017) and urgency (doxazosin 27 of 45, placebo 16 of 42; P = 0.041). Frequency improved with doxazosin therapy (doxazosin 26 of 59, placebo 15 of 55; P = 0.062). Adverse events, most frequently dizziness and headache, were usually mild and transient and led to a discontinuation of doxazosin therapy in one patient. No clinically significant changes in sexual function or blood pressure were seen.

Conclusion: Doxazosin was well-tolerated and produced both urodynamic and symptomatic improvement in men with BPH, thereby providing a satisfactory alternative to existing drugs with the additional benefit of once daily dosage.