Doxazosin in benign prostatic hyperplasia: effects on blood pressure and urinary flow in normotensive and hypertensive men.

OBJECTIVES

To assess the effects of doxazosin, a selective alpha 1 adrenoceptor inhibitor, on blood pressure and urinary flow in normotensive and hypertensive (sitting diastolic blood pressure more than 90 mm Hg) men with prostatic hyperplasia (BPH).

METHODS

Patients (n = 232) with bladder outflow obstruction due to BPH, classified as normotensive or hypertensive, were enrolled into two, double-blind, placebo-controlled studies. After a washout period of at least 1 week, patients were randomized to doxazosin or placebo, and treatment was continued for 9 to 12 weeks. In addition to measures of standing and sitting blood pressures, the patients' response to treatment was also assessed with regard to urinary flow. Although the protocols differed, they were consistent enough to permit pooling of a number of variables.

RESULTS

Results from the two studies demonstrated that doxazosin produced a clinically significant reduction in blood pressure only in hypertensive patients (systolic blood pressure/diastolic blood pressure: baseline 162/99 mm Hg, endpoint 143/89 mm Hg); little or no reduction was evident in normotensive patients (systolic blood pressure/diastolic blood pressure: baseline 139/82 mm Hg, endpoint 134/78 mm Hg). Similar effects in terms of uroflow were seen in hypertensive and normotensive patients. The maximum flow rate in hypertensive patients treated with doxazosin increased from 8.82 to 10.84 mL/s (+ 23%) and in normotensive patients treated with doxazosin from 8.52 to 10.90 mL/s (+ 28%). A greater than 30% improvement in maximum flow rate was achieved in 46 of 97 (47.4%) patients in the doxazosin group and 26 of 98 (26.5%) patients in the placebo group. Treatment with doxazosin was effective and generally well tolerated. The majority of side effects were mild or moderate, only slightly higher in the active treatment group compared with placebo, and similar in hypertensive and normotensive patients.

CONCLUSIONS

Treatment with doxazosin is effective and well tolerated in the treatment of BPH. It appears to be a particularly appropriate therapy for men with both BPH and hypertension but can be safely administered to normotensive men without causing significant blood pressure reduction. The beneficial effects on urinary flow are similar, irrespective of blood pressure.