Controlled-release doxazosin as combination therapy in hypertension: the GATES study.

Doxazosin gastrointestinal therapeutic system (GITS) or placebo was added to the antihypertensive therapy of uncontrolled hypertensive patients in a prospective, randomized, double-blind trial. Patients received doxazosin GITS 4 mg/d (n=89) or placebo (n=86) for 6 weeks in addition to entry antihypertensive medication. Doxazosin GITS was increased to 8 mg/d after 2 or 4 weeks if patients did not respond (sitting blood pressure <140/90 mm Hg and 10/10-mm Hg decrease from baseline). Reductions from baseline in sitting and standing blood pressures were greater with doxazosin GITS than placebo at all time points (p</=0.017) except Week 1 sitting systolic pressure (p=0.068). The response rate was greater in the doxazosin GITS group (37.3%) than the placebo group (10.7%; p<0.001). With the exception of postural hypotension (7% compared with 0.0%), the frequency of adverse events was similar for doxazosin GITS and placebo. Doxazosin GITS was effective as combination antihypertensive therapy with the major classes of antihypertensive agents.