A single-blind study of doxazosin in the treatment of essential hypertension when added to nonresponders to angiotensin-converting enzyme inhibitor therapy

Abstract

Doxazosin, a selective α 1-inhibitor, was assessed in hypertensive patients with sitting diastolic blood pressures (DBPs) of 95 to 114 mm Hg while receiving a stable dose of captopril or enalapril. Fifty-six patients were entered into the study that involved three phases: (1) a 2-week baseline period, (2) a 10-week period in which patients received doxazosin, 1 to 8 mg, once daily, and (3) a 4-week maintenance period. After 14 weeks of doxazosin treatment, 95% of the patients were therapy successes (sitting DBP either ≤90 mm Hg with ≥5 mm Hg reduction or ≥10 mm Hg reduction) at a mean daily dose of 2.4 mg. Ninety-three percent achieved blood pressure control (sitting DBP ≤90 mm Hg) at a mean dose of 2.3 mg once daily. By the final treatment visit, systolic/diastolic sitting blood pressures for efficacy evaluable patients were reduced by 16 17 mm Hg from a mean baseline of 158 101 mm Hg to a final value of 143 84 mm Hg . Throughout the study (2 to 14 weeks), all blood pressure reductions from baseline were significant ( p < 0.05). There was only one side effect (vertigo) that warranted dose reduction, and only one patient was withdrawn from therapy (nausea). Most side effects were mild or moderate and disappeared or were tolerated with continued therapy. No clinically significant laboratory changes were apparent, and no trends were observed with regard to organ systems or correlations with dose or duration of treatment. The investigators' global assessment of efficacy of once-daily doxazosin therapy was excellent or good for 94% of patients and fair or poor for 6% of patients. The investigators' global assessment of patient toleration of doxazosin treatment was excellent or good for 93% of the 56 patients evaluated and fair or poor for 7% of patients. Total cholesterol was significantly decreased ( p = 0.03), and the ratio of high-density lipoprotein to total cholesterol was significantly increased ( p = 0.02) after doxazosin therapy. From baseline to final visit there was a highly significant reduction of 24% ( p < 0.001) in calculated coronary heart disease risk score on the basis of the Framingham equation.