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

Doxazosin, a selective alpha 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 less than or equal to 90 mm Hg with greater than or equal to 5 mm Hg reduction or greater than or equal to 10 mm Hg reduction) at a mean daily dose of 2.4 mg. Ninety-three percent achieved blood pressure control (sitting DBP less than or equal to 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 less than 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 There was only one side effect (vertigo) that warranted dose reduction, and only one patient was withdrawn from therapy (nausea).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.(ABSTRACT TRUNCATED AT 250 WORDS)