Alpha-blockade and thiazide treatment of hypertension. A double-blind randomized trail comparing doxazosin and hydrochlorothiazide.

This trial involved 107 patients in a two-group, parallel, double-blind, randomized study comparing the diuretic, hydrochlorothiazide (HCTZ) (dose 25 to 50 mg) and the alpha 1 antagonist, doxazosin (dose 2 to 16 mg). All randomized participants were followed for at least 1 year. Participants were recruited from the community. The study was carried out in four phases: Phase I-Baseline; Phase II-Monotherapy Titration; Phase III-Combination Therapy Titration; and Phase IV-Maintenance. The following measures were carried out: blood pressure, biochemistries, lipids/lipoproteins, quality of life, ambulatory electrocardiograms, echocardiograms, adverse experiences, and drug adherence. Both drugs were well tolerated, with only 4% taken off doxazosin and 7% off HCTZ. Adverse experiences were uncommon and mostly mild. Both drugs were effective in managing hypertension over 1 year of therapy. There was no difference noted in terms of efficacy of blood pressure lowering between the two study drugs, nor was there any evidence of tolerance developing or of any serious adverse effects. Average final doses for drugs were 7.8 mg for doxazosin and 36 mg for HCTZ. The results show that, over the course of 1 year, both drugs significantly lowered systolic and diastolic pressures compared to baseline; doxazosin (-19 and -16 mm Hg); HCTZ (-22 and 15 mm Hg). Blood pressure lowering was not significantly different between drugs. Sitting heart rate was not affected by drugs. Changes in quality of life measures were similar between groups. Echocardiographic measures at 1 year showed significant between-drug differences in change in left internal end systolic and diastolic dimensions and end systolic stress. Both doxazosin and HCTZ were effective drugs over 1 year for treating hypertension.