Efficacy and tolerability of doxazosin alone or in combination with chlorthalidone in essential hypertension

This study investigated (1) the efficacy and safety of doxazosin versus enalapril when added to a diuretic regimen in essential hypertensive patients and (2) the effect of doxazosin alone or combined with chlorthalidone on postural hemodynamics, the renin-angiotensin-aldosterone system, renal function, and plasma catecholamines. Doxazosin reduced blood pressure comparably to enalapril; when added to chlorthalidone, doxazosin showed an additive effect, although to a lesser extent than that obtained when enalapril was added to chlorthalidone. One patient treated with doxazosin alone stopped therapy because of severe headache. The hemodynamic and humoral response to tilting was comparable for doxazosin and enalapril either alone or in combination with chlorthalidone. In particular, no patient experienced symptomatic orthostatic hypotension after the first dosing of doxazosin even when the diuretic regimen was initiated. These findings confirm the efficacy and safety of doxazosin alone or in combination with diuretics.