Antihypertensive dose-response relationships: studies with the selective alpha 1-blocking agent terazosin

Terazosin is a selective alpha 1-adrenergic-blocking agent indicated for the treatment of hypertension. The aim of this multicenter study, performed in 256 patients with mild to moderate essential hypertension, was to define the dosing characteristics of terazosin (in the range of 1 to 80 mg) administered once daily. Patients were randomly assigned to placebo or active treatment groups; each group received 3 months of treatment, which comprised three ascending doses of terazosin, each administered for a 1-month period. As determined by conventional office measurements of supine diastolic blood pressure and by automated ambulatory blood pressure monitoring, there was a clear antihypertensive dose-response relationship for terazosin in the range of 1 to 5 mg daily. Except for the 80 mg dose, none of the doses above 5 mg (10 to 40 mg) appeared to provide additional efficacy. Both the office measurements and the monitoring data indicated that the ratio of trough (effect at the end of the dosing interval) to peak (maximum effect during the dosing interval) was at least 50% or greater during treatment with the 5 mg dose. Thus the 5 mg dose appeared to provide meaningful clinical antihypertensive efficacy and to sustain its effects throughout the full 24-hour period.