The relationship between terazosin dose and blood pressure response in hypertensive patients.

A double-blind, randomized, placebo-controlled, multicenter study was conducted to describe the dose-response curve for terazosin on blood pressure. A total of 128 patients with mild to moderate essential hypertension (supine diastolic blood pressure, 100 to 114 mmHg) participated in the study. The study consisted of a 4-week single-blind placebo lead-in period and a 14-week double-blind treatment period. Patients were randomized in equal numbers to four parallel treatment groups: terazosin 1, 2, and 5 mg; terazosin 2, 5, and 10 mg; terazosin 20, 40, and 80 mg; and placebo. The 24-hour ambulatory blood pressure measurements were performed at the end of the placebo lead-in period and at the end of each 4-week fixed-dose period. The nonlinear, mixed-effect model computer program was used to analyze the dose-response relationship. There was a strong dose-response relationship between fall in blood pressure and the 1 to 10 mg terazosin dose, as well as a plateauing of response for terazosin doses above 10 mg. The maximum antihypertensive response (Emax) to terazosin was 10.7 mmHg for systolic blood pressure and 8.0 mmHg for diastolic blood pressure. The daily dose of terazosin, which produced 50% of the maximum response (ED50), was 3.0 mg for systolic blood pressure and 1.5 mg for diastolic blood pressure. The results of this study suggest that although some patients may benefit from terazosin doses of greater than 10 mg, doses up to 10 mg will maximize therapeutic benefit for most patients, with acceptable side effects.