Comparative trials of terazosin with other antihypertensive agents

The efficacy and safety of terazosin were compared with those of other antihypertensive drugs in three parallel-group, randomized, double-blind studies in which 133 patients with mild to moderate hypertension participated. In two studies, terazosin monotherapy was compared with placebo and prazosin (study M79-073), or with hydrochlorothiazide (study M80-012). In a third study (M80-013), the combination of terazosin plus hydrochlorothiazide was compared with the combination of prazosin plus hydrochlorothiazide. Doses of study medications were administered twice daily and were increased at weekly intervals until the average supine diastolic blood pressure was 90 mm Hg or less, with a decrease from baseline of at least 10 mm Hg, or until the maximum specified dosage of a given study drug was reached. In general, all active treatments resulted in significant decreases from baseline in supine and standing blood pressures. There was no significant difference between terazosin- and prazosin-treated patients for changes from baseline to the final visit in supine or standing blood pressure measurements (study M79-073). Hydrochlorothiazide had a significantly greater effect on supine diastolic blood pressure when compared with terazosin (study M80-012). Otherwise, there were no significant differences between active treatment groups. Overall, no regimen caused clinically important changes in pulse rates, body weights, laboratory test results, physical examinations, or electrocardiograms. The incidence of side effects was approximately the same for all drugs; the most common side effects were headache, dizziness, malaise, asthenia, and nasal congestion. The results of these studies suggest that terazosin exhibits antihypertensive activity that is quantitatively similar to that of prazosin in patients with mild to moderate hypertension, and that a dose of 1 to 10 mg twice daily is well tolerated.