Thirty hypertensive outpatients were treated with moxonidine for 4 weeks in an intraindividual comparison study. After a wash-out period of at least 2 weeks the same patients were given prazosin for 4 weeks. The initial daily doses were 0.2 mg moxonidine and 1 mg prazosin. The antihypertensive dose was titrated individually until the diastolic blood pressure (BP) fell below 95 mm Hg.
Within 3 days of dose titration, a mean dose of 0.37 mg moxonidine produced a significant decrease in BP from a mean of 184/100 to 155/90 mm Hg, while in prazosin treated patients 5 to 8 days were necessary to reduce the BP from 180/100 to 149/89 mm Hg; the mean prazosin dose was 2.8 mg. In addition to the lower dose of moxonidine compared to prazosin, it was found that in 67% of patients moxonidine was given once daily whilst prazosin was administered three-time daily in 73%.
Within the first week of moxonidine treatment 14/30 patients experienced dryness of the mouth, but it was so mild that the patients did not want to discontinue the trial. In contrast, 3/30 patients discontinued therapy with prazosin because of side effects. The most frequent adverse effects of prazosin were orthostatic dysregulation in 6 patients, pain in the chest in 5, giddiness and tachycardia in 4 and nervousness in 3 patients; no patient had these complaints whilst on moxonidine.
In intraindividual comparisons with moxonidine, efficacy, tolerance and the well-being of the patients were significantly better than when on prazosin.