Comparison of moxonidine and clonidine HCl in treating patients with hypertension.

In a six-week multicenter, double-blind comparison study, moxonidine and clonidine HCl were tested in 122 and 30 outpatients, respectively, with mild to moderate hypertension (World Health Organization stage I and II; highest measured diastolic blood pressure, 90 to 115 mm Hg). Each agent reduced systolic and diastolic blood pressure to a similar significant extent: moxonidine, 25.4 and 12.4 mm Hg, respectively; clonidine, 25.3 and 10.0 mm Hg, respectively (P less than .001 vs baseline). The mean individually titrated dose of moxonidine and clonidine HCl was found to be 0.36 mg/d. Clonidine slightly reduced heart rate in patients assuming an upright position by 3 beats/min at the end of dose titration (P = .018), while moxonidine did not. Two patients receiving moxonidine and three patients taking clonidine HCl discontinued therapy because of side effects. However, patients administered clonidine experienced significantly more side effects (53%) compared with a 30% incidence of adverse effects associated with moxonidine (P = .031). The most frequent adverse effect of both agents was dryness of mouth, which was mentioned significantly more often with clonidine (47%) than with moxonidine (20%) (P = .005). Edemas were found in 0.8% and 17% of patients during six-week treatment with moxonidine and clonidine, respectively (P = .001). Accordingly, moxonidine was tolerated significantly better than clonidine (P less than .001) in this parallel comparison study. Moxonidine is as effective as clonidine in monotherapy of mild to moderate essential hypertension and, additionally, neither drug produces clinically important changes in biochemical parameters.