Comparative antihypertensive effects of guanabenz and methyldopa

The effects of guanabenz acetate, a centrally acting alpha-adrenergic, non-sodium-retaining antihypertensive agent, were compared with those of methyldopa in 248 hypertensive outpatients during a one-year, double-blind, multi-center study. Mean supine diastolic blood pressure (SDBP) decreased from 102 to 91 mmHg (P less than 0.01) among 78 guanabenz-treated patients and from 101 to 92 mmHg (P less than 0.01) among 89 methyldopa-treated patients who completed six months of treatment. Clinically significant individual SDBP decreases occurred in 76% of the guanabenz-treated patients and in 63% of the methyldopa-treated patients (P less thn 0.05). Blood pressure remained unchanged during the second six months, with response of 82% and 60%, respectively, for guanabenz and methyldopa (P less than 0.05). Although drowsiness and dry mouth occurred more frequently with guanabenz, evidence of fluid retention, such as weight gain, edema, and congestive heart failure, was significantly more frequent with methyldopa than with guanabenz. Because it does not induce volume expansion, guanabenz, unlike methyldopa, may be useful as sole initial antihypertensive therapy.