Long-term therapy of hypertension with guanabenz.
Guanabenz, a centrally acting antihypertensive (alpha-agonist) that does not induce secondary sodium retention or other metabolic disturbances, was evaluated for up to two years at 19 investigational sites. In 329 patients completing six months of therapy, the mean supine diastolic blood pressure (SDBP) fell from 101 to 90 mmHg (P less than 0.01). Clinically significant individual SDBP decreases occurred in 74% of the patients by week 2, and these reductions were maintained in 72% at six months. Mean weight was reduced 1.4 lb (P less than 0.01), and mean supine pulse rate was decreased 5 beats/min (P less than 0.01). The most frequent effective doses were 8 and 16 mg BID (range, 2 to 32 mg BID). Principal side effects, usually mild, were sedation (31%), dry mouth (24%), dizziness (6%), and weakness (6%). Postural hypotension, impotence, and abrupt discontinuation symptoms were rare or absent. There were no clinically significant drug-related laboratory changes other than a 10 mg/100 ml mean serum cholesterol decrease. Two hundred twenty-two patients completed one year of therapy, and 80 completed two years, with little change in any parameters other than improvement in mean SDBP to 85 mmHg and in individual response rate to 84%. These results suggest that guanabenz is safe and effective for initial and sole therapy of hypertension.