Long-term evaluations of therapeutic efficacy and safety of guanfacine.

To assess the long-term efficacy and safety of guanfacine, a centrally acting alpha-adrenergic agonist, 580 mild, moderate and severe hypertensive subjects were treated with the drug for 1 year. Mean ages of both the 257 women and 323 men were 52 years. Most had essential hypertension; 55 patients had renal, 22 renovascular and 4 endocrine-related hypertension. When possible, 1- to 3-week washout periods were used before and after treatment. Doses up to 20 mg/day were used in some patients. Diuretics, beta blockers, vasodilators or some combination thereof were used in some patients. After the 1-year study, 169 patients were continued on therapy for another year, and 54 were evaluated for 5 to 7 years. Normalized blood pressures (BPs) were achieved in 54%, 66% and 63% of patients in the first, second, and 5- to 7-year groups, respectively. Guanfacine, alone and in combination, proved safe and effective. Once- and twice-a-day doses were superior to 3-times-a-day dosing. Lower doses were more effective and produced fewer side effects. Large-scale, open-field studies evaluated the effect of low-dose therapy in 1,234 Belgian, 3,504 French and 4,627 German patients, with average BPs of 180/103 mm Hg. The average BP reduction during treatment was 16%. Most Belgian (56%) and French (74%) patients received 2 mg/day; 60% of German patients received 1 mg/day throughout the study. BPs normalized in 71% of Belgian, 58% of French and 61% of German patients.