The antihypertensive effect of guanfacine compared with methyldopa

Guanfacine (BS 100-141) (N-amidino-2-(2,6-dichlorophenyl)-acetamide hydrochloride) is a centrally acting alpha-adrenergic receptor agonist. A comparison of its anti-hypertensive effect with that of methyldopa was made in patients with essential hypertension. After a wash-out period of 8-10 days, 33 patients with hypertension of different degrees of severity were treated with guanfacine or methyldopa, both combined with clorexolone, in a randomized double-blind study extending over 8 weeks. Blood pressure was reduced significantly by both drug treatments, compared with the placebo. The incidence of side-effects with both drugs was low. Those that did occur decreased after adjustment of dosage. Guanfacine was clinically effective in all patients with various degrees of hypertension, but treatment with methyldopa was inadequate in 30% of patients even at maximum dosage. Up to 40 hours after abrupt drug withdrawal, no rebound hypertension was noted in the guanfacine group.