The antihypertensive effects and side-effects of guanfacine and clonidine were compared in a single-blind, cross-over study. 2. The study consisted of two active treatment periods of 6 weeks each, which were both preceded by a 2 weeks placebo period. Thirty ambulatory, hypertensive patients (blood pressure WHO severity grades I-II) were admitted to the study. The results are based on the 24 patients who completed the study. 3. The optimal daily dose of guanfacine was in over half of the patients 3-4 mg, and of clonidine correspondingly 0.3-0.45 mg. A similar and statistically significant decrease in blood pressure was achieved with both drugs. 4. The most common side-effects with both drugs were tiredness and dryness of the mouth.
