Long-term clinical experience with guanfacine.

Efficacy of guanfacine was studied in 20 hypertensive patients and 20 patients with diabetes mellitus and hypertension in a 12-month follow-up. Besides routine biochemical parameters, glycaemia, platelet aggregation and the parameters of serotonergic and adrenergic activity (5-hydroxyindoleacetic acid and vanilmandelic acid urinary excretion) were investigated. Blood pressure was well controlled and no changes in glucose levels occurred in either of the study groups. The decrease in the urinary excretion of vanilmandelic and 5-hydroxyindoleacetic acid was more marked in hypertensive patients with normal glucose tolerance. These data suggest that activity of both adrenergic and serotonergic systems may be more impaired in diabetes. Further, changes in the serotonergic system are not caused only by antiserotonergic drugs. Finally, guanfacine was shown to be an effective and suitable drug for the long-term treatment of hypertension, particularly in patients with diabetes mellitus II.