EFFECTS OF CLONIDINE ON CEREBRAL BLOOD-FLOW IN HYPERTENSIVE PATIENTS

The chronic effect of clonidine on cerebral blood flow was studied in a two-month open study. Ten hypertensive patients (six men and four women) with a mean age of 59.6 years (range, 43 to 68 years) were included. None of the patients had been treated with antihypertensive drugs prior to the study. The cerebral blood flow was measured by atraumatic xenon-133 inhalation technique at the beginning of the study and after a two-month treatment with 150 to 300-mu-g of clonidine once a day. Blood pressure fell from 178.3 +/- 9.7/103.3 +/- 8.2 mmHg to 143.5 +/- 9.0/87.9 +/- 8.6 mmHg (P < 0.05/P < 0.05). No global or focal cerebral blood flow alteration could be detected in the entire group of patients. At the individual level, no patient exhibited a decrease in cerebral blood flow, whereas three had a marked increase in cerebral blood flow. We conclude that the chronic administration of clonidine in patients with uncomplicated mild hypertension had no adverse effect on cerebral blood flow.