[Effects of clonidine on various blood-coagulation parameters in hypertension]

The effect of oral clonidine on prothrombin time, partial thromboplastin time, blood fibrinogen, fibrinolytic activity and platelet count was investigated in 25 hypertensive and 7 normal subjects. High plasma fibrinogen levels were present in 80% of the hypertensive patients and prolonged lysis time in 28%; the means values were 487 +/- 135 mg % and 223 +/- 62 min., respectively. The other coagulation tests were normal. 0,300-0,450 mg/day clonidine per os for 15 days both decreased fibginogen levels (mean 406 +/- 149; p less than 0.05) and shortened lysis time (mean 153 +/- 78 min; p less than 0.005). No changes were noted in the normal subjects. The pathophysiological mechanism of these findings is discussed and their possible implications for the treatment of hypertension are emphasised.