CLINICAL ASPECTS OF BLOOD PRESSURE CRISIS DUE TO WITHDRAWAL OF CENTRALLY ACTING ANTIHYPERTENSIVE DRUGS

Abstract

1 Sudden cessation of antihypertensive therapy, in particular centrally acting drugs such as clonidine, may cause a withdrawal syndrome characterised by a rapid increase in blood pressure, headaches, tremor, restlessness and nausea. 2 The withdrawal syndrome is associated with a marked increase in sympathetic activity, as indicated by the increased levels of urinary and plasma catecholamines. 3 The clonidine withdrawal syndrome is reproducible. 4 The crisis can be managed acutely either by reinstituting the drug which has been withdrawn or by giving α- and β-adrenoceptor blocking drugs, either separately or in the form of labetalol. 5 The withdrawal syndrome can now be reproduced in animal models, but in spite of extensive studies, the exact underlying mechanism remains to be elucidated.