THE PHARMACOLOGY OF CENTRALLY ACTING ANTIHYPERTENSIVE DRUGS

Abstract

Aspects of centrally acting antihypertensive agents are reviewed with an emphasis on compounds acting on central α‐adrenoceptors, in the ponto‐medullary region of the brain. Central α‐adrenoceptors are stimulated by clonidine, guanfacine and also α‐methyldopa, which is presumed to act via α‐methylnoradrenaline, generated in vivo after biotransformation of α‐methyldopa in the brain. Stimulation of the central α‐adrenoceptors decreases peripheral sympathetic tone and thus a fall in blood pressure and bradycardia. The central α‐adrenoceptors involved in the antihypertensive effect of clonidine, guanfacine and α‐methyldopa appear to be located at postsynaptic sites and of the α 2 subtype. The pharmacological basis of side effects, including withdrawal phenomena and drug interactions of the centrally acting antihypertensives is reviewed.