Clinical pharmacology of centrally acting antihypertensive agents

The centrally acting agents are one of several differing classes of drugs now available for antihypertensive therapy. The availability of newer pharmacologic classes, including the beta-blockers, alpha-blockers. ACE inhibitors and calcium channel blockers, has resulted in a relative decline in the use of the centrally acting drugs. A major reason for this change in emphasis has been the perception by clinicians that the centrally acting agents, although effective, tend to produce symptomatic side effects that are difficult or unacceptable for patients. Some recent innovations in administering the centrally acting drugs appear to have addressed this problem. The pharmacokinetic characteristics of agents such as the transdermally administered clonidine or oral guanfacine appear to provide them with sustained efficacy without concomitant adverse effects. A further attribute of these drugs is their ability to decrease blood pressure without producing sodium retention. A growing awareness of the importance of treatment-induced metabolic effects has further served to reawaken interest in these agents. Specifically, they do not appear to produce alterations in glucose metabolism, and possibly may even have some slight beneficial effects on the blood lipid profile. Their ability to cause regression of left ventricular muscle hypertrophy, and possibly to enhance diastolic function, may add a further dimension of cardiovascular protection beyond their antihypertensive efficacy.