First-line pharmacological treatment of hypertension.

Abstract

Over the last two decades, the treatment of arterial hypertension has improved considerably. Several new well-tolerated antihypertensive drugs have be- come available which have enhanced the therapeutic possibilities available to the physician at the expense of other compounds such as the centrally acting sympatholytic agents. In most industrialized coun- tries. four classes of antihypertensive drugs are recommended for first-line therapy, i.e. diuretics, beta-blockers, angiotensin converting enzyme (ACE) inhibitors and calcium antagonists [ 1-31. These drugs have the advantage of lowering blood pressure by different mechanisms. Thus diuretics increase urinary sodium excretion and thereby reduce total body sodium which is often augmented in patients with essential hypertension. The antihypertensive efficacy of beta-blockers results in part from their ability to reduce cardiac output via their negative inotropic and chronotropic properties. Another im- portant effect of beta-blockers takes place at the nerve endings of the sympathetic nervous system. At the presynaptic level, beta-adrenergic stimulation by norepinephrine or epinephrine enhances the amount of norepinephrine released for a given nervous activity. Beta-blocking agents, by blocking the acti- vation of presynaptic receptors, thus reduce the efflux of norepinephrine. In addition, beta-blockers that are devoid of intrinsic sympathetic activity decrease renin secretion, an effect that may also contribute to the ability of these agents to lower blood pressure. In contrast to beta-blockers, ACE inhibitors interfere specifically with the renin-angio- tensin system. These agents decrease blood pressure because they inhibit the conversion of angiotensin I into the potent vasoconstrictor angiotensin TI. In addition to its vasoconstrictor properties, angiotensin