Additive effect of beta-adrenergic blockers in combination with vasodilators in lowering blood pressure.

Complications of hypertension are by far the greatese preventable public health problem in many of the developed countries of the world. Pharmacologic interventions which primarily involve drug interactions are the generally available and effective means of preventing or delaying these hypertensive complications. Mechanisms of beneficial antihypertensive drug interactions involve simultaneous reduction or control of blood volume (diuretic agents) and decrease of peripheral resistance. Reduction of peripheral resistance without producing intolerable side effects has recetnly been achieved by a complex drug interaction. This interaction involves simultaneous vasodilation and inhibition by beta-adrenergic blocking agents of reflex activation of the renin-angiotensin axis. Clonidine, by effects similar to propranolol, can substitute for propranolol in some patients, or add to the beneficial effects of this important drug interaction.