Pharmacology of ACE inhibitors versus AT1 blockers

Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II type 1 (AT1) receptor blockers share a number of common properties, including their ability to lower blood pressure. However, they can be differentiated based on their individual effects on the renin-angiotensin system, the fibrinolytic system and the actions of bradykinin. They act at different points in the cascade of events that constitute the renin-angiotensin system. In animal models of atherosclerosis, ACE inhibition was associated with a significant reduction in the percentage surface area of lesions, while no similar effect was evident with AT1 receptor blockade. In the fibrinolytic system, both ACE inhibition and AT1 receptor blockade were associated with reduced aldosterone levels, although the effect was greater with ACE inhibition; only ACE inhibition was associated with a significant reduction in plasminogen activation inhibitor-1. By blocking the degradation of bradykinin, ACE inhibitors potentiate the ability of bradykinin to reduce blood pressure and stimulate the release of tissue-type plasminogen activator from the vasculature, an effect not seen with AT1 receptor blockers.