ACE inhibitors versus AT1 blockers in the treatment of hypertension and syndrome X.

Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II type 1 (AT1) receptor blockers are two separate classes of drugs. Although they are both effective antihypertensive agents, they exert their effects through different pharmacological mechanisms. Nonetheless, they have often proved indistinguishable in terms of the surrogate endpoints used in short term clinical studies. Considerable data are available on the long term benefits of ACE inhibition; however, studies looking at the long term effects of AT1 receptor blockade are not yet complete. If ACE inhibitors prove to be distinguishable from AT1 receptor blockers in terms of disease-related outcomes, the reason may be the selective effects of ACE inhibitors on insulin resistance and insulin-mediated vascular function.