Rationale for double renin-angiotensin-aldosterone system blockade

Area of Science:

• Cardiovascular Pharmacology
• Renal and Vascular Medicine

Background:

• Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) provide cardiovascular protection beyond blood pressure reduction.
• These drug classes exert tissue-protective effects on the heart, vasculature, and kidneys, contributing to reduced mortality and morbidity.

Purpose of the Study:

• To elucidate the distinct mechanisms of action for ACE inhibitors and ARBs in cardiovascular protection.
• To explore the potential for combination therapy, particularly with telmisartan, in high-risk patient populations.

Main Methods:

• Comparison of mechanisms: ACE inhibitors reduce angiotensin II and potentiate bradykinin-induced nitric oxide (NO) release.
• ARBs block angiotensin II type 1 (AT(1)) receptors and may stimulate angiotensin II type 2 (AT(2)) receptors, also leading to NO release.
• Investigation of telmisartan's unique properties as a selective peroxisome proliferator-activated receptor-gamma (PPAR-gamma) activator, enhancing insulin sensitivity without weight gain.

Main Results:

• ACE inhibitors and ARBs achieve similar clinical outcomes through different pathways.
• Telmisartan demonstrates additional benefits by activating PPAR-gamma, improving insulin sensitivity.
• Combination therapy with ACE inhibitors and ARBs is being evaluated for enhanced efficacy in high-risk patients.

Conclusions:

• The complementary mechanisms of ACE inhibitors and ARBs support their use in combination therapy for high-risk cardiovascular patients.
• Telmisartan offers unique advantages, including insulin sensitization, without associated weight gain.
• Ongoing trials like ONTARGET are crucial for validating the benefits of combination therapy involving telmisartan.