From the FDA Drug Label
- 1 Mechanism of Action Angiotensin II [formed from angiotensin I in a reaction catalyzed by angiotensin converting enzyme (ACE, kininase II)] is a potent vasoconstrictor, the primary vasoactive hormone of the renin-angiotensin system, and an important component in the pathophysiology of hypertension. The Renin-Angiotensin-Aldosterone (RAA) system is a complex physiological pathway that plays a crucial role in regulating blood pressure and fluid balance.
- Renin is an enzyme released by the kidneys in response to decreased blood volume or low blood pressure.
- Angiotensin I is formed when renin acts on a protein called angiotensinogen.
- Angiotensin II is a potent vasoconstrictor that is formed when angiotensin I is converted by angiotensin-converting enzyme (ACE).
- Aldosterone is a hormone released by the adrenal glands in response to angiotensin II, which promotes sodium retention and water absorption, increasing blood volume and pressure. The RAA system is blocked by losartan, which selectively blocks the binding of angiotensin II to the AT1 receptor, reducing vasoconstriction and aldosterone secretion 1.
From the Research
The Renin-Angiotensin-Aldosterone System (RAAS) is a vital system that maintains plasma sodium concentration, arterial blood pressure, and extracellular volume, and its imbalance can result in various chronic and acute diseases, as discussed in the study by 2. The RAAS is a complex system that involves the coordinated action of several enzymes, hormones, and receptors to regulate blood pressure and fluid balance.
- The system is initiated by the release of renin, which converts angiotensinogen to angiotensin I.
- Angiotensin I is then converted to angiotensin II by angiotensin-converting enzyme (ACE), which is a potent vasoconstrictor and stimulates the release of aldosterone.
- Aldosterone promotes sodium retention and water absorption, leading to increased blood pressure. The RAAS plays a crucial role in maintaining cardiovascular and renal health, and its dysregulation is implicated in various diseases, including hypertension, heart failure, and kidney disease, as highlighted in the study by 3.
- The study by 4 suggests that RAAS inhibitors, such as ACE inhibitors and angiotensin II receptor blockers, can provide benefits beyond blood pressure reduction, including reducing morbidity and mortality.
- However, the study by 5 notes that the efficacy of RAAS blockers in hypertension may not extend beyond blood pressure reduction. In terms of management, the use of RAAS inhibitors, such as ACE inhibitors and angiotensin II receptor blockers, is recommended as a first-line treatment for hypertension, as discussed in the study by 6.
- These agents can help to reduce blood pressure, decrease morbidity and mortality, and slow the progression of kidney disease.
- Additionally, lifestyle modifications, such as dietary changes and exercise, can also help to regulate the RAAS and reduce blood pressure, as suggested in the study by 2.