Angiotensin II Receptor Blockers (ARBs) for Hypertension Treatment: Mechanism and Types- Pharmocology Notes

Angiotensin II Receptor Blockers (ARBs) are a class of medications commonly used to treat hypertension (high blood pressure). They work by targeting the renin-angiotensin-aldosterone system (RAAS), a regulatory system that plays a significant role in blood pressure control. Here's how ARBs work to treat hypertension:

Blockade of Angiotensin II Receptors: ARBs work by blocking the action of angiotensin II at its receptors, specifically the angiotensin II type 1 receptors (AT1 receptors). Angiotensin II is a potent vasoconstrictor, meaning it causes blood vessels to narrow. By inhibiting the effects of angiotensin II, ARBs prevent blood vessels from constricting, leading to vasodilation (widening of the blood vessels).

Vasodilation: The vasodilation induced by ARBs results in a reduction in peripheral vascular resistance. With less resistance to blood flow, blood can move more easily through the blood vessels. As a consequence, the heart does not have to work as hard to pump blood, and this leads to a decrease in blood pressure.

Reduction in Aldosterone Production: Angiotensin II also stimulates the release of aldosterone, a hormone that promotes the retention of sodium and water by the kidneys. ARBs reduce the production of aldosterone, resulting in increased excretion of sodium and water in the urine. This reduces blood volume, leading to lower blood pressure.

Improvement in Cardiac Function: By reducing the workload on the heart and improving blood flow, ARBs can help improve cardiac function. This is particularly important for individuals with hypertension and heart conditions such as heart failure.

Protection of Organs: ARBs are not only used to lower blood pressure but also to protect target organs, such as the heart and kidneys, from the damaging effects of hypertension over time.

Examples of commonly prescribed ARBs for the treatment of hypertension

Losartan (Cozaar)

Valsartan (Diovan)

Irbesartan (Avapro)

Olmesartan (Benicar)

Candesartan (Atacand)

Telmisartan (Micardis)

Eprosartan (Teveten)