Angiotensin II receptor blocker

• Angiotensin II receptor blockers (ARBs) are a class of medications used primarily in the management of hypertension (high blood pressure) and certain cardiovascular conditions.
• They work by blocking the action of angiotensin II, a hormone that constricts blood vessels and stimulates the release of aldosterone, leading to increased blood pressure.
• By inhibiting the effects of angiotensin II, ARBs help relax blood vessels, reduce blood pressure, and mitigate the strain on the cardiovascular system.

Renin ang pathway 2

Mechanism of Action

• Angiotensin II exerts its effects by binding to specific receptors, namely angiotensin II type 1 receptors (AT1 receptors), located on the surface of blood vessels, heart muscle cells, and other tissues.
• ARBs selectively block these AT1 receptors, preventing angiotensin II from binding to them.
• By doing so, ARBs inhibit the vasoconstrictive and pro-inflammatory effects of angiotensin II.

Clinical Uses

The primary clinical applications of angiotensin II receptor blockers include:

Hypertension:

• ARBs are widely used as first-line agents in the treatment of hypertension. By relaxing blood vessels, they lower blood pressure and help maintain it within a target range.

Heart Failure:

• ARBs may be prescribed to patients with heart failure who cannot tolerate angiotensin-converting enzyme (ACE) inhibitors. They help reduce the workload on the heart by dilating blood vessels and improving cardiac function.

Diabetic Nephropathy:

• ARBs are effective in slowing the progression of diabetic nephropathy, a common complication of diabetes characterized by kidney damage.
• They can help preserve kidney function and reduce proteinuria (presence of excess protein in the urine) in patients with diabetes.

Post-Myocardial Infarction:

• Following a myocardial infarction (heart attack), ARBs may be prescribed to certain patients to improve outcomes and reduce the risk of future cardiovascular events.

Examples of ARBs

Several angiotensin II receptor blockers are available on the market, including:

• Losartan
• Valsartan
• Irbesartan
• Candesartan
• Olmesartan
• Telmisartan

Adverse Effects

Common side effects associated with angiotensin II receptor blockers include:

• dizziness, fatigue, headache, and gastrointestinal symptoms such as nausea and diarrhea. In rare cases, more serious adverse effects, such as angioedema (swelling of the face, lips, tongue, or throat), allergic reactions, and changes in kidney function, may occur.

Precautions and Contraindications

Some precautions and contraindications include:

• Pregnancy: ARBs should generally be avoided during pregnancy due to the potential risk of harm to the developing fetus.

• Renal Impairment: Dose adjustments may be necessary in individuals with impaired kidney function to prevent further deterioration of renal function.

• Hyperkalemia: ARBs can increase potassium levels in the blood. Close monitoring is needed, particularly in patients with pre-existing hyperkalemia or conditions that may predispose them to elevated potassium levels.

• Drug Interactions: ARBs may interact with other medications, including nonsteroidal anti-inflammatory drugs (NSAIDs), potassium-sparing diuretics, and certain antihypertensive drugs. Close monitoring and appropriate dose adjustments may be required.

References

Gradman, A.H., & Basile, J.N. (2017). Angiotensin receptor blockers. In Drug Therapy for Hypertension (pp. 99-118). Springer. Unger, T. (2002). The role of the renin-angiotensin system in the development of cardiovascular disease. American Journal of Cardiology, 89(2A), 3A-9A. Lexicomp Online. Angiotensin II Receptor Blockers (ARBs).

See Also

• Angiotensin-Converting Enzyme Inhibitors
• Renin-Angiotensin-Aldosterone System
• Hypertension
• Heart Failure
• Diabetic Nephropathy
• Myocardial Infarction
• Antihypertensive Medications
• Hyperkalemia

• Dailymed label info on Angiotensin II receptor blocker
• FDA Angiotensin II receptor blocker

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