How do ACE & ARB's Work? (+ Pharmacology)

Summary

This video explains the renin-angiotensin-aldosterone system (RAAS) and its relevance to blood pressure regulation. It breaks down how ACE inhibitors and ARBs work to block the effects of angiotensin 2, which causes water and sodium retention, thereby lowering blood pressure. The video also covers common ACE inhibitors like lisinopril, enalapril, and ramipril, as well as ARBs like losartan, olmesartan, and valsartan. Additionally, it discusses the indications for using these drugs, their side effects (including dry cough with ACE inhibitors), and who should avoid them, with a quiz at the end to test viewers' understanding.

Takeaways

• 😀 The renin-angiotensin-aldosterone system (RAAS) starts with angiotensinogen produced in the liver, which is converted to angiotensin I by renin.
• 😀 Angiotensin I is then converted to angiotensin II by the angiotensin-converting enzyme (ACE), which plays a central role in regulating blood pressure.
• 😀 Angiotensin II binds to receptors in the kidneys, leading to increased sodium and water retention and elevated aldosterone levels, all contributing to higher blood pressure.
• 😀 ACE inhibitors work by blocking the ACE enzyme, preventing the formation of angiotensin II, thereby lowering sodium, water retention, and blood pressure.
• 😀 Angiotensin II receptor blockers (ARBs) work by blocking the receptors that angiotensin II binds to, helping to reduce sodium and water retention and lower blood pressure.
• 😀 Common ACE inhibitors include lisinopril (brand name Zestril), enalapril (Vasotec), and ramipril (Altace), all of which end in 'pril'.
• 😀 Common ARBs include losartan (Cozaar), olmesartan (Benicar), and valsartan (Diovan), all of which end in 'sartan'.
• 😀 ACE inhibitors and ARBs are commonly used for treating hypertension, heart failure, chronic kidney disease, and as cardio-protective agents for diabetic patients.
• 😀 Some common side effects of ACE inhibitors and ARBs include hypotension, increased potassium levels, and rare instances of angioedema (swelling of the lips, tongue, or throat).
• 😀 A unique side effect of ACE inhibitors is a dry cough, which occurs due to the increased levels of bradykinin caused by ACE inhibition, and is seen in about 10% of patients.
• 😀 ACE inhibitors and ARBs should not be used in patients with high potassium levels, a history of angioedema, or during pregnancy due to their Category X classification.

Q & A

What is the renin-angiotensin-aldosterone system (RAAS)?

The RAAS is a hormonal system that regulates blood pressure, fluid balance, and sodium levels in the body. It starts with the peptide angiotensinogen being converted to angiotensin 1 by renin, which is then converted to angiotensin 2 by the ACE enzyme. Angiotensin 2 increases sodium and water retention, as well as aldosterone production, contributing to higher blood pressure.

How do ACE inhibitors work?

ACE inhibitors block the ACE enzyme, preventing the conversion of angiotensin 1 to angiotensin 2. This reduces the effects of angiotensin 2, such as sodium and water retention, and the production of aldosterone, ultimately lowering blood pressure.

What is the mechanism of action of ARBs (angiotensin receptor blockers)?

ARBs block the angiotensin 1 receptors on the kidneys, preventing angiotensin 2 from binding and triggering the retention of sodium, water, and aldosterone. This also leads to a reduction in blood pressure.

Which drug is the first-line ACE inhibitor, and what are its brand names?

Lisinopril is the first-line ACE inhibitor, and its brand names include Zestril and Prinivil.

What is the significance of ramipril in ACE inhibitors?

Ramipril is often referred to as an 'alternate ACE' due to its different dosing schedule compared to other ACE inhibitors like lisinopril and enalapril.

What is the relationship between ACE inhibitors and bradykinin?

ACE inhibitors not only block the conversion of angiotensin 1 to angiotensin 2 but also inhibit the breakdown of bradykinin. Increased levels of bradykinin can lead to side effects like a dry cough.

What are some common side effects of ACE inhibitors and ARBs?

Common side effects include hypotension (low blood pressure), hyperkalemia (increased potassium levels), and, for ACE inhibitors, a dry cough. A rare but serious side effect for both ACE inhibitors and ARBs is angioedema (swelling of the lips, throat, and tongue).

Why should ACE inhibitors and ARBs be avoided during pregnancy?

Both ACE inhibitors and ARBs are classified as category X for pregnancy because they can harm the developing fetus, leading to potential birth defects or complications.

What are some common conditions for which ACE inhibitors and ARBs are prescribed?

These drugs are commonly prescribed for patients with hypertension (high blood pressure), heart failure, chronic kidney disease, and type 2 diabetes due to their blood pressure-lowering and kidney-protective properties.

How can ACE inhibitors and ARBs benefit patients with chronic kidney disease and type 2 diabetes?

In patients with chronic kidney disease or type 2 diabetes, ACE inhibitors and ARBs help protect kidney function by reducing the damage caused by high blood pressure and excess sugar filtration, thus preventing further kidney deterioration.