ACE inhibitors

Question 1

What are the indications for ACE inhibitors?

Answer 1

1) HTN

2) Chronic heart failure

3) Prevention of adverse cardiovascular events in IHD, Cerebrovascular disease, Peripheral vascular disease

4) Diabetic Nephropathy: to reduce progression of nephropathy

5) Chronic Kidney Disease (CKD) with proteinuria: to reduce proteinuria

Question 2

What is the MOA of ACE inhibitors

Answer 2

ACE inhibitors inhibit Angiotensin converting enzyme (ACE), which converts Angiotensin 1 to Angiotensin 2. Angiotensin 2 is a vasoconstrictor and stimulates Aldosterone secretion. Blocking Angiotensin 2 in:

• HTN: vasodilation > lowers BP
• CKD: vasodilation of efferent glomerular arteriole > lower intraglomerular pressure, which slows progression of CKD
• Chronic heart failure: Reducing aldosterone concentration promotes sodium and water excretion > reduce venous return (preload) > reduce EF

Question 3

What are the side effects of ACE inhibitors?

Answer 3

• Hypotension (particularly after the first dose)
• Hyperkalemia (because a lower Aldosterone level promotes K+ retention)
• Worsening renal failure (particularly in Renal artery stenosis, as vasoconstriction of the efferent glomerular arteriole is needed to maintain glomerular filtration)
• Dry cough (due to an increased level of bradykinin, which is normally inactivated by ACE)
• Angioedema
• Anaphylactic reactions

Question 4

ACE inhibitors are contraindicated in ?

Answer 4

• Renal artery stenosis
• Acute Kidney Injury (AKI)
• women who are breastfeeding or pregnant
• Caution in CKD (give at a lower dose & monitor renal function)

Advise that if they develop diarrhea or vomiting, to maintain their fluid intake, and stop the ACE inhibitor until their symptoms resolve (Why? To reduce the risk of dehydration, low blood pressure, and kidney damage)

Question 5

Which drugs interact with ACE inhibitors negatively?

Answer 5

• Potassium-elevating drugs (potassium supplements, aldosterone antagonists, potassium-sparing diuretics)
• NSAID with an ACE inhibitor increases the risk of nephrotoxicity

Question 6

How do you monitor a person on ACE inhibitors?

Answer 6

Get a baseline U&E before starting and repeat 1-2 weeks into treatment and after increasing dose.

Question 7

When do you HOLD/STOP ACE inhibitors?

Answer 7

Stop or decrease dose if:
* serum Cr rises > 30%
* eGFR falls > 25%
* serum K rises > 5.0mmol/L

STOP if serum K rises > 6.0mmol/L

Question 8

When do you HOLD/STOP ACE inhibitors?

Answer 8

Stop or decrease dose if:
* serum Cr rises > 30%
* eGFR falls > 25%
* serum K rises > 5.0mmol/L

STOP if serum K rises > 6.0mmol/L

Question 9

Examples of ACE inhibitors

Answer 9

• Enalapril
• Ramipril
• Lisinopril
• Perindopril