ACE inhibitors Flashcards
Mechanism of action
Inhibit angiotensin-converting enzyme which results in the relaxation and widening of blood vessels - this lowers BP and improves blood flow to the heart muscle
Contraindications
- PHx angio-oedema associated with previous exposure to ACEi
- Hereditary or recurrent angio-oedema
- Diabetes mellitus or eGFR <60, who are also taking aliskiren
- Pregnant and those planning pregnancy due to risks to fetus
- Breastfeeding
A patient has become pregnant. She is taking an ACEi. What should you do?
Ideally stop treatment with ACEi as soon as pregnancy is detected
If appropriate, start alternative treatment
1st line labetolol, if not then nifedipine MR, if not then methyldopa
Why should ACEi not be taken if breastfeeding
Not recommended as there is limited info on safety in breastfeeding women
Cautions
- Black African/Caribbean origin, or primary aldosteronism (may respond less well)
- Renal impairment (hyperkalaemia & other adverse effects more common, may need dose reduction)
- Diuretics
- Diabetes (increased risk of hyperkalaemia, may reduce BG)
- Hypertrophic cardiomyopathy or aortic or mitral valve stenosis
- Peripheral vascular disease or generalised atherosclerosis (risk of silent renovascular disease)
- Severe or unstable heart failure (initiate under specialist supervision only)
- Severe or asymptomatic aortic stenosis (risk hypotension)
- Collagen vascular disease (possible increased risk agranulocytosis; blood counts recommended)
Which people are more likely to experience first-dose hypotension?
- High dose diuretics
- Low sodium diet
- On dialysis
- Dehydrated
- Cerebrovascular disease
- Ischemic heart disease
- Heart failure
Advice to patients taking their first dose
- Take first dose in evening to avoid feeling dizzy from first-dose hypotensive effect, then if the drug is well-tolerated, future doses can be taken in the morning
- Advice not featured in BNF or info from manufacturers
Who will require low starting doses of ACEi?
People more prone to adverse effects
- elderly
- frail
- renal impairment
- low-dose diuretics (e.g. bendro 2.5mg OD)
Who will need to be referred to secondary care to initiate ACEi drug therapy? (diuretics)
People who are taking high dose diuretics (more than 80mg furosemide or equivalent)
When should ACEi be initiated in secondary care, under specialist supervision and careful clinical monitoring
○ Severe heart failure
○ Receiving multiple or high -dose diuretic therapy (e.g. more than 80mg furosemide or equivalent)
○ Receiving concomitant ARB or aliskiren
○ Hypovolemia
○ Hyponatraemia (plasma sodium lese than 130mmol/L)
○ Hypotension (systolic BP below 90)
○ Unstable heart failure
○ Haemodynamically significant LV Inflow or outflow impediment (e.g. stenosis of aortic or mitral valve)
○ High dose vasodilator therapy
○ Known renovascular disease
You observe that a patient has had an increase in their serum creatinine and potassium after starting ACEi/having had an increased dose
Some increase in serum creatinine and potassium is expected! Different levels will require different steps
A patient has serum potassium levels of 5.0mmol/L or above. What do you do?
○ Investigate other causes of hyperkalaemia and treat accordingly
○ Stop or reduce dose of K-sparing diuretics (amiloride, triamterene, spironolactone) or nephrotoxic drugs (e.g. NSAIDs)
A patient has serum potassium levels that persist between 5.0-5.9mmol/L despite having taken measures such as investigating other causes of hyperkalaemia and treating them, and stopping or reducing the dose of K-sparing diuretics. What do you do?
Reduce dose of ACEi to previously tolerated lower dose and recheck levels in 5-7 days
If serum K+ persists above 6mmol/L despite having taken measures to fix this (e.g. considering and treating other causes of hyperkalaemia, stopping or reducing the dose of K-sparing diuretics, reducing dose of ACEi). What do you do?
STOP ACEi
why are they cautioned in diabetes
may lower GC; increased risk of hyperkalaemia
