Cardiovascular - Diuretics Flashcards
What are examples of loop diuretics and when are they used?
E.g. furosemide, bumetanide,
Acts on ascending limb of loop of henle
Used is HF - IV in acute, when there is odema or breathlessness in chronic
Give examples of thiazide and related diuretics, and when are they used?
Thiazide
Bendroflumethiazide
Cyclopenthiazide
Thiazide related Indapamide Metolazone Chlortalidone Xipamide
Act on the DCT
Used in hypertension and heart failure
Give an example of a potassium sparing diuretics and where does it act?
Amiloride
Acts on the collecting duct
Give examples of aldosterone antagonists and when are they used?
Spironolactone - adjunct in heart failure
Eplerenone - used in HF after MI, and in men who are experiencing oestrogen like side effects
Give an example of an osmotic diuretic and when is this used?
Mannitol
Used in cerebral odema
Give an example of a carbonic anhydrase inhibitor and when is this used?
Acetazolamide
Used in glaucoma and altitude sickness (unlicensed)
How do diuretics work?
Inhibit NaCl reasorption in the nephron, thereby inhibiting water reabsorption, so there is an increase in urine volume
What should a patient do if they are taking a diuretic and are experiencing diarrhoea or vomiting? Why?
Stop taking the diuretic for 1-2 days and increase fluid intake
To prevent dehydration, AKI, hypotension and worsening heart failure
What monitoring needs to be done for patients on diuretics?
Measure BP, electrolytes and renal function:
1-2 weeks after any change
Once treatment is stable, monitor every 6 months
What are more potent, loop or thiazide diuretics?
Loop
What has a longer duration of action, loop or thiazide diuretics?
Thiazide
What electrolyte and metabolic disturbances are associated with thiazides?
Hypokalaemia Hyponatraemia Hyperuricaemia Hypercalcaemia Increased glucose levels Lipids
Which thiazides are preferred in
a) hypertension
b) heart failure
c) diabetes
a) indapamide
b) bendroflumethiazide
c) indapamide
Which thiazide has the smallest effect on glucose levels?
Indapamide
What conditions can thiazide and loops exacerbate?
Diabetes
Gout
Some diuretics can cause hypokalaemia. When is this especially dangerous?
When patients are also taking a cardiac glycoside e.g. digoxin
Patients who have severe CHD
Potassium sparing diuretics e.g. amiloride can be used
Why can chlortalidone be given on alternate days to control odema?
It had a longer duration of action
What diuretic is used in acute heart failure?
IV furosemide
Why should diuretics be given in the morning (or before 4pm)?
To prevent them from interfering with sleep due to diuresis
Can you give potassium sparing diuretics with potassium supplements?
No
Can potassium sparing diuretics be given alongside ACE Inhibitors?
No - increased risk of hyperkalaemia
What are the indications of spironolactone?
Adjunct in heart failure
Liver cirrhosis and acites
Primary hyperaldosteronism
What is the minimum eGFR for thiazides?
30ml/min/1.73m2
What is the effect of thiazides on diabetes?
Increase in glucose
Indapamide has the lowest effect on glucose
How can hypokalaemia affect the liver?
It can cause hepatic encephalopathy
What is the effect of loop diuretics on patients with an enlarged prostate?
Can cause urinary retention
Although loops normally increase urine production
Which diuretics can cause hypokalaemia
Loop
Thiazide
Which diuretics can cause hyperkalaemia
Potassium sparing
Should spironolactone be taken with or after food?
Yes
In what condition are aldosterone antagonists contraindicated in?
Addisons Disease
What diuretic can make urine look blue under certain lights?
Triamterene
If a patient taking furosemide 40mg has resistant oedema, what can be done?
Switch to bumetanide 1mg
