Potassium-Sparing Diuretics

Question 1

What are some examples of potassium-sapring diuretics

Answer 1

• Spironolactone (aldosterone antagonist), amiloride (co-amilofruse, co-amilozide)

Question 2

What are the indications for use

Answer 2

• As part of combo therapy for Tx of HYPOKALAEMIA (arising from loop- or thiazide-diuretic therapy)

Question 3

What is the mechanism of action

Answer 3

• Weak diuretics alone
• In combo w/ other diuretic counteract K+ loss + enhance diuresis
• Amiloride acts on distal convuluted tubules (kidney)

–> inhibits reabsorption Na (+ so H2O) by epithelial Na channels –> ++ excretion w/ retention of K+

–> counteracts losses in loop/thiazide diuretics

–> Amiloride usually in combo w. furosemide or hydrochlorothiazide

Question 4

What are some side effects

Answer 4

• Uncommon at low doses
• GI upset
• In combo w. other diuretics –> dizziness, hypotension, urinary symptoms
• still risk of kypokalaemia, hyperkalaemia, hyponatraemia

Question 5

What are some contra-indications

Answer 5

• Severe renal impairment
• Hyperkalaemia
• combo therapy shouldn’t be started in hypokalaemia
• Hypovolaemia (all diuretics)

Question 6

What are some interactions

Answer 6

• K elevating drugs (K supplements, aldosterone antagonist)

- Careful w. digoxin + lithium (all diuretics) - renal clearance altered