B / 11 : Potassium sparing diuretics, ADH antagonists, osmotic diuretics

Question 1

What are the K+ sparing diuretics? (3)

Answer 1

• Spironolactone
• Eplerenone
• Amiloride

SEPAM

Question 2

Spironolactone
- MOA
- Effect
- Indication
- SE
- ROA

Answer 2

• Aldosterone inhibitor
• Inhibits expression of Na+/K+ ATP-ase and the luminal Na transporters
• For primary and secondary hyperaldosteronism, antiandrogenic uses
• Hyperkalemia, metabolic acidosis
• Oral

Question 3

Eplerenone
- MOA
- Effect
- Indication
- SE
- ROA

Answer 3

• Aldosterone inhibitor
• Inhibits expression of Na+/K+ ATP-ase and the luminal Na transporters
• Same as spironolactone + for patients with LV dysfunction
• Hyperkalemia, metabolic acidosis
• Oral

Question 4

Amiloride
- MOA
- Effect
- Indication
- Side-effects
- ROA

Answer 4

• Inhibits ENaC
• Inhibition of Na reabsorption : natriuresis, K+ retention
• For hypertension, Liddle’s syndrome (overactive ENaC)
• Hyperkalemia, metabolic acidosis
• Oral

Question 5

What is an ADH antagonist?

Answer 5

Tolvaptan

Question 6

Tolvaptan
- MOA
- Effect
- Indication
- SE
- ROA

Answer 6

• ADH antagonist
• No aquaporin channel in collecting tubule : increased water excretion
• For chronic HF, SIADH, polycystic kidney disease
• Thirst, polyuria, nocturia
• Oral

Question 7

What is an osmotic diuretic?

Answer 7

Mannitol + glycerol

Question 8

Mannitol + Glycerol
- MOA
- Effect
- Indication
- SE
- ROA

Answer 8

• Osmotic diuretic
• Inhibits Na reabsorption in proximal tubule + decreased viscosity of blood + inhibition of renin secretion
• For acute renal failure, cerebral edema, increased intraocular edema
• Pulmonary edema, HF exacerbation, Na imbalance
• PARENTERALLY!!! very strong

Question 9

What is the point of combining mannitol with glycerol?

Answer 9

Glycerol avoids rebound edema, which is likely to be observed with only mannitol