Potassium-sparing diuretics + osmotic diuretics

Question 1

Potassium-sparing diuretics - 2 groups plus their drugs (2 in each group)

Answer 1

Epithelial sodium channel blockers (triamterene and amiloride).
Aldosterone receptor antagonists (spironolactone and eplerenone)

Question 2

Amiloride and triamterene - MOA

Answer 2

Block sodium channels in late distal tubule and collecting duct. Indirect reduction of K secretion.

Question 3

Potassium-sparing diuretics - effects

Answer 3

Modest natriuresis.

Decreased kaliuresis.

Question 4

Potassium-sparing diuretics - indications

Answer 4

Hypokalemia by thiazides or loop diuretics.
Aldosterone antagonists: hirsutism, polycystic ovary.
Spironolactone: primary hyperaldosteronism.

Question 5

Potassium-sparing diuretics - adverse effects

Answer 5

Hyperkalemia.
Aldosterone antagonists: gynecomastia, impotence (mainly spironolactone).
Amiloride, triamterene: Blood cell deficiencies, GI distress.

Question 6

Spironolactone and eplerenone - MOA

Answer 6

Competitive inhibition of aldosterone binding to mileralocorticoid receptors in late distal tubule and collecting duct. This prevents increased gene expression for sodium channels and sodium pump.

Question 7

Potassium-sparing diuretics - usefulness for disorders

Answer 7

Very useful: Hypokalemia.

Useful: Cirrhosis, CHF, hyperaldosteronism, HT, nephrotic syndrome, pulmonary edema.

Question 8

Potassium-sparing diuretics - interactions

Answer 8

ACE inhibitors or K supplements: hyperkalemia.

Amiloride, triamterene: renal failure with NSAIDs.

Question 9

Osmotic diuretics - 2 drugs

Answer 9

Glycerol and mannitol

Question 10

Glycerol and mannitol - MOA

Answer 10

Increase osmotic pressure of plasma and attracts water.
Mannitol: filtered by glomerulus and not reabsorbed. Osmotically attracts and retains water which reduces Na concentration in tubular fluid.

Question 11

Glycerol - indications and adm

Answer 11

Acute glaucoma. Adm orally for this purpose.

Question 12

Mannitol - indictions

Answer 12

Cerebral edema, acute glaucoma.
Improve renal function in oliguric phase of acute renal failure.
Maintain renal function.
Reduce toxicity of antineoplastic platinum compounds (e-g- cisplatin), and to excrete other toxic substances.

Question 13

Osmotic diuretics - adverse effects

Answer 13

Excessive volume expansion (heart failure, pulmonary congestion, edema). Nausea, vomiting.

Question 14

Osmotic diuretics - interactions

Answer 14

Potentiates other diuretics.