B / 10 : Potassium excreting (wasting) diuretics

Question 1

What are extrarenal diuretics?

Answer 1

Diuretics that act outside the nephron (caffeine, dopamine)

Question 2

What are the groups of diuretics?

Answer 2

• Primarily salt excreting diuretics
• Primarily water excreting diuretics
• Osmotic diuretics

Question 3

What are the primarily salt excreting diuretics and their targets? (4)

Answer 3

• Carbonic anhydrase inhibitors (proximal tubule)
• Loop diuretics (thick ascending loop of Henle)
• Thiazides (distal convoluted tubule)
• K+ sparing diuretics (upper part of collecting tubules)

Question 4

What are the primarily water excreting diuretics and their target?

Answer 4

ADH antagonists (lower part of collecting tubules)

Question 5

What is a carbonic anhydrase inhibitor?

Answer 5

Acetazolamide

Question 6

Acetazolamide
- MOA
- Effect
- Indications
- Contraindication
- SE
- ROA

Answer 6

• Inhibits carbonic anhydrase in PCT
• Causes loss of HCO3-, K+ wasting, Na is reabsorbed
• For glaucoma, edemas, epilepsy
• Hepatic encephalopathy
• Hyperchloremic metabolic acidosis, hypokalemia, renal stones
• Oral, parenteral

Question 7

Is acetazolamide often used as a diuretic?

Answer 7

No, it is a sulfonamide derivative

Question 8

What are 2 examples of loop diuretics?

Answer 8

• Furosemide
• Etacrynic acid

Question 9

What is the MOA of loop diuretics?

Answer 9

Inhibition of NKCC2

Question 10

Furosemide
- MOA
- Effect
- Indication (5)
- SE
- ROA

Answer 10

• Inhibits Na/K/2Cl transporter in the thick ascending loop
• Na and K excretion (water excretion) + stimulatory effect of COX2 enzymes (vena cava dilation)
• For acute pulmonary edema, congestive HF, hypertension, renal failure, ascites
• Hypokalemia, metabolic alkalosis, ototoxicity, nephritis
• oral, parenteral

Question 11

Furosemide dose

Answer 11

20-40mg

Question 12

Etacrynic acid
- MOA
- Indication

Answer 12

• Loop diuretic (same as furosemide)
• Used in gout, for patients with sulfa allergy (not a sulfa drug)

Question 13

What are 2 thiazide diuretics?

Answer 13

• Hydrochlorothiazide
• Indapamide

Question 14

What is the MOA of thiazide diuretics?

Answer 14

inhibition of NCC : inhibition of NaCl reabsorption in DCT

Question 15

Hydrochlorothiazide
- MOA
- Effect
- Indication
- SE
- ROA

Answer 15

• Inhibition of NCC
• Causes natriuresis - K+ wasting, hypercalcemia
• For congestive HF, hypertension, nephrogenic hypercalciuria, nephrogenic diabetes insipidus
• Hypokalemia, hypercalcemia, metabolic alkalosis, decreased GFR, weakness
• Oral

Question 16

Indapamide
- MOA
- Effect
- Indication

Answer 16

• Thiazide-like diuretic : inhibits NCC
• Same as thiazides
• For congestive HF, hypertension

Question 17

What can be another effect of thiazide diuretics?

Answer 17

They may act as potent openers of K+ channels, resulting in hyperpolarization and vasodilation + decrease in insulin release