Diuretics

Question 1

What are diuretics?

Answer 1

Drugs which act on the kidney to increase urine production + eliminate water from the body

Question 2

What are the 5 main classes of diuretics?

Answer 2

• loops diuretics
• potassium sparing diuretics
• thiazide + thiazide-like diuretics
• carbonic anhydrase inhibitors
• osmotic diuretics

Question 3

Where do carbonic anhydrase inhibitors work?

Answer 3

PCT

Question 4

Where do osmotic diuretics work?

Answer 4

Across whole nephron but mainly PCT

Question 5

Where do loop diuretics work?

Answer 5

Loop of Henle (ascending limb)

Question 6

Where do potassium sparing diuretics work?

Answer 6

Distal DCT + collecting duct

Question 7

Outline how carbonic anhydrase inhibitors work

Answer 7

• PCT
• inhibit carbonic anhydrase
  H2CO3 => CO2 + H2O is prevented
• less H+ inside cell to swap with Na+ in nephron

Question 8

Outline how osmotic diuretics work

Answer 8

• PCT
• increases osmotic pressure within kidney
• inhibits reabsorption of water
• increases water excretion with little effect on Na+

Question 9

Example of osmotic diuretics

Answer 9

Mannitol

Question 10

Uses of osmotic diuretics

Answer 10

• acute renal failure due to shock or trauma
• acute drug poisoning
• decrease intracranial + intraocular pressure before ophthalmic or brain procedures

Question 11

Side effects of osmotic diuretics

Answer 11

• hyponatremia > headaches, nausea, vomiting
• extracellular volume expansion > complicates heart failure + pulmonary oedema
• contraindicated in chronic heart failure
• excessive use > dehydration + hypernatremia ??

Question 12

How do loop diuretics work?

Answer 12

• loop of Henle
• blocks NKCC cotransporter
• build up of Na+, K+ and Cl-
• given orally or via IV
• increase urine volume

Question 13

What is the most potent diuretic?

Answer 13

Loop diuretics

Question 14

Uses of loop diuretics

Answer 14

Emergency situations:
- severe oedema associated with congestive heart failure + nephrotic syndrome
- oliguric AKI
- hypercalcaemia
- hyperkalaemia
- acute pulmonary oedema
- toxicity of Br, F + I

Question 15

Two example of loop diuretics

Answer 15

bumetanide
furosemide

Question 16

Side effects of loop diuretics

Answer 16

• hypovolaemia
• hyponatremia
• hypokalaemia
• hypomagnesaemia
• metabolic alkalosis
• postural hypotension

Question 17

How can loop diuretics cause metabolic alkalosis?

Answer 17

Increases urine volume > decreases blood volume > increased bicarbonate conc. > increased pH

Question 18

What is needed when using potassium sparing diuretics to avoid hypokalaemia?

Answer 18

Dietary potassium supplements

Question 19

Where do thiazide + thiazide like diuretics work?

Answer 19

DCT

Question 20

Two examples of thiazide + thiazide like diuretics

Answer 20

bendroflumethiazide
indapamide

Question 21

Uses of thiazide + thiazide like diuretics

Answer 21

For treatment of:
- essential hypertension
- mild heart failure
- calcium nephrolithiasis due to hypercalciuria
- osteoporosis
- nephrogenic diabetes insipidus polyuria

Question 22

How can thiazide + thiazide like diuretics cause hypercalcemia?

Answer 22

• NaCL transporter blocked
• less Na+ in cell
• more drawn in from blood via NaCa cotransporter in basolateral membrane
• more Ca2+ leaves + is reabsorbed

Question 23

How do thiazide + thiazide like diuretics work?

Answer 23

DCT
- block Na+Cl- transporter

Question 24

Example of potassium sparing diuretic

Answer 24

amiloride

Question 25

Example of aldosterone antagonist

Answer 25

*spironolactone*

Question 26

Uses of potassium sparing diuretic + aldosterone antagonists

Answer 26

- secondary hyperaldosteronism - hepatic cirrhosis - nephrotic syndrome - hypertension treatment

Question 27

How do potassium sparing diuretics + aldosterone antagonists work in the CD + DCT

Answer 27

- **PSD**: block ENAC channels - **AA**: decrease aldosterone > decreased ENAC + ROMK

Question 28

What type of drug is *mannitol*?

Answer 28

Osmotic diuretic

Question 29

What type of drug is *bumetanide*?

Answer 29

Loop diuretic

Question 30

What type of drug is *furosemide*?

Answer 30

Loop diuretic

Question 31

What type of drug is *bendroflumethiazide*?

Answer 31

Thiazide + thiazide like diuretic

Question 32

What type of drug is *indapamide*?

Answer 32

Thiazide + thiazide like diuretic

Question 33

What type of drug is *amiloride*?

Answer 33

Potassium sparing diuretic

Question 34

What type of drug is *spironolactone*?

Answer 34

Aldosterone antagonist

Question 35

What is diuresis?

Answer 35

The excretion of water in the urine

Question 36

What is natriuresis?

Answer 36

Excretion of sodium in the urine

Question 37

Issues with osmotic diuretics administer via IV

Answer 37

Water drawn towards it in blood vessels on route to kidney: - expands extracellular fluid volume - decreases blood viscosity - Inhbits renin release