diuretics

Question 1

what are the classes of diuretics?

Answer 1

carbonic anhydrase inhibitors
loop 
thiazide
potassium sparing
osmotic

Question 2

name carbonic anhydrase inhibitors

Answer 2

acetazolamide

Question 3

what is the definition of a diuretic?

Answer 3

stops sodium from being reabsorbed

Question 4

what part of the kidneys do carbonic anhydrase inhibitors work on?

Answer 4

PCT

Question 5

what is the net effect of carbonic anhydrase in the PCT?

Answer 5

allows bicarbonate to be pumped out into the blood and Na+ to be reabsorbed into the PCT from the urine

Question 6

what is the mode of action of CA inhibitors?

Answer 6

block CA so they stop the dissociation of H2CO3 in the urine so CO2 isnt absorbed into the PCT
- Stops Na+ from being reabsorbed by inhibiting the absorption of bicarbonate

Question 7

what is acetazolamide used for?

Answer 7

glaucoma
epilepsy
mountain sickness

Question 8

why is acetazolamide used in acute mountain sickness?

Answer 8

• respiratory alkalosis occurs as you ascend bc PaO2 decreases so minute ventilation increases to compensate
• acetozolamide creates metabolic acidosis to compensate for the respiratory alkalosis
• stops cerebral and pulmonary oedema

Question 9

what are the side effects of carbonic anhydrase inhibitors?

Answer 9

Metabolic acidosis
Sedation
Sulphonamide antibiotics
Bone marrow suppression

Question 10

what are the contraindications of CA inhibitors?

Answer 10

Contra indicated in significant CKD

Question 11

name loop diuretics

Answer 11

frusemide

bumetanide

Question 12

what part of the kidneys do loop diuretics act on?

Answer 12

thick ascending limb of the loop of henle

act on the Na/K/Cl cotransporter

Question 13

what is the mode of action of loop diuretics?”

Answer 13

blocks the action of the Na/K/Cl transporter so Na+, K+ and Cl- are all excreted
also leads to more magnesium and calcium in the urine –> hypocalcaemia and hypomagnesium

Question 14

what is the most potent diuretic?

Answer 14

loop diuretics

Question 15

what do loop diuretics cause the excretion of?

Answer 15

potassium
sodium
water
calcium
magnesium

Question 16

what are the indications of loop diuretics?

Answer 16

Hypertension
Heart failure
Volume overload from CKD

Question 17

what are the side effects of loop diuretics?

Answer 17

hypokalaemia
dehydration –> acute kidney failure
kidney stones (bc of the high levels of calcium in the urine)
deafness (at high doses)

Question 18

name thiazide diuretics

Answer 18

Bendroflumethiazide
Hydrochlorothiazide
Thiazide like drugs:
Chlorthalidone
 Indapamide
 Metolazone

Question 19

what part of the kidneys do thiazide diuretics act on?

Answer 19

distal convoluted tubule

Na/Cl cotransporter

Question 20

what do thiazide diuretics lead to the excretion of?

Answer 20

Na
Cl
water

Question 21

what do thiazide diuretics lead to the reabsorption of?

Answer 21

calcium

high levels of blood calcium and low levels of urine calcium

Question 22

what are the clinical uses of thiazide diuretics?

Answer 22

Primarily an antihypertensive

Reduction in plasma volume
Reduction in peripheral resistance (causes slight vasodilation)

Question 23

what are the side effects of thiazide diuretics?

Answer 23

Electrolyte effects:
Hypokalaemia
Hypercalcaemia
Hyponatraemia (particularly in old people)

Hyperglycaemia
Hypercholesterolaemia

Question 24

what are the groups of potassium sparing diuretics and name examples of each

Answer 24

• Epithelial Na Channel antagonists: Amiloride and Triamterene
• Aldosterone antagonists: Spironolactone and Eplerenone

Question 25

what are the targets of potassium sparing diuretics?

Answer 25

collecting tubule

Question 26

what is the mode of action of potassium sparing diuretics like amiloride?

Answer 26

Blocks sodium channels (ENaC)
Prevents sodium reabsorption
Don’t prevent K+ secretion so no hypokalaemia bc less K+ and H+ are being exchanged for the Na+

Question 27

what are the clinical uses of amiloride?

Answer 27

Heart failure
Hypokalaemia (from other diuretics)
Co-amilofruse
Co-amilozide
Cirrhosis

Question 28

what are the side effects of amiloride?

Answer 28

hyperkalaemia

hyponatremia

Question 29

what is the mode of action of spironolactone?

Answer 29

Aldosterone receptor antagonist

Competitively binds receptors at the aldosterone-dependent sodium-potassium exchange site in the collecting tubule

Question 30

what are the uses of aldosterone inhibitors?

Answer 30

hyperaldosteronism (Conns)
heart failure
Hypokalaemia
Cirrhosis

Question 31

what are the side effects of aldosterone inhibitors?

Answer 31

hyperkalaemia!!
gynecomastia
hyponatraemia (Cirrhosis)

Question 32

what is the most important clinical osmotic diuretic?

Answer 32

mannitol

Question 33

what are osmotic diuretics?

Answer 33

Any osmotically active molecule that is freely filtered in the glomerulus, and is not reabsorbed by the tubules

Question 34

what is the mechanism of action of osmotic diuretics?

Answer 34

Osmotically active molecule in the tubular lumen: stops water absorption
Reduces reabsorption of all solutes:
Sodium, potassium, urea…
Molecule ‘drags’ sodium from interstitial space

Question 35

what are the clinical indications of osmotic diuretics?

Answer 35

cerebral oedema

oliguric acute renal failure

Question 36

what are the side effects of osmotic diuresis?

Answer 36

• Transient fluid overload - Pulmonary odema
• Other non pharmacological osmotic diuretics: Glucose, DKA/HHS,
  Urea - Disequilibrium syndrome

Question 37

when do you not use diuretics?

Answer 37

When hypotensive
When dehydrated
When hypokalaemic (Loop/Thiazide)
When hyperkalaemic (Amiloride, aldosterone antagonists)
Post surgery, with a poor urine output