Diuretics

Question 1

Which diuretics work at the PCT?

Answer 1

SGLT2 inhibitors
CA inhibitors
Mannitol

Question 2

How does mannitol work?

Answer 2

It works on the descending loop of henle, preventing water from being reabsorbed.

Question 3

Where do thiazide diuretics work?

Answer 3

On the Na/Cl exchanger in the DCT

Question 4

How does spironolactone work?

Answer 4

Spironolactone works on the ADH receptors

Question 5

What are the problems associated with CA inhibitors ?

Answer 5

Hypokalaemic metabolic acidosis

Tolerance after 2-3 days

Question 6

What problems are associated with mannitol?

Answer 6

Reduced ICV

Hypernatremia risk

Question 7

Loop diuretics work on which ion channel?

Answer 7

NKCC2

Question 8

What effect do loop diuretics have?

Answer 8

Loss of Na and water
Hypokalaemic metabolic alkalosis
Increased calcium loss (due to the loss of K back diffusion driving divalent cation reabsorption).

Question 9

What are the effects of thiazide diuretics?

Answer 9

Loss of Na and water
Hypokalaemic metabolic alkalosis
Increased calcium reabsorption

Question 10

How does spironolactone work?

Answer 10

It prevents aldosterone from binding to the mirealcorticoid receptor, decreasing expression of ENaC and Na/K ATPase on the principle cells of the collecting ducts.

Question 11

How does amiloride work?

Answer 11

Blocks ENaC in the principle cells in the collecting duct

Question 12

Give the name of a ADH antagonist

Answer 12

Tolvaptan - blocks the V2 receptor and is used to treat hyponatraemia and prevent enlargement of cysts in APCKD

Question 13

For someone being treated for bipolar disorder, what are the possible implications of the treatment?

Answer 13

Lithium inhibits action of ADH and then works as a diuretic

Question 14

What natural substances have a diuretic action?

Answer 14

Alcohol- inhibits ADH

Caffeine- increase GFR and decrease Na reabsorption

Question 15

State the generic adverse drug reactions of diuretics

Answer 15

Hypovolaemia and hypotension- can lead to AKI
Electrolyte disturbance
Metabolic abnormalities
Anaphylaxis/ photosensitivity rash

Question 16

Name the adverse drug reactions of thiazides

Answer 16

Gout 
Hyperglycaemia
Erectile dysfunction
Increased LDL and TG
Hypercalcaemia

Question 17

State the common ADRs of spironolactone

Answer 17

Hyperkalaemia
Impotence
Painful gynaecomastia

Question 18

What is the common ADR of bumetanide?

Answer 18

Myalgia

Question 19

State furosemide common ARDs

Answer 19

Ototoxicity
Alkalosis
Increased LDL and TG
Gout

Question 20

State some typical uses for diuretics

Answer 20

Hypertension - thiazide, spironolactone
Heart failure - loop diuretics, spironolactone, SGLT2 inhibitors
Decompensated liver disease-spironolactone and loop diuretics, tolvaptan
Nephrotic syndrome - loop diuretic, thiazides, potassium sparing supplements
CKD- loop diuretics, SGLT2 inhibitors

Question 21

Why would an ACEi not be prescribed with a K sparing diuretic?

Answer 21

Increased risk of hyperkalaemia

Question 22

Why would a aminoglycoside not be co-prescribed with a loop diuretic?

Answer 22

Ototoxicity and nephrotoxicity

Question 23

Why is digoxin not co-prescribed with a thiazide or loop diuretic?

Answer 23

Hypokalaemia, resulting in increased digoxin binding and toxicity

Question 24

Why are beta-blockers not co-prescribed with thiazides?

Answer 24

Hyperglycaemia, hyperlipidemia and hyperuricaemia

Question 25

Why are steroids and thiazides/loop diuretics not co-prescribed?

Answer 25

Increased risk of hypokalaemia

Question 26

Why is lithium not prescribed with thiazides?

Answer 26

Lithium toxicity

Question 27

Why is lithium not co-prescribed with loop diuretics?

Answer 27

Reduced lithium levels

Question 28

Why are carbamazepine and thiazides not co-prescribed?

Answer 28

Increased risk of hyponatreamia