diuretics

Question 1

what can diuretics be used to treat?

Answer 1

cardiovascular drug
management of heart failure
antihypertensives (3rd line)

Question 2

How do diuretics work generally?

Answer 2

Increases Na+ excretion (NATRIURESIS)
Na+ is followed by water
Decrease extracellular/plasma volume (reduces oedema and blood pressure)

Question 3

What are 4 diuretics and where do they work in the nephron?

Answer 3

Osmotic agents - PCT
Loop diuretics - loop of henle
Thiazides - DCT (fine tuning and less powerful)
K-sparing agents - CD, to prevent K+ loss

Question 4

How do osmotic diuretics work?

Answer 4

Increases osmolaltity

reduces passive reabsorption of H2O

Question 5

How do loop diuretics work

Answer 5

Blocks Na+/2CL-/K+ sumporter of thick ascending limb (mau block Cl- binding site)- creates a hypertonic interstitium - more conc urine

Question 6

what ions are we worried about when using loop diuretics

Answer 6

K+
Na+
Ca2+ and Mg2+

Question 7

what are some effects of loop diuretics

Answer 7

Potassium loss - hypokalamia

Question 8

How do Thiazides work? Why aren’t they strongly recommend anymore?

Answer 8

Inhibit active Na+ reabsorption and accompanying Cl-

No longer recommended strongly due to risk of causing diabetes.

Question 9

Why aren’t thiazides used in CKD

Answer 9

Usually ineffective if they cant’t get to the transporter in the PCT which they are excreted out of first.

Question 10

what 2 drugs can cause hypokalaemia. How do they do it?

Answer 10

loop diuretics
thiazides

decreases Na+ in ECF - loops block NaCl entry to macula densa - activates RAA - Na+ retention and K+loss

Question 11

what is the receptor for aldosterone?

Answer 11

mineralcorticoid receptor

Question 12

what is the protein stimulated by aldosterone?

Answer 12

AIP- aldosterone-induced proteins

Question 13

what are some reasons why K+ is secreted more when diuretics are used?

Answer 13

Increased channels on apical side, promoting sodium reabsorption - so more K moved into cell by Na/K pump. K moves down conc gradient and leaves via urine

Question 14

why is diuretic use increase risk of alkalosis

Answer 14

Na+ delivery to DCT associated with H+ loss (Na+/H+ antiporters)
leads to alkalosis

Question 15

K-sparing diuretics

What are the 3 drugs? How do they work?

Answer 15

Aldosterone receptor antagonists - less action, less Na+ reabsorbed
Na+ channel blockers - in combination reduce K+ loss
ACEIs cause hyperkalaemia and so negate the effect of K=losing diuretics

Question 16

How do aldosterone receptor antagonists work?

Answer 16

prevents insertion of Na+ pumps and channels

used in hyperaldosteronism

Question 17

Sodium-channel blockers

On which part of the nephron do they work? How do they work?

Answer 17

block luminal Na+ channels in late DCT and CD

Na+ no longer retained at expense of K+

Question 18

what drug can slow down diabetic retinopathy?

Answer 18

ACEis

by blocking RAA activation?

Question 19

Counselling points
When should they be taken
Avoid what foods
What risks are there?
What drug can reduce effects of loop diuretics?

Answer 19

Take in morning

avoid excess salt

risks - incr urine flow, postural hypotension, worsen diabetes, gout

NSAIDs may reduce effect