29 - Diuretics

Question 1

What are diuretics

Answer 1

Diminish sodium re-absorption at different sites of the nephron –> Increase Na and H20 loss –> decrease in blood volume

Question 2

What percent of bloody supply do kidneys receive

Answer 2

25%

Question 3

How much do the kidneys filtrate a day

Answer 3

120ml/min

180L filtrate a day

Question 4

What are they classes of diuretic

Answer 4

Carbonic anhydrase inhibitors
Loop
Thiazide
Potassium sparing diuretics - prevents excess K+ excretion
Osmotic diuretics

Question 5

Where do carbonic anhydrase inhibitors act on

Answer 5

Proximal convulated tubule

Question 6

How do carbonic anhydrase inhibitors work

Answer 6

CA is needed to absorb bicarb so that Na+ can be reabsorbed

Question 7

Example of CA inhibitor

Answer 7

Acetazolamide

Question 8

What is acetazolomide used for

Answer 8

Glaucoma
Epilepsy
Mountain Sickness (it can appose the alkalosis with acidosis)

Question 9

Side effects of CA inhibitors

Answer 9

Metabolic acidosis (contraindicated in chronic kidney disease)
Sedation
Sulphonamide antibiotics (bone marrow suppression)

Question 10

Examples of loop diuretics

Answer 10

Frusemide

Bumetanide

Question 11

Where do loop diuretics act

Answer 11

Thick ascending limb (Na/K/2Cl symporter)

Question 12

What do loop diuretics act on

Answer 12

Block the Cl- portion of the symporter

Question 13

What do loop diuretics cause to be excreted

Answer 13

K+
Na+
H2O
Ca2+
Mg

Question 14

Indications of loop diuretics

Answer 14

Hypertension
Heart failure
Volume overload for CKD

Question 15

Side effects of loop diuretics

Answer 15

Hypokalaemia

Dehydration –> acute renal failure, kidney stones, deafness

Question 16

Where do thiazide diuretics act on

Answer 16

Distal convulated tubule

Question 17

What is the mechanism of thiazide diuretics

Answer 17

Inhibits Na and Cl- from urine to tubule

Acts on Na+/Cl- symporter

Question 18

Examples of thiazide diuretics

Answer 18

Bendroflumethiazide

Hydrochlorothiazide

Question 19

Thiazide like like drugs

Answer 19

Chlothalidone
Indapamide
Metolazone

Question 20

How does thiazide diuretics act as a hypertensive

Answer 20

Reduces plasma volume and peripheral resistance

Question 21

Side effects of thiazide diuretics

Answer 21

Hypokalaemia, hypercalcaemia, hyponatraemia, hyperglycaemia, hypercholesterolaemia

Question 22

What do potassium sparing diuretics do

Answer 22

Prevent excess K+ excretion

Question 23

Type of potassium sparing diuretics

Answer 23

Epithelial Na Channel antagonists (ENaC)

Aldosterone antagonists

Question 24

Examples of ENaC antagonists

Answer 24

Amiloride, Triamterene

Question 25

Where does ENaC act on and what does it do

Answer 25

Acts on collecting ducts/late DCT | prevents Na into cell from urine

Question 26

Amiloride uses

Answer 26

Heart Failure Hypokalaemia Cirrhosis

Question 27

Amiloride side effects

Answer 27

Hyperkalaemia | Hyponatraemia

Question 28

Aldosterone antagonists

Answer 28

Spironolactone | Eperenone

Question 29

Where do aldosterone antagonist work

Answer 29

Collecting tubule

Question 30

What do aldosterone antagonists do

Answer 30

Inhibit aldosterone which normally upregulates Na+/K+ on basolateral membrane of intercalated cells

Question 31

Indications for aldosterone antagonists

Answer 31

Hyperaldosteronism (Conns) Heart failure Hypokalaemia Cirrhosis

Question 32

SE of aldosterone antagonissts

Answer 32

Hyperkalaemia Gynecomastia Hyponatraemia

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

Example of osmotic diuretic

Answer 34

Mannitol IV - fast acting, fast metabolism

Question 35

What does mannitol do

Answer 35

Increase osmolality in the tubular lumen – stops water absorption

Question 36

MoA of osmotic diuretics

Answer 36

Reduces re absorption of all solutes (Na, K+,urea, drags Na from interstitium)

Question 37

Indications of osmotic diuretics

Answer 37

Cerebral oedema | Oliguric acute renal failure

Question 38

Side effects of osmotic diuretics

Answer 38

Transient fluid overload | Urea (disequilibrium syndrome)

Question 39

When to not use diuretics

Answer 39

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