Diuretics

Question 1

MoA loop diuretics

Answer 1

inhibit Na+ K+ 2Cl- symporter in ascending loop of henle

Question 2

MoA thiazide diuretics

Answer 2

inhibit Na/Cl symporter in distal convuluted tubule

Question 3

MoA K+ sparing diuretics

Answer 3

aldosterone antagonists

so inhibit the reabsorption of Na+ and water
inhibit excretion of K+ and H+

Question 4

indications furosemide

Answer 4

pulmoanry oedema
chronic HF
resistant HTN

Question 5

dosing furosemide

Answer 5

Furosemide: 20-40mg mane for management of oedema (resistant oedema – 80-120mg daily); 40-
80mg daily for resistant hypertension

Question 6

adverse effects all diuretics

Answer 6

electrolyte disturbance
- hyponautraemia
- hypokalamia (except spiro)
- hypochloraemia

dehydration –> hypovolemia –> hypotension
- postural hypotension
- AKI

metabolic
hyperglycaemia
hyperuricaemia
hypercalcaemia

Question 7

specific adverse effect loop diuretics eg furosemide

Answer 7

ototoxicty

Nephrotoxicity

Hepatic encephalopathy

Question 8

specific adverse effects potassium sparing diuretics

Answer 8

Hyperkalaemia

Gynaecomastia/hypogonadism, impotence in males, menstrual irregularities in females

Question 9

interactions all diuretics

Answer 9

other antihypertensives (increased hypotensive effect)

lithium (increased lithium conc)

NSAIDs (imp diuresis and increased risk nephtox)

other hyponautraemia causing drugs

Question 10

specific interactions spironolactone/K+ sparing

Answer 10

Drug affecting RAAS (increased risk of hyperkalaemia) – ACE inhibitors, ARBs, direct renin inhibitors

 Other potassium sparing diuretics e.g. amiloride, triamterene (increased risk of
hyperkalaemia)

 Potassium supplements

Question 11

specific interactions furosemide/loop diuretics

Answer 11

 Aminoglycoside antibiotics and vancomycin (increased risk of ototoxicity)

 Digoxin (risk of cardiotoxicity)

Question 12

drug monitoring diuretics

Answer 12

loop and thiazide: U&Es at baseline and throughout

spironolactone: Baseline U&E and LFT. Re-check U&E after 1 week then every month for the first
3 months and 3 monthly thereafter for a year then 6 monthly for the duration of therapy.

Question 13

specific indications spironolactone

Answer 13

ascites

Question 14

why are LFTs monitored spironolactone

Answer 14

Spironolactone has been linked to rare cases of clinically apparent drug induced liver disease

Question 15

how do loop diuretics cause hypokalaemia?

Answer 15

direct reduced reabsorption of Na, K and 2Cl-

Question 16

how do thiazide diuretics cause hypokalaemia

Answer 16

reduced reabsorption of Na and Cl by NaCl co-transporter

–> more Na in DCT –> downstream increase in aldosterone mediated pumps which reabsorb Na and excrete K+ (Na/K pump)

Question 17

examples loop diuretics

Answer 17

furosemide
Bumetanide

Question 18

example thiazide diuretics

Answer 18

thiazide:
bendroflumothiazide

thiazide-like (longer acting):
Indapamide
Chlorthalidone.
Hydrochlorothiazide

Question 19

examples potassium sparing diuretics

Answer 19

spironolactone
Eplerenone
Amiloride