Lecture 6: Diuretic Agents

Question 1

what is reabsorption of water very dependent on

Answer 1

Na+

Question 2

what is the main site of action of carbonic anhydrase inhibitors

Answer 2

proximal tubule

Question 3

what is the main site of action of osmotic diuretics

Answer 3

• proximal tubule

- descending loop of henle

Question 4

what is the main site of action of thiazides and thiazide like diuretics

Answer 4

early distal tubule

Question 5

what is the main site of action of potassium sparing diuretics

Answer 5

• late distal tubule

- early collecting tubule

Question 6

example of a loop diuretic

Answer 6

furosemide

Question 7

how do loop diuretics work

Answer 7

• inhibit NKCC2 transporter in the thick ascending limb of loop of henle
• reduced Na+ reabsorption leads to profound diuresis

Question 8

unwanted effects of loop diuretic use

Answer 8

• dehydration
• hypokalaemia
• metabolic alkalosis
• hypokalaemia can potentiate effects of cardiac glycosides
• deafness when used with aminoglycoside antibiotics

Question 9

where do thiazide diuretics act

Answer 9

• distal tubule

- on Na+/Cl- cotransporter

Question 10

examples of thiazide diretics

Answer 10

• bendroflumethiazide

- hydrochlorothiazide

Question 11

examples of thiazide like diuretics

Answer 11

• indapamide (preferred for hypertension)
• metolazone (good combined with loop diuretic)
• xipamide (lowers BP with less side effects)

Question 12

unwanted effects of thiazide diuretics

Answer 12

• plasma K+ depletion
• metabolic alkalosis
• increased plasma uric acid and gout
• hyperglycaemia
• increased plasma cholesterol with long term use
• reverisble male impotence

Question 13

what is the current preferred diuretic for resistant hypertension

Answer 13

indapamide

Question 14

symptoms of mild hypokalaemia

Answer 14

• fatigue
• drowsiness
• dizziness
• muscle weakness

Question 15

symptoms of severe hypokalaemia

Answer 15

• arrhythmias
• muscle paralysis
• death

Question 16

examples of aldosterone antagonists

Answer 16

• eplerenone

- spironolactone

Question 17

examples of non-aldosterone antagonists

Answer 17

• amiloride

- triamterene

Question 18

what is the active metabolite of spironolactone

Answer 18

canrenone

Question 19

what are aldosterone antagonists used for

Answer 19

• oedema

- heart failure

Question 20

unwanted effects of aldosterone antagonists

Answer 20

• hyperkalaemia
• metabolic acidosis
• GI upsets
• gynaecomastia, menstrual disorders, testicular atrophy

Question 21

how do non-aldosterone antagonists work

Answer 21

block luminal Na+ channel on distal tubule

Question 22

unwanted effects of non-aldosterone antagonists

Answer 22

• hyperkalaemia
• metabolic acidosis
• GI issues
• skin rashes

Question 23

example of carbonic anhydrase inhibitor

Answer 23

azetozolamide

Question 24

what are carbonic anhydrase inhibitors used for

Answer 24

• glaucoma

- epilepsy

Question 25

unwanted effects of carbonic anhydrase inhibitors

Answer 25

• metabolic acidosis

- enhances renal stone formation

Question 26

what were the potential ADH antagonists

Answer 26

• lithium
• demeclocycline
• now developing tolvaptan

Question 27

issue with the ADH antagonists

Answer 27

• can cause diabetes insipidus
• can cause renal failure
• lithium can cause tremors, mental confusion, cardiotoxicity
• demeclocycline shouldn’t be used in patients with liver disease

Question 28

what is tolvaptan being used for

Answer 28

• treatment of hyponatriuraemia

- in fast track clinical trials for polycystic kidney disease