2.3 Clinical Aspects: Diuretics

Question 1

Dieretic:

Answer 1

drug that increases the rate of urine flow

Question 2

How are diretics achieved?

Answer 2

increased Na+ exretion (+ an anion like chloride) - water follows

Question 3

site of action for diuretics?

Answer 3

different diuretics act in different parts of the tubules

Question 4

Weakest diuretic?

Answer 4

Carbonic anhydrase inhibitors
- acetazolamide (ACE), diclorphenamide

Question 5

Carbonic anhydrase inhibitors : main clinical use?

Answer 5

treatment of glaucoma

Question 6

Where do Carbonic anhydrase inhibitors occur

Answer 6

Proximal tubule

Question 7

main purpose of Carbonic anhydrase inhibitors ?

Answer 7

reabsorb sodium bicarbonate –> acid secretion will occur in response

Question 8

Effects of CAI:

Answer 8

-increase in bicarbinate extretion in urine
- increased urine pH
- metabolic acidosis

Question 9

Side effects of CAI:

Answer 9

-reduce renal blood flow and GFR
- metabolic acidosis
-alkaline in urine (bladder stones)
- Hypokalaemia ( increased distal delivery of Na+)

Question 10

Where are osmotic diuretics filtered?

Answer 10

freeliy filtered at the glomerulus
- tend to sit in urine

Question 11

Osmotic diuretics increase?

Answer 11

• osmolarity of tubular fluid (& plasma)
• excretion of almost all electrolytes

Question 12

Example of osmotic diuretics?

Answer 12

Mannitol

Question 13

Osmotic diuretics pull…

Answer 13

water out of intercellular space and into extracellular space

Question 14

major sit of action for osmotic diuretics?

Answer 14

loop of Henle

Question 15

osmotic diuretics do what?

Answer 15

• expand ECF, decrease blood viscocity, inhibit renin release
• Increase RBF and reduce medullary tonicity
  -reduce water reabsorption (lowers NaCl in tubule)

Question 15

osmotic diuretics do what?

Answer 15

• expand ECF, decrease blood viscocity, inhibit renin release
• Increase RBF and reduce medullary tonicity
  -reduce water reabsorption (lowers NaCl in tubule)

Question 16

What type of reabsorption is osmotic diuretic?

Answer 16

passive reabsorption

Question 17

Osmotici diuretics: clinical uses

Answer 17

Mainly for :
- intacranial pressure / cerebral oedema (brain tumor

rarely used for :
- acute glaucoma (topical from CAI prefereed)
- acute kidney injury (renal failure

Question 18

side effects of osmotic diuretics:

Answer 18

• volume expansion (cant be used in over-hydrated patient)
• can cause pulmonary oedema
• intracranial heomorrage via bleed in brain ( volume expansion would increase)

Question 19

Most common diuretics?

Answer 19

loop diuretics:
ex: Furosemide

Question 20

are loop diuretics weak or potent?

Answer 20

Potent

Question 21

How do loop diuretics work?

Answer 21

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

Question 22

Most common reason to use loop diuretics?

Answer 22

acute and chronic heart failure patients (specifically pulmonary oedema)
-get rid of NaCl and reduce ECF volume

Question 23

Loop diuretics mechanism of action:

Answer 23

• increase excretion of Na and Cl
• prevent formation of hypertonic medullary interstitium (V potent)
• increase excretion of Ca2+ and Mg

Question 24

loop diuretics: side effects:

Answer 24

- abnormal fluid and electrolyte balance - increase Na delivery to diastal tubule results in loss of H+ and K+

Question 25

Thiazides diuretics inhibit:

Answer 25

Na/ Cl symport in the distal convulted tubule

Question 26

Thiazides diuretics used in treatment of?

Answer 26

oedema associated with heart failure and cirrhosis

Question 27

Veterinary use of Thiazide?

Answer 27

quite limited: -additive therapy/ refractory heart failure - prevent calcium oxalate urolithiasis

Question 28

potassium sparing diuretics:

Answer 28

cells in late distal tubule and collecting duct - ENaC inhibitors (ex: amiloride) -Mineralcorticosteroid (ex: spironolactone)

Question 29

Diuretics with proximal sites of action increase delivery of ___ to distal tubule to increase?

Answer 29

delivery of Na+ to the distal tubule to increase K+ and H+ excretion

Question 30

ENac Inhibitors: Increase __ excretion decrease ___ and ___ excretion

Answer 30

increase Na+ excretion decrease H+ and L+ excretion

Question 31

ENaC side effects:

Answer 31

-limited diuretic potency (not much Na+ reabsorbed) - contra-indicated in hyperkalaemia

Question 32

ENaC inhibitors:

Answer 32

- not used in veterinary use often - sometimes used as 2nd diuretic in refractory oedema

Question 33

Aldosterone effects:

Answer 33

- binds to mineralcortical steroid receptor - regulates expression of aldosterone induced proteins (ENaC) - Increase Na+ conductance in lumen and Na+ pump activity -

Question 34

Aldosterone antagonist:

Answer 34

commonly used in managment of heart failure and hepatic cirrhosis -anti-fibrotic effects

Question 35

spironolactone redes risk of

Answer 35

hypokalaemia - which can lead to hepatic coma