Flashcards in Diuretics Deck (22):
What are diuretics?
Increase water loss from kidneys by decreasing sodium reabsorption at different sites
What are the 5 classes of diuretics?
Carbonic anhydrase inhibitors
Potassium sparing diuretic
What is the mechanism of carbonic anhydrase inhibitors?
- work on the PCT
- carbonic anhydrase converts H2CO3 into H2O and CO2 which is absorbed by the PCT
- acts within PCT to transform H2CO3 to H+ and HCO3- and HCO3- is absorbed into blood whilst H+ excreted to restarts process
- therefore CA inhibitors stop reabsorption of bicarbonate
When are CA inhibitors used clinically?
Lead to metabolic acidosis
Counteract AMS, HACE, PACE - counter-acts respiratory alkalosis due to hyperventilation
Side effects of CA inhibitors?
- metabolic acidosis
- bone marrow suppression
What is the mechanism of thiazide like diuretics?
Work on the DCT
- Na/K+ ATPase pump out Na+ and pump in K+
- Na+ and Cl- are reabsorbed from DCT lumen due to conc gradient created
- diuretics BLOCK Na+/Cl- symport transporter decreasing sodium reabsorption as no conc. gradient = diuresis as water will follow sodium into lumen
What are the clinical effects of thiazide like diuretics?
Blood volume reduction
Side effects of thiazide diuretics
Examples of thiazide like diuretics
What is the mechanism of loop diuretics?
- work on ascending limb of LOH
- inhibits Na/K/2CL co-transporter
- decreases absorption of magnesium and calcium (through inhibiting potassium reabsorption into the cell as co-transporter inhibition prevents conc. gradient forming to allow Na+/K+ ATPase to function for K+ to re-enter the cells)
Side effects of loop diuretics?
Hypokalemia as potassium excreted not absorbed
Examples of loop diuretics?
What is the mechanism of potassium sparing diuretics?
- act on collecting tubules
- epithelial sodium channel antagonists:
block channels, do not affect potassium channels, increased sodium loss = diuresis
What is the clinical use of potassium sparing diuretics?
Side effects of potassium sparing diuretics
What are spironolactone and eplerenone examples of?
- upregulate epithelial sodium channels (ENACs)
- decrease sodium reabsorption = diuresis
- K+ not affected
What is the clinical use of spironolactone/eplerenone?
What are the side effects of spironolactone/eplerenone?
Examples of osmotic diuretics?
Mechanism of osmotic diuretics
Any osmotically active molecule is free filtered from glom and not reabsorbed in tubules so sodium/potassium/water all dragged out from interstitial space
What is the clinical use of osmotic diuretics?
Cerebral oedema/raised intracranial pressure