Diuretics Flashcards
Where do loop diuretics act?
The thick ascending limb of the loop of Henle
Mechanism of action of loop diuretics?
Block the triple co-transporter
What do loop diuretics do?
Prevent dilution of the filtrate in the TAL, increasing the load of Na+ reaching the late nephron
How do loop diuretics enter the nephron?
OAT
Example of a loop diuretic?
Furosemide
Indications for loop diuretic use?
Nephrotic syndrome
Acute hypercalcaemia
Hypertension
Chronic heart/kidney failure
Cons of loop diuretics?
Hypovolaemia
Hypotension
Calcium and magnesium depletion
Hypokaleamia
Where do thiazide diuretics act?
Early distal tubule
Mechanism of action of thiazide diuretics?
Block Na+/Cl- cotransporter
What do thiazide diuretics do?
Increase Na+ load reaching the late nephron
Increase calcium reabsorption
How do thiazide diuretics enter the nephron?
OAT
Example of a thiazide diuretic?
Bendroflumethiazide
Indications for thiazide diuretic use?
Mild heart failure
Hypertension
Renal stone disease
Nephrogenic diabetes insipidus
Cons of thiazide diuretics?
Hypovolaemia
Hypotension
Hypokalaemia
Magnesium depletion
Where do osmotic diuretics act?
Proximal tubule
How do osmotic diuretics enter the nephron?
Filtration
Mechanism of action of osmotic diuretics?
Increase the filtrate osmolarity, opposing the reabsorption of water
Example of an osmotic diuretic?
Mannitol
Indications for use of osmotic diuretics?
Acute raised ICP/IOP
To prevent hypovolaemic renal failure to maintain urine flow
Cons of osmotic diuretics?
Secondary hyponatraemia - increased fluid volume decreases sodium concentration and the gradient for its reabsorption
Examples of potassium sparing diuretics?
Spironolactone
Amiloride
Mechanism of action of amiloride?
Blocks apical Na+ channels
Mechanism of action of spironolactone?
Competes with aldosterone, reducing Na+ reabsorption
What do potassium sparing diuretics do?
Increase Na+ excretion and decrease K+ excretion
Indications for potassium sparing diuretic use?
Hypertension
Heart failure
Primary and secondary hyperaldosteronism
Cons of spironolactone?
Gynaecomastia
How do carbonic anhydrase inhibitors work?
Increase bicarbonate excretion along with Na+, K+ and H2O
Cons of carbonic anhydrase inhibitors
Cause an alkaline urine and metabolic acidosis
No longer used as diuretics but used instead for:
Glaucoma
Altitude sickness prophylaxis
Infantile epilepsy
Where do carbonic anhydrase inhibitors act?
Proximal tubule
Example of carbonic anhydrase inhibitor?
Acetazolamide
