Diuretics Flashcards
(37 cards)
What are diuretics?
Drugs which act on the kidney to increase urine production + eliminate water from the body
What are the 5 main classes of diuretics?
- loops diuretics
- potassium sparing diuretics
- thiazide + thiazide-like diuretics
- carbonic anhydrase inhibitors
- osmotic diuretics
Where do carbonic anhydrase inhibitors work?
PCT
Where do osmotic diuretics work?
Across whole nephron but mainly PCT
Where do loop diuretics work?
Loop of Henle (ascending limb)
Where do potassium sparing diuretics work?
Distal DCT + collecting duct
Outline how carbonic anhydrase inhibitors work
- PCT
-
inhibit carbonic anhydrase
H2CO3 => CO2 + H2O is prevented - less H+ inside cell to swap with Na+ in nephron
Outline how osmotic diuretics work
- PCT
- increases osmotic pressure within kidney
- inhibits reabsorption of water
- increases water excretion with little effect on Na+
Example of osmotic diuretics
Mannitol
Uses of osmotic diuretics
- acute renal failure due to shock or trauma
- acute drug poisoning
- decrease intracranial + intraocular pressure before ophthalmic or brain procedures
Side effects of osmotic diuretics
- hyponatremia > headaches, nausea, vomiting
- extracellular volume expansion > complicates heart failure + pulmonary oedema
- contraindicated in chronic heart failure
- excessive use > dehydration + hypernatremia ??
How do loop diuretics work?
- loop of Henle
- blocks NKCC cotransporter
- build up of Na+, K+ and Cl-
- given orally or via IV
- increase urine volume
What is the most potent diuretic?
Loop diuretics
Uses of loop diuretics
Emergency situations:
- severe oedema associated with congestive heart failure + nephrotic syndrome
- oliguric AKI
- hypercalcaemia
- hyperkalaemia
- acute pulmonary oedema
- toxicity of Br, F + I
Two example of loop diuretics
bumetanide
furosemide
Side effects of loop diuretics
- hypovolaemia
- hyponatremia
- hypokalaemia
- hypomagnesaemia
- metabolic alkalosis
- postural hypotension
How can loop diuretics cause metabolic alkalosis?
Increases urine volume > decreases blood volume > increased bicarbonate conc. > increased pH
What is needed when using potassium sparing diuretics to avoid hypokalaemia?
Dietary potassium supplements
Where do thiazide + thiazide like diuretics work?
DCT
Two examples of thiazide + thiazide like diuretics
bendroflumethiazide
indapamide
Uses of thiazide + thiazide like diuretics
For treatment of:
- essential hypertension
- mild heart failure
- calcium nephrolithiasis due to hypercalciuria
- osteoporosis
- nephrogenic diabetes insipidus polyuria
How can thiazide + thiazide like diuretics cause hypercalcemia?
- NaCL transporter blocked
- less Na+ in cell
- more drawn in from blood via NaCa cotransporter in basolateral membrane
- more Ca2+ leaves + is reabsorbed
How do thiazide + thiazide like diuretics work?
DCT
- block Na+Cl- transporter
Example of potassium sparing diuretic
amiloride
