Diuretics Flashcards
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
Example of aldosterone antagonist
spironolactone
Uses of potassium sparing diuretic + aldosterone antagonists
- secondary hyperaldosteronism
- hepatic cirrhosis
- nephrotic syndrome
- hypertension treatment
How do potassium sparing diuretics + aldosterone antagonists work in the CD + DCT
- PSD: block ENAC channels
- AA: decrease aldosterone > decreased ENAC + ROMK
What type of drug is mannitol?
Osmotic diuretic
What type of drug is bumetanide?
Loop diuretic
What type of drug is furosemide?
Loop diuretic
What type of drug is bendroflumethiazide?
Thiazide + thiazide like diuretic
What type of drug is indapamide?
Thiazide + thiazide like diuretic
What type of drug is amiloride?
Potassium sparing diuretic
What type of drug is spironolactone?
Aldosterone antagonist
What is diuresis?
The excretion of water in the urine
What is natriuresis?
Excretion of sodium in the urine
Issues with osmotic diuretics administer via IV
Water drawn towards it in blood vessels on route to kidney:
- expands extracellular fluid volume
- decreases blood viscosity
- Inhbits renin release
