7.2 Diuretics Flashcards
What is diuresis?
Increased formation of urine by the kidney
What is a diuretic?
A drug which promotes the formation of urine (diuresis)
When may a diuretic be used?
Hypertension Heart failure Oedema Kidney failure Hypercalcaemia Glaucoma Cerebral oedema
Where do loop diuretics act?
Loop of Henle
Which membrane channel do loop diuretics block?
Na-K-2Cl co-transporter
Where do thiazide diuretics act?
Easly DCT
Which membrane channel do thiazide diuretics block?
Na-Cl transporter
Where do K+ sparing diuretics act in the kidney?
Late DCT and collecting duct
Give an example of an aldosterone antagonist
Spironolactone
How do aldosterone antagonists work as diuretics?
Inhibit the aldosterone receptor to reduce Na+ reabsorption
Name a drug which increases the osmolarity of the filtrate in the kidney to act as a diurectic
Mannitol
How can a carbonic anhydrase inhibitor act as a diuretic?
Carbonic anhydrase can no longer break down convert H+ and HCO3- to CO2 and H2O
Reduces Na+ and HCO3- reabsorption
How do loop diuretics enter the nephron?
Organic anion pathway
Give an example of a loop diuretic
Furosemide
Give an example of a K+ sparing diuretic
Amiloride
How can loop and thiazide diuretics cause hypokalaemia?
Increased Na+ reabsorption by principle cells in the DCT due to lack of reabsorbion earlier in nephron
Favourable gradient for K+ excretion
Loss of K+ in the urine
Hypokalaemia
How can Na+ channel inhibitors and aldosterone antagonists cause hyperkalaemia?
Reduce Na+ absorption
Reduce K+ loss in urine
Hyperkalaemia
What is hepatic encephalopathy?
Reversible syndrome of impaired brain function which occurs in cirrhosis with advanced liver failure.
What are the symptoms are hepatic encephalopathy?
Confusion
Coma
Flapping tremors
Constructional apraxia
Other than diuretics what other things can cause diuresis?
Alcohol- inhibits ADH release
Coffee
Diabetes- polyuria
