Potassium Sparing diuretics

Question 1

examples

Answer 1

spironolactone, triamterene, spironolactone and epleronone

Question 2

mechanism of action of amiloride and triempterene

Answer 2

blocks the APICAL Na+ channel in the late distal convoluted tubule and the collecting ducts (i.e. blocks the ENAC channel)

Question 3

which is more potent amiloride or triemterene

Answer 3

AMILORIDE IS 10X MORE POTENT

Question 4

how do amiloride and triemterene enter the nephron

Answer 4

via the organic cation system in the proximal convoluted tubule

Question 5

which is better absorbed through the GI tract

Answer 5

triemptere is better absorbed through the GI tract than amiloride

Question 6

potassium sparing diuretics are

Answer 6

weak diuretics on their own so should be combined with a thiazide or loop diuretics (thiazide and loop diuretics activate the RAAS SYSTEM DUE TO NATRIURESIS AND HYPOVALAEAMIA, aldosterone antagonists potentiate the action of thiazide and loop diuretics as they block aldosterone)

Question 7

aldosterone antagonists are

Answer 7

spironolactone and epleronone

Question 8

mechasnim of action of aldosterone antagonists

Answer 8

competes with aldosterone for binding to intre-cellualr receptors causing:

1. decreased gene expression and reduced synthesis of protein mediators that activate the Na+ channels in the apical membrane (ENAC CHANNELS)
2. decreased number of Na/K+ ATPase pumps in the basolateral membrane

Question 9

ie spironolactone and epleronone

Answer 9

competitively antagonist the action of aldosterone at cytoplasmic aldosterone receptors and they gain access to the cytoplasm via the base-lateral membrane

Question 10

is spironolactone and epleronon well absorbed

Answer 10

yes both are well sobbed form the GI tract

Question 11

spironolactone gets rapidly what

Answer 11

metabolites in the liver to its active metabolite called carenone which accounts for half of the drugs action

Question 12

side affects of potassium sparing diuretics

Answer 12

HYPERKALAEMIA AND A METABOLICA CIDOSIS

Question 13

spironolactone can cause hormonal disturbances such as

Answer 13

gynaecomastia, impotence and menstrual irregularities

Question 14

clinical uses of potassium sparing diuretics

Answer 14

• heart failure where they improve mortality
• primary hyperaldosteronism (which can’t be treated with surgery), secondary hyperaldosteronism
• resistant essential hypertension

Question 15

what should you not give to anyone on a potassium sparing diuretic

Answer 15

potassium supplementation because they are already at increased risk of hyperkalaemia