Diuretics Flashcards
Where does loop diuretics take action and what does it do?
selective inhibition of NaCl reabsorption in thick ascending limb of Loop of Henle
What are the consequences of loop diuretics?
- inhibits K going back into the urine to create that positive potential to reabsorb Mg and Ca and thus, Mg and Ca are not reabsorbed back into the blood
- induce activity of PGE2 which inhibits activity of macula densa and cannot decrease GFR
What effect does NSAIDs have on loop diuretics?
reduce efficacy
Where does thiazide diuretics take action and what does it do?
inhibit NaCl transport in distal convoluted tubule
What are the consequences of thiazide diuretics?
- Slight increase of blood calcium levels
- induce expression of COX2
How does thiazide diuretics increase Ca levels?
- Volume depletion causes active Na reabsorption in proximal convoluted tubule which causes passive Ca reabsorption
- Distal convoluted tubule blocks reabsorption of Na into the convoluted tubule which causes Na/Ca exchange on the basolateral membrane
- Usually not a problem unless there is secondary condition that also causes hypercalcemia
What effect does NSAIDs have on thiazide diuretics?
reduce efficacy
Where does potassium-sparing diuretics take action and what does it do?
prevent Na absorption, decrease K secretion in collecting tubules
drugs that are loop diuretics
- furosemide
- torsemide
drugs that are thiazide diuretics
hydrochlorothiazide
drugs that are potassium-sparing diuretics
- spironolactone
- eplerenone
- triamterene
How does spironolactone and eplerenone work?
Direct antagonism of aldosterone receptors
What does aldosterone do?
- binds to mineralocorticoid receptors
- they stimulate Na reabsorption through ENaC
- aldosterone also stimulates Na/K
In which patients would spironolactone or eplerenone be best?
if patient has excessive mineralocorticoids or high aldosterone levels
How does triamterene work?
Prevent Na absorption via ENaC –> Na/K inhibits on basolateral side
