Diuretics Flashcards
what % of sodium reabsorbed in each nephron segments?
Proximal - 60%
LOH - 15-25%
Distal tubule 5-10%
CD 4%
how do diuretics act in pts w/ chronic renal disease?
CKD: decreased renal blood flo wand anionic metabolites –> reduce diuretic renal excretion rate
nephrotic syndrome: hypoalbuminemia increases Vd and decreases renal excretion rate
why does diuretic resistance occur? (3)
- decreased renal clearance
- sodium retention in response to increased ATII, catecholamines, aldosterone, and resistance to ANP
- DCT hypertrophy
options for management of diuretic resistance
increase dose
use loop diuretic and thiazide diuretic in combo
restrict fluid and salt intake
add aldosterone antagonist
avoid vasodilator that impairs renal perfusion
how to treat nephrogenic DI?
thiazides and amiloride
options for modifying drug dosage in pts w/ renal impairment
select drug cleared by non renal mechanisms
OR
reduce infusion rate, maintain w/ dose interval according to fraction of renal total clearance
which drug for Liddle’s
amiloride
HCT
inhibits NaCL cotransporter in DT
increases K excretion, enhances Ca reabsorption
Furosemide
Blocks Na-K-2Cl symporter in TAL –> blocks urinary diluting and conc capacity
increases distal Na delivery –> more K excretion
increases Ca and Mg excretion
tox from furosemide
ototoxicity
hyperuricemia
hypersensitivity
spironolactone
K-sparing diuretic: competitive antagonism w/ aldosterone
blocks MR-induced increase in ENaC expression and membrane insertion
SE of spironolactone
hyperkalemia
endocrine abnormalities: gynecomastia, impotence
mannitol
osmotic diuretic - decreases water resorption
enhanced Na and K excretion through solute drag
indications for mannitol
glaucoma
cerebral edema
maybe AKI
(times when you need to rapidly shrink intracellular volume)
acetazolamide
carbonic anhydrase inhibitor: blocks bicarb resorption in PT; increases urinary excretion of Na and bicarb
causes metabolic acidosis
less H+ available in distal tubule –> more K+ secretion