Diuretics Flashcards

1
Q

what % of sodium reabsorbed in each nephron segments?

A

Proximal - 60%
LOH - 15-25%
Distal tubule 5-10%
CD 4%

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2
Q

how do diuretics act in pts w/ chronic renal disease?

A

CKD: decreased renal blood flo wand anionic metabolites –> reduce diuretic renal excretion rate
nephrotic syndrome: hypoalbuminemia increases Vd and decreases renal excretion rate

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3
Q

why does diuretic resistance occur? (3)

A
  1. decreased renal clearance
  2. sodium retention in response to increased ATII, catecholamines, aldosterone, and resistance to ANP
  3. DCT hypertrophy
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4
Q

options for management of diuretic resistance

A

increase dose
use loop diuretic and thiazide diuretic in combo
restrict fluid and salt intake
add aldosterone antagonist
avoid vasodilator that impairs renal perfusion

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5
Q

how to treat nephrogenic DI?

A

thiazides and amiloride

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6
Q

options for modifying drug dosage in pts w/ renal impairment

A

select drug cleared by non renal mechanisms
OR
reduce infusion rate, maintain w/ dose interval according to fraction of renal total clearance

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7
Q

which drug for Liddle’s

A

amiloride

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8
Q

HCT

A

inhibits NaCL cotransporter in DT

increases K excretion, enhances Ca reabsorption

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9
Q

Furosemide

A

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

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10
Q

tox from furosemide

A

ototoxicity
hyperuricemia
hypersensitivity

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11
Q

spironolactone

A

K-sparing diuretic: competitive antagonism w/ aldosterone

blocks MR-induced increase in ENaC expression and membrane insertion

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12
Q

SE of spironolactone

A

hyperkalemia

endocrine abnormalities: gynecomastia, impotence

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13
Q

mannitol

A

osmotic diuretic - decreases water resorption

enhanced Na and K excretion through solute drag

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14
Q

indications for mannitol

A

glaucoma
cerebral edema
maybe AKI
(times when you need to rapidly shrink intracellular volume)

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15
Q

acetazolamide

A

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

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16
Q

toxicities from acetazolamide

A

hypokalemia
calcium stones b/c alkaline urine
hypersensitivity rxns to sulfa

17
Q

acetazolamide indications

A

mountain sickness
glaucoma
metabolic alkalosis

18
Q

amiloride

A

ENaC channel blocker

19
Q

indications for amiloride

A

diuretic in hypokalemia
Liddle’s disease
in combo w/ thiazides to prevent Li-induced nephrogenic DI

20
Q

eplerenone

A

K-sparing diuretic - like spironolactone but more selective for MR receptors (over androgen and progesterone)

21
Q

DDAVP/desmopressin

A

long-acting analogue of vasopressin w/ high selectivity for V2 receptors over V1
for tx central DI

22
Q

which diuretic can cause hyperkalemia?

A

spironolactone

23
Q

calcium-sparing diuretics

A

thiazide