Exam 4: Diuretics Flashcards Preview

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Flashcards in Exam 4: Diuretics Deck (35):
1

Prototype thiazide diuretic:

Hydrochlorothiazide

2

Site of action of thiazides:

Distal convoluted tubule

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MoA of thiazides:

Impairs Na+/Cl+ reabsorption, drawing water into the filtrate to be excreted

4

Precaution with thiazides:

K+ depleting

5

HTN mechanism of thiazides:

Peripheral vasodilation

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Anesthesia concerns with thiazides:

Electrolytes: hypokalemia, hypochloremia, hypomagnesemia
Muscle weakness that potentiates NMBs
Nephropathy
Increased risk of dig toxicity
Fluid volume depletion

7

Dose effects of thiazides:

Increased dose has little extra effect

8

Prototype loop diuretic:

Furosemide

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Site of action of loop diuretics:

Thick ascending loop of Henle

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MoA of furosemide:

Inhibit the passive transport of K+/Na+/Cl- from the lumen, keeping them + water in the filtrate

11

PK of furosemide:

Onset: 2 - 10min (IV)
Extensively protein bound
Renal secretion!

12

Indications for furosemide:

Mobilization of edema
Reduction of ICP
Hypercalcemia
Differential dx of oliguria

13

Dosage of furosemide:

0.1 - 1.0 mg/kg (titrate)

14

Electrolyte changes with loop diuretics:

Hypokalemia
Hypochloremia

15

A/E of loop diuretics:

Potentiation of NMBs
Presynaptic cAMP inhibition, ACh release

16

Drug interactions with loop diuretics:

Nephrotoxicity when administered with aminoglycosides and cephalosporins

Possible cross reactivity to sulfonamide allergy

Decreases renal clearance of lithium

17

Prototype drug for osmotic diuretics:

Mannitol

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Site of action of osmotic diuretics:

Tubules

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MoA of osmotic diuretics:

Increased osmolarity in tubule → Na+, Cl-, HCO3- excreted along with water

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Concern with osmotic diuretics:

Increases plasma osmolarity and intravascular volume; can cause pulmonary edema in poor LV function

21

PK of osmotic diuretics:

Do not enter cells; must be given IV
Onset: 10 - 15min
Duration: 2 hrs
100% renally excreted

22

Indications for mannitol:

Differential dx of oliguria (after furosemide)
Prophylaxis for ARF
↓ ICP
↓ IOP

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Dose of mannitol:

0.25 - 1 g/kg IV

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Anesthesia concerns with mannitol:

Pulmonary edema
Hypovolemia
Electrolyte changes

25

Two classes of potassium sparing diuretics:

Epithelial Na+ channel blockers
Aldosterone antagonists

26

Prototype epithelial Na+ channel blocker:

Triamterene

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Site of action of triamterene:

Collecting duct

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MoA of triamterene:

Na+ channel blockade in the luminal membrane; non-competitive antagonism of aldosterone

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A/E of triamterene:

Can cause hypERkalemia

30

Prototype aldosterone antagonist:

Spironolactone

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MoA of spironolactone:

Competitive aldosterone antagonist; weak and usually combined with other diuretics

32

Indications for spironolactone:

HF
Ascites
Low-renin hypertension
Hypokalemia
Conn's syndrome

33

Prototype carbonic anhydrase inhibitor:

Acetazolamide

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MoA of acetazolamide:

Blocks the action of carbonic anhydrase, increasing HCO3-, Na+, and H2O in urine

35

Indications for acetazolamide:

Glaucoma
Altitude sickness
ICP