Pharm of Diuretics/ Use in AKI

Question 1

how do diuretics increase the rate of urine flow?

Answer 1

inhibit reabsorption of solutes thereby increasing fluid excretion

Question 2

Acetazolamide MOA

Answer 2

inhibits carbonic anhydrase

CA normally converts H2CO3 to CO2 and H2O and vice versa

Question 3

effects of acetazolamide on urinary excretion

Answer 3

rapid rise in urinary excretion of HCO3-

increase in urinary pH to approx 8 and metabolic acidosis

Question 4

indications for acetazolamide

Answer 4

altitude sickness and secondary glaucoma

Question 5

osmotics

Answer 5

mannitol, urea
agent that is freely filtered at the glomerulus
creates an osmotic driving force inside the tubular lumen, keeping the water from leaving (thus increases urinary excretion of nearly all electrolytes)

Question 6

therapeutic uses for mannitol, urea

Answer 6

• dialysis disequilibrium syndrome (mannitol)
• glaucoma, intraocular surgery (both)
• reduction of cerebral edema pre and post neurosurgery (both)

Question 7

Loop; high ceiling diuretics

Answer 7

furosemide, bumetanide, ethacrynic acid
**most efficacious of the diuretic agents
AKA “potassium wasting diuretics”

Question 8

loop diuretic MOA

Answer 8

block the Na+,K+,2Cl- cotransporter (NKCC2) in the thick ascending limb of loop of Henle
reabsorption of Na, K, Cl is decreased

Question 9

side effects of loop diuretics

Answer 9

○ Increase excretion of K+ and H+

○ Interferes with ability to build up tonicity/ hypermedullary interstitium in the kidney

Question 10

thiazides

Answer 10

sulfonamide structure= metolazone and indapamide
benzothiadiazine structure= chlorothiazide and HCTZ
enhance the potency of CA inhibitors

Question 11

thiazides MOA

Answer 11

inhibit a Na+/Cl- symporter in the distal tubule (so Na remains in the tubular fluid along with water)

Question 12

thiazide effect on urinary excretion

Answer 12

inc excretion of Na and Cl
some thiazides are weak CA inhibitors and increase HCO3- excretion
inc excretion of K+ and H+ due to increased delivery of Na+ to distal tubule

Question 13

potassium sparing

Answer 13

spironolactone, amiloride, triamterene

aldosterone antagonist= spironolactone

Question 14

MOA of amiloride and triamterene

Answer 14

block Na+ transport chains in the late distal tubule and collecting duct

Question 15

potassium sparing effects on urinary excretion

Answer 15

mild inc in excretion of Na

clinical efficacy of spironolactone is directly proportional to the endogenous levels of aldosterone

Question 16

indications for potassium sparing

Answer 16

coadministered w/ thiazide or loop diurectics for edema and HTN to offset loss of K+
spironolactone= diuretic of choice for pts with hepatic cirrhosis!

Question 17

what are the most effective drugs to use in AKI to produce diuresis?

Answer 17

mannitol and loop diuretics

Question 18

disadvantages of mannitol

Answer 18

only given parenterally and is cleared by the kidneys, thus it can cause a hyperosmolar state

Question 19

what are the most frequently used diuretics in AKI pts?

Answer 19

furosemide and bumetanide

furosemide= available PO and parenteral and lower cost but has variable bioavailability and potential for ototoxicity