Pharm of Diuretics/ Use in AKI Flashcards
how do diuretics increase the rate of urine flow?
inhibit reabsorption of solutes thereby increasing fluid excretion
Acetazolamide MOA
inhibits carbonic anhydrase
CA normally converts H2CO3 to CO2 and H2O and vice versa
effects of acetazolamide on urinary excretion
rapid rise in urinary excretion of HCO3-
increase in urinary pH to approx 8 and metabolic acidosis
indications for acetazolamide
altitude sickness and secondary glaucoma
osmotics
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)
therapeutic uses for mannitol, urea
- dialysis disequilibrium syndrome (mannitol)
- glaucoma, intraocular surgery (both)
- reduction of cerebral edema pre and post neurosurgery (both)
Loop; high ceiling diuretics
furosemide, bumetanide, ethacrynic acid
**most efficacious of the diuretic agents
AKA “potassium wasting diuretics”
loop diuretic MOA
block the Na+,K+,2Cl- cotransporter (NKCC2) in the thick ascending limb of loop of Henle
reabsorption of Na, K, Cl is decreased
side effects of loop diuretics
○ Increase excretion of K+ and H+
○ Interferes with ability to build up tonicity/ hypermedullary interstitium in the kidney
thiazides
sulfonamide structure= metolazone and indapamide
benzothiadiazine structure= chlorothiazide and HCTZ
enhance the potency of CA inhibitors
thiazides MOA
inhibit a Na+/Cl- symporter in the distal tubule (so Na remains in the tubular fluid along with water)
thiazide effect on urinary excretion
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
potassium sparing
spironolactone, amiloride, triamterene
aldosterone antagonist= spironolactone
MOA of amiloride and triamterene
block Na+ transport chains in the late distal tubule and collecting duct
potassium sparing effects on urinary excretion
mild inc in excretion of Na
clinical efficacy of spironolactone is directly proportional to the endogenous levels of aldosterone
indications for potassium sparing
coadministered w/ thiazide or loop diurectics for edema and HTN to offset loss of K+
spironolactone= diuretic of choice for pts with hepatic cirrhosis!
what are the most effective drugs to use in AKI to produce diuresis?
mannitol and loop diuretics
disadvantages of mannitol
only given parenterally and is cleared by the kidneys, thus it can cause a hyperosmolar state
what are the most frequently used diuretics in AKI pts?
furosemide and bumetanide
furosemide= available PO and parenteral and lower cost but has variable bioavailability and potential for ototoxicity
