Diuretics DSA I Flashcards
topical ophthalmic CAIs
brinzolamide
dorzolamide
diuretics
increase sodium excretion and amount of urine produced by kidney
diuretic
increases urine volume
natriuretic
increased renal sodium excretion
K in proximal tubule
paracellular pathway
HCO3 reabsorption in PCT
initiated by action of Na/H exchanger
-luminal membrane of proximal tubule epithelial cell
membrane and cytoplasm carbonic anhydrase catalyze
> H2CO3 to CO2 and H2O at luminal membrane
> and CO2 and H2O H2CO3 in cytoplasm
straight segment of proximal tubule
acid secretory systems
-organic acids to lumen from blood
thin descending loop
water reabsorption
thin ascending loop
water and ion/solute impermeable
thick ascending limb
Na/K/2Cl cotransporter
NKCC2 or NK2Cl
dilutes luminal fluid
thick ascending loop potassium?
increased K in cell - back diffusion of K out of cell
- lumen positive charge - drive reabsorption of Mg and Ca
- paracellular pathway
distal convoluted tubule
Na/Cl cotransporter calcium channels (regulated by PTH)
diuretic induced changes in K
occur in collecting tubule
ENaC
Na channels in collecting tubule
-more Na to CT > more K out of cell > hypokalemia
aldosterone
increases ENaC and Na/K ATPase
-more Na reabsorption and K secretion
ADH
aquaporins to apical membrane in collecting tubule
-V2 receotpr
regulated by serum osmolality and volume status
alcohol
decreased ADH release and increases urine production
CAI pharmacy
- oral administration
- secreted prox tubule (dosing change renal insufficiency)
- no first pass
- carbonic anhydrase (-) and NHE3 (-)
- 45% bicarb reabsorption inhibited > acidosis (30 mins)
- decreased efficiency after multiple days of use
CAI toxicity
- metabolic acidosis and bicarbonatirua
- renal stones - calcium salts insoluble basic pH
- hypokalemia
- drowsiness and parasthesias
- sulfa allergy
CAI contraindications
-cirrhosis - decreased urine pH - less ammonia released-
>hyperammonemia and hepatic encephalopathy
-hyperchloremic acidosis or COPD
>worsen metabolic or respiratory acidosis
CAI clinical use
-rarely as diuretics
-glaucoma - reduces aqueous humor formation
> decreased IOP
>topical formulations
-also used for urinary alkalinization, metabolic alkalosis, acute mountain sickness, epilepsy
loop diuretic pharmacy
- oral administration
- eliminated by kidney - flitration/secretion
- half life correlates with secretion (act luminal side)
- coadmin with acids - reduced activity (same secretion)
loop diuretic mechanism
(-) Na/K/2Cl cotransporter
- block Na, K, Cl, Mg, Ca transport
- induce prostaglandin synthesis
- increased K excretion
loop diuretic toxicity
- overuse - hyponatremia, reduced GFR, circ collapse, thrombohemolysis, hepatic encephalopathy
- hypokalemic metabolic alkalosis (K and H loss)
- precipitate gout attacks (hyperuricemia)
- hearing loss (ototoxicity)
- sulfa allery (furosemide, bumetanide, torsemide)
- hypomagnesemia