Osmotic Diuretics

Question 1

Osmotic diuretics

Answer 1

substances that are filtered at the glomerulus but aren’t completely reabsorbed
i.e. mannitol and glucose

–Due to effects on tubular fluid osmolality, also impair NaCl reabsorption in PT and ThALH

–potent, lead to increased excretion of H20 and NaCl

–falling out of favor

Question 2

Osmotic diuretics (MOA in PT…)

Answer 2

MINOR!!!

Osmotically inhibit Na and H20 reabsorption

Question 3

Osmotic diuretics (MOA in Loop of Henle)

Answer 3

MAJOR!!!!

• -given in large doses, increases osmolarity of plasma
• -extract H2O from peripheral tissues and decrease blood viscosity
• -increase medullary renal blood flow and reduce its tonicity
• -Impair H20 reabsorption by thin descending limb of Henle’s loop
• -Impair NaCl and urea extraction by thin ascending limb
• -(also weakly interfere’s w/ transport processes in TALH)

Question 4

Osmotic diuretics (net effect)

Answer 4

significantly increase urine w/ small increments of NaCl and other ions
(Increases amount of urine the most of the diuretics, but mostly free water)

Question 5

Osmotic diuretics (Clinical uses)

Answer 5

• -treatment of dialysis disequilibrium syndrome
• -Reduce intra cranial pressure (head trauma…IV dosage) IMMEDIATE EFFECT!!! (MOA unknown)
• -Reduce intraocular pressure

Question 6

Mannitol

Answer 6

Injection

Question 7

Side Effects

Answer 7

• -Volume overload

- -Contraindicated in cardiac failure (b/c expansion in blood volume)