Mannitol

Question 1

MoA

Answer 1

1. osmotic diuretic that functions at the PCT and Loop of Henle only
   
   • these are the only locations where H20 can move from interstitial space –> renal tubule lumen for excretion
   • **prevents the reabsorption of Na+ back into the blood –> keeps H20 in the tubule lumen

Question 2

Clinical Uses

Answer 2

1. intracranial HTN (question will usually talk about papilledema)
   
   • induces high osmotic gradient in the blood vessels –> water influx occurs –> solvent drag
2. drug overdose

Question 3

Adverse Effects & Contraindications

Answer 3

1. pulmonary edema
   
   • **contraindicated in HF patients for this reason
   • high osmotic pressure from mannitol –> high hydrostatic pressure after water influx occurs –> larger-than-normal pressure gradient between pulmonary blood vessels and interstitial space, causing fluid to leak out of the pulmonary vasculature
2. dehydration from polyuria
   
   • **contraindicated in renal failure patients because high GFR is required to filter so much fluid
     
     • renal failure patients cannot increase GFR to accommodate –> more renal damage occurs from pressure of the fluid