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Flashcards in Osmotic Diuretics Deck (7):

Where do osmotic diuretics exert their effects?

The proximal tubule (~65%)


Benefits of osmotic diuretics?

Helps to eliminate intracellular volume


Mannitol (Osmitrol)

prototype for osmotic diuretics; also used --> urea, glycerin, and isosorbide


MOA of Mannitol?

- non-metabolized 6-C sugar; freely filtered w/ minimal absorption

- Inability to reabsorb the solute keeps water in the PT lumen; this water is delivered to the distal portion of the nephron where much of it is excreted.

- Acts throughout the body to pull water out of cells

- Net effect after administration is to excrete total body water in excess of plasma electrolytes


PK of mannitol?

Distributes in EC fluid, must give IV in large amounts sufficient to raise its osmolality (eg 50-200 grams over 24 hours)

- Effects are noticeable within 30-60 minutes, and is eliminated unchanged in urine over 6-8 hrs


Adverse effects of osmotic diuretics?

- EC volume is acutely ↑ bc mannitol sucks water out of cells --> can exacerbate HF

- HA, nausea, vomiting, and fluid & electrolyte imbalance can occur


Therapeutic uses of mannitol?

- Prophylaxis of RF, keeps some fluid volume in the tubules to prevent them from collapsing when the GFR is very low

- Reduction of intracranial pressure

- Reduction of intraocular pressure (trx glaucoma) when pts don't respond to other therapy