Osmotic diuretic

  • Osmotic diuretic
  • Renal:
    • Acts on PCT and descending limb of loop of Henle
    • Opposes the action of ADH in collecting tubules
  • CNS:
    • Alters Starling forces as it does not cross intact blood-brain barrier
    • Draws water out of cells and reduces intracellular volume, which reduces intracranial volume and ICP
  • Poor absorption (oral administration causes osmotic diarrhoea rather than diuresis)
  • Not metabolised
  • Excreted by glomerular filtration in 30-60 minutes
Clinical uses
  • Reduction of intracranial pressure in intracranial haemorrhage:
    • 1-2g/kg as IV bolus over 15 minutes
    • ICP should fall within 60-90 minutes
  • Reduction of IOP before ophthalmologic procedures
  • Controversial, for diuresis in haemolysis or rhabdomyolysis
Adverse effects
  • Extracellular volume expansion
    • Flash APO
    • Relative hyponatraemia prior to diuresis
    • Headache, nausea and vomiting
  • Dehydration, hyperkalaemia, hypernatraemia
  • Hyponatraemia in renal failure (mannitol cannot be excreted)
  • AKI in 6-7%
  • Renal failure
  • CCF due to risk of APO
Further Reading

Pharmacology 101

Top 200 drugs

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Adult/Paediatric Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner

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