Pharm 101: Metaraminol

Class

Vasopressor

Pharmacodynamics
  • Synthetic sympathomimetic
  • Direct and indirect (via noradrenaline release) alpha 1 receptor agonist
  • Organ system effects:
    • Vasoconstriction: increases SVR/PVR, increases BP
    • Reflex bradycardia
    • Cardiac output either unchanged or decreased
    • Indirect increase in coronary artery flow
    • Reduced blood flow to viscera, kidneys, skin
Pharmacokinetics
  • IV administration
  • Onset of action 1-2 minutes
  • Duration of action 20-60 minutes
  • Half-life: minutes
Clinical uses
  • IV administration:
    • Bolus 0.5-2 mg
    • Infusion 0.5-10 mg/hr titrated to BP parameters
  • Shock:
    • Temporising measure whilst other treatment instituted (fluids etc.)
  • Sympathetic nervous system failure e.g. spinal injury or anaesthesia
Adverse effects
  • Bradycardia (reflex)
  • Arrhythmias
References
  • Forrest P. Vasopressors. Royal Prince Alfred Hospital, Sydney, Australia.
  • Better Safe Care Victoria. Clinical Guideline: Metaraminol. Melbourne, Australia.
  • Katzung BG. Basic & Clinical Pharmacology. 14th ed. United States of America: McGraw-Hill Education; 2018. 149 p.
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MBBS CCPU (RCE, Biliary, DVT, E-FAST, AAA) Rob is an Emergency Medicine Advanced Trainee based in Melbourne, Australia. He has special interests in medical education, ECG interpretation, and the use of diagnostic and procedural ultrasound in the undifferentiated and unwell patient.

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