Pharm 101: Adrenaline

Class

Endogenous catecholamine
Vasopressor


Pharmacodynamics
  • Alpha and beta agonist
    • Beta 1 = positive inotropy and chronotropy
    • Alpha = vasoconstriction
    • Beta 2 = skeletal muscle vasodilation, may explain decreased DBP sometimes seen
  • Non-selective adrenergic agonist:
    • Potent beta-1 receptor activity causes positive inotropy and chronotropy
    • Moderate alpha-1 receptor activity causes peripheral vasoconstriction and increases SVR
    • Moderate beta-2 receptor activity causes skeletal muscle vasodilation (may explain decreased DBP sometimes seen), and relaxes bronchial smooth muscle and stabilises mast cells

Pharmacokinetics
  • IV/IM/ETT/SC administration
  • Onset of action 1-2 minutes
  • Half-life 5 minutes
  • Duration of action 2-10 minutes
  • Metabolised by MAO and COMT to VMA and metadrenaline
  • Urinary excretin of metabolites

Clinical uses
  • To increase CO/HR, MAP and coronary blood flow
  • Septic shock:
    • In addition to noradrenaline (first line agent) to raise MAP
  • Cardiac arrest
  • Anaphylaxis
  • Bronchospasm causing respiratory distress
  • Infusion (central):
    • 6mg adrenaline in 100ml 5% dextrose (final concentration 60 microg/ml)
    • 1ml/hr = 1 microg/min
    • Starting dose: 1-4 microg/min, titrate to BP
    • Usual dose range: 1-20 microg/min

Adverse effects
  • Angina, tachycardia, arrhythmias and palpitations
  • Tissue ischaemia or necrosis due to vasoconstriction
  • Hyperglycaemia
  • Lactic acidosis

Precautions/contraindications
  • Hypotension due to uncorrected hypovolaemia
  • Tachycardia and arrhythmias
  • Hypersensitivity to sulphites
  • Wean gradually to avoid hypotension

Further reading

References
  • Katzung BG. Basic & Clinical Pharmacology. 14e. 2018: 96-97
  • Better Safe Care. Melbourne, Australia: Victorian Agency for Health Information; 2018. Adrenaline (epinephrine). 2019 May 07 [cited 2020 Aug 02].

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MBBS (UWA) CCPU Emergency Medicine Trainee with interests in medical education, ECG interpretation, and the use of point-of-care ultrasound in the undifferentiated patient. Co-author of the LITFL ECG Library | Twitter

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