ADRENALINE

  • Important ED drug – know PK and PD
Structure/Class
  1. Endogenous catecholamine
Pharmacodynamics
  1. Binds to α and β receptors (α1 = α2; β1 = β2 activity). Acts through G proteins leading to increase in cAMP and downstream effects.
  2. Organ system effects as follows:
    • Cardiovascular
      • Increased inotropy and chronotropy
      • Vasoconstriction in almost all vascular beds (vasodilation in hepatic and skeletal muscle)
    • Respiratory
      • Bronchodilation
Absorption/administration
  1. IV (bolus/infusion). Can also be given IM/SC/Neb/ETT.
Distribution
  1. Crosses the placenta, but does not cross BBB.
Metabolism
  1. Metabolised at the sympathetic nerve ending via COMT/MAO pathways. Metabolised to VMA and excreted in the urine.
Excretion
  1. Renal. T ½ of 1-3 minutes
Indications
  1. Anaphylaxis and severe allergic reactions
  2. Cardiac arrest – facilitates increased blood flow secondary to vasoconstriction
  3. Asthma (nebulized)
  4. Croup
  5. Adjunct for LA – prolongs LA action and reduces bleeding.
Contraindications
  1. IHD
  2. Severe hypertension
  3. Severe hyperthyroidism
  4. Phaeochromocytoma
  5. Glaucoma
Special precautions
  1. Avoid using with LA in fingers/toes/ears
Interactions
Adverse events
  1. Increased cardiac irritability and arrhythmias
  2. Cerebral haemorrhage
  3. Increased BP
  4. Local ischemia
Dosing/administration
  1. 300microg IM for anaphylactic reaction
  2. Bolus/infusion – start at 5mics/min and titrate as required.
Toxicology
  1. If severe vasoconstriction (e.g. extravasation in digits) may be reversed with phentolamine (competitive antagonist at α1 and α2 receptors)
Withdrawal syndrome
Special notes