EXAMPLES  Adrenaline, dopamine, dobutamine, isoprenaline

MECHANISM OF ACTION 

  • Actions vary depending on which receptors are stimulated.
  • Adrenalineactsona-(peripheral vasculature)and-adrenoceptors(myocardium), producing positive inotropic and chronotropic effects.
  • Low-dose dopamine and dobutamine stimulate b1-adrenoceptors in the myocardium, predominantly increasing contractility.

INDICATIONS 

  • Cardiogenic shock.
  • Septic shock.
  • Acute hypotension.
  • Cardiac arrest (adrenaline)

CAUTIONS AND CONTRA-INDICATIONS

  • Phaeochromocytoma (dopamine).
  • Atrial and ventricular tachyarrhythmias (dobutamine)

SIDE-EFFECTS

  • Nausea and vomiting.
  • Hypotension/hypertension .
  • Peripheral vasoconstriction.
  • Tachycardia

METABOLISM AND HALF-LIFE 

  • Metabolised by the liver, kidney or plasma MAO and COMT; t½ 2min.

MONITORING 

  • Continuous cardiac monitoring in a high-dependency area is required.
  • Monitoring of oxygen saturation, urine output and renal function is also necessary.

DRUG INTERACTIONS. 

  • Adrenaline should not be used with other sympathomimetic agents due to the additive effect.
  • Hypertensive crisis when given in combination with MAOIs.
  • Hypertension and reflex bradycardia when given in combination with b blockers

IMPORTANT POINTS. 

  • In patients with septic or haemorrhagic shock, the volume must be replaced (though this may worsen cardiogenic shock), after which sympathomimetics may be required to improve cardiac output.
  • Often used in the intensive care setting to maintain perfusion to vital organs. Adrenaline is used as part of the Resuscitation Council UK guidelines