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  • Ephedrine.

Class of drug

  • Mixed alpha- and beta-adrenergic agonist.
  • Sympathomimetic amine.



  • Direct and indirect sympathomimetic effects - increased cardiac output, blood pressure and heart rate.
  • Increased intramuscular blood flow in horses (triceps muscle) at higher doses (0.1-0.2 mg/kg).
  • Inhibits the actions of monoamine oxidase on norepinephrine.
  • Bronchodilation.
  • Amphetamine-like structure causes CNS excitement and increase in MAC during inhalational anesthesia    .

The indirect effect results in the exhaustion of norephinephrine stores at nerve endings following repeated doses. This results in the phenomenon of tachyphylaxis whereby a reduced response is seen following repeated doses.


  • Treatment of hypotension    .
  • Treatment of shock unresponsive to fluid replacement.

The administration of ephedrine is not a substitute for appropriate fluid resuscitation during shock.

Adverse reactions

Effects of overdosage

  • Due to its amphetamine-like structure, CNS excitability may occur in conscious horses.

Other reported reactions

  • Increase in MAC during inhalational anesthesia.
  • May manifest as awakening following administration.
  • Arrhythmias.

Reporting of reactions

  • Use the Suspect Adverse Reaction Surveillance Scheme (SARSS) in the UK.


  • Discontinued administration.
  • General supportive measures.

Antidote for overdose

  • Beta-blockers, eg propanolol, and alpha-1 antagonists, eg phentolamine, may be necessary to control tachycardia and hypertension respectively.
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