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.
- 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.
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.
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.