Ephedrine

Ephedrine is a mixed-acting sympathomimetic with both direct adrenergic effects and indirect stimulation of norepinephrine release. Its principal veterinary application is short-term vasopressor support during anesthesia. Oral use for urinary incontinence is an older application, reflecting its ability to increase adrenergic stimulation of urethral smooth muscle.

Group

Sympathomimetic

Mechanism of Action

Ephedrine increases norepinephrine availability at sympathetic nerve terminals and directly stimulates alpha- and beta-adrenergic receptors. Alpha-mediated vascular contraction increases peripheral resistance, while beta1 effects can increase cardiac contractility and heart rate. These combined actions can improve arterial pressure. Alpha-adrenergic stimulation of urethral smooth muscle can also increase urethral closure pressure.

Dose Rates

Dog

Use / stage	Dose	Route	Schedule	Instructions
Urinary incontinence	4 mg/kg	PO	Every 8–12 h
Urinary incontinence	12.5–50 mg/animal	PO	Every 8–12 h	Historical alternative fixed regimen.
Vasopressor support	0.75 mg/kg	IM, SC	As needed
Bronchospasm — Maintenance	1–2 mg/kg	PO	Every 8–12 h
Urinary incontinence	1.2 mg/kg	PO	Every 8 h
Anesthetic hypotension infusion	5–10 mcg/kg/min	IV	Continuous	Titrate to blood pressure; tachycardia and tachyphylaxis can limit use.

Cat

Use / stage	Dose	Route	Schedule	Instructions
Urinary incontinence	2–4 mg/kg	PO	Every 12 h
Vasopressor support	0.75 mg/kg	IM, SC	As needed
Anesthetic hypotension infusion	5–10 mcg/kg/min	IV	Continuous	Titrate to blood pressure; tachycardia and tachyphylaxis can limit use.
Alternative incontinence range	Reference only	PO		The additional text prints both 2–4 mg/kg every 6–12 hours and 2–4 mg/cat every 8 hours. The mass basis differs substantially; preserve the established fixed-dose regimen until that discrepancy is resolved.

Indications

Treatment of selected anesthesia-associated hypotension when adrenergic cardiovascular support is indicated.
Historical oral treatment of urethral sphincter mechanism incompetence and associated urinary incontinence in dogs.

Contraindications

Cardiovascular disease

Interactions

Other adrenergic agonists potentiate effects.

Adverse effects

Vasoconstriction, tachycardia or reflex bradycardia

Preparations

Preparation	Form	Strength	Route
Ephedrine injection 25 mg/mL Hydrochloride-labelled source presentation; dose/strength salt equivalence must be confirmed.	Injection	25 mg / mL	IM, SC
Ephedrine injection 50 mg/mL Hydrochloride-labelled source presentation; dose/strength salt equivalence must be confirmed.	Injection	50 mg / mL	IM, SC

Monitoring and Administration

Monitor heart rate, rhythm and blood pressure. Oral incontinence use has largely been replaced by other therapies.