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CARDIOVASCULAR SYSTEM › CARDIAC THERAPY › CARDIAC STIMULANTS EXCL. CARDIAC GLYCOSIDES › Adrenergic and dopaminergic agents
methoxamine
C01CA10
Forms & Strengths
- Injection: 20 mg/mL in 1 mL ampoules
Adult Dosing
- Intravenous (IV): 3 to 5 mg slowly in emergency hypotension
- Intramuscular (IM): 10 to 15 mg for hypotensive states
Pediatric Dosing
- Safety and efficacy in pediatric patients not established
Indications
- Support of blood pressure during spinal anesthesia
- Treatment of acute hypotensive states during surgical procedures
Mechanism of Action
- Direct alpha-1 adrenergic receptor agonist causing peripheral vasoconstriction
- Produces marked increase in total peripheral resistance and blood pressure
- Triggers reflexive bradycardia via vagal stimulation
Contraindications
- Hypersensitivity to methoxamine or sympathomimetics
- Severe hypertension
- Peripheral vascular disease due to risk of ischemia
- Use with halogenated hydrocarbon anesthetics (risk of severe ventricular arrhythmias)
Adverse Reactions
- Severe hypertension
- Reflex bradycardia
- Headache
- Piloerection
- Extravasation necrosis at injection site
Drug Interactions
- Halogenated hydrocarbon anesthetics (e.g., halothane) increase myocardial irritability and risk of arrhythmias
- MAO inhibitors and tricyclic antidepressants may potentiate the pressor response leading to hypertensive crisis
- Beta-blockers may result in severe unopposed alpha-mediated vasoconstriction
Curated Content: Needs Vetting Before Put to Clinical Use