No

Alpha₁ Agonist

Treatment of hypotension occurring during general anesthesia; to terminate episodes of supraventricular tachycardia; treatment of shock

C

Hypersensitivity to methoxamine or any component

1% to 10%:

Cardiovascular: Hypertension (severe)

Gastrointestinal: Vomiting

<1%: Ventricular ectopic beats, fetal bradycardia, headache, urinary urgency, diaphoresis

Symptoms of hypertension and bradycardia

Decreased pressor effect with phenothiazines

Increased pressor effects with guanethidine, oxytocics, TCAs, Rauwolfia alkaloids, lithium, methyldopa

Increased arrhythmias with bretylium

Direct-acting sympathomimetic amine with similar actions as phenylephrine; causes vasoconstriction primarily via alpha-adrenergic stimulation

Adrenergic effect:

Onset of action: I.M.: Within 15 minutes

Duration: I.M.: 1.5 hours; I.V.: ~1 hour

Pressor activity:

Onset of action: I.M.: 15-20 minutes; I.V.: Within 1-2 minutes

Duration: ~1-1.5 hours

Elimination: Not well defined

Adults:

Supraventricular tachycardia: I.V.: 10 mg

During spinal anesthesia: I.M.: 10-20 mg

Can be given IVP slowly at rate of 1 mg/minute; for I.V. infusion, dilute 35-40 mg in 259 mL D₅W

None reported

Psychotropics may alter pressor response; monitor blood pressure

Injection, as hydrochloride: 20 mg/mL (1 mL)

Aviado DM Jr and Wnuck AL, "Mechanisms for Cardiac Slowing by Methoxamine," J Pharmacol Exp Ther, 1957, 119(1):99-106.