Methoxamine: Indication, Dosage, Side Effect, Precaution

This information is not country-specific. Please refer to the Malaysia prescribing information.

Generic Medicine Info

Indications and Dosage

Intramuscular
Prophylaxis of hypotension during anaesthesia

Adult: 10-15 mg shortly before or with spinal anaesthesia. Up to 20 mg may be required at high levels of anaesthesia. About 15 min should elapse before repeating a dose.

Intramuscular
Hypotensive states

Adult: As hydrochloride: Moderate hypotension: 5-10 mg.

Intravenous
Hypotensive states

Adult: As hydrochloride: Emergency: 3-5 mg by slow inj. May be supplemented by IM inj for a more prolonged effect. About 15 min should elapse before repeating a dose.

Intravenous
Paroxysmal supraventricular tachycardia

Adult: As hydrochloride: 10 mg by slow inj over 3-5 min.

Contraindications

Severe hypertension.

Special Precautions

Hyperthyroidism, bradycardia, partial heart block, myocardial disease, poor left ventricular function, severe arteriosclerosis, pre-existing vascular disease. Pregnancy and lactation.

Adverse Reactions

Excessive BP elevations particularly with high dosage, ventricular ectopic beats, reflex bradycardia; nausea, vomiting; headache (often severe), anxiety; sweating, pilomotor response; feeling of cold and other skin sensations resulting from piloerection; uterine hypertonus, fetal bradycardia, urinary urgency.

Overdosage

Symptoms: Undesirable elevations in BP and/or bradycardia. Management: α-adrenergic blocking agent (e.g. phentolamine) may be used for severe hypertension. Bradycardia may be abolished by atropine.

Drug Interactions

Potentiation of pressor effects with MAOIs, TCAs, vasopressin, ergotamine, ergonovine or methylergonovine, sympathomimetic decongestants, certain appetite suppressants and amphetamine-like psychostimulants.

Lab Interference

May increase plasma cortisol and adrenocorticotropic hormone (ACTH) levels; use caution when interpreting plasma cortisol and ACTH levels.

Action

Description:
Mechanism of Action: Methoxamine has mainly direct effects on α-adrenergic receptors. It causes prolonged peripheral vasoconstriction and consequently a rise in arterial BP.
Onset: IV: Within 0.5-2 min. IM: Within 15-20 min.
Duration: IV: 10-15 min. IM: 1.5 hr.

Storage

Store at controlled room temperature (15-30°C). Protect from light.

MIMS Class

Vasoconstrictors

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