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Methoxamine Uses, Dosage, Side Effects & Mechanism | DrugsAtlas

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DRUG NAME: Methoxamine

Therapeutic Class: Adrenergic agonist

Subclass: α1-adrenergic receptor agonist

Speciality: Anaesthesiology

Schedule (India): Schedule H

Route(s): Intravenous (IV), Intramuscular (IM)

Formulations Available in India:

Injection: 10 mg/mL in 1 mL ampoule

INDICATIONS + DOSING — FOR CLINICIAN USE ONLY

Primary Indications (Approved / Standard in India)

▶ Treatment of Hypotension during Spinal or Epidural Anaesthesia (including obstetric use — caesarean section)

IV Bolus (Hospital/Specialist Setting Only):

Parameter	Recommendation
Starting dose	2.5–5 mg slow IV bolus
Titration	Repeat 2.5–5 mg every 5–10 minutes based on systolic BP response
Usual maintenance dose	2.5–15 mg total (divided doses)
Maximum dose	30 mg/day

Clinical Notes:

Reserved for hypotension accompanied by reflex bradycardia
Pure α1 action produces vasoconstriction with minimal direct cardiac stimulation
Ensure adequate circulating volume before administration

IM Use (Rarely Used):

Parameter	Recommendation
Starting dose	10–20 mg IM
Titration	Not applicable
Usual maintenance dose	10–20 mg single dose
Maximum dose	20 mg per injection

Clinical Notes:

Onset: 15–30 minutes
Duration: 2–3 hours
Reserved when IV access unavailable

Secondary Indications — Adults Only (Off-label)

Indication	Dose	Details
Vasopressor support in perioperative hypotension (non-obstetric) — OFF-LABEL	Starting dose: 2.5–5 mg IV bolus; Titration: Based on BP response; Maximum: 15 mg total	Specialist only — typically anaesthesia practice. Preferred where bradycardia coexists with hypotension. Evidence basis: Anaesthesia practice, comparative studies with phenylephrine/ephedrine

PAEDIATRIC DOSING (Specialist Only)

Primary Indications

⚠️ NOT RECOMMENDED for routine paediatric use.

Only under specialist (paediatric critical care/anaesthesia) supervision.

▶ Hypotension Unresponsive to Fluid Bolus during Paediatric Anaesthesia (OFF-LABEL)

Parameter	Recommendation
Starting dose	0.1 mg/kg IV bolus
Titration	Repeat 0.1 mg/kg every 10 minutes based on BP response
Usual maintenance dose	0.1–0.2 mg/kg per dose
Maximum dose	0.5 mg/kg per dose (not exceeding adult doses)

Safety Monitoring:

Continuous BP and ECG monitoring mandatory
Use only in tertiary care settings with paediatric critical care facilities

Secondary Indications — Paediatric (Off-label)

Not applicable. No established secondary indications in paediatric population. Limited data available.

Age Restrictions:

Not recommended below 1 year of age except under intensive care anaesthesia supervision

RENAL ADJUSTMENT

Renal Function	Recommendation
Mild–Moderate impairment	No dosage adjustment required
Severe impairment	No dose change; use with caution due to increased sensitivity to vasopressors
Haemodialysis	No specific data; use cautiously under monitoring

HEPATIC ADJUSTMENT

Severity	Recommendation
Mild impairment	No dose adjustment required; monitor BP closely
Moderate impairment	No dose change needed; exercise caution with repeated dosing
Severe impairment	Use cautiously; avoid repeated dosing unless under continuous monitoring; specialist supervision recommended

CONTRAINDICATIONS

Severe hypertension
Phaeochromocytoma
Hyperthyroidism
Known hypersensitivity to methoxamine or formulation excipients
Angina pectoris or known coronary artery disease
Concurrent use with MAOIs (within 14 days)

CAUTIONS

Elderly patients — greater sensitivity to pressor effects
Pre-existing bradycardia — may worsen due to baroreceptor-mediated vagal response
History of cardiac arrhythmias
Underlying heart disease — monitor cardiac status
Hypovolaemia — ensure adequate volume status prior to use
Patients on tricyclic antidepressants
Peripheral IV administration — risk of extravasation injury

PREGNANCY

Aspect	Details
Overall safety	May be used for spinal hypotension during labour or caesarean section; no documented teratogenicity
When to use	Specialist obstetric anaesthesia use only; when benefit outweighs risk
Preferred alternatives	Phenylephrine (preferred at some centres)
Monitoring required	Maternal BP (continuous), fetal heart rate, uteroplacental perfusion

LACTATION

Aspect	Details
Compatibility	Likely compatible if single-dose used during labour/anaesthesia
Expected levels in milk	No data available; assumed low due to short half-life and single-dose use
Preferred alternatives	Phenylephrine (similar profile)
Infant monitoring	Monitor for feeding adequacy if used peripartum

ELDERLY

Aspect	Recommendation
Starting dose	2.5 mg IV (lower end of range)
Titration	Slower titration; lower total doses advisable
Extra risks	Exaggerated BP response, reflex bradycardia, cardiac arrhythmias
Monitoring	Close cardiac rhythm and BP monitoring essential

MAJOR DRUG INTERACTIONS

Interacting Drug	Effect/Risk	Management
MAOIs	Severe hypertensive crisis	Avoid concomitant use; contraindicated within 14 days of MAOI use
Tricyclic antidepressants	Potentiation of hypertensive effect	Avoid combination or use significantly reduced doses
Halogenated general anaesthetics (e.g., halothane)	Increased risk of cardiac arrhythmias	Avoid or use with extreme caution
Other vasopressors (e.g., norepinephrine, phenylephrine)	Additive pressor effects; risk of severe hypertension	Avoid combination unless under specialist guidance

MODERATE DRUG INTERACTIONS

Interacting Drug	Effect/Risk	Management
Non-selective beta-blockers	May worsen bradycardia; blunts compensatory cardiac response	Monitor HR closely; consider atropine availability
Digitalis glycosides	Increased risk of arrhythmias	Monitor ECG
Diuretics	Hypovolaemia may worsen vasopressor response	Ensure adequate volume status before use
Corticosteroids	May enhance pressor responsiveness	Monitor BP more frequently

COMMON ADVERSE EFFECTS

Headache
Nausea
Dizziness
Anxiety or restlessness
Reflex bradycardia
Injection site burning or discomfort

SERIOUS ADVERSE EFFECTS

Adverse Effect	Notes
Severe hypertension	Risk of intracranial haemorrhage (rare)
Myocardial ischaemia	Especially in patients with underlying coronary disease
Ventricular arrhythmias	May require immediate discontinuation
Severe reflex bradycardia	Risk of asystole; atropine may be required
Tissue necrosis	If extravasation occurs; use central line for prolonged infusions

MONITORING REQUIREMENTS

Timing	Parameters
Baseline	Blood pressure (supine), heart rate, ECG (if comorbid cardiac disease), volume status assessment
During use	Continuous BP and HR monitoring; ECG monitoring during IV administration; watch for signs of bradycardia
After administration	Monitor for extravasation injury at peripheral IV site; observe for delayed hypotension or rebound effects
Long-term	Not applicable (acute use only)

BRANDS AVAILABLE IN INDIA

Vasoxyl (Abbott)
Mexon (Samarth Pharma)
Methodrin (Neon Labs)

PRICE RANGE (INR)

Formulation	Price Range	Notes
Injection 10 mg/mL (1 mL ampoule)	₹8–₹20 per ampoule	Not currently under NPPA price control

Available in government hospitals for obstetric anaesthesia

CLINICAL PEARLS

Methoxamine is preferred over phenylephrine/ephedrine when hypotension is accompanied by bradycardia — pure α1 action avoids direct cardiac stimulation.
Pure α1 agonist — causes vasoconstriction without β1-mediated tachycardia, making it ideal for baroreceptor-mediated hypotension with bradycardia.
Anticipate reflex bradycardia — keep atropine readily available during administration.
Always assess volume status first — methoxamine is contraindicated in hypovolaemic shock; fluid resuscitation takes priority.
Exercise caution with repeated dosing in elderly and high-risk obstetric patients — start low, titrate slowly.
Extravasation risk — use central venous access if prolonged or repeated dosing anticipated; phentolamine infiltration may be required for extravasation.

VERSION

RxIndia v0.9 — 18 Feb 2026

REFERENCES

CDSCO-approved product inserts (Vasoxyl)
Indian Pharmacopoeia (IP)
AIIMS Obstetric Anaesthesia Protocol
API Textbook of Medicine
Goodman & Gilman’s The Pharmacological Basis of Therapeutics
Indian anaesthesia specialist practice recommendations
WHO drug information (supportive)

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This platform is designed strictly for healthcare professionals. Data provided is synthesized from authoritative pharmacological sources and clinical registries. Do not use for consumer medical decisions. Always verify critical dosing and contraindications with official institutional protocols and peer-reviewed journals.

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