Drug reference

methohexitone

Ultra-short-acting barbiturate anaesthetic · Sedative-Hypnotic

START

Induction: 1–1.5 mg/kg IV slowly (≈70–100 mg)

TYPICAL MAX

Titrated to effect (no fixed maximum)

STOP IF

Apnoea/laryngospasm, severe hypotension, or porphyria

WATCH

Airway, ventilation, BP; resuscitation equipment ready

CDSCO approvedATC N01AF01

Dose laddermg/d

Renal dose adjustmenteGFR mL/min/1.73m²

KDIGO 2024 + manufacturer label

Pharmacokineticsplasma · t hours

ONSET: 29s · 30 s
PEAK: 47s · ~45 s
t½: 4h · t½
DURATION: 6min · 5–7 min

EXCRETION

Hepatic metabolism; renal metabolites

route + CYP

INTERACTIONS

2 major

SEVERE in our sources

PREGNANCY

Use only if clearly needed (obstetric induction — neonatal depression possible).

FDA category + note

Top interactionssee all 5 →

Cns DepressantsSevereDatabaseKimi deep-research + Cla
Drugs Precipitating PorphyriaSevereDatabaseKimi deep-research + Cla

Mechanism

Potentiates GABA-A receptor chloride conductance and depresses the reticular activating system, producing rapid loss of consciousness; ultra-short action via redistribution.

Indications

Induction of general anaesthesiaAnaesthesia for brief proceduresAnaesthesia for electroconvulsive therapy

Dosing

Adult: Induction: 1–1.5 mg/kg IV (≈50–120 mg) at ~1 mL/5 s; ECT: 0.5–1 mg/kg IV. Maintenance: intermittent 20–40 mg or infusion.
Pediatric: Rectal 25 mg/kg (selected); IV per anaesthetist.
Renal adjustment: No fixed adjustment; titrate to effect.
Hepatic adjustment: Reduce dose in severe hepatic impairment (hepatic metabolism).
Geriatric: Reduce dose; greater cardiorespiratory depression.
Max dose: Titrated to effect (no fixed maximum; ~1–1.5 mg/kg induction)

Pharmacokinetics

Onset

Loss of consciousness within 30 s (IV)

Peak effect

~45 s

Duration

5–7 min (single dose, redistribution)

Half-life

~4 h (terminal)

Bioavailability

IV 100%

Protein binding

~73%

Metabolism

Hepatic (demethylation/oxidation)

Excretion

Renal (metabolites)

Contraindications

Porphyria (acute intermittent/variegate)
Hypersensitivity to barbiturates
Absence of suitable airway/resuscitation facilities
Caution: status asthmaticus, severe cardiovascular instability

Side effects

Common

Respiratory depression/apnoeaHypotensionInjection-site painInvoluntary muscle movements/hiccupsCoughing

Serious

Laryngospasm/bronchospasm
Cardiorespiratory depression/arrest
Acute porphyric crisis
Anaphylaxis
Seizures (paradoxical, lowered threshold in some)

Pregnancy & lactation

Pregnancy

Use only if clearly needed (obstetric induction — neonatal depression possible).

Lactation

Single peri-procedural dose; brief interruption reasonable.

Drug interactions

Cns Depressants

Severe

Database

Additive CNS/respiratory depression

Reduce doses; controlled ventilation