II. Indications
- Procedural Sedation (esp. Electroconvulsive Therapy or ECT)
III. Contraindications
- Absolute Contraindications
- Acute Intermittent Porphyria
- Barbiturates Hypersensitivity
- Relative Contraindications
- Cardiovascular disease
- Hypotension
- Respiratory depression or uncontrolled respiratory disease
IV. Precautions: Standard Procedural Sedation precautions
- Close cardiopulmonary monitoring (e.g. Pulse Oximetry, Blood Pressure, End-Tidal CO2)
- Airway management (e.g. suction, LMA, Endotracheal Intubation)
- Breathing management (e.g. Supplemental Oxygen, Bag Valve Mask)
V. Mechanism
- See Barbiturate
- Rapid onset, short acting Barbiturate (barbituric acid derivative)
- Cerebral Cortex and cerebellar Sedative-Hypnotic
VI. Dosing
-
Procedural Sedation
- Start: 1 mg/kg IV
- Next: 0.5 mg/kg every 2-5 minutes
- Induction
- See Rapid Sequence Intubation
- Adults: 50-120 mg (mean 70 mg) IV push given as 10 mg (1 ml of 1% solution) every 5 seconds until effect
VII. Pharmacokinetics
- Half-Life: 3-6 hours
- Onset
- IV: Immediate
- IM: 2-10 minutes
- PR: 5-15 minutes
- Duration
- IV: 10-20 minutes
- PR: 45 minutes
- Metabolism
- Slow hepatic metabolism to inactive substances
- Excretion
- Primarily excreted in urine (minimal excretion in sweat and stool)
VIII. Adverse Effects
- See Barbiturates
- See Procedural Sedation
- Laryngospasm (rare)
- Administering additional Methohexital dose typically stops the laryngospasm
- Respiratory Depression or Apnea
- Hiccoughs
- Hypotension
IX. Resources
- Methohexital (Stat Pearls)
X. References
- LoVecchio (2019) Crit Dec Emerg Med 33(7): 28