Methohexital Dosage

Medically reviewed by Drugs.com. Last updated on Aug 16, 2023.

Usual Adult Dose for Anesthesia

Induction of Anesthesia:

• Administer 1 to 1.5 mg/kg of a 1% solution IV a rate of about 1 mL/5 seconds; gaseous anesthetics and/or skeletal muscle relaxants may be administered concomitantly.
• The induction dose usually provides anesthesia for 5 to 7 minutes.

Maintenance of Anesthesia:

• Administer intermittent IV injections of 20 to 40 mg of the 1% solution every 4 to 7 minutes OR administer 3 mL of a 0.2% solution by continuous IV infusion per minute.
• Individualize the rate of flow for each patient.
• For longer surgical procedures, a gradual reduction in the rate of administration is recommended.
• Other parenteral agents (e.g., narcotic analgesics) are usually used with this drug during longer procedures.

Uses:

• For IV induction of anesthesia prior to the use of other general anesthetic agents.
• For IV induction of anesthesia and as an adjunct to subpotent inhalational anesthetic agents (e.g., nitrous oxide in oxygen) for short surgical procedures; this drug may be given by infusion or intermittent injection.
• For use along with other parenteral agents, usually narcotic analgesics, to supplement subpotent inhalational anesthetic agents (e.g., nitrous oxide in oxygen) for longer surgical procedures.
• As IV anesthesia for short surgical, diagnostic, or therapeutic procedures associated with minimal painful stimuli.
• To induce a hypnotic state.

Usual Pediatric Dose for Anesthesia

One month or older:
Induction of Anesthesia:
IM: 6.6 to 10 mg/kg using a 5% solution
Rectal: 25 mg/kg using a 1% solution

Uses: Pediatric patients 1 month and older:

• For IM or rectal induction of anesthesia prior to the use of other general anesthetic agents.
• For IM or rectal induction of anesthesia and as an adjunct to subpotent inhalational anesthetic agents for short surgical procedures.
• As IM or rectal anesthesia for short surgical, diagnostic, or therapeutic procedures associated with minimal painful stimuli.

Renal Dose Adjustments

Renal impairment: Use with caution.

Liver Dose Adjustments

Hepatic impairment: Use with caution.

Precautions

US BOXED WARNINGS:

• This drug should be used only in hospital or ambulatory care settings that provide for continuous monitoring of respiratory (e.g., pulse oximetry) and cardiac function. Immediate availability of resuscitative drugs and age- and size-appropriate equipment for bag/valve/mask ventilation and intubation, and personnel trained in their use and skilled in airway management should be assured. For deeply sedated patients, a designated individual other than the practitioner performing the procedure should be present to continuously monitor the patient.

Safety and efficacy have not been established in patients younger than 1 month.

Consult WARNINGS section for additional precautions.

US Controlled Substance: Schedule IV

Dialysis

Data not available

Other Comments

Administration advice:

• All routes of administration are often associated with hiccups, coughing, and/or muscle twitching, which may also impair pulmonary ventilation. Following induction, temporary hypotension and tachycardia may occur.

Storage requirements:

• Store unopened vials at 20C to 25C (68F to 77F).
• Reconstituted solutions are stable at room temperature for 24 hours.

Reconstitution/preparation techniques:

• Freshly prepare solutions of this drug and use promptly.
• Only use bacteriostatic-free diluent. Recommended diluents are based on route of administration.
• The preferred diluent for intermittent IV and rectal administration is sterile water for injection; 5% dextrose injection, or 0.9% sodium chloride injection are also acceptable diluents.
• For continuous drip anesthesia, prepare a 0.2% solution by adding 500 mg of this drug to 250 mL of diluent; for this dilution, either 5% glucose solution or isotonic (0.9%) sodium chloride solution only is recommended as the diluent instead of sterile water for injection to avoid extreme hypotonicity.
• The preferred diluent for IM administration is sterile water for injection; 0.9% sodium chloride injection is also an acceptable diluent.

IV compatibility:

• Incompatible diluents: Lactated Ringer's Injection.

General:

• Preanesthetic medication is advisable. This drug may be used with any of the recognized preanesthetic medications.
• Outpatients should be released in the company of another individual, and no skilled activities, such as operating machinery or driving a motor vehicle, should be engaged in for 8 to 12 hours.

Monitoring:

• This drug should only be administered by trained personnel in facilities equipped to assist in maintaining ventilation, administering oxygen, and treating anaphylaxis.
• Observe patients during and after use of this drug for cardiopulmonary arrest.

Patient advice:

• When appropriate, patients should be instructed about the hazards of drowsiness that may follow use of this drug.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer