Methohexital (Brevital)

ED / ICU / Transport

Monitored settings only: hospital or ambulatory care. This is not a prehospital drug and not a transport drug.

• Brief procedural sedation for short procedures: e.g., elective or ED electrical cardioversion. The label covers IV anesthesia for short procedures with minimal painful stimuli. It gives no analgesia, so add one for any painful procedure. ED and cardiology sedation depend on the institution and on the clinician's credentials.
• Who may give it: anesthesia professionals (anesthesiologist, nurse anesthetist, anesthesiologist assistant) or physicians credentialed for deep sedation under facility policy. It is not an EMS or critical-care transport drug, and it is not in the National EMS Scope of Practice Model. The RN's role is the designated monitor and assistant, per facility policy. The FDA label differs only in emphasis. It requires a hospital or ambulatory care setting with continuous respiratory and cardiac monitoring, plus a designated person other than the practitioner doing the procedure to watch a deeply sedated patient.

Other Uses

• Anesthesia for electroconvulsive therapy (ECT): the most common ECT induction agent. It is chosen because it interferes little with the induced seizure.
• IV induction of general anesthesia (FDA-labeled): given ahead of inhaled or other anesthetic agents.
• Maintenance anesthesia for short procedures (FDA-labeled): intermittent IV boluses or an infusion, given with nitrous oxide. Rarely used today.
• Pediatric induction or sedation for short, minimally painful procedures (FDA-labeled, age >1 month): IM or rectal only. Sedation for imaging is one example.

Every dose below traces back to the FDA label or a named study. The cardioversion regimen is off-label and comes from one 2022 trial. Facility sedation policy decides who gives the drug and how it is monitored.

Available Forms

• 500 mg lyophilized powder, multi-dose vial (Brevital and generics), buffered with sodium carbonate. Reconstitute before use. On current labels, it is the only US vial size.
• 1% solution (10 mg/mL): for intermittent IV and rectal use
• 0.2% solution (2 mg/mL): for continuous IV infusion
• 5% solution (50 mg/mL): for IM use in children only

Adult Dosing

Pediatric Dosing

Run the pediatric math against weight-based dosing. That page is for calculation checks.

Continuous Infusion

Preparation & Administration

• Diluent: Bacteriostatic-free only. Lactated Ringer's is incompatible. Never use it.
• 1% (IV or rectal): 500 mg plus 50 mL sterile water for injection (preferred), D5W or NS.
• 0.2% (infusion): reconstitute 500 mg with 15 mL, then add to 235 mL D5W or NS (250 mL total). Sterile water is the wrong choice here. It would be markedly hypotonic.
• 5% (IM, children only): 500 mg plus 10 mL sterile water for injection (preferred) or NS.
• Push rate: induction at about 1 mL of 1% every 5 sec.
• Line: confirm the catheter is in a vein and inject into a free-flowing IV; stop at once for burning pain, blanching, cyanosis or swelling. Flush before and after (alkaline solution).
• Stability: Prepare it fresh and use it promptly. It stays chemically stable 24 hr at room temperature. Look for haze or precipitate before you use it.

Contraindications

• Latent or manifest porphyria
• Known hypersensitivity to barbiturates
• Any patient in whom general anesthesia is contraindicated

Precautions

• Shock, severe cardiovascular instability, severe hepatic dysfunction: The label says these may justify another agent.
• Seizure history, especially partial (focal) seizures: Methohexital can provoke seizures.
• Asthma, COPD, status asthmaticus: Use caution, and extreme caution in status asthmaticus. Laryngospasm and bronchospasm can occur.
• Severe hypertension or hypotension, myocardial disease, heart failure, severe anemia, extreme obesity: Use caution. Titrate slowly to effect.
• Debilitated patients or impaired respiratory, circulatory, renal, hepatic or endocrine function: Use caution, and start at the low end of the dose range.
• Chronic barbiturate or phenytoin therapy: These may reduce the effect. Expect to need higher doses.

Hold / Reassess If

• No airway-skilled provider, bag-valve-mask, suction, oxygen or continuous monitoring at the bedside: do not give.
• Shock or severe cardiovascular instability: resuscitate first or consider another agent (the label lists these as possible reasons to choose another induction agent; it sets no BP threshold).
• Burning pain along the limb, blanching, blotchy cyanosis or swelling during injection: stop immediately (possible intra-arterial or perivascular injection).

Common

• Hiccups, coughing and muscle twitching: They turn up often, by every route. They can impair ventilation.
• Transient hypotension and tachycardia after induction (hypotension in 8% after 0.5 mg/kg for cardioversion in the 2022 trial)
• Apnea or hypoventilation: In the 2022 cardioversion trial, 16% needed airway maneuvers (jaw thrust, chin lift).
• Injection-site pain and thrombophlebitis (less injection pain than propofol in the 2022 trial)
• Emergence delirium, restlessness or anxiety, mostly with postoperative pain
• Nausea and vomiting (low if fasting), headache, salivation, occasional shivering

Serious / Life-Threatening

Overdose & Toxicity Management

• Signs: They show within seconds of an IV overdose (delayed after rectal dosing). Expect CNS and respiratory depression, hypotension from lost vascular tone, and twitching that builds toward convulsive-like movements. Massive exposure can cause pulmonary edema and cardiac arrest.
• Management: secure the airway, oxygenate and ventilate; IV fluids, then vasopressor or inotrope for hypotension; benzodiazepine for convulsions, with general anesthesia and paralysis if refractory.
• No antidote: flumazenil and naloxone do not reverse barbiturates. Call the regional poison center (1-800-222-1222).

Clinically Significant Interactions

IV Compatibility

• Diluents: See Preparation & Administration. Never use lactated Ringer's or a bacteriostatic diluent.
• Incompatible: Acidic solutions are the problem: atropine, succinylcholine and metocurine. Label testing also showed haze with scopolamine and tubocurarine. Flush before and after. Give every other drug from its own syringe.
• Verify with an institutional compatibility resource.

• Pediatrics: The label covers IM and rectal use only, in children older than 1 month. IV use is not established (see the Pediatric Dosing table). Apnea is reported with every route. Repeated or prolonged anesthetic exposure (>3 hr) under age 3 years carries the FDA developing-brain warning. Don't delay needed procedures because of it.
• Neonates: Neither safety nor effectiveness is established below 1 month of age.
• Pregnancy: No adequate human studies exist. Animal studies at 4–7 times the human dose showed no fetal harm. Anesthetic exposure longer than 3 hr in the third trimester carries the same FDA developing-brain warning as in young children (primate data). Don't delay needed procedures for that. It crosses the placenta rapidly, and it has been used for cesarean delivery. In an emergency, don't withhold needed anesthesia. Choose the agent with the anesthesia or obstetric team.
• Lactation: The label advises caution. LactMed reports very small amounts in milk. After a single dose there is no waiting period, so breastfeeding can resume once the mother is alert enough to nurse. If other anesthetic agents are combined, follow the advice for the most problematic drug.
• Older Adults: Start at the low end of the dose range. Heart, lung, liver and kidney disease, and interacting drugs, are more common in this group.
• Renal Impairment: No specific adjustment is established. The kidneys clear its metabolites. Use caution and titrate.
• Hepatic Impairment: No specific adjustment is established. The liver clears it by metabolism. Severe hepatic dysfunction may be a reason to choose another agent.
• Obesity / Dosing Weight: The label gives no dosing weight, and it advises caution in extreme obesity. Titrate in small increments to effect.
• Seizure Disorders: It can provoke seizures, especially in partial (focal) epilepsy. Have a benzodiazepine ready.

Mechanism of Action

• Barbiturate site on the GABA-A receptor → it keeps the chloride channel open longer. That gives rapid hypnosis and amnesia, with little analgesia.
• Methylated oxybarbiturate → at least twice as potent as thiopental. It lasts about half as long.
• Little anticonvulsant effect compared with other IV anesthetics → it preserves the ECT seizure. It can still provoke seizures in susceptible patients.
• Dose-related respiratory and circulatory depression → depression rises with dose, bringing apnea and hypotension.

Pharmacokinetics

• Half-life: After one dose, redistribution ends the effect. The label gives no elimination half-life. It accumulates less in fat than thiobarbiturates, so recovery is faster. Repeated doses or an infusion still accumulate.
• Metabolism: The liver demethylates and oxidizes it. Side-chain oxidation ends its activity.
• Elimination: The kidneys clear it, by glomerular filtration of its metabolites.
• Rectal bioavailability: about 17%.

Generic Name

Methohexital sodium (methohexital sodium for injection, USP)

Brand Names

Brevital Sodium (US); generic methohexital sodium for injection

Pharmacologic Class

Ultrashort-acting methylated oxybarbiturate; GABA-A receptor modulator

Therapeutic Class

IV general anesthetic induction agent; procedural sedative-hypnotic

Controlled Substance

C-IV

ISMP High-Alert

Yes: ISMP high-alert medication (anesthetic agents, general, IV)

Look-Alike / Sound-Alike

Brevital / Brevibloc (esmolol), on the ISMP confused drug names list