Methylated oxybarbiturate intravenous anesthetic

Plain-language summaryIntrigue 55 / 100

Methohexital sodium (Brevital) is an ultrashort-acting methylated oxybarbiturate introduced by Eli Lilly in 1960. It differs from thiopental in retaining oxygen at the 2-position (oxybarbiturate, not thiobarbiturate) and adding a methyl group on the N-1 nitrogen. The 1-methyl substitution speeds hepatic metabolism roughly four-fold, shortening elimination half-life to about four hours and giving faster awakening with minimal residual sedation after a single induction dose. The dominant modern use is electroconvulsive therapy: methohexital is the preferred ECT induction agent in many practices because it has minimal anticonvulsant effect at induction doses, while propofol and thiopental both raise seizure threshold and shorten ECT seizures. Cardiovascular and respiratory effects mirror thiopental. Standard barbiturate cautions apply (porphyria, the 1-methyl group does not eliminate porphyrinogenicity). Not stocked by Kodiac. This monograph is provided for research and educational reference.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

Our opinion on this compoundEstablished workhorse

35/100

Ultrashort barbiturate anesthetic with a genuine ECT niche but no live research frontier worth prioritizing

Look, methohexital is a legitimate clinical tool. It’s not a research compound in any frontier sense. Eli Lilly synthesized it in 1956, it entered clinical use as Brevital in 1960, and the mechanism is GABA-A barbiturate-site positive allosteric modulation, which is about as well-characterized as pharmacology gets. The N-1 methyl substitution accelerates hepatic clearance and shortens elimination half-life relative to thiopental, but we’re talking about a pharmacokinetic refinement on a 70-year-old scaffold. The chemistry is interesting in a historical sense. It’s not a frontier mechanism.

The one genuinely interesting thing about methohexital is its ECT niche, and its worth understanding why that niche exists. Propofol is a real problem for electroconvulsive therapy because it raises seizure threshold and shortens seizure duration. Thiopental does this too, to a lesser degree. Methohexital at induction doses produces minimal anticonvulsant effect, which means the procedure can generate a therapeutically adequate seizure without requiring excessive electrical stimulus to compensate. That’s not a trivial distinction in ECT practice. It’s why methohexital has persisted in anesthesia formularies long after propofol displaced barbiturates almost everywhere else. Comparative trials against propofol and ketamine for ECT induction make up the most active corner of the current literature. That work has genuine clinical utility.

The evidence base is solid for what it is. Decades of clinical use, real comparative trial data in ECT populations, well-mapped safety profile. The main adverse effects, myoclonus on injection and the porphyria contraindication shared with all barbiturates, are established and unsurprising. The 1-methyl substitution does not eliminate porphyrinogenicity. None of this is news.

What we don’t like from a library perspective: theres no open mechanistic question that methohexital is positioned to answer in 2025. GABA-A allosteric modulation has more selective probes. ECT mechanism research is real but methohexital’s role there is as a clinical comparator, not a tool for interrogating novel biology. Any preclinical group studying barbiturate-site allosterics or chloride channel kinetics has better options. Any investigator already working in the ECT space knows this compound well and doesn’t need us to introduce it.

Honestly, the differentiation score is the only thing elevating this above pure historical footnote territory. Within ECT induction agent selection, methohexital has a real clinical argument in many practices. That’s a meaningful real-world distinction. But the bench research frontier is thin, procurement priority is low unless your lab has an active ECT anesthesia or GABA-A barbiturate-site program, and the compound’s overall research appeal in 2025 reflects a tool that solved a specific clinical problem a long time ago and hasn’t produced new questions since.

Novelty: 12
Mechanism promise: 15
In-category differentiation: 38
Evidence quality: 65
Translational signal: 65
Research bench value: 28

Rationale Methohexital scores low on novelty and mechanism because it is a 1956 barbiturate with identical GABA-A pharmacology to thiopental, differentiated only by faster clearance kinetics from the N-1 methyl substitution. Evidence and translational scores are pulled up by decades of ECT clinical use, but there is no open mechanistic question here that a bench scientist would find compelling in 2025.

Methylated oxybarbiturate intravenous anesthetic

An ultrashort-acting methylated oxybarbiturate with faster recovery than thiopental, used principally for electroconvulsive therapy and brief procedural anesthesia.

Abstract

Methohexital sodium (alpha-DL-1-methyl-5-allyl-5-(1-methyl-2-pentynyl)barbituric acid sodium; CAS 22151-68-4; molecular formula C14H17N2NaO3; molecular weight 284.29 free acid) is a methylated oxybarbiturate intravenous anesthetic synthesized by Eli Lilly in 1956 and introduced clinically as Brevital in 1960. The compound differs from thiopental in retaining oxygen at the 2-position (oxybarbiturate rather than thiobarbiturate) and carrying a methyl group on the N-1 nitrogen. The 1-methyl substitution accelerates hepatic metabolism (clearance approximately 4-fold faster than thiopental on a milligram basis) and shortens elimination half-life to approximately 4 hours, enabling faster awakening with minimal residual sedation after a single induction dose. Mechanism is GABA-A positive allosteric modulation at the barbiturate site, identical to thiopental. The principal clinical niches in modern practice are electroconvulsive therapy (where the brief duration enables rapid recovery in serial-ECT outpatient settings) and brief procedural sedation in patients with contraindications to propofol. Methohexital is the dominant induction agent for ECT in many practices owing to its minimal anticonvulsant effect at induction doses (versus propofol and thiopental, which raise seizure threshold and shorten ECT seizure duration, requiring higher electrical stimulus). Cardiovascular and respiratory effects are similar to thiopental. The principal historical safety concerns are myoclonus on injection (a propofol-class adverse event also seen with methohexital) and the standard barbiturate contraindications (porphyria; the 1-methyl substitution does not eliminate the porphyrinogenic effect). Maximum recommended dose for induction is 1 to 1.5 mg/kg.

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Tag: Methylated oxybarbiturate intravenous anesthetic

Methohexital

Abstract

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