barbiturates
Enable an AI agent to identify barbiturate substances and preparations, assess their material condition and context-dependent hazards, and determine which handling or use actions require verification or professional authorization.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
Researched by: Codex + Grok
Purpose and description
Enable an AI agent to identify barbiturate substances and preparations, assess their material condition and context-dependent hazards, and determine which handling or use actions require verification or professional authorization.
Barbiturates are 5,5-disubstituted (and often N-alkylated) pyrimidine-2,4,6-triones, including 2-thio analogues, that bind a distinct site on the GABA-A receptor, prolong chloride-channel open time and, at anaesthetic concentrations, open the channel without GABA, producing dose-dependent CNS depression from sedation through general anaesthesia.
It can be Classify a documented substance as a barbiturate member, non-member or unresolved candidate.; Compare labelled and measured content while preserving analyte identity, units and quantity basis.; Request confirmatory identification or quarantine a preparation when identity or condition is insufficiently supported.; Retrieve compound-specific evidence for an intended use and flag missing professional assessment.; Check whether storage, transfer, dispensing or disposal is supported by the applicable authorization and material state.; Route a reported hazardous exposure to an emergency assessment workflow without generating an individualized treatment plan..
Distinguishing features
Require a named chemical identity and an explicit structural membership rule; sedation or an informal drug name alone does not establish that a substance is a barbiturate.
Distinguish a specified barbiturate from other depressants through compound-specific documentation or analytical identification, rather than shared effects. Barbiturates overlap in effects with alcohol, benzodiazepines and other depressants. [DEA barbiturates fact sheet](https://www.dea.gov/sites/default/files/2025-01/Barbiturates-2024-Drug-Fact-Sheet.pdf)
Resolve the active moiety, salt and formulation separately: phenobarbital sodium injection is a preparation with a stated concentration and additional ingredients, rather than an unspecified quantity of phenobarbital. [DailyMed product label](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=b42d35de-a07a-4db5-998d-d4dbb92342cf)
Distinguish a material containing a barbiturate from a biological specimen with a reported barbiturate signal; record the latter as evidence of detection with its own identification limits.
Scope
+ Chemical class membership, named compounds, salts and explicitly unresolved structural boundaries.
+ Barbiturate content in bulk substances, medicinal preparations and mixtures.
+ Evidence distinguishing declared identity, presumptive detection and confirmed composition.
+ Preparation strength, material integrity, storage history and suitability for an intended handling action.
+ Compound-specific effect profiles, exposure hazards and links to applicable use restrictions.
- Patient diagnoses, physiological state and longitudinal clinical records.
- Prescribing decisions, individualized dosing, withdrawal regimens and poisoning treatment protocols.
- Manufacturing processes and chemical synthesis instructions.
- Complete models of benzodiazepines, opioids, alcohol and other neighbouring drug classes.
- Full pharmaceutical product, supply-chain transaction and jurisdictional law models.
Characteristics
- Compound and class-membership basis
- Named compound linked to a chemical identifier, structural reference and membership decision Prevents effects, brand names or uncertain screening results from substituting for chemical identity.
- Chemical and preparation form
- Specified parent form or salt; bulk material, tablet, capsule, solution, mixture or unresolved preparation Determines how quantities, compatibility and permitted routes must be interpreted.
- Barbiturate content
- mg/unit, mg/mL or mass fraction, with the named analyte and salt-versus-active-moiety basis Supports meaningful quantity comparisons without implying clinical dose equivalence.
- Identity evidence state
- Declared, presumptive, analytically confirmed, conflicting or unknown Limits which identification-dependent actions the available evidence supports.
- Material suitability
- Unassessed, supported for a specified purpose, quarantined, expired or rejected Separates having the expected name from being suitable for a particular use.
- Effect-time profile
- Onset and duration in minutes or hours; elimination half-life in hours, each with compound, route and evidence context Prevents a broad duration category from becoming a universal prediction for every preparation or exposure.
- Interaction and vulnerability constraints
- Links to compound-specific interaction evidence and relevant clinical-context assessments Allows hazards to constrain actions while patient assessment remains in a neighbouring model.
- Action authorization
- Compound or preparation linked to jurisdiction, effective date, intended action and required authority Prevents an agent from assuming one permission applies to every barbiturate and use.
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 18 findings · 28 questions.
Barbiturate identity Establish what the material is and why it belongs within this registry entry.
Shared depressant effects and ambiguous names cannot establish chemical class membership.
Class membership
Define the structural and terminological boundary of barbiturates.
Membership rule
Record the adopted chemical definition and its treatment of related structures without assuming every derivative has the same activity.
- Which authoritative chemical definition determines membership in the barbiturate class? definition
- How does that definition treat barbituric acid itself, thiobarbiturates and derivatives without established depressant activity? boundary
Compound resolution
Resolve the particular substance behind a class, product or informal name.
Resolved active identity
Associate the material with a named compound, chemical form and evidence trail.
- Which barbiturate compound and chemical form does the label, certificate or analytical report identify? provenance
- Does the reported name denote an active compound, a salt, a brand or a combination preparation? definition
Composition and identification Determine what a preparation contains and how confidently its content is known.
Barbiturate identity alone does not establish preparation strength, additional ingredients or analytical certainty.
Preparation content
Represent the barbiturate component within its actual material presentation.
Strength and coingredients
Record labelled or measured barbiturate content, its quantity basis and other ingredients relevant to the intended action.
- What is the barbiturate content per unit or volume, and is it expressed as the salt or active moiety? measurement
- Which other active ingredients, solvents or preservatives must be considered before comparing or using this preparation? boundary
Analytical confidence
Keep presumptive class detection separate from compound-specific confirmation.
Identification evidence
Record the sample, method, reported specificity and uncertainty behind an identification.
- Which method and reference material support the reported identity, and does the result identify a class or a specific compound? provenance
- What detection limits, interferences or unresolved constituents restrict interpretation of this result? measurement
Preparation condition Assess whether the particular barbiturate material remains suitable for its proposed purpose.
Suitability depends on formulation-specific condition and handling evidence, not merely a correct compound name.
Stability and storage
Relate documented storage and preparation history to applicable stability limits.
Condition history
Record expiry, opening or preparation events and excursions against evidence for the exact formulation.
- Which storage, expiry and post-opening or post-preparation limits apply to this barbiturate formulation? provenance
- Do recorded temperature, light exposure and elapsed time remain within those supported limits? measurement
Route-specific integrity
Evaluate physical integrity and quality requirements relevant to the proposed route or laboratory purpose.
Suitability decision
Distinguish observed appearance from documented purity, sterility or compatibility assurance.
- What evidence supports the required purity, container integrity and, where applicable, sterility of this preparation? provenance
- Do particles, precipitation, damaged packaging or missing compatibility evidence require withholding this preparation from its intended use? action
Effects and exposure hazards Connect a specific barbiturate to supported effect profiles and exposure-related action constraints.
Barbiturates can produce respiratory depression, dependence and hazardous withdrawal; these hazards require explicit assessment boundaries. [DEA barbiturates fact sheet](https://www.dea.gov/sites/default/files/2025-01/Barbiturates-2024-Drug-Fact-Sheet.pdf)
Compound-specific effects
Record effects and timing with their compound, preparation and route context.
Effect profile
Keep intended effects, observed effects and elimination measurements distinct.
- Which intended effects are supported for this compound and preparation in the proposed use context? provenance
- What evidence establishes onset, effect duration and elimination half-life, and under which route and exposure conditions? measurement
Hazard escalation
Identify exposure contexts that require clinical review or urgent assessment.
Exposure constraints
Link reported exposure, coexposures and repeated-use history to professional assessment requirements.
- Which compound-specific interactions, contraindications and dependence or withdrawal concerns apply to the linked exposure context? boundary
- Does the linked report describe suspected overdose, impaired breathing, reduced responsiveness or abrupt cessation requiring escalation through an established clinical workflow? action
Authorized use and custody Determine which actions are supported for the identified barbiturate in its actual legal and operational context.
Permissions must attach to the exact substance, preparation, jurisdiction and action rather than to the class name alone.
Use eligibility
Connect a proposed human, veterinary or research use to the relevant product and professional authority.
Intended-use authority
Record the documented basis for an intended use without treating chemical identity as clinical approval.
- What current label, protocol or professional authorization supports the intended use of this exact preparation? provenance
- Which restrictions prevent substitution across compounds, formulations, routes or human and veterinary contexts? boundary
Controlled material actions
Link proposed custody changes and disposal to current substance-specific requirements.
Handling permission
Record the authority and evidence needed to store, transfer, dispense or dispose of the material.
- Which current jurisdictional classification and preparation-specific exceptions apply to this material? provenance
- Is the proposed actor authorized for the requested handling action, and what custody or disposal record must accompany it? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Kinds and varieties
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Ultra-short-acting intravenous anaesthetics (thiopental, methohexital)
- Short-acting hypnotics (pentobarbital, secobarbital)
- Intermediate-acting sedative-hypnotics (amobarbital, butalbital)
- Long-acting anticonvulsants (phenobarbital, methylphenobarbital)
- Oxybarbiturates (oxygen at C2; most oral agents)
- Thiobarbiturates (sulfur at C2; thiopental, thiamylal)
- Butalbital combination analgesics for tension-type headache
- Deoxybarbiturates used as anticonvulsants (primidone, metabolised in part to phenobarbital)
- Which of these kinds and varieties hold for the sense of barbiturates this model covers, and on what evidence? provenance
Identifiers and schemes
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Wikidata - Q412006 - Item for the barbiturate chemical/pharmacological class, not a single substance.
- WHO ATC - N05CA* - Plain barbiturate hypnotics and sedatives (e.g. N05CA01 pentobarbital, N05CA04 barbital).
- WHO ATC - N05CB* - Barbiturates in combination.
- DrugBank category - DBCAT000728 - Barbiturates as a drug class.
- CAS - 67-52-7 - Parent heterocycle barbituric acid (2,4,6-pyrimidinetrione); individual drugs have their own CAS numbers.
- UN 1971 Convention INN - twelve scheduled INNs (e.g. phenobarbital, pentobarbital, secobarbital, amobarbital, butalbital, barbital) - International control is by named substance, not by the class as a whole.
- Which of these identifiers and schemes hold for the sense of barbiturates this model covers, and on what evidence? provenance
Standards and regulation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- UN Convention on Psychotropic Substances, 1971 (Commission on Narcotic Drugs / INCB): twelve barbiturates in Schedules II-IV (secobarbital typically II; amobarbital, butalbital, cyclobarbital, pentobarbital III; phenobarbital, barbital and several others IV).
- WHO Expert Committee on Drug Dependence (ECDD): medical and scientific assessment that feeds CND scheduling under the 1971 Convention.
- United States Controlled Substances Act: barbiturates fall in Schedules II-IV by substance and dosage form (amobarbital, pentobarbital and secobarbital generally II except some suppository forms; phenobarbital, barbital and mephobarbital IV; many remaining derivatives III).
- US FDA labelling: currently approved clinical barbiturates include phenobarbital, methohexital, butalbital combinations, pentobarbital, primidone and amobarbital.
- American Geriatrics Society 2023 Beers Criteria: barbiturates (including butalbital, phenobarbital and primidone) listed as potentially inappropriate in older adults.
- National controlled-substance lists that implement the 1971 Convention (examples: UK Misuse of Drugs Act Class B for many agents; Germany BtMG Anlage III; Canada CDSA Schedule IV; Brazil Class B1).
- Which of these standards and regulation hold for the sense of barbiturates this model covers, and on what evidence? provenance
Real-world use
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Phenobarbital as a low-cost first-line antiepileptic in many low-resource countries and as a standard treatment for neonatal seizures.
- Parenteral phenobarbital or pentobarbital for benzodiazepine-resistant or refractory status epilepticus, and high-dose barbiturate coma for refractory intracranial hypertension after severe traumatic brain injury.
- Methohexital for electroconvulsive therapy (preferred because it lengthens seizure duration) and for short procedural sedation.
- Butalbital combined with aspirin or acetaminophen plus caffeine (Fiorinal, Fioricet and generics) for tension-type headache.
- Primidone for essential tremor and as an anticonvulsant.
- Veterinary euthanasia solutions based on pentobarbital, and use of pentobarbital or (historically) thiopental in some US lethal-injection protocols.
- Largely displaced as routine hypnotics and anxiolytics by benzodiazepines, and as the default IV induction agent by propofol (thiopental withdrawn from the US market in 2011).
- Which of these real-world use hold for the sense of barbiturates this model covers, and on what evidence? provenance
Typical measurements
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Phenobarbital therapeutic serum concentration - 10-30 - mg/L
- Phenobarbital concentration associated with fatality - ~80 - mg/L
- Phenobarbital adult oral bioavailability - ~90 - %
- Phenobarbital time to peak plasma concentration - 2-4 - h
- Clinical duration of action (by class) - ultra-short: minutes after IV bolus (redistribution); short/intermediate: 2-6; long: >6 - h
- Phenobarbital IV loading dose (status epilepticus / neonates) - 15-20 - mg/kg
- Reported world manufacture of phenobarbital (INCB, 2024) - 308 - t
- Which of these typical measurements hold for the sense of barbiturates this model covers, and on what evidence? provenance
Failure modes and hazards
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Dose-dependent respiratory depression, apnoea and cardiovascular collapse; there is no specific antidote, only supportive care, urinary alkalinisation, multi-dose charcoal and, in severe cases, extracorporeal removal.
- Narrow therapeutic index; overdose has historically been a leading method of fatal self-poisoning among sedative-hypnotics.
- Physical dependence with life-threatening withdrawal (tremor, delirium, seizures, autonomic instability) after abrupt stop, especially of short- and intermediate-acting agents and chronic butalbital combinations.
- Strong induction of CYP1A2, 2B6, 2C9 and 3A4/5, reducing efficacy of warfarin, steroids, other antiepileptics, immunosuppressants and hormonal contraceptives.
- Induction of ALA synthetase with precipitation of acute hepatic porphyrias (absolute contraindication).
- Teratogenicity of phenobarbital monotherapy (major malformations) and neonatal depression or sedation via placental and breast-milk transfer.
- Severe cutaneous and hepatic reactions, including DRESS, Stevens-Johnson syndrome and toxic epidermal necrolysis, especially with phenobarbital.
- Thiopental extravasation causing tissue necrosis (vesicant); histamine release with some thiobarbiturates.
- Medication-overuse headache and dependence from repeated butalbital combination analgesics.
- Additive CNS and respiratory depression with opioids, benzodiazepines and alcohol.
- Which of these failure modes and hazards hold for the sense of barbiturates this model covers, and on what evidence? provenance
Regional variation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- British Approved Names historically used the -one ending (phenobarbitone, amylobarbitone, barbitone) where USAN/INN use -al (phenobarbital, amobarbital, barbital).
- Phenobarbital remains a first-line antiepileptic in many low- and middle-income countries because of cost; in high-income practice it is largely second-line except in neonates and selected refractory settings.
- Thiopental has been unavailable in the United States since the 2011 manufacturing withdrawal tied to lethal-injection use; it remains in use as an induction and neuroanaesthetic agent in some other jurisdictions.
- US CSA schedules do not map one-to-one onto the 1971 Convention Green List; notably, butalbital-acetaminophen-caffeine (Fioricet) is exempt from US controlled-substance status, while butalbital-aspirin-caffeine (Fiorinal) remains Schedule III.
- National lists differ in tightness: many barbiturates are UK Class B, German Anlage III (special prescription form), Canadian Schedule IV, and Brazilian Class B1.
- Some intermediate-acting agents (e.g. allobarbital) saw more use in parts of Central and Eastern Europe than in North America.
- Which of these regional variation hold for the sense of barbiturates this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Benzodiazepines - Both are GABA-A positive allosteric modulators, but they occupy different sites; benzodiazepines only increase GABA's effect, whereas barbiturates prolong channel open time and can directly gate the channel at high concentration. Flumazenil reverses benzodiazepines and does not reverse barbiturates.
- Propofol - Replaced thiopental as the usual IV induction agent; it is a hindered phenol, not a pyrimidinetrione. Distinguished by structure (GC-MS/LC-MS) and by a typically faster offset without barbiturate immunoassay reactivity.
- Barbituric acid - The unsubstituted parent heterocycle (CAS 67-52-7) lacks CNS activity because it is insufficiently lipophilic; activity requires 5,5-disubstitution (and often N-alkylation or C2 sulfur).
- Z-drugs (e.g. zolpidem) - Non-benzodiazepine hypnotics that act at the benzodiazepine site of GABA-A, not the barbiturate site; effects are flumazenil-sensitive, unlike barbiturate effects.
- Glutethimide and related piperidinediones - Historically used as non-barbiturate sedative-hypnotics with a similar clinical picture; the heterocycle is a glutarimide, separated from barbiturates by GC-MS or LC-MS.
- Hydantoin anticonvulsants (phenytoin) - Share a related ureide chemistry and anticonvulsant use, but do not act as barbiturate-site GABA-A channel openers; distinguished by structure and by sodium-channel rather than chloride-channel pharmacology.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of barbiturates this model covers, and on what evidence? provenance
Sources
- Barbiturates - Clinical indications, GABA-A mechanism, duration classes, dosing, therapeutic range, adverse effects, contraindications, overdose management, US FDA-approved agents, and replacement by benzodiazepines and propofol.
- Barbiturates drug profile - Chemistry of the barbituric-acid scaffold (CAS 67-52-7), 5-phenyl anticonvulsant SAR, duration classification, and the twelve internationally controlled barbiturates with CAS numbers and 1971 Convention schedules.
- Schedules of the Convention on Psychotropic Substances of 1971, as at 6 December 2025 (ST/CND/1/Add.2/Rev.11) - Current INN listing and schedule placement of controlled barbiturates (e.g. amobarbital, butalbital, pentobarbital in Schedule III; phenobarbital in Schedule IV).
- Psychotropic Substances 2025 - International manufacture and trade: phenobarbital remains the most manufactured controlled psychotropic by mass (308 t reported in 2024).
- Barbiturates (category DBCAT000728) - Class definition as derivatives of barbituric or thiobarbituric acid used as GABA modulators, hypnotics, anaesthetics or anticonvulsants, with member drugs.
- ATC code N05 - N05CA Barbiturates, plain - WHO ATC grouping N05CA (plain barbiturate hypnotics) and N05CB (combinations), with assigned codes such as N05CA01 pentobarbital and N05CA04 barbital.
What the second pass must settle
- Which authoritative definition should settle the boundary around barbituric acid, thiobarbiturates and structurally related compounds without established pharmacological activity?
- Does an existing Vercy world model already own this concept, requiring vr.tr.barbiturates to link to it rather than become a separate publication?
- Which compound- and formulation-specific references provide adequate coverage of stability, compatibility and effect timing without unsupported class-wide extrapolation?
- Which analytical methods and reporting conventions support reliable distinctions between class screening, confirmed compound identity and quantified content across material and biological samples?
- Which jurisdictions and human, veterinary or research contexts must be covered initially, and how will their changing authorizations be maintained?