paracetamol

Ingredient name resolution

Record the evidence connecting a encountered name to the paracetamol registry identity.

1. Does the observed name denote paracetamol itself, a label abbreviation or a product containing it? definition
2. Which authoritative ingredient record supports this name mapping? provenance

Specific identity evidence

Record whether the actual sample has been distinguished from plausible substitutes or related compounds.

1. Which identity method and reference material were used on this sample? measurement
2. Can that method distinguish paracetamol from the related compounds or mixtures plausible in this context? boundary
3. What further confirmation is required before the material may be treated as identified? action

Solid form suitability

Record measured form and particle properties without assuming that every paracetamol batch behaves identically.

1. What solid form and particle-size distribution have been measured, using which methods? measurement
2. Which of those properties are acceptance requirements for the intended formulation process? boundary

Dissolved or dispersed content

Distinguish total paracetamol content from its physical distribution in the sampled preparation.

1. Is the paracetamol dissolved, suspended or of undetermined physical distribution in this preparation? measurement
2. Under what temperature, medium and sampling conditions was concentration measured? measurement
3. Does observed precipitation or non-uniformity require referral to the preparation's quality procedure? action

Assay and impurity assessment

Record paracetamol assay, the required impurity panel and unresolved analytical gaps.

1. What paracetamol assay result was obtained, on what reporting basis and with what uncertainty? measurement
2. Which related substances, residual solvents and other contaminants does the applicable specification require testing? boundary
3. Do the results and method quantitation limits support an acceptance decision? action

Purpose-specific release

Link the batch, sampling record, certificate and responsible release decision.

1. Which manufacturer lot, sample and test report establish the evidence chain for this material? provenance
2. For which purpose and specification version was this batch released? boundary
3. Do missing, inconsistent or unverified records require quarantine? action

Condition history

Record storage requirements, exposure history and the evidence needed to resolve excursions.

1. Which documented storage requirements apply to this paracetamol grade and container? provenance
2. What temperature, moisture, light or container-integrity excursions are documented or unknown? measurement
3. What stability evidence or retesting is required to resolve an excursion? action

Retest and disposition

Distinguish expiry, retest requirements and handling-triggered reassessment.

1. Does this material carry an expiry date or a retest date, and what evidence establishes it? provenance
2. Have opening, repacking or possible contamination invalidated the earlier release basis? boundary
3. Should the material remain released, be retested, be quarantined or enter an authorised disposal workflow? action

Strength and quantity

Keep ingredient mass, liquid volume and dosage-unit count distinct.

1. What verified paracetamol strength, dosage form and route belong to the linked product? provenance
2. What paracetamol mass corresponds to the recorded volume or number of units? measurement
3. Are strength, release characteristics or co-ingredients different enough to prevent an assumed substitution? boundary

Aggregate exposure check

Sum linked paracetamol exposures over explicit intervals and identify incomplete histories.

1. Which administered or suspected doses across all products and routes contribute to the interval being assessed? measurement
2. Which current product instructions or clinician-approved constraints apply to the linked recipient? provenance
3. Does suspected excess exposure require immediate clinical escalation rather than waiting for a complete calculation? action

Recipient-specific review

Require an applicable clinical review when ingredient warnings affect a proposed use; liver disease and serious skin reactions are relevant examples. [FDA acetaminophen overview](https://www.fda.gov/drugs/safe-use-over-counter-pain-relievers-and-fever-reducers/acetaminophen)

1. Does the linked clinical record identify a paracetamol warning, previous reaction or unresolved contraindication relevant to this use? boundary
2. Which qualified decision-maker or clinical workflow must resolve that restriction before proceeding? action

Kinds and varieties

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Immediate-release oral solids (tablets, capsules, chewable and dispersible tablets)
• Paediatric and adult oral liquids and suspensions
• Rectal suppositories
• Intravenous infusion solution
• Fixed-dose combinations with opioids, NSAIDs, caffeine, or multi-symptom cold/flu actives
• Modified-release / prolonged-release oral forms (historically marketed; marketing authorisations suspended in the EU)
• Pharmacopoeial-grade bulk substance (API) versus finished dosage form
• Veterinary analgesic preparations

1. Which of these kinds and varieties hold for the sense of paracetamol 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 - Q57055 - Item for the substance paracetamol / acetaminophen.
• CAS Registry Number - 103-90-2 - Primary CAS for N-(4-hydroxyphenyl)acetamide.
• IUPAC / CAS name - N-(4-hydroxyphenyl)acetamide - Systematic chemical name used in pharmacopoeias and the Merck Index.
• INN - paracetamol - WHO International Nonproprietary Name; used in most of the world and on the WHO EML.
• USAN - acetaminophen - United States Adopted Name; also the usual name in Canada and Japan.
• UNII - 362O9ITL9D - FDA Substance Registration System unique ingredient identifier.
• ATC - N02BE01 - WHO ATC for paracetamol as a single agent; combinations use N02BE51 / N02BE71.
• PubChem CID - 1983 - NCBI PubChem compound record.
• DrugBank - DB00316 - DrugBank drug record.
• ChEBI - CHEBI:46195 - ChEBI chemical entity.
• EC / EINECS - 203-157-5 - ECHA substance information 100.002.870.
• InChIKey - RZVAJINKPMORJF-UHFFFAOYSA-N - Standard InChIKey for C8H9NO2 paracetamol.
• WHO EML entry - paracetamol (acetaminophen) - Core list since 1977; also on the EMLc.

1. Which of these identifiers and schemes hold for the sense of paracetamol 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.

• WHO Model List of Essential Medicines (and EMLc), World Health Organization - core analgesic/antipyretic, first listed 1977, current 23rd list (2023).
• The International Pharmacopoeia, USP, Ph. Eur., BP and JP monographs - identity, purity and assay of the substance and finished products (quality specifications; editions not re-read here).
• US FDA OTC analgesic/antipyretic framework and prescription-combination limit - adult maximum 4,000 mg acetaminophen in 24 hours; reduced acetaminophen per dosage unit in prescription combinations (FDA, including the 2014 combination-product action).
• EMA/CMDh Article 31 referral under Directive 2001/83/EC - marketing authorisations for modified- and prolonged-release paracetamol recommended for suspension because overdose management is unreliable.
• MHRA (United Kingdom) - pack-size and general-sales controls; 2012 lowering of the Rumack-Matthew treatment line to 100 mg/L at 4 hours.
• ANSM / French labelling rule (from 2020) - mandatory pack warning that exceeding the dose can destroy the liver.
• Pregnancy advice aligned across EMA, MHRA, WHO and FDA - first-line analgesic/antipyretic when needed, lowest effective dose, shortest duration.

1. Which of these standards and regulation hold for the sense of paracetamol 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.

• Sold over the counter worldwide as single-ingredient tablets (commonly 500 mg; 325 mg in North America) under brands such as Tylenol, Panadol, Doliprane and Calpol, and as unbranded generics.
• Used in hospitals as intravenous infusion for postoperative and emergency analgesia and for fever when the oral route is unavailable.
• Compounded into hundreds of combination cold, flu, migraine and opioid-analgesic products, which is the main route of unintentional extra dosing.
• First-line short-course treatment of pain and fever in pregnancy, and a standard paediatric antipyretic/analgesic in oral-liquid and suppository form.
• Used off-label or in specialist neonatal practice to promote closure of patent ductus arteriosus.
• On national essential-medicines lists and in primary-care protocols for headache, dysmenorrhoea, musculoskeletal pain and fever, including where NSAIDs are contraindicated.

1. Which of these real-world use hold for the sense of paracetamol 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.

• Molecular mass - 151.17 (exact mass of C8H9NO2) - g·mol−1
• Melting point - 169-170.5 - °C
• Solid density - 1.293 - g·cm−3
• Adult single oral dose - 500-1000 - mg
• Adult maximum daily dose (labelled) - 3000-4000 (4 g is the FDA labelled ceiling; several European labels use 3 g as the usual maximum) - mg/24 h
• Paediatric oral dose - about 15 per dose, not exceeding about 60 per day - mg/kg
• Plasma elimination half-life (therapeutic) - 1.9-2.5 - h
• Serum concentration used to decide antidote treatment at 4 h after a single acute ingestion - 100 (UK treatment line) or 150 (US, Australia, New Zealand) - mg/L
• Acute single-ingestion amount associated with risk of hepatic injury in adults - about 7.5-10, or about 150 mg/kg; many severe cases exceed 15 - g

1. Which of these typical measurements hold for the sense of paracetamol 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.

• Acute overdose produces NAPQI that depletes hepatic glutathione and causes centrilobular necrosis, acute liver failure, and death unless N-acetylcysteine is given in time; this is a leading cause of acute liver failure in the United States, Europe and Australia.
• Repeated supratherapeutic ingestion (staggered overdose), including stacking of combination products that all contain paracetamol, can cause the same injury at cumulative doses near or only modestly above the labelled daily maximum.
• Chronic heavy alcohol use, malnutrition, pre-existing liver disease and enzyme-inducing drugs increase the risk of injury at a given dose.
• Modified-release overdose is hard to plot on the Rumack-Matthew nomogram, which is why EU regulators suspended those products.
• Ten-fold and mg/mL confusion errors with intravenous solutions, especially in children.
• Coexistence of 120 mg/5 mL and 125 mg/5 mL oral liquids on one market, which WHO flags as a prescribing and dispensing hazard.
• Rare severe cutaneous reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis) reported to the FDA.
• Delay in seeking care because early overdose symptoms (nausea, pallor, abdominal pain) are non-specific and liver injury peaks days later.

1. Which of these failure modes and hazards hold for the sense of paracetamol 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.

• The INN and WHO/EML name is paracetamol (United Kingdom, EU, Australia, most of the world); the USAN and usual North American and Japanese name is acetaminophen; Chinese practice uses 对乙酰氨基酚 and the older 扑热息痛.
• Usual labelled adult daily maximum is 4 g in the United States; French and some other European labelling treats 3 g/day as the ordinary ceiling, with 4 g only exceptionally.
• The Rumack-Matthew treatment threshold at 4 hours is 150 mg/L in the United States, Australia and New Zealand, and 100 mg/L in the United Kingdom since 2012.
• Modified-release oral paracetamol was taken off the EU market after the Article 31 referral; immediate-release products remain widely available.
• Legal supply ranges from general-sales (UK GSL) and US OTC through prescription-only pack sizes or combinations; Australia uses SUSMP scheduling that splits OTC and S4.
• Brand landscape differs: Tylenol dominates the US/Canada consumer market, Panadol is the common international GSK brand, Doliprane in France, Calpol for UK paediatric liquids.

1. Which of these regional variation hold for the sense of paracetamol 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.

• Ibuprofen and other NSAIDs - NSAIDs have clinically useful anti-inflammatory and antiplatelet activity and GI/renal risk; paracetamol has negligible anti-inflammatory effect at ordinary doses (WHO: not recommended for anti-inflammatory use) and a hepatic rather than gastro-renal toxicity profile. Assay or INN on the label, not the shared 'pain and fever' indication, separates them.
• Acetylsalicylic acid (aspirin) - Aspirin irreversibly inhibits platelet COX-1 and is anti-inflammatory; paracetamol does not. Distinguish by INN/USAN, and by the absence of antiplatelet effect and Reye-syndrome concern with paracetamol.
• Phenacetin - Withdrawn analgesic that is metabolised to paracetamol but is associated with analgesic nephropathy and carcinogenicity; current pharmacopoeial identity tests and the absence of phenacetin from modern EML/OTC lists separate the two.
• Metacetamol (3-hydroxyacetanilide) - Positional isomer (meta- versus para-hydroxy). Separated by melting point, chromatographic retention and the standard InChIKey RZVAJINKPMORJF-UHFFFAOYSA-N, which is unique to the para isomer.
• Piracetam - Unrelated nootropic whose name is easily misread or misspelled as paracetamol. Separated by INN, indication (vertigo/cognition versus pain/fever), and chemical formula (piracetam is C6H10N2O2, not C8H9NO2).
• Combination products labelled only by brand - Cold/flu and opioid combinations contain paracetamol plus other actives; the patient may already be at the daily paracetamol ceiling. Separated only by reading the full qualitative and quantitative composition, not the front-of-pack pain-relief claim.

1. Which of these neighbouring kinds and how to tell them apart hold for the sense of paracetamol this model covers, and on what evidence? provenance