Clinical beta

FMBM is currently in clinical beta. Content is for professional review/testing and must not replace local protocols, senior clinical judgment, or official prescribing references.

Drug Monograph

Paracetamol

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USE IF: Pain or fever without contraindications

AVOID IF: Severe liver disease, overdose risk

Acetaminophen

Analgesic / Antipyretic

AdultPediatricHigh Yield

Indication

Pain · Fever

At a glance

INDICATION → Pain / fever (first-line when appropriate)

ADULT DOSE → 500–1000 mg PO q4–6h PRN · IV per product

MAX DOSE → 4 g/day (≤3 g if elderly, liver disease, alcohol use)

CONTRA → Severe liver failure · APAP hypersensitivity

ANTIDOTE → NAC per protocol — start when criteria met

Quick facts

Onset

~30 min PO analgesia (variable); fever often ↓ ~30–60 min.

Duration

q4–6h PRN typical; duration varies by dose & formulation.

Routes

PO, PR, IV (formulation / region-specific).

Pregnancy

Often first-line when indicated — align with OB reference + label.

Renal

Renal alone usually less dose driver than hepatic — follow label / institution.

Hepatic

Main toxicity organ — ↓ dose, ↑ interval, or avoid by severity.

Do not miss

NAC most effective within 8 hours — start immediately if overdose suspected

Max dose

  • 4 g/day (≤3 g if elderly, liver disease, alcohol use) — sum every route + product in 24 h.

Hepatotoxicity

  • Dose-dependent — early LFTs may mislead · ↑ risk with alcohol, fasting, malnutrition.

NAC timing

  • NAC: don’t wait for symptoms if treatment criteria met.

Hidden APAP / combos

  • Combo cold/flu/sleep OTC hides APAP — ask what else in 24 h.

Warfarin

  • Regular APAP + warfarin → check INR on start or dose change.

Indications

Primary

  • Headache
  • Musculoskeletal / soft-tissue pain
  • Fever

Secondary

  • Post-op pain (multimodal adjunct)
  • Dental / orofacial pain (short course)
  • Antipyresis when APAP-first per protocol

Other

  • Inpatient / ED pathways where APAP is first-line antipyretic or analgesic

Dosing

Standard: 500—1000 mg q4—6h PRN (use lower dosing in elderly, frail, liver disease)

Max daily dose

  • 4 g/day (≤3 g if elderly, liver disease, alcohol use).
  • Frailty / repeated courses — often ≤3 g/day per judgment + reference.
  • Interacting hepatotoxins — lower still.

Adult — PO

  • 500–1000 mg q4–6h PRN.
  • Never add dose without 24 h APAP total from all products/routes.

Adult — IV

  • Mg/dose per registered product (e.g. Ofirmev-class — verify local monograph).
  • Typical infusion ~15 min; IV + PO + PR = one 24 h APAP total.

Pediatric

  • 10–15 mg/kg q4–6h PRN.
  • Liquids: confirm mg/mL; prescribe mg/dose, not mL alone.

Renal adjustment

  • Mild–moderate renal impairment: often standard intervals — follow label.
  • Severe renal failure: per institution; still track cumulative APAP + liver risk.

Hepatic adjustment

  • Severe hepatic impairment: avoid or drastically ↓ dose / ↑ interval.
  • Chronic liver disease: treat ≤3 g/day (or less) as default until reassessed.

Warnings

Clinical warnings

  • Cumulative 24 h load matters more than a single large tablet.
  • Chronic daily use + alcohol → ↓ ceiling, shorten course, consider LFTs if prolonged.
  • Patients stack cold/flu + pain products without recognizing duplicate APAP.

Adverse effects

  • Therapeutic doses: usually minimal GI/CNS vs NSAIDs.
  • Overdose / high cumulative dose: hepatotoxicity (may be delayed).
  • Rare: hypersensitivity / serious skin reactions (context-dependent).

Contraindications / caution

Do not use

  • Anaphylaxis / serious hypersensitivity to acetaminophen or excipients.
  • Severe active liver failure when any added hepatotoxic load unacceptable.

Use caution / avoid high doses

  • Chronic alcohol use disorder — lower daily max; counsel on hidden APAP.
  • Cirrhosis / chronic hepatitis / steatosis — assume lower safe ceiling.
  • Multiple OTC “symptom” products — audit 24 h APAP before more Rx/OTC.

Drug interactions

  • Warfarin + regular APAP → monitor INR on start/escalation/chronic overlap.
  • Alcohol → ↑ hepatotoxicity risk; ↓ APAP ceiling; shorten duration.
  • Other hepatotoxins (e.g. some AEDs, TB drugs, MTX) → additive liver insult — count all.
  • Combo OTC/Rx products → duplication risk — reconcile before dosing.

Special populations

Pediatrics

Weight-based mg/kg; verify mg/mL on liquids; infant vs child concentrations differ.

Pregnancy

Generally acceptable for pain/fever when indicated — lowest effective dose, shortest time; OB reference.

Breastfeeding

Usual doses compatible in most references — document total maternal APAP.

Elderly

Polypharmacy + combos → default lower ceiling (often ≤3 g/day); review all OTC.

Liver disease

↓ dose / ↑ interval / avoid by severity; alcohol history mandatory.

Renal impairment

Renal alone less driving than hepatic; watch stacked organ risks in complex patients.

Administration

  • PO: with or without food per label.
  • Verify mg per tablet, capsule, or mL before give/dispense.
  • PR: match pediatric vs adult strength.

Infusion / dilution

  • IV APAP: ~15 min infusion unless local policy differs.
  • Diluent / line compatibility per pharmacy protocol.

Monitoring

  • 24 h APAP total (all routes, all brands).
  • LFTs if high-risk, prolonged, or supratherapeutic exposure suspected.
  • INR if warfarin + new regular APAP.

Overdose / toxicity

IF SUSPECTED OVERDOSE → START NAC IMMEDIATELY (do not wait for labs or nomogram)

Recognition

  • Early: asymptomatic or nonspecific.
  • Later: RUQ pain, ↑ LFTs, coagulopathy, encephalopathy.
  • Single overdose, staggered ingestions, or hidden therapeutic misadventure.

Immediate actions

  • ABCs, glucose; APAP level + plot per protocol when indicated.
  • LFTs, INR, renal function; early poison center / toxicology.

Antidote

  • NAC per protocol — time-sensitive; many DoH/Gulf centers use modern 2-bag infusion — match local guideline (no dosing tables here).
  • Do not defer for “clinical hepatitis” if level/timing meets treatment.

Decontamination

  • Charcoal if early + protected airway + substantial ingestion — per poison center.

Escalation

  • Rising transaminases, coagulopathy, AMS → escalate / hepatology / transplant pathway per protocol.
  • Consider hemodialysis in massive overdose with severe acidosis, elevated lactate, or very high levels (EXTRIP guidance).

Clinical pearls

Common mistakes, resistance logic, and bedside traps

3 AM safety check

  • Before signing: list every APAP product in last 24 h — if unknown, don’t add.

Prescribing mistake #1

  • Discharge PRN opioid–APAP while patient already uses OTC APAP around the clock — reconcile composite daily APAP.

Warfarin overlap

  • Scheduled APAP for days can move INR — “safe OTC” still needs monitoring.

Quick wins

  • One brand ≠ one ingredient — read “acetaminophen / paracetamol” on every label.
  • Elderly + “just Tylenol” weeks → still cumulative hepatotoxicity risk.
  • Document max daily APAP on discharge when any opioid–APAP combo is sent.

LFTs early

  • Normal LFTs early do NOT exclude toxicity — liver injury is delayed.

Pharmacy Tool

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Paracetamol (Acetaminophen) 25 mg/mL oral suspension

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Pharmacokinetics

  • PO: rapid absorption; food effect varies by formulation.
  • Hepatic metabolism dominant; renal excretion of metabolites.
  • t½ ~2–4 h typical adults — context & formulation matter.

Mechanism of action

  • Analgesia / antipyresis: central COX-related + other CNS pathways (incompletely mapped).

Common brand names

Saudi Arabia

Adol · Fevadol

Global

Calpol · Ofirmev · Panadol · Tylenol · Efferalgan

Common trade names are curated examples only — formulations and availability vary. Verify the exact product name with your local pharmacy and national regulator before prescribing or dispensing.

Country practice notes

  • Practice: First-line analgesic/antipyretic before NSAIDs in many Gulf/MOH protocols when appropriate.
  • Safety: Pediatrics strictly weight-based (mg/kg); SFDA messaging aligns with concentration-safe prescribing.
  • Warning: High OTC (Adol/Fevadol/combos) — reconcile before new PRN.
  • Practice: Metabolic/HCV — lower daily max; document alcohol.

Saudi Arabia — confirm with local formulary.