Acetaminophen
Brand: Paracetamol / Tylenol
NSAID
Analgesic / Antipyretic
Chemistry
| PubChem |
CID: 1983 |
Structure
Pharmacokinetics
| Half-life | 2 hours |
| Tmax | 0.75 h |
| Bioavailability | 80 % (approx) |
| Protein Binding | 20 % |
| Volume of Distribution | 0.9 L/kg (approx) |
| Clearance Route | hepatic |
| Active Metabolites | NAPQI (toxic; formed via CYP2E1) |
| Notes | Verify dose limits with local guideline. Adult: 500–1000 mg PO q4–6h PRN. Weight-based option: 10–15 mg/kg per dose (max per-dose limit applies). Use lower max dose in liver disease or low body weight. Children >3 months: 10–15 mg/kg per dose q4–6h. Max daily dose per paediatric guideline. Adult: 500–1000 mg PO q4–6h PRN. Weight-based option: 10–15 mg/kg per dose (max per-dose limit applies). Use lower max dose in liver disease or low body weight. Children >3 months: 10–15 mg/kg per dose q4–6h. Max daily dose per paediatric guideline. Avoid in severe hepatic impairment. Use reduced maximum daily dose (≤2000 mg/day) in chronic liver disease. Beware of combination OTC products containing paracetamol to prevent unintentional overdose. Precise weight-based formula added. Follow hepatic limit 2000 mg/day if liver disease or alcohol use. |
⚠️ Safety & Warnings
Severity: Moderate
Adverse Effects:
Nausea, rash, elevated Liver enzymes (ALT/AST) at high dose, rare genetic susceptibility (defective glutathione metabolism → NAPQI accumulation)
Contraindications:
Severe hepatic impairment, acute Liver failure
Precautions:
Caution in chronic alcohol use, malnutrition, genetic glutathione deficiency / metabolic polymorphisms (ACYP/CYP2E1 variants), long-term hepatotoxicity risk