Paracetamol

Mechanism of Action

• Central analgesic effect via activation of descending serotonergic pathways.
• May inhibit prostaglandin (PG) synthesis or influence cannabinoid receptors.

Administration

• Oral (suspension, tablets, liquid), IV, and rectal (suppository).

Side Effects

• Common:
  • Drowsiness and tiredness
  • Rashes and itching
• Overdose:
  • Liver damage/failure
  • Abdominal pain, nausea, vomiting
  • Seizures, coma, and death

Metabolism and Excretion

• Readily absorbed from the gastrointestinal tract (peak plasma in 10-60 minutes).
• Distributed into most body tissues.
• Metabolized extensively in the liver.
• Excreted in urine as inactive glucuronide and sulfate conjugates (less than 5% unchanged).
• Metabolites include a hydroxylated intermediate with hepatotoxic activity.
• Overdosage (more than 150mg/kg or 10g total ingested) can cause irreversible liver damage if untreated.

Contraindications

• Hypersensitivity to paracetamol or excipients.
• IV Paracetamol: Severe liver disease.
• Rectal Paracetamol: Avoid in neutropenic patients.