2014A11 Compare and contrast the management of an overdose of aspirin with that of an overdose of paracetamol.

Paracetamol

Aspirin

Pathophysiology

· Saturated glucuronidation, sulfation

·  ↑NAPQI -> glutathione exhaustion -> cell damage

·  Centrilobular necrosis

·  Uncoupled oxidative phosphorylation -> ↑VO₂ and VCO₂ -> metabolic acidosis, hyperthermia

·  Resp depression in children

·  Resp alkalosis in adults

Risk factors

· Malnutrition

· Liver disease

· Children

Complications

· Fulminant liver failure

· Coagulopathy

· Hypoglycaemia

· Death

· Seizure

· Cerebral oedema

· Cardiac arrest

Toxic dose

· 200mg/kg or 10g, whichever is less

· 150-300mg/kg: mild-mod

· >300mg/kg: severe

Toxic thing

· NAPQI

· Aspirin

· Salicylic acid

Toxin elimination

· Hepatic metabolism

· Hepatic metabolism

· Renal excretion

Symptoms

· Abdo pain, vomiting

· Later: jaundice

· Nausea, tinnitus, dizziness, blurred vision

Treatment

· N-acetyl cysteine

· Dosing using nomogram

· Activated charcoal for adsorption if recent ingestion (e.g. <2 hours)

· Supportive

· +/- Liver transplantation

· Forced alkaline diuresis e.g. HCO₃^- -> traps metabolite in urine

· Haemodialysis

· Activated charcoal for adsorption if recent ingestion (e.g. <2 hours)

· Supportive