GIMedicalsPharmacology

Paracetamol (Acetaminophen) Poisoning

Paracetamol (Acetaminophen) Poisoning is very common and usually seen in attempted suicide because it is readily available.

Toxic dose = 150mg/kg (75mg/kg if malnourished) or 12g in adults may be fatal (10-15g ~ 20-30 tablets)
Max. Therapeutic dose = 4g/day

Acute poisoning:
1 hr = larvage + activated Charcoal
4 hr = Paracetamol level
8 hr = N-acetylcysteine (within 8 hr, effectiveness is the same, afterwards it declines); alternative – Methionine
12 hrs = Review and repeat INR q12h
24 hr = review with results (see criteria for transfer)
48 h = review (if INR normal and pt stable, possible home)

N-acetylcysteine

  • to replenish hepatic glutathione

IVI regieme

1. 150mg/kg in 200mL of 5%DW x 15min
2. 50mg/kg in 500mL of 5%DW x 4 hr
3. 100mg/kg in 1L of 5%DW x 16 hr

 

Criteria for transfer:

  • Encephalopathy or increased ICP
  • INR >2.0 at <48 hr – or >3.5 at <72h (peak at 72-96h) N.B. LFTs are NOT good markers
  • Renal impairment ( Creat > 200), consider HD if >400) * monitor urine output and daily U&Es
  • Acidosis / Blood pH <7.3
    • Lactate > 3.5 mg/dL (0.39 mmol/L) 4 hrs after early fluid resuscitation
    • Lactate > 3 mg/dL (0.33 mmol/L) after full fluid resuscitation at 12 hours
  • Systolic BP < 80mmHg

 

King’s College Hospital Criteria for Liver transplantation

Paracetamol liver failure

  • Arterial pH <7.3 24 h after ingestion

Or all of the following:

  • PT > 100s
  • Creat > 300
  • Grade III or IV encephalopathy

Non-paracetamol liver failure

  • PT > 100s

Or 3 out of 5 of the following:

  1. Drug-induced liver failure
  2. Age <10 or >40y old
  3. >1wk from 1st Jaundice to encephalopathy
  4. PT > 50s
  5. Bilirubin > 300

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