Rule of 150 and 4
a. Begin treatment if: Paracetamol is ingested at a dose >150 mg/kg
Threshold to begin treatment is half the dose (75 mg/kg) in high risk cases:
1. Regular ethanol consumption: >21 Units/week in male and >14 Units/week in female
2. Regular use of enzyme inducing drugs: carbamazepine, phenytoin, phenobarbitone, rifampicin
3. Conditions causing glutathion depletion: malnutrition, HIV, eating disorder, cystic fibrosis
Remember the 3 E – Ethanol, Enzyme inducer, Eating disorder
b. Within 4 hours of ingestion: Oral/NG/OG Activated Charcol (1/50, i.e. 1 gm/kg or 50 gm)
c. Send Serum APAP level after 4 hours post-ingestion and Start NAC if: Serum APAP level >150 microgram/ml at 4 hours post-ingestion (or use Rumack-Matthew normogram for acute ingestion upto 24 hours) OR Ingested dose >150 mg/kg and Serum APAP level cannot be obtained within 8 hours post-ingestion or patient presents after 8 hours or if the dosing is staggered
![rumack matthew normogram](https://epomedicine.com/wp-content/uploads/2019/08/rumack-matthew.jpg)
d. NAC dosing:
- Loading: 150 mg/kg IV in 200 ml (3 ml/kg) 5%DW over 1 hour
- Maintenance: 150 mg/kg IV in (21 ml/kg) 1500 ml 5%DW over 20 hours.
- 1/3rd in 1st 4 hours
- 2/3rd in later 16 hours
Oral dose of NAC:
1. Loading: 140 mg/kg
2. Maintenance: 70 mg/kg every 4 hours for 17 doses
Rechecking serum APAP level:
1. IV NAC dosing: at 20 hours
2. Oral NAC dosing: at 24 hours
NAC can be started empirically if serum APAP level is not obtained within 8 hours and it can be stopped prior to completion of total regimen if:
a. APAP level returns to 0
b. INR <2
c. AST normalizes
King’s college Criteria
It is used for predicting fulminant hepatic failure and referral to the transplant center.
Mnemonic: A or B, C and D
a. Acidosis: Arterial pH <7.3 or lactate >3 OR
b. All of the following:
- Bleeding risk: PT >100s or INR >6.5
- Creatinine: >3.4 mg/dl
- Drowsiness: Hepatic Encephalopathy Grade III or IV
References:
- Wallace CI, Dargan PI, Jones ALParacetamol overdose: an evidence based flowchart to guide managementEmergency Medicine Journal 2002;19:202-205.
- The Washington Manual of Medical Therapeutics – By Hemant Godara
![dr. sulabh kumar shrestha](https://epomedicine.com/wp-content/uploads/2020/07/profile.jpg)
He is the section editor of Orthopedics in Epomedicine. He searches for and share simpler ways to make complicated medical topics simple. He also loves writing poetry, listening and playing music.