15- Paracetamol and Liver Toxicity Flashcards
What is the limit for OTC slaes of paracetamol
No legal limit of OTC sales but pharmacists need to use professional judgement
What is IV paracetamol liscenced for
Short term treatment of moderate pain and fever when other routes of admin are limitedW
What are the advantages of IV paracetamol
Rapidly achieves therapeutic concentrations and pain relief
Removes variability in the absorption after surgery
Reduces morphine/opioid dose requirements and side effects
What are the disadvantages of IV paracetamol
Dose based on the body weight: children, adults
Dose reduced; hepatocellular insufficiency, chronic alcoholism, chronic malnutrition, dehydration
What is the dose for IV paracetamol
Adults 50kg- 750mg every 4-6hours
Adults who weigh 40kg 600mg every 4-6hours
What is the toxic metabolite of paracetamol
NAPQI
WHat factors increase the risk of paracetamol toxicity
induction of CYP2E1 and CYP3A4 isoenzymes
chronic high levels of ethanol intale
enzyme inducers- carbamazepine, phenobarbital, phenytoin, rifampicin, rifabutin, st johns wort
Increased INR and GGT
Glutathione depletion
- malnourished
Abnormal renal or hepatic function
What are the initial symptoms of paracetamol toxicity
Nausea and Vomiting
What are the symptoms of paracetamol toxicity after 24 hours
Jaundice, liver pain, impaired consciousness, asterixis, foeter hepaticus, haemorrhage, increased LFTs
How long does chronic liver failure take in paracetamol overdose
2-3 days
When can activated charcoal be used for paracetamol overdose
if under 8 hours after ingestion
150mg/kg over< 1 hour
What shows that damage is unlikely
no paracetamol and liver function is normal at 24hours
When do you give N-acetylcysteine for paracetamol overdose
If the timed paracetamol level is on or above the treatment line
When do you not use the nomogram for paracetamol toxicity
If the timing of paracetamol ingestion is unclear
What are the guidelines following paracetamol overdose
Cross-math blood- in case its needed
Serum glucose- hypoglycaemia
Renal function- electrolytes, blood urea nitrogen and creatinine
Urinalysis- proteinuria and haematuria
Pancreatic injury- lipase, amylase
Abdominal ultrasound- liver, kidneys, pancreas
