Paracetemol Overdose Flashcards

1
Q

How would you calculate total dose of paracetamol in the last 24 hours?

A

Number of tablets x mg per tablet

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2
Q

What is the max amount of paracetamol that should be consumed in a 24 hour period?

A

4g (8 tablets)

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3
Q

How would you calculate dose of paracetamol taken in mg/kg in 24 hours?

A

Total dose in 24 hours in mg/ patients weight in kg

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4
Q

What important conditions in the patients medical history should be carefully considered if there is suspected paracetamol overdose?

A
  1. Alcoholic liber disease
  2. Cystic fibrosis
  3. Chronic liver disease
  4. An eating disorder/ fasting
  5. Regular intake of enzyme-inducing drugs
  6. Significant alcohol intake
  7. HIV
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5
Q

At what stage should TOXBASE, NPIS or A&E be contacted in suspected paracetamol overdose?

A
  1. More than 75mg/kg
  2. Any doubt over the amount taken
  3. Staggered overdose >24 hours
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6
Q

What does NPIS stand for?

A

National poisons information service

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7
Q

Who should be called in the first instance of suspected paracetamol overdose?

A

Either TOXBASE or NPIS

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8
Q

Who should be contacted if TOXBASE or NPIS are unavailable in the instance of paracetemol overdose?

A

Local A&E department

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9
Q

What is another name for paracetemol?

A

Acetaminophen

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10
Q

What are the two different types of overdose?

A
  • acute overdose and staggered overdose
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11
Q

What type of overdose is described:

Excessive ingestion over a period of <1hour in the context of self harm.

A

Acute overdose

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12
Q

What type of overdose is described:

Excessive ingestion over >1 hour in the context of treating pain, can also occur with intent of self harm.

A

Staggered overdose

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13
Q

What is a therapeutic overdose?

A

An overdose within the context of treating pain

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14
Q

What dosage of paracetemol taken in a 24 hour period would suggest serious toxicity?

A

> 150mg/kg

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15
Q

What dosage of paracetemol taken in a 24 hour period would suggest likley toxicity?

A

> 75mg/kg

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16
Q

What dosage of paracetemol taken in a 24 hour period would suggest unlikely toxicity?

A

<75mg/kg

17
Q

What is glutathione?

A

It is an intrahepatic antioxidant which binds to a toxic metabolite of paracetemol which is then excreted.

18
Q

How does depleted glutathione levels put a patient at higher risk from paracetemol overdose?

A

Puts patient at higher risk of liver injury secondary to paracetemol excess

19
Q

What patients are at risk of depleted glutathione levels?

A
  • malnourished
  • psychiatric disorders
  • chronic disease (HIV, CF, liver disease)
  • alcohol use
20
Q

What affect does long term medication that induces liver cytochrome p450 inducers/enzymes have on the risk associated with paracetemol overdose?

A

Presence of Cytochrome P450 inducers increases risk of liver injury secondary to paracetemol overdose

21
Q

What are common medications that induce liver cytochrome p450? ,

A
  • antiepileptics
  • antibiotics
  • anti-retrovirals
  • St John’s wort
22
Q

What are common signs of excess paracetemol overdose within the first 24 hours?

A

Nausea and vomiting
General abdominal pain

23
Q

What are common signs of excess paracetemol overdose after 2-3 days (acute liver injury)?

A
  • RUQ abdominal pain
  • jaundice
  • hepatomegaly
  • loin pain
24
Q

What medication is used to treat paracetemol overdose?

A

N-Acetylcysteine (NAC)

25
Q

How does NAC treat paracetemol overdose?

A

By increasing hepatic glutathione

26
Q

Within how many hours of the overdose event should NAC be given in order for it to have near 100% efficacy in preventing paracetemol induced hepatotoxicity?

A

Within first 8 hours