Paracetamol Flashcards

1
Q

What are indications for paracetamol use?

A
  • First-line analgesia
  • Antipyretic
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2
Q

What is the mechanism of action of paracetamol?

A

Has at least two separate mechanisms of action, one on the COX pathway, and one on the cannabinoid system.

  • COX pathway - thought to be a selective COX-2 inhibitor, meaning that in theory it does not block production of protective prostaglandins associated with COX-1, but does block the prostaglandins that are associated with COX-2 and ultimately the production of pain.
  • Cannabinoid system - Paracetamol is metabolised to AM404 which has several effects; prevention of the neuronal uptake of a cannabinoid produced naturally, called anandamide, a compound which activates nociceptors and leads to the perception of pain.
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3
Q

How can paracetamol be given?

A
  • Orally
  • IV
  • PR
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4
Q

What is the most serious complication of using paracetamol?

A
  • Paracetamol toxicity
  • Hepatotoxicity
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5
Q

How is paracetamol toxic to the liver?

A

Paracetamol is metabolised by cytochrome P450 enzymes to a toxic metabolite (N-acetyl-p-benzoquinone imine [NAPQI]), which is conjugated with glutathione before elimination. After overdose, this elimination pathway is saturated, and NAPQI accumulation causes hepatocellular necrosis

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6
Q

What are side effects of paracetamol?

A

Liver failure

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7
Q

When should you take caution with paracetamol use?

A
  • Chronic alcohol use
  • Malnutrition
  • Low BMI
  • Severe hepatic impairment
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8
Q

What is the usual dose of paracetamol in adults?

A

0.5-1g every 4-6 hours

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9
Q

What do you need to determine before administering paracetamol?

A

Patients weight

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10
Q

What weight would you consider reducing the dose of paracetamol?

A

<50kg

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11
Q

What dose of paracetamol would you prescribe if someone weighed less than 50kgs?

A

15mg/kg every 4-6 hours

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12
Q

How would you administer IV paracetamol?

A

Pre-prepared as a solution that can be infused undiluted over 15 minutes or diluted in 0.9% sodium chloride or 5% glucose solution before administration

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13
Q

Managmenet of apracetamol overdose

A

N-acetly cysteine

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