Paracetamol Flashcards
What is another name for paracetamol?
Acetaminophen
What is the main advantage of paracetamol?
It is generally the safest analgesic at treatment doses
How is paracetamol thought to work?
Inhibits COX-3 and partially inhibits COX-2 and reduction in prostaglandins.
COX inhibition is associated with increased pain threshold and a reduction in prostaglandins
What is the advantage of paracetamol not inhibiting COX-1?
It does not cause peptic ulceration
How can paracetamol be given?
- PO
- Effervescent tablets
- IV
- PR
When should IV paracetamol be avoided?
In people with a body weight <50kg or those at risk of hepatotoxicity
When should effervescent paracetamol tablets not be given?
In hypernatraemia due to their high sodium content
What are the indications for paracetamol?
- Mild to moderate pain
- Pyrexia
- Post-immunisation pyrexia (unlicensed)
What are the cautions/contraindications for paracetamol?
- Hepatocellular insufficiency
- Chronic alcohol intoxication
- Malnutrition - Caution in <50kg
How should paracetamol use be monitored?
- Review pain severity or measure temperature
- Monitor serum levels in suspected/known overdose 4 hours after ingestion
How long can paracetamol take to work?
30 minutes
What drugs can paracetamol interact with?
CYP450 inducers e.g. phenytoin and carbamazepine
What effect can CYP450 inducers have on paracetamol?
Increase rate of NAPQI production and increase the risk of toxicity
What are the rare side-effects of paracetamol?
- Malaise
- Skin reactions
- Flushing and tachycardia (with IV use)
What skin reactions may be caused by paracetamol?
- Acute generalised exanthematous pustulosis
- TEN
- Stevens-Johnson syndrome
What are the other potential side-effects of paracetamol?
- Thrombocytopenia
- Leukopenia
- Neutropenia
- Hypotension (IV use)
What are the effects of paracetamol overdose?
- Hepatocellular necrosis
- Acute renal tubular necrosis
What mnemonic can be used to remember the risk factors for paracetamol toxicity?
COMA
What does the COMA mnemonic for risk factors for paracetamol toxicity stand for?
- Chronic alcohol abuse
- On drugs that induce CYP450
- Malnourished individuals
- Anorexic individuals
What advice should be given to patients using paracetamol?
- Stick to the prescribed dose
- Check if any OTC drugs contain paracetamol e.g. co-codamol
- Seek immediate help if an overdose is suspected
What advice can patients be given if they have reached the maximum safe dose of paracetamol?
Consider other forms of analgesia e.g. NSAIDs
