Paracetamol Flashcards Preview

3: Drugs for Clinical Medicine > Paracetamol > Flashcards

Flashcards in Paracetamol Deck (21)
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1
Q

What is another name for paracetamol?

A

Acetaminophen

2
Q

What is the main advantage of paracetamol?

A

It is generally the safest analgesic at treatment doses

3
Q

How is paracetamol thought to work?

A

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

4
Q

What is the advantage of paracetamol not inhibiting COX-1?

A

It does not cause peptic ulceration

5
Q

How can paracetamol be given?

A
  • PO
  • Effervescent tablets
  • IV
  • PR
6
Q

When should IV paracetamol be avoided?

A

In people with a body weight <50kg or those at risk of hepatotoxicity

7
Q

When should effervescent paracetamol tablets not be given?

A

In hypernatraemia due to their high sodium content

8
Q

What are the indications for paracetamol?

A
  • Mild to moderate pain
  • Pyrexia
  • Post-immunisation pyrexia (unlicensed)
9
Q

What are the cautions/contraindications for paracetamol?

A
  • Hepatocellular insufficiency
  • Chronic alcohol intoxication
  • Malnutrition - Caution in <50kg
10
Q

How should paracetamol use be monitored?

A
  • Review pain severity or measure temperature

- Monitor serum levels in suspected/known overdose 4 hours after ingestion

11
Q

How long can paracetamol take to work?

A

30 minutes

12
Q

What drugs can paracetamol interact with?

A

CYP450 inducers e.g. phenytoin and carbamazepine

13
Q

What effect can CYP450 inducers have on paracetamol?

A

Increase rate of NAPQI production and increase the risk of toxicity

14
Q

What are the rare side-effects of paracetamol?

A
  • Malaise
  • Skin reactions
  • Flushing and tachycardia (with IV use)
15
Q

What skin reactions may be caused by paracetamol?

A
  • Acute generalised exanthematous pustulosis
  • TEN
  • Stevens-Johnson syndrome
16
Q

What are the other potential side-effects of paracetamol?

A
  • Thrombocytopenia
  • Leukopenia
  • Neutropenia
  • Hypotension (IV use)
17
Q

What are the effects of paracetamol overdose?

A
  • Hepatocellular necrosis

- Acute renal tubular necrosis

18
Q

What mnemonic can be used to remember the risk factors for paracetamol toxicity?

A

COMA

19
Q

What does the COMA mnemonic for risk factors for paracetamol toxicity stand for?

A
  • Chronic alcohol abuse
  • On drugs that induce CYP450
  • Malnourished individuals
  • Anorexic individuals
20
Q

What advice should be given to patients using paracetamol?

A
  • Stick to the prescribed dose
  • Check if any OTC drugs contain paracetamol e.g. co-codamol
  • Seek immediate help if an overdose is suspected
21
Q

What advice can patients be given if they have reached the maximum safe dose of paracetamol?

A

Consider other forms of analgesia e.g. NSAIDs