Describe the pharmacological effects of paracetamol.  Outline its toxicity and management.

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College Answer

Main points expected for a pass included:

· Actions and mechanism of actions of paracetamol. These include inhibition of cylooxygenase
(COX) activity and prevention of prostaglandin (PG) production. More marks
were given for mention of a central COX 1 variant as the possible enzyme responsible for
paracetamol’s central versus peripheral effects. Knowledge of the central sites of action
was expected.

· Outline of toxicity. Candidates were expected to demonstrate knowledge of toxic doses,
conditions enhancing toxicity (alcohol intake, chronic use etc), and the mechanism of
hepatic toxicity and other organ toxicity (especially renal). A detailed list of clinical
features of toxicity was not required.

· Management of toxicity. Candidates performed well in this section with good knowledge
of timing, toxic doses, use of paracetamol levels and the nomogram to determine whether
N-acetylcysteine should be administered. Mechanism of action of NAC was expected.
Mention of monitoring (liver failure) and supportive therapy gained marks, but detailed
explanations were not required

Syllabus G2e2c
Stoelting 4th edition page 285
Rand Dale 5th page 244