Pharmacology: analgesics - paracetamol

Question 1

PARACETAMOL
MOA
- What enzyme does it act on?
- Where about does it act? Impacts of this?

Answer 1

COX enzymes (unsure whether COX-1 or COX-2)
In the brain and spinal cord - avoids GI ADRs

Question 2

PARACETAMOL
Indications?

Answer 2

Managing mild-moderate pain
Anti pyretic

Question 3

PARACETAMOL
What happens when it is used with opioids?
Implications of this?

Answer 3

Has a synergistic effect
So, can use a lower dose of opioids to get the same effect –> less opioid related ADRs

Question 4

PARACETAMOL
- Where is it metabolised?
- Why is NAPQI toxic?
- What is the rate limiting step?

Answer 4

Liver
Denatures proteins –> liver damage
NAC conversion

Question 5

PARACETAMOL
What happens during an overdose?
Antidotes:
- In short term (<2 hours)
- In long term?

Answer 5

NAPQI build up, due to saturation of NAC pathway.

Short term: activated charcoal (binds to and prevents absorption of paracetamol)
Long term: administer NAC