Non-Opiod analgesic

Question 1

What is the alternative name for paracetamol?

Answer 1

Acetaminophen

Question 2

How does paracetamol work?

Answer 2

COX inhibitor that is highly selective for COX 2

Question 3

What effects does paracetamol inhibiting COX 1 and COX 2 have?

Answer 3

COX 1: Weakly selective for COX1 meaning it has less side effects than NSAIDS in terms of Ulceration, Renal Failure and Cardiovascular events
COX 2: Inhibition of COX 2 in the CNS causes:
- decrease prostaglandins in the thermoregulatory centre of hypothalamus = antipyretic
- Increase in pain threshold

Question 4

What affect do NSAIDs have the paracetamol is weaker at?

Answer 4

Anti-inflammatory effects

Question 5

What are the common indications of paracetamol?

Answer 5

1. Acute and chronic pain

2. Antipyretic: helps fever and symptoms eg. shivering

Question 6

What are the contra-indications of using paracetamol?

Answer 6

1. Hepatic Insufficiency e.g. excessive alcohol use (Reduce dose)
2. Underweight
3. Malnutrition
4. Severe hepatic impairment

Question 7

Why should you reduce the dose of paracetamol in people with hepatic insufficiency e.g. excessive alcohol use?

Answer 7

These people have an increase in NAPQI which causes hepatoceullar necrosis

Question 8

Why should paracetamol be avoided in those underweight, malnutrition and have hepatic impairment/

Answer 8

They have reduced glutathione stores therefore can not conjugate NAPQI leading to hepatocullar necrosis

Question 9

What are the common interactions with paracetamol

Answer 9

CYP450 inducers increase the rate of NAPQI production
Warfarin: paracetamol can increase the INR
Alcoholics

Question 10

What are the side effects of paracetamol

Answer 10

Usually only with overdose:

• Liver failure
• Hepatoceullar necrosis due to NAPQI build up during overdose

Question 11

What do you give to treat a paracetamol overdose?

Answer 11

• IV infusion acetylcysteine or glutathione