paracetamol

Question 1

what is paracetamol used for?

Answer 1

mild pain first line of WHO ladder, weak analagesia

can be given as an anti-pyrexial to reduce fever

Question 2

MOA

Answer 2

works on COX1 , acts as a cox1 inhibitor therefore reducing prostaglandin synthesis therefore no risk of GI ulceration
works by increasing pain threshold and reducing PGE2 conc in thermoregulatory regions in hypothalamus

Question 3

SE

Answer 3

very few
does not cause peptic ulceration
in overdose can cause liver failure as of hepatocellular necrosis

Question 4

CI

Answer 4

those at risk of liver toxicity such as alcoholics, previous overdose, reduce gluthionine production e.g. in low body mass, malnutrition or hepatic impairment

Question 5

what can be given to those who have taken an overdose

Answer 5

acetyl cysteine (gluthionine precursor) to treat toxicity

Question 6

DI

Answer 6

be cautious of those on co-codamol check prescriptions!

metabolised by p450 be cautious of p450 inducers- carbamazepine, phenytoin to avoid liver toxicity by increasing NAPQI production

Question 7

metabolism mechanism

Answer 7

paracetamol metabolised in liver by enzyme cytochrome p450, into NAPQI a toxic metabolite, conjugated with gluthionine into cysteine and mercupatine acid and excreted into the urine.