Paracetamol OD Flashcards
define paracetamol OD
12g = 24 tablets or 150mg/Kg in adults may be fatal
if weight >110kg use weight as 110kg to avoid underestimation
if malnourished 75mg/Kg can kill
symptoms of paracetamol OD
0-24hr = asymoptomatic or mild nausea, vom, lethargy, malaise
24-72hr = RUQ pain, vomiting
later - jaundice and confusion (encephalopathy) from liver damage (the main danger) +- AKI
signs of paracetamol OD
0-24hr = none
24-72hr = liver enlargement and tenderness
>72hr = jaundice, coagulopathy, hypoglycaemiam renal angle pain
aetiology of paracetamol OD
12g = 24 tablets or 150mg/Kg in adults may be fatal
if weight >110kg use weight as 110kg to avoid underestimation
if malnourished 75mg/Kg can kill
RF for paracetamol OD
chronic alcohol abusers
on enzyme inducing drugs - increase cytochrome p450 activity eg anticonvulsants or anti-TB
malnourishment
anorexia nervosa
HIV - more suseptible to the toxic effects
commonly associated with ingestion of other substances eg alcohol
epidemiology of paracetamol OD
most common intentional drug OD in UK
70000/yr
female more
100 deaths/yr - reduced with legislation
pathology of paracetamol OD
at therapeutic levels metabolised in liver by conjugation with glucuronate or sulphate and excreted in kidneys
<7% metabolised bt cytochrome p450 mixed function oxidases to toxic, highly reactive intermediate - NAPQI - inactivated by conjugation with glutathione
at toxic levels - conjugation and glutathione stores are overwhelmed = NAPQI induced oxidative damage and acute liver necrosis
investigations for paracetamol OD
paracetamol levels 4hr post ingestion - absorbed rapidly so peak levels within 4hrs
assess need to treat based on normogram
FBC
UE
glucose
LFT
clotting screen
lactate
ABG - for degree of acidosis
