acetaminophen OD Flashcards
IV acetaminophen
ofirmev
lab indicator of acetaminophen toxicity
elevated ALT values
problem of opioids+acetaminophen
addicitve drug+ dose dependant toxin = bad trouble
2011 upper dose limit with opioids
325/tablet
reduced daily dose of APAP
3 gm/day in adult
dosage than can cause liver damage
4gm/2 hr (adult)
absorption time of APAP in theraputic dose
1 hr
absorption time of APAP in OD
4 hr
type of metabolism in APAP
1st order
elimination t 1/2 in normal dose of APAP
2.5 hours
anti-inflamatory effect of APAP
weak
advantages of APAP
no effect on neutrophil activation, not a gastric irritant, no effect on bleeding
mechanism of liver metabolism of APAP
90% glucuranidation or sulfation then elminated by kidneys
toxic metabolite of APAP
NAPQI
enxyme converting APAP to NAPQI
CYP P450
detoxes NAPQI endogenously
glutathione
mech of toxicity in APAP OD
normal pathways overwhelmed NAPQI built up glutathione depleted NAPQi binds to proteins, forming adducts ROS damages hepatocytes
drug that induces more CYP2E1 and accelerates APAP toxicity
EtOH
reason alchoholics are susceptiple to APAP toxicity
loss of glutithione
APAP toxic dose in child
150 mg/kg
APAP toxic dose in adult
10g
theraputic dose in kids
75 mg/kg
time of phase 1 APAP toxicity
.5 to 24 hours
time of phase 2 APAP toxicity
24-72 hours
time of phase 3 APAP toxicity
72-96 hours
time of phase 4 APAP toxicity
4-14 days
sx of Phase 1 APAP toxicity
N/v, elevated liver enzymes (possibly asymptomatic)
sx of Phase 2 APAP toxicity
RUQ abdom tenderness, elevated ALT/AST, clotting factors impaired
sx of Phase 3 APAP toxicity
jaundice, coagulation defects, hepatic encephalopathy, renal failure, death
sx of Phase 4 APAP toxicity
death, or resolution of liver failure
treatment for acute APAP toxicity
N-acetylcysteine (NAC)
MOA of N-acetylcysteine (NAC)
glutathione substitute - detoxes NAPQI
risks of N-acetylcysteine (NAC) IV
possible anaphylaxis
how much higher is the risk of liver failure if treatment with MAC is over 10 hours
4x
adverse effects of N-acetylcysteine (NAC)
lots of vomiting, anaphylaxis with IV
prevention of anaphylaxis in IV N-acetylcysteine (NAC)
preload with antihistamines and steroids
indications of treatment with N-acetylcysteine (NAC)
hx of toxic injestion
right of line in rumack nomigram
elevated ALT
axes of Rumack nomogram
X - Serum APAP
Y - hours from OD
approx APAP serum level to treat after 4 hours
> 200
limitations of Rumack
applies only to acute ingestions not as valid in Kids limited to 24 hours does not handle extended release pills, or EtOH not for chronic OD
time frame to induce vomiting in APAP OD
<2 hours
indication for liver transplant referral
encephalopathy, uncontrolled liver enzymes
