Chemistry 11 (Poisons) Flashcards
95% of lead ingested is distributed in
RBCs and bone
lead is toxic by ___ and ___
inhibiting enzymes with sulfhydrul group
toxic to mitochondria directly
in kidneys, lead is toxic to
renal tubular cells
lead inhibition of ___ in RBC precursors leads to buildup of ____
gamma-ALA-dehydratase and ferrochetalase
free etythrocytes protoporphyrin (FEP)
___ and ___ are increased in both lead poisoning and iron def
FEP and ZPP
lead inhibition of ___ causes increaqsed osmotic fragility of RBCs
sodium channel ATPases
2 ways iron def enhances lead tox
last step of heme synth (iron into protoporphyrin) inhibited by iron def
increased intestinal absorption of iron and lead
end stage renal manifestations of lead tox
aminoaciduria
glycosuria
phasphaturia
syndrome that looks like end stage lead tox on kidneys
Fanconi renal syndrome
classic peripheral neurpathic symptom of lead tox
bilatera wrist drop
preferred method for testing lead
atomic absorption spectrophotometry
blood level of lead that needs to be detected
10 microgram/dL
lead chelating agenst
dimercaprol (BAL), CaNa-EDTA, D-penicillamine, succimer
blood lead level indication for inpatient tx
> 70
CO has greater affinity for ___ than ____
Fetal than HbA
2 ways CO is toxic
directly to intracellular oxidative mechanisms
increased production of NP
CO levels in non-smoker and smoker
0.4-2%
2-6%
CO can be produced endogenously by
breakdown of heme
hepatic metabolism of dichloromethane (methylene chloride) in paint and removers
method that may give falsely reassuring O2 sat in CO poisoning
pulse-ox
In pt with CO poisoning from fire, should also test for
cyanide
T1/2 of CO on room air and 100% O2
6hrs, 1hr
Rumack-Matthew nomogram is for
acetaminophen
timing of initial blood sample for tylenol
4hrs post ingestion
tx for tylenol tox
n-acetylcysteine
any single tylenol level of ___ is high risk
> 5
potentially toxic tylenol dose
> 150mg/kg
non-toxic tylenol metabolite made by
conjugation with glucuronide or sulfate
toxic tylenol metabolite made by
P450 system
N-acetyl-p-benzoquinoneimine(NAPQI)
how is NAPQI normally detoxified
by glutathione
histology of tylenol tox
centrilobular necrosis with periportal sparing
mechanism of cyanide tox
inihibits cytochrome a3 to uncouple electron transport leading to severe anion gap lactic acidosis
test for cyanide
thiocyanate
other lab abnormality clue to cyanide tox
increased glucose
decreased arterial venous O2 gap suggests
cyanide
Tx for cyanide
- sodium nitrite or amyl nitrite - forms methemoglobin which binds cyanide
- then sodium thiosulfate combines with it to form thiocyanate which is non-toxic
classic A/B disorder in aspirin tox
combined met acidosis and resp alkalosis
mechanism for resp alkalosis in aspirin
stimulates resp center in medulla
mortality of aspirin best correlated with
6hr plasma level >130mg/dL
most toxic form of arsenic
Arsine gas
ARF with death in 24-48hr
fate of ingested arsenic
excreted in urine, skin, hair, nails
toxicity of arsenic via
inihibition of oxidating productiono f ATP
symptoms of arsenic
n/v, bloody diarrhea, abd pain, cytopenias, basophilic stippling, peripheral neuropathy, nephropathy, skin hyperpigmentation and hyperkeratosis, “mees lines” in nails
basophilic stippling seen in
lead, arsenic
most reliable test for arsenic
quantitative 24hr urine
urine arsenic falsely increased by
recent seafood ingestion
toxic effects of tricyclics due to
anticholinergic effects (amytryptiline strongest)
2 main adverse effects of tricyclics
CNS tox and widened QRS complex
organophosphate and carbamate toxic by
inhibiting acetylcholinesterase
“mescarinic toxidrome” =
organophosphate cholinergic effects
test for organophosphate
erythrocytes cholinesterase activity or metabolites in urine
elemental vs organic mercury in GI tract
elemental not absorbed via GI, organic is
acute elemental mercury tox
resp distress and renal failure
chronic elemental mercury tox
acrodynia or erethrism
Acrydynia (Feer syndrome)
sweating, hemodynamic instability, desquamative erythematous rash on palms and soles, increased urinare catecholamines (like pheochromocytoma)
erethism
personality change, fine motor disturbances
organic mercury tox
visual field constriction, peripheral neuropathy, tremor, hearing lsos
tests for mercury
elemental: 24 hr urinary
organic: while blood or hair
