toxicology Flashcards
what should not be given as an antidote to TCA OD
physostigmine
**can cause heart block or asystole
most toxic beta blocker
propanolol
high levels of beta blockers can block what channels
sodium
beta blocker OD sxs
lipophilic – cross CNS = seizures and coma
bradycardia
hypotension
pindolol OD sxs
hypertension
tachycardia
IV glucagon for beta blocker OD tx does what
inc cAMP
TCA toxicity: CA reuptake inhibition
tachycardic
hypertensive
TCA anticholinergic effects
sedation
coma
TCA alpha blockade effects
hypotension
TCA on cardiac myocytes
quinidine like blockade of cardiac fast sodium channels
QRS widening
slowed conduction and depressed cardiac contractility
inhibits VG K+ channels = QT prolongation
TCA toxicity management
sodium bicarb for quinidine like toxicity
NE - for hypotension
never give physostigmine
hyperthermia
myoclonic jerking
muscle rigidity
serotonin syndrome
tx serotonin syndrome
cyproheptadine
5HT2 antagonist
nalmefene
opioid OD tx
naloxone
opioid OD tx
theophyline acute intoxication
vomiting/hematemesis
coarse tremor, anxiety
tachycardia
metabolic acidosis: hypokalemia, low PO4, high Ca2+, high glucose
SEVERE - seizures (most common in acute), hypotension, arrhythmias
theophylline chronic intoxication
**dysrhythmias (more common with chronic)
minimal GI sxs, less likely to have seizures
theophylline OD tx
propranolol, esmolol
benzo/barb for seizures
sulfonylurea/meglitinides OD tx
IV dextrose
octreotide
hyperthermia
lead pipe rigidity
metabolic acidosis
confusion
neuroleptic malignant syndrome
neuroleptic malignant syndrome tx
physical cooling tx
benzo for agitation
dantroline, bromocriptine, amantadine - unknown effectiveness
formic acid
toxicity of methanol poisoning
causes acidosis, retinal damage, and blindness
methanol directly –> CNS depression
fomepizole
compeitiive inhib of alcohol dehdyrogenase = dec production of formic acid
ethanol use in methanol toxicity
competitive inhibitor of alcohol dehdyrogenase = dec production of formic acid
ethylene glycol toxicity
metabolized to aldehdyes and oxalate:
acidosis
renal damage
GI sxs
Ca2+ oxalate crystals
ethylene glycol toxicity tx
fomepizole
ethanol
if acidotic: sodium bicarb
same as methanol poisoning
pralidoxime
splits phosphate enzyme bond as the pesticide has phosphorylated AchE
postively charged - doesn’t cross BBB, no reversal of CNS effects
carbamates
inhibit AchE by carbamoylation of active site
carbamate OD tx
atropine
warfarin OD tx
vitamin K - doesn’t restore for 6 or more hours
initally give fresh frozen plasma or whole blood
Cyanide toxicity
binds Fe3+ strongly - prevents from serving as electron acceptor
CN OD tx: antidote kit
provide pool of ferric iron to compete with CN
cyanide antidote kit:
- amyl nitrite pearls: inhale
- sodium nitrite: IV
- sodium thiosulfate (donate sulfur to form thiocyanate via rhodanese)
forms methemoglobin –> cyanmethemoglobin and cyochrome oxidase is restored
give methylene blue
CN OD tx: cyanokit
hydroxocobalamin (B12 precursor)
–> reacts with CN to form cyancobalamin
**no methemoglobin produced
lead OD tx
seizures - diazepam
cerebral edema - mannitol, dexamethasone
chelation
arsenic poisoning
pyruvate dehydrogenase complex sensitive to trivalent arsenicals
pentavalent: uncouple oxidative phosphorylation
hemolysis via depletion of glutathione
arsenic OD tx
ACUTE - chelate: dimercaprol (w/in 24 hours), unithiol
CHRONIC - succimer or unithiol (after 24 hours)
supportive: IV hydration, osmotic diuresis with mannitol - maintain urine output
acute mercury poisoning tx
unithiol
IM dimercaprol
oral succimer
chronic mercury poisoning tx
unithiol and succimer
dimercaprol may redistribute mercury to CNS - NOT USED
vomiting
GI bleedings
lethargy
gray cyanosis
iron toxicity
iron chelator
deferoxamine
