Toxicology Flashcards
Charcoal, optimal ratio of charcoal: toxin poorly bound (4)
10:1 small molecules (lithium, iron, cyanide), hydrocarbons, alcohol, acid/alkalai
Antidotes
BAL, DMS (3)
FFP / Vit K / PCCs
Calcium, glucagon, gluc/insulin, intralipids
Sodium nitrite, sodium thiosulfate, hydroxycobalamine
Arsenic, mercury, lead (add EDTA)
warfarin
calcium channel blocker
cyanide
Antidote 2
Alkaline diuresis, hemodialysis (2)
Bicarbonate, ethanol, dialysis, 4-MP (2)
Glucagon, intralipids
Protamine
Aspirin, barbiturates
ethylene glycol, methanol
beta blocker
heparin
Antidote 3
pyridoxine (a.k.a.) sodium bicarbonate, intra-lipids methylene blue (2) calcium, magnesium
INH; vitamin B6
TCA
nitrates, met hemoglobin EMEA
hydrofluoric acid
Dereroxamine
atropine, 2-PAM
octreotide and two other things
Physostigmine
Iron
organophosphate (cholinergic and central nicotinic)
Oral hypoglycemic along with glucagon and glucose
anticholinergics if severe (but not for TCA)
Anion gap formula
MUDPILES pneumonic
(Na) - (Cl + CO2), normal < 12
MUDPILES pneumonic - causes of anion gap metabolic acidosis
M Methanol, metformin, massive ingestions
U Uremia
D DKA
P Paraldehyde
I Iron, INH
L Lactic acidosis (CO, CN)
E Ethylene glycol
S Salicylates
Increased osmolar gap (3)
false positives
amphetamines
TCAs
PCP
Alcohol toxic (acetone, isopropanol, methanol, ethylene glycol) or not, mannitol, ketoacidosis
Osmolar gap = Actual - Calculated (nl 285-295) = 2 Na + BUN/18 + Glu/18 + EtOH/4.6
amphetamines: Sudafed
TCAs: cyclobenzaprine, carbamazepine, diphenhydramine, phenothiazines
PCP: ketamine, dextromethorphan
Drug levels helpful when predictive of subsequent toxicity or guides specific therapy (5)
Iron, lithium, acetaminophen, aspirin, digoxin
Anticholinergic toxidrome
classic examples (5)
key difference with similar toxidrome:
“Hot as hell, blind as a bat, dry as a bone, red as a beet, mad as a hatter”; Dry, flushed skin, dry mucus membranes, mydriasis, decreased bowel sounds, urinary retention
examples: atropine, antihistamine, Jimsonweed, Parkinson’s medications (L dopa), , phenothiazines, TCAs
key difference: sympathomimetic has diaphoresis rather than dry skin
Anticholinergic treatments of
Classic toxidrome (Mad as hatter…..) normal and if severe
wide complex tachycardia
torsade de pointes
Benzodiazepines, Physostigmine if very severe and no TCA
bicarbonate
magnesium, overdrive pacing
Sympathomimetic treatment
Mimic of opiod OD
Benzodiazepine
Clonidine
Cholinergic toxidrome
Key examples (2) and mechanism
muscarinic effects mnemonic
Organophosphate insecticides, chemical warfare agents, some mushrooms
inhibit cholinesterases -> increases acetylcholine
SLUDGEM- Bs
salivation, lacrimation, urination, diarrhea, GI distress, emesis, miosis
Bs: –Bradycardia, Bronchospasm, Bronchorrhea
Cholinergic toxidrome
Nicotinic effects (3)
tx
Muscle weakness, fasciculations, respiratory failure
atropine, 2-PAM (Pralidoxime)
Withdrawal syndromes
common treatment for alcohol, barbiturates, benzodiazepines, cocaine, clonidine
Benzodiazepines, clonidine
Tylenol tox
mechanism
stages
Saturated normal metabolism shifts to minor pathway cytochrome P450 -> when glutathione depletes, toxic free radical metabolits NAPQI accumulates and damages hepatocytes
Tylenol tox
toxic ingestion mg/kg; grams average adult
4 hour toxic level
Mech
Use > 24 hours presentation?
140 mg per kilo, 7 to 10 g
140 at four hours
provides necessary cofactor to metabolize NAPQI
>24 hours: yes
Wernicke’s encephalopathy sx (4)
Korsakoff’s psychosis sx (2)
Wernicke’s encephalopathy: Oculomotor crisis
CN VI palsy (lateral rectus), nystagmus, ataxia, global confusion
Korsakoff’s psychosis: Retrograde amnesia, confabulation
Methanol
metabolic presentation
Pathogenesis
Key symptom
Other sx (3)
Anion gap metabolic acidosis with increased osmolar gap
alcohol dehydrogenase creates formaldehyde and formic acid
Visual changes/blindness
Seizures, resp failure, pancreatitis
Methanol
Antidote (2)
Adjuncts if refractory to above (2)
Fomepizole (4MP) -> prevents conversion leading to renal excretion
Ethanol (preferentially metabolized)
Dialysis, bicarbonate
Ethylene glycol
toxidrome key:
mechanism of toxicity
toxidrome key: altered mental status + elevated anion and osmolar gap acidosis
mechanism of toxicity: toxic metabolites oxalic acid and glycolic acid
other findings: renal failure, hematuria, hypocalcemia; calcium oxalate crystals in the urine
Ethylene glycol
treatment similar to other toxic alcohols unique treatment (2)
supportive treatment
treatment similar to other toxic alcohols: fomepizole (4MP)
unique treatment: pyridoxine, thiamine
supportive treatment: bicarbonate four acidosis, dialysis for severe acidosis and/or high blood levels
Isopropyl alcohol
toxidrome compared to other toxic alcohols
symptoms (4)
treatment (2) and how differenent from other toxic alcohols
toxidrome compared to other toxic alcohols: ketosis /elevated osmolar gap WITHOUT anion gap or acidosis
symptoms: altered mental status plus hemorrhagic gastritis, pulmonary edema, hypotension
treatment: supportive care +/- hemodialysis
Tx difference: NO role for fomepizole or EtOH since metabolite less toxic than the toxin
Cocaine
similar toxidromes with key difference
Similar to anticholinergic toxidrome
cocaine: diaphoresis, dilated pupils
anticholinergic: skin dry instead of sweaty
cholinergic: pupils pinpoint instead of dilated
Toxicology pearls
bradycardia pneumonic (6)
tachycardia pneumonic (4)
Bradycardia
P Propranolol (beta blockers), poppies (opioids)
A Anticholinesterase drugs
C Clonidine, calcium channel blockers
E Ethanol, other alcohols
D Digoxin
Tachycardia
F Freebase (cocaine)
A Anticholinergics, antihistamines, amphetamines
S Sympathomimetics, solvent abuse
T Theophylline