Toxicology — toxidromes & antidotes

◆The 5 toxidromes

• •Anticholinergic: hot (fever), dry (no sweat), red (flushed), blind (mydriasis), mad (delirium), full bladder, bowel quiet → atropine, antihistamines, TCAs, antipsychotics, scopolamine
• •Cholinergic (DUMBELS or SLUDGE): Diarrhea, Urination, Miosis, Bradycardia, Emesis, Lacrimation, Salivation → organophosphates, sarin, pilocarpine; treat with atropine + pralidoxime
• •Sympathomimetic: HTN, tachycardia, mydriasis, DIAPHORESIS (vs anticholinergic which is dry), agitation → cocaine, methamphetamine; benzos, NOT β-blockers (unopposed α)
• •Opioid: miosis, respiratory depression, decreased mental status, decreased bowel sounds → heroin, fentanyl, oxycodone; naloxone
• •Sedative-hypnotic: CNS depression with normal vitals (or mild slowing) → benzos, barbs, ETOH, GHB; flumazenil (rarely used — seizure risk)

◆Antidote quick reference

• •Acetaminophen → N-acetylcysteine (NAC); follow Rumack-Matthew nomogram
• •Aspirin / salicylates → alkalinize urine (bicarbonate), hemodialysis if severe; supportive
• •Anticholinergic → physostigmine (cautious; not for TCAs)
• •Benzodiazepines → flumazenil (rarely used)
• •β-blocker / CCB → glucagon, high-dose insulin / euglycemia, calcium, lipid emulsion if refractory
• •Carbon monoxide → 100% O2 first; hyperbaric O2 for severe (loss of consciousness, pregnancy, cardiac involvement)
• •Cyanide → hydroxocobalamin (turns urine pink) OR amyl nitrite + sodium nitrite + sodium thiosulfate
• •Digoxin → digoxin-specific Fab (Digibind) for life-threatening toxicity (hyperK, arrhythmia)
• •Heparin → protamine sulfate
• •Iron → deferoxamine
• •Lead → succimer (PO, kids), EDTA or BAL (severe)
• •Methanol / ethylene glycol → fomepizole (or ethanol); hemodialysis
• •Methemoglobinemia → methylene blue
• •Opioid → naloxone
• •Organophosphate → atropine + pralidoxime
• •TCA → IV sodium bicarbonate (treats wide QRS)
• •Warfarin → vitamin K + 4-factor PCC (or FFP)

◆MUDPILES — anion gap acidosis

• •Methanol
• •Uremia
• •DKA (also AKA, starvation)
• •Propylene glycol
• •Iron, INH (isoniazid)
• •Lactic acidosis (sepsis, shock, metformin, cyanide, CO)
• •Ethylene glycol
• •Salicylates

◆Specific poisonings

• •TCA overdose: anticholinergic + wide QRS + seizures + hypotension → IV sodium bicarbonate (narrows QRS)
• •Salicylates: tinnitus + tachypnea + mixed primary respiratory alkalosis + AG metabolic acidosis; treat with alkalinization + dialysis if severe
• •Acetaminophen: phase 1 (0–24 hr) asymptomatic; phase 2 (24–72) RUQ pain + ↑ AST/ALT; phase 3 (72–96) hepatic failure; NAC before phase 3
• •CO poisoning: headache + nausea + confusion; cherry-red skin (rare); SpO2 reads NORMAL (falsely); diagnosis carboxyhemoglobin level; treat 100% O2 then HBO if severe
• •Methanol: visual changes ('snowstorm'), papilledema; metabolized to formic acid; fomepizole + dialysis
• •Ethylene glycol: CNS depression + AG acidosis + AKI from calcium oxalate crystals in urine; fomepizole + dialysis
• •Iron overdose (kids): initial GI symptoms → quiescent phase → shock + metabolic acidosis → hepatic necrosis; deferoxamine
• •Lead: abdominal pain + neuropathy + microcytic anemia + basophilic stippling; succimer in kids
• •Lithium: tremor + ataxia + confusion + seizures; hydrate + hemodialysis if severe (>4 mEq/L or severe symptoms)
• •Cocaine chest pain: AVOID β-blockers (unopposed α); benzos + nitrates first; phentolamine for refractory HTN

◆GI decontamination

• •Activated charcoal: within 1 hour of ingestion; not for caustics, hydrocarbons, metals (lead, iron, lithium), alcohols
• •Whole bowel irrigation: PEG; for sustained-release, packets (body packers), iron, lead
• •Gastric lavage: rarely used now
• •Forced emesis (syrup of ipecac): NO LONGER RECOMMENDED
• •Urinary alkalinization: salicylates, phenobarbital
• •Hemodialysis: METHANOL, ethylene glycol, salicylates (severe), lithium, theophylline, valproate

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