Toxicological Emergencies and Overdose Management Flashcards

Which antidote is used for acetaminophen (Tylenol) overdose to prevent hepatotoxicity?

Answer: N-acetylcysteine (NAC)

N-acetylcysteine replenishes glutathione stores and detoxifies NAPQI, the hepatotoxic acetaminophen metabolite, preventing liver failure when administered within the treatment window.

A patient is found unresponsive in a closed garage with altered mental status, severe headache, and cherry-red skin. What poisoning is most likely?

Answer: Carbon monoxide

Carbon monoxide binds hemoglobin with approximately 200 times the affinity of oxygen, causing tissue hypoxia; the classic cherry-red skin finding is caused by carboxyhemoglobin.

What is the treatment for hemodynamically unstable beta-blocker overdose refractory to initial resuscitation measures?

Answer: High-dose insulin euglycemic therapy and calcium

High-dose insulin euglycemic therapy improves cardiac contractility in beta-blocker overdose by providing an alternative metabolic substrate; calcium supports hemodynamics by partially overcoming blockade.

Which benzodiazepine reversal agent must be used with extreme caution in patients with chronic benzodiazepine use or seizure history?

Answer: Flumazenil

Flumazenil can precipitate severe withdrawal seizures in benzodiazepine-dependent patients and in those whose epilepsy is controlled by benzodiazepines, making it potentially life-threatening in these populations.

A patient ingested methanol and presents with visual disturbances and high anion-gap metabolic acidosis. What is the antidote?

Answer: Fomepizole (4-MP)

Fomepizole inhibits alcohol dehydrogenase, preventing conversion of methanol to formic acid, the toxic metabolite responsible for metabolic acidosis and optic nerve damage.

For severe calcium channel blocker overdose with cardiogenic shock unresponsive to vasopressors and calcium, which advanced therapy is recommended?

Answer: Intravenous lipid emulsion therapy

Intravenous lipid emulsion creates a 'lipid sink' in the bloodstream that sequesters lipophilic calcium channel blockers and may also provide cardiac energy substrate, improving hemodynamics in refractory toxicity.

A patient collapsed at a house fire presents with unconsciousness, severe lactic acidosis, and cardiovascular collapse from suspected cyanide poisoning. What is the preferred antidote?

Answer: Hydroxocobalamin (Cyanokit)

Hydroxocobalamin directly binds cyanide to form nontoxic cyanocobalamin and is the preferred agent in fire victims because, unlike nitrites, it does not worsen concurrent carbon monoxide-induced hypoxia.