FPGEE Toxicology 5 — Questions and Answers
Question 1: Which statement best describes the concept of bioactivation in toxicology?
- The parent compound is always more toxic than its metabolite
- Phase I metabolism converts a non-toxic compound to a reactive toxic metabolite (Correct answer)
- Phase II conjugation always detoxifies compounds before excretion
- Bioactivation only occurs in the kidney
Correct answer: Phase I metabolism converts a non-toxic compound to a reactive toxic metabolite
Bioactivation refers to Phase I metabolic conversion of a relatively non-toxic parent compound into a reactive, more toxic metabolite, as occurs with acetaminophen to NAPQI via CYP2E1.
Question 2: A patient presents with anticholinergic toxidrome. Which agent is used to treat severe central anticholinergic toxicity with seizures or coma?
- Atropine
- Physostigmine (Correct answer)
- Pyridostigmine
- Naloxone
Correct answer: Physostigmine
Physostigmine is a tertiary amine cholinesterase inhibitor that crosses the blood-brain barrier and reverses central and peripheral anticholinergic effects.
Question 3: Whole bowel irrigation with polyethylene glycol is MOST appropriate for which of the following ingestions?
- Acetaminophen taken 1 hour ago
- Sustained-release verapamil taken 3 hours ago (Correct answer)
- Ethanol ingestion
- Organophosphate dermal exposure
Correct answer: Sustained-release verapamil taken 3 hours ago
Whole bowel irrigation is indicated for sustained- or extended-release formulations because activated charcoal and gastric lavage are less effective at removing these drug forms from the gut.
Question 4: The TESS (Toxic Exposure Surveillance System) primary purpose in pharmacovigilance is to:
- Provide individualized antidote dosing recommendations
- Collect and analyze data on poisoning exposures to identify trends and guide prevention (Correct answer)
- Approve new antidotes for market use
- Set legal exposure limits for occupational toxins
Correct answer: Collect and analyze data on poisoning exposures to identify trends and guide prevention
TESS (now part of NPDS) aggregates poison control center case data to monitor poisoning trends, identify emerging threats, and guide public health policy.
Question 5: Which of the following correctly describes the hepatotoxicity mechanism of acetaminophen overdose?
- Direct inhibition of hepatic protein synthesis by the parent compound
- CYP2E1 converts APAP to NAPQI, which depletes glutathione and binds cellular proteins causing necrosis (Correct answer)
- Accumulation of acetaminophen glucuronide conjugate causing bile duct obstruction
- Immune-mediated destruction of hepatocytes triggered by sulfate conjugates
Correct answer: CYP2E1 converts APAP to NAPQI, which depletes glutathione and binds cellular proteins causing necrosis
CYP2E1 oxidizes acetaminophen to NAPQI; when glutathione stores are depleted, NAPQI binds covalently to hepatocyte proteins causing centrilobular necrosis.
Question 6: A warehouse worker presents with acute pulmonary edema after inhaling a gas with a pungent, bleach-like odor following mixing of household cleaners. Which gas is the most likely cause?
- Carbon monoxide
- Chlorine gas (Correct answer)
- Hydrogen cyanide
- Ammonia
Correct answer: Chlorine gas
Mixing bleach (sodium hypochlorite) with acids (e.g., vinegar) generates chlorine gas, which causes pulmonary edema via hydrolysis to hydrochloric and hypochlorous acid in the airways.
Question 7: In the context of the FPGEE, which route of exposure is generally associated with the fastest onset of systemic toxicity?
- Oral ingestion
- Dermal absorption
- Intravenous injection (Correct answer)
- Inhalation
Correct answer: Intravenous injection
Intravenous injection delivers drug directly into systemic circulation with immediate distribution, bypassing absorption barriers and first-pass metabolism, resulting in the fastest onset.
FPGEE Toxicology 5
Which statement best describes the concept of bioactivation in toxicology?