Toxicology USMLE Step 1 Practice Question
A 27-year-old man presents to the emergency department with severe muscle cramps, abdominal rigidity, diaphoresis, and hypertension (BP 168/102 mmHg, HR 118/min) after sustaining a bite while cleaning a woodpile 4 hours ago. Temperature is 37.2°C and SpO2 is 98% on room air. Physical examination reveals no fang marks or local swelling. Serum creatinine is normal. Which of the following best describes the mechanism of the toxin involved?
Answer choices
- AInhibits aldehyde dehydrogenase
- BCauses massive release of neurotransmitters from presynaptic terminalsCorrect answer
- CBlocks presynaptic release of acetylcholine
- DOxidizes hemoglobin iron to Fe3+
- EInhibits cytochrome oxidase
- FNicotinic receptor blockade
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.