A 4-year-old boy is brought to the emergency department who was found drinking antifreeze while the father was working on their car. A primary component of antifreeze is ethylene glycol, an alcohol converted to toxic metabolites by the liver enzyme alcohol dehydrogenase. To prevent toxicity, the physician could administer ethanol, which would compete with ethylene glycol for the enzyme. In order to avoid administering ethanol to this patient, the physician could instead give which of the following drugs that would also prevent metabolism of ethylene glycol?

Correct Answer: C

Rationale: Ethylene glycol toxicity requires blocking alcohol dehydrogenase. Fomepizole inhibits this enzyme, preventing toxic metabolite formation. Bicarbonate treats acidosis, not metabolism. Disulfiram blocks aldehyde dehydrogenase. Furosemide and Methanol (E) are irrelevant. Fomepizole's specificity avoids ethanol's risks in a child, ensuring safe detoxification.

Correct Answer: B

Rationale: Pentazocine, a mixed opioid agonist-antagonist, acts as a kappa receptor agonist and a partial mu receptor agonist, providing analgesia in opioid-naive patients. However, in a heroin addict with high mu receptor tolerance, pentazocine's partial antagonism at mu receptors can displace full agonists like heroin, precipitating withdrawal symptoms—sweating, restlessness, and heightened pain perception. Tolerance to pentazocine itself wouldn't typically increase pain; it would reduce efficacy. Pentazocine is an effective analgesic in appropriate contexts, so ineffectiveness isn't the issue. Incorrect dosing might alter efficacy or toxicity but wouldn't specifically cause this withdrawal-like reaction. The patient's history of heroin use explains this response, as pentazocine's antagonist properties disrupt the opioid equilibrium, unmasking withdrawal in a dependent individual.

Correct Answer: C

Rationale: Tetracycline is a broad-spectrum antibiotic that can be rendered ineffective if taken with certain substances that interfere with its absorption. Dairy products, such as milk, contain calcium, which binds to tetracycline in the gastrointestinal tract, forming insoluble complexes that prevent the drug from being absorbed into the bloodstream. This interaction significantly reduces its therapeutic efficacy, making it crucial to instruct the client to avoid milk when taking the medication. Similarly, antacids (containing magnesium, aluminum, or calcium) and iron supplements also chelate tetracycline, decreasing its bioavailability, so choices A and B are incorrect and potentially harmful instructions. Reducing vitamin intake is unrelated to tetracycline's administration or efficacy, as vitamins do not typically interfere with its action unless specifically combined with minerals like iron or calcium. Therefore, the priority instruction is to avoid milk, ensuring the drug's effectiveness, which makes choice C the correct and most critical discharge teaching point.

Correct Answer: C

Rationale: Preventing seasonal allergies involves blocking histamine (antihistamines, choice A), reducing inflammation (corticosteroids, choice B), or stabilizing mast cells . Mast cell stabilizers (e.g., cromolyn) prevent histamine release, a proactive approach. Decongestants relieve symptoms, not prevent. Choice C highlights a preventive mechanism, key for allergy management education.

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.