A 16-year-old female was rescued from a house fire and transported to the emergency department. She has no serious burns but is beginning to show signs of cyanide toxicity. She is given sodium nitrite as an antidote. How will sodium nitrite help in this case?

Correct Answer: D

Rationale: Cyanide toxicity from smoke inhalation blocks cytochrome oxidase. Sodium nitrite oxidizes hemoglobin iron to methemoglobin, which binds cyanide, reducing toxicity. Urine pH , chelation , inactivation , and enzyme regeneration (E) don't apply. This shifts cyanide away from mitochondria, aiding recovery.

Correct Answer: A

Rationale: The therapeutic serum range for phenobarbital (luminal) when used for anxiety is typically between 5-10 mcg/ml. This range is considered effective in controlling anxiety symptoms while minimizing the risk of toxicity. Higher serum levels (options B, C, D) may increase the risk of adverse effects such as sedation, respiratory depression, and overdose. Therefore, monitoring the serum levels of phenobarbital is essential to ensure the medication is at a therapeutic range for the intended treatment.

Correct Answer: C

Rationale: Lipid-soluble drugs distribute widely, crossing membranes like the blood-brain barrier easily, unlike water-soluble ones. The barrier blocks some, not all, drugs. High blood flow aids delivery, not hinders. Protein complexes limit free drug, not enable crossing. Lipid solubility enhances distribution, a pharmacokinetic truth.

Correct Answer: C

Rationale: The most common electrolyte finding resulting from the administration of furosemide (Lasix) is hypokalemia. Furosemide is a loop diuretic that works by blocking the reabsorption of sodium and chloride in the ascending loop of Henle in the kidneys. This results in increased excretion of water and electrolytes, including potassium. Hypokalemia can lead to various complications such as cardiac arrhythmias, muscle weakness, and fatigue. Therefore, patients receiving furosemide should be closely monitored for potassium levels, and supplementation may be necessary to prevent and treat hypokalemia.

Correct Answer: A

Rationale: Abruptly stopping lorazepam, a benzo, after 2 years triggers withdrawal-tachycardia, fever, cramps-due to GABA downregulation, per pharmacology. It's not safe-dependence forms. Opioid-like symptoms (pupils, constipation) don't fit. Calmness contradicts withdrawal. These signs reflect cessation risk, needing taper.