A patient was admitted to the emergency department with a pulse oximeter reading of 85% after a successful prehospital resuscitation from cardiac arrest due to an asthma attack. What is the most important initial drug to administer as ordered?

Correct Answer: D

Rationale: Oxygen is the most important initial intervention for a patient with a low pulse oximeter reading (85%) to correct hypoxia and prevent further complications. While epinephrine (A) and albuterol (C) are used to treat asthma, oxygen is the priority to address the immediate hypoxia. Sodium bicarbonate (B) is not indicated unless there is severe metabolic acidosis.

Correct Answer: A

Rationale: Aplastic anemia is the most severe form of bone marrow toxicity, characterized by pancytopenia and bone marrow failure. It can be life-threatening and requires immediate intervention. Thrombocytosis, leukocytosis, and granulocytosis are not typically associated with drug-induced bone marrow toxicity.

Correct Answer: D

Rationale: Elimination half-life measures how quickly a drug is cleared from plasma. Naloxone's half-life is about 1-2 hours, used for opioid reversal. Morphine's is 2-4 hours, reflecting its duration as an analgesic. Methadone's is long, 15-60 hours, suiting addiction maintenance. Fentanyl's is 2-4 hours, typical for anesthesia. Remifentanil, an ultra-short-acting opioid, has a half-life of 3-10 minutes due to rapid esterase metabolism, making it ideal for procedures needing quick offset. Its brevity contrasts with others, ensuring minimal residual effects, a key advantage in critical care settings where rapid recovery is essential.

Correct Answer: C

Rationale: Adrenaline, or epinephrine, is a catecholamine that exerts its effects through adrenergic receptors, which are G-protein-coupled, making its action via G-proteins a true statement. Alpha receptor stimulation typically inhibits adenylate cyclase, reducing cyclic AMP (cAMP) production, which aligns with its known pharmacology and is also true. Adrenaline can indeed be administered via inhalation (e.g., for asthma), orally (though less common), and parenterally (e.g., intramuscularly in anaphylaxis), confirming this as true. However, adrenaline does have active metabolites, such as metanephrine and normetanephrine, produced via catechol-O-methyltransferase (COMT) metabolism, making the statement about having no active metabolites false. In cardiac arrest, it facilitates CPR by causing peripheral vasoconstriction, increasing coronary perfusion pressure, which is true. The false statement here is about the absence of active metabolites, as adrenaline's breakdown products retain some activity, a key point in understanding its pharmacokinetics and duration of effect.

Correct Answer: B

Rationale: High-dose androgen therapy in females is occasionally used as a palliative treatment for certain breast cancers, particularly hormone-sensitive types, where it suppresses estrogen-driven tumor growth, offering symptom relief in advanced stages. Using androgens for athletic performance enhancement, while possible due to their anabolic effects, isn't a clinical indication and is illegal in regulated settings. Brain cancer lacks evidence supporting androgen use, as it doesn't target neurological malignancies. Sexual reassignment involves testosterone for masculinization, but high doses in a clinical context typically align with cancer care, not transition protocols. The breast cancer rationale reflects a recognized, albeit niche, therapeutic use, leveraging androgens' anti-estrogenic properties to slow disease progression, making it the most defensible clinical justification in this scenario.