A 78-year-old woman with ovarian cancer and pancreatitis is hospitalized for acute treatment of a massive pulmonary embolism. She is immediately given an intravenous dose of alteplase once the diagnosis of pulmonary embolism was made. Characteristics of this agent include which of the following?

Correct Answer: D

Rationale: Alteplase treats pulmonary embolism by dissolving clots. Success at clot resolution is correct-it converts plasminogen to plasmin, breaking fibrin. Option , free plasminogen, is less specific than its fibrin-bound action. Option , high antigenicity, and , low specificity, are false-alteplase is fibrin-specific and recombinant. Option (E), long half-life, isn't true. Its efficacy in clot lysis is key in this acute setting.

Correct Answer: C

Rationale: Phenobarbital, a barbiturate, binds to a distinct site on the GABA_A receptor, enhancing GABA's inhibitory effects by prolonging chloride channel opening. At high doses, it uniquely can directly open these channels without GABA, leading to profound CNS depression—useful in anesthesia or seizure control but risky due to overdose potential. Diazepam, a benzodiazepine, also acts on GABA_A receptors but only enhances GABA's effect, not independently opening channels, limiting its action to GABA availability. Ethanol affects GABA_A receptors indirectly and lacks this specific high-dose capability. Baclofen targets GABA_B receptors, influencing potassium channels, not chloride, and is unrelated to this mechanism. Dronabinol, a cannabinoid, has no GABA_A activity. Phenobarbital's ability to independently activate chloride channels at high doses distinguishes it, aligning with the scenario described and explaining its utility and risks in clinical settings.

Correct Answer: A

Rationale: Vancomycin is an antibiotic used to treat serious infections like MRSA, but it can cause significant adverse effects, including nephrotoxicity (kidney damage) and hypersensitivity reactions, such as rashes. The symptoms of an upper body rash and decreased urine output suggest a possible allergic reaction or renal impairment, both of which are potentially life-threatening if the drug continues to be administered. Holding the next dose prevents further exposure to the drug, which could exacerbate the reaction or damage, while notifying the physician ensures prompt medical evaluation and intervention. Obtaining an X-ray or urine specimen might provide additional data but doesn't address the immediate risk. Administering an antihistamine could mask symptoms without addressing the underlying issue, potentially delaying critical treatment. Thus, the priority is to stop the drug and seek physician guidance, making choice A the most appropriate action.

Correct Answer: D

Rationale: Oxymetazoline relieves congestion quickly but risks rebound if overused. 'Take this medication exactly as directed as there is no antidote if you overdose' emphasizes adherence to prevent misuse . Hand washing and not swallowing reduce risks. It acts fast, not over days . Choice D ensures safe use, critical for nasal decongestants.

Correct Answer: D

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