A 35-year-old man with HIV disease presents to the emergency department with a severe headache and fever for the past 6 h. His fever was measured to be 103°F. He also has chills, stiff neck, and nausea. He is diagnosed with Cryptococcus neoformans meningitis and started on amphotericin B. What is the mechanism of action of amphotericin B?

Correct Answer: A

Rationale: The correct answer is A) Binds ergosterol. Amphotericin B works by binding to ergosterol, a key component of the fungal cell membrane, forming pores that disrupt membrane integrity and ultimately leading to cell death. This mechanism is specific to fungal cells, making amphotericin B an effective antifungal agent. Option B) Inhibits cell wall synthesis is incorrect because this is the mechanism of action of drugs like echinocandins, not amphotericin B. Option C) Inhibits DNA synthesis is incorrect as this is the mechanism of action of antifungal drugs like flucytosine. Option D) Inhibits ergosterol synthesis is incorrect as amphotericin B does not inhibit ergosterol synthesis but rather binds to ergosterol already present in the fungal cell membrane. Understanding the mechanism of action of chemotherapy drugs is crucial for nurses and healthcare professionals to provide safe and effective care to patients receiving these medications. In the context of the NCLEX exam, knowledge of drug mechanisms helps in selecting the most appropriate treatment options and understanding potential side effects and interactions.

Correct Answer: C

Rationale: In this scenario, the correct answer is C) Cytarabine. Cytarabine is a chemotherapy drug that interferes with DNA synthesis after its metabolite is incorporated into the growing DNA strand. This drug is classified as an antimetabolite and acts by inhibiting DNA polymerase, thereby disrupting DNA replication in rapidly dividing cells like cancer cells. Now, let's discuss why the other options are incorrect: A) 5-Fluorouracil: This drug works by inhibiting thymidylate synthase, which is involved in DNA synthesis, but it does not interfere with DNA synthesis after its metabolite is incorporated into the DNA strand. B) Cyclophosphamide: Cyclophosphamide is an alkylating agent that works by cross-linking DNA strands, leading to DNA damage, rather than interfering with DNA synthesis as described in the question. D) Methotrexate: Methotrexate is a folate antagonist that inhibits dihydrofolate reductase, thereby disrupting the synthesis of tetrahydrofolate, which is essential for purine and pyrimidine synthesis. However, it does not interfere with DNA synthesis after its metabolite is incorporated into the DNA strand. Educational Context: Understanding the mechanisms of action of chemotherapy drugs is crucial for nurses and healthcare providers caring for patients undergoing cancer treatment. Knowledge of how these drugs work helps in administering them safely, monitoring for side effects, and educating patients about potential adverse reactions. In the case of cytotoxic drugs like Cytarabine, knowing that it interferes with DNA synthesis can aid in predicting and managing side effects related to bone marrow suppression and gastrointestinal toxicity.

Correct Answer: B

Rationale: In this scenario, the correct answer is B) 6-Mercaptopurine. Allopurinol inhibits xanthine oxidase, which is an enzyme responsible for metabolizing 6-Mercaptopurine. When allopurinol is co-administered with 6-Mercaptopurine, it can lead to increased levels of 6-Mercaptopurine in the body, causing toxicity and adverse effects like GI upset and elevated liver enzymes, as seen in the patient. Option A) 5-Fluorouracil is not affected by allopurinol and can be safely used in patients taking allopurinol. Option C) 6-Thioguanine is also metabolized by different pathways and is not significantly impacted by allopurinol. Option D) Bleomycin is not metabolized by xanthine oxidase and therefore not contraindicated in patients taking allopurinol. In an educational context, understanding drug interactions is crucial in ensuring safe and effective patient care. This case highlights the importance of considering potential interactions between medications, especially in patients with comorbidities. Health care professionals need to be aware of how certain drugs can affect each other's metabolism and efficacy to prevent adverse outcomes.

Correct Answer: A

Rationale: Infliximab is a monoclonal antibody that targets and blocks tumor necrosis factor-alpha (TNF-α), which is a key inflammatory cytokine involved in rheumatoid arthritis pathogenesis. The correct answer is A) Anti-TNF antibody. By binding to TNF-α, infliximab reduces inflammation and joint damage in rheumatoid arthritis. Option B) Directly binds to TNF receptor is incorrect because infliximab binds to TNF-α, not its receptor. Option C) Inhibits cyclooxygenase is incorrect as cyclooxygenase inhibitors are typically nonsteroidal anti-inflammatory drugs (NSAIDs), not biologics like infliximab. Option D) Inhibits dihydrofolate reductase is incorrect as this mechanism is related to folate antagonists like methotrexate, not infliximab. Understanding the mechanism of action of chemotherapy drugs like infliximab is crucial for nurses and healthcare professionals to provide safe and effective care to patients with rheumatoid arthritis. Knowing how infliximab works helps in monitoring for side effects, assessing treatment effectiveness, and educating patients on their medication regimen.

Correct Answer: B

Rationale: In this scenario, the correct answer is B) Complete blood counts. When a patient is prescribed clozapine, regular monitoring of complete blood counts is essential due to the risk of agranulocytosis, a potentially life-threatening condition characterized by a severe decrease in white blood cell count. Early detection through routine blood monitoring can prevent serious complications. Option A) BUN/Creatinine is incorrect because clozapine does not typically have a direct impact on renal function. Monitoring kidney function is more relevant for other medications or conditions that affect the kidneys. Option C) Liver function tests are not the primary concern with clozapine use. While liver function tests may be monitored for some medications, it is not the key parameter for patients on clozapine. Option D) Pulmonary function tests are not typically necessary for monitoring patients on clozapine. Clozapine is not known to have significant effects on pulmonary function. In an educational context, understanding the rationale behind monitoring parameters for specific medications is crucial for safe and effective patient care. Students and healthcare professionals need to recognize the importance of tailored monitoring based on the pharmacological properties and potential side effects of each drug. This case highlights the significance of regular complete blood counts in patients on clozapine to promptly identify and manage adverse events.