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Drug Interactions and Adverse Effects Flashcards

7 cards from real NAPLEX QBANK practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. A patient stabilized on an SSRI is prescribed tramadol for acute pain. Which serious adverse reaction is most likely to result from this combination?

    Answer: Serotonin syndrome

    Both SSRIs and tramadol increase serotonergic activity, and their concurrent use can precipitate serotonin syndrome characterized by hyperthermia, autonomic instability, and neuromuscular abnormalities.

  2. A patient stabilized on warfarin begins amiodarone therapy for atrial fibrillation. What dose adjustment to warfarin is typically required?

    Answer: Decrease warfarin dose by 30–50%

    Amiodarone inhibits CYP2C9, the primary enzyme responsible for metabolizing warfarin's active S-enantiomer, resulting in elevated INR and requiring a 30–50% reduction in warfarin dose.

  3. Which antibiotic class most significantly inhibits CYP3A4 and increases the risk of statin-induced rhabdomyolysis?

    Answer: Macrolides

    Macrolides such as clarithromycin and erythromycin inhibit CYP3A4, reducing statin metabolism, elevating plasma statin concentrations, and markedly increasing the risk of myopathy and rhabdomyolysis.

  4. What is the primary mechanism by which NSAIDs increase the toxicity of low-dose methotrexate?

    Answer: Competing with methotrexate for renal tubular secretion

    NSAIDs compete with methotrexate for renal tubular secretion via OAT transporters, reducing its elimination and causing dangerous accumulation and toxicity.

  5. Which drug combination is most likely responsible for a patient developing a prolonged QTc interval on ECG?

    Answer: Azithromycin and haloperidol

    Both azithromycin and haloperidol independently prolong the QT interval by blocking cardiac hERG potassium channels; their combination synergistically increases the risk of torsades de pointes.

  6. A patient maintained on lithium for bipolar disorder begins taking ibuprofen regularly for arthritis pain. What effect on lithium levels is expected?

    Answer: Lithium levels will increase

    NSAIDs inhibit prostaglandin-mediated renal vasodilation, reducing renal blood flow and lithium clearance, which raises serum lithium levels and increases the risk of toxicity.

  7. Which adverse effect is characteristic of ACE inhibitors but is NOT shared by angiotensin receptor blockers (ARBs)?

    Answer: Dry, persistent cough

    ACE inhibitors prevent bradykinin degradation, causing its accumulation in the airways and resulting in a dry, persistent cough; ARBs do not affect bradykinin metabolism.