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Drug Interactions and Contraindications Flashcards

7 cards from real CAOP 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 on warfarin is prescribed ibuprofen for pain. What is the primary concern with this combination?

    Answer: Increased bleeding risk due to additive anticoagulation and GI mucosal damage

    NSAIDs like ibuprofen inhibit platelet aggregation and damage the GI mucosa, and can also displace warfarin from protein binding, increasing bleeding risk.

  2. Which combination of antihypertensive agents poses the greatest risk of dangerous hyperkalaemia?

    Answer: ACE inhibitor + potassium-sparing diuretic

    ACE inhibitors reduce aldosterone secretion and potassium excretion; combining with potassium-sparing diuretics (e.g., spironolactone) can cause life-threatening hyperkalaemia.

  3. A patient taking a monoamine oxidase inhibitor (MAOI) is started on sertraline. What potentially fatal interaction can occur?

    Answer: Serotonin syndrome due to excessive serotonergic activity

    Combining MAOIs with SSRIs can cause serotonin syndrome, a life-threatening condition characterised by hyperthermia, agitation, tremor, and clonus.

  4. Amiodarone is added to a patient's regimen that includes digoxin. What is the expected pharmacokinetic outcome?

    Answer: Amiodarone inhibits P-glycoprotein and CYP, increasing digoxin plasma levels

    Amiodarone inhibits P-glycoprotein-mediated renal excretion of digoxin and reduces its volume of distribution, typically doubling digoxin levels and requiring a dose reduction.

  5. Metformin should be withheld before and after administration of iodinated contrast media primarily because of the risk of:

    Answer: Contrast-induced nephropathy leading to metformin accumulation and lactic acidosis

    Contrast media can impair renal function; reduced renal clearance allows metformin to accumulate, increasing the risk of potentially fatal lactic acidosis.

  6. Concomitant use of a statin and gemfibrozil significantly increases the risk of:

    Answer: Rhabdomyolysis due to increased statin plasma concentrations

    Gemfibrozil inhibits CYP2C8 and OATP1B1, markedly increasing statin exposure and the risk of myopathy and rhabdomyolysis, particularly with cerivastatin (withdrawn) and simvastatin.

  7. Which of the following medications is most commonly associated with QT interval prolongation and torsades de pointes when combined with other QT-prolonging agents?

    Answer: Domperidone

    Domperidone blocks hERG potassium channels, prolonging the QT interval; combining it with other QT-prolonging drugs (e.g., azithromycin, antifungals) markedly increases the risk of torsades de pointes.