PSA Medication Safety 2 — Questions and Answers
Question 1: A patient stabilized on warfarin is prescribed ibuprofen for knee pain. What is the most significant safety concern?
- Decreased warfarin absorption from the gastrointestinal tract
- Increased bleeding risk due to combined antiplatelet effects and GI irritation (Correct answer)
- Hyperkalemia from the combined use of both drugs
- Irreversible renal failure requiring dialysis
Correct answer: Increased bleeding risk due to combined antiplatelet effects and GI irritation
NSAIDs like ibuprofen potentiate warfarin's anticoagulant effect and independently inhibit platelet aggregation, significantly increasing the risk of serious bleeding.
Question 2: Which drug combination carries the highest risk of causing serotonin syndrome?
- Sertraline and metformin
- Fluoxetine and tramadol (Correct answer)
- Citalopram and amlodipine
- Paroxetine and lisinopril
Correct answer: Fluoxetine and tramadol
Tramadol inhibits serotonin reuptake and, when combined with an SSRI like fluoxetine, can cause life-threatening serotonin syndrome.
Question 3: An elderly patient on lisinopril is started on spironolactone for heart failure. Which electrolyte disturbance requires immediate monitoring?
- Hyponatremia
- Hypercalcemia
- Hyperkalemia (Correct answer)
- Hypomagnesemia
Correct answer: Hyperkalemia
Both ACE inhibitors and potassium-sparing diuretics like spironolactone reduce potassium excretion, creating a high risk of dangerous hyperkalemia.
Question 4: Why should metformin be withheld before administration of iodinated contrast media?
- It causes an allergic reaction when combined with iodine
- Contrast-induced nephropathy can lead to metformin accumulation and lactic acidosis (Correct answer)
- It reduces the effectiveness of the contrast agent
- It causes hyperglycemia rebound after the procedure
Correct answer: Contrast-induced nephropathy can lead to metformin accumulation and lactic acidosis
If contrast causes acute kidney injury, metformin cannot be cleared and accumulates to levels that can cause life-threatening lactic acidosis.
Question 5: A patient on simvastatin 40 mg daily is prescribed clarithromycin for a respiratory infection. What is the primary concern?
- Reduced statin efficacy due to enzyme induction
- Myopathy or rhabdomyolysis due to elevated simvastatin levels (Correct answer)
- QT interval prolongation from both drugs combined
- Hepatotoxicity from the antibiotic alone
Correct answer: Myopathy or rhabdomyolysis due to elevated simvastatin levels
Clarithromycin is a potent CYP3A4 inhibitor that dramatically increases simvastatin plasma levels, raising the risk of myopathy and rhabdomyolysis.
Question 6: A patient on digoxin presents with bradycardia, nausea, and reports seeing yellow-green halos around lights. What is the most likely explanation?
- Acute myocardial infarction presenting with visual aura
- Digoxin toxicity (Correct answer)
- Hypoglycemia with neurological symptoms
- Hyperkalemia causing cardiac and visual effects
Correct answer: Digoxin toxicity
Classic digoxin toxicity presents with bradycardia or arrhythmias, gastrointestinal symptoms, and characteristic xanthopsia (yellow-green visual disturbances).
Question 7: Which drug combination is most likely to cause dangerous QT interval prolongation?
- Amoxicillin and metronidazole
- Haloperidol and azithromycin (Correct answer)
- Metformin and atorvastatin
- Lisinopril and amlodipine
Correct answer: Haloperidol and azithromycin
Both haloperidol and azithromycin independently prolong the QT interval; combining them significantly increases the risk of Torsades de Pointes.
PSA Medication Safety 2
A patient stabilized on warfarin is prescribed ibuprofen for knee pain.
What is the most significant safety concern?