CPJE Drug Interactions and Therapeutics Flashcards
6 cards from real CPJE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CPJE Drug Interactions and Therapeutics flashcards as text
Which class of antibiotics is avoided in patients with myasthenia gravis due to neuromuscular blockade?
Answer: Fluoroquinolones
Fluoroquinolones can block neuromuscular transmission and exacerbate weakness in patients with myasthenia gravis.
A patient on methotrexate is prescribed trimethoprim. What serious toxicity can result?
Answer: Severe bone marrow suppression
Both methotrexate and trimethoprim inhibit dihydrofolate reductase, and their combination causes additive antifolate toxicity including bone marrow suppression.
Which substrate is most affected by rifampin co-administration due to strong CYP3A4 induction?
Answer: Oral contraceptives
Rifampin is a potent CYP3A4 inducer that significantly reduces plasma levels of oral contraceptives, risking contraceptive failure.
Combining ACE inhibitors with potassium-sparing diuretics poses a risk of which electrolyte abnormality?
Answer: Hyperkalemia
Both ACE inhibitors and potassium-sparing diuretics reduce potassium excretion, and their combination can cause dangerous hyperkalemia.
A patient on phenytoin is started on fluconazole. What is the expected outcome?
Answer: Phenytoin toxicity due to elevated levels
Fluconazole inhibits CYP2C9, which metabolizes phenytoin, leading to accumulation and potential toxicity including nystagmus and ataxia.
Which combination is most likely to cause prolonged QT interval and torsades de pointes?
Answer: Azithromycin and haloperidol
Both azithromycin and haloperidol independently prolong the QT interval, and their combination significantly increases the risk of torsades de pointes.