Drug Interactions and Adverse Effects Flashcards
6 cards from real Pharm.D. Doctor of Pharmacy practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Drug Interactions and Adverse Effects flashcards as text
Which mechanism explains the interaction between rifampin and oral contraceptives?
Answer: Rifampin induces CYP3A4, accelerating estrogen metabolism and reducing contraceptive efficacy
Rifampin is a potent CYP3A4 inducer that accelerates the hepatic metabolism of estrogen and progestin in oral contraceptives, significantly reducing their plasma levels and contraceptive efficacy.
Which adverse effect is specifically associated with aminoglycoside antibiotics and requires regular monitoring?
Answer: Nephrotoxicity and ototoxicity
Aminoglycosides (e.g., gentamicin, tobramycin) are associated with concentration-dependent nephrotoxicity and ototoxicity, requiring serum level monitoring and renal function assessment.
A patient on sildenafil is prescribed a nitrate for angina. What is the primary concern?
Answer: Severe hypotension due to additive vasodilation
Both sildenafil (PDE5 inhibitor) and nitrates increase cGMP, causing profound additive vasodilation and potentially life-threatening hypotension — this combination is absolutely contraindicated.
Which adverse effect is most concerning with long-term proton pump inhibitor (PPI) use?
Answer: Hypomagnesemia and increased risk of Clostridioides difficile infection
Long-term PPI use is associated with hypomagnesemia, hypokalemia, increased risk of C. difficile infection, and reduced absorption of calcium, vitamin B12, and iron.
Which lab finding is characteristic of heparin-induced thrombocytopenia (HIT)?
Answer: Platelet count drop of ≥50% from baseline, typically 5–14 days after heparin initiation
HIT is characterized by a ≥50% platelet count drop from baseline occurring 5–14 days after heparin initiation due to antibodies against heparin-platelet factor 4 complexes.
Which drug interaction mechanism is responsible for the increased bleeding risk when NSAIDs are combined with anticoagulants?
Answer: NSAIDs inhibit platelet aggregation and may displace anticoagulants from protein binding sites
NSAIDs inhibit platelet aggregation by blocking thromboxane A2 synthesis and can displace highly protein-bound anticoagulants, increasing free drug levels and compounding bleeding risk.