Pharmacotherapy Review & Drug Interactions Flashcards
7 cards from real MTM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Pharmacotherapy Review & Drug Interactions flashcards as text
A patient with chronic kidney disease (eGFR 20 mL/min) is taking gabapentin. What dose adjustment is required?
Answer: Reduce dose and/or frequency; gabapentin is renally eliminated
Gabapentin is exclusively renally eliminated without hepatic metabolism, requiring significant dose reduction in renal impairment to prevent neurotoxicity.
Which drug interaction mechanism explains the reduced effectiveness of oral contraceptives when rifampin is co-administered?
Answer: Rifampin induces CYP3A4, accelerating estrogen metabolism
Rifampin is a potent CYP3A4 inducer that significantly increases the metabolism of ethinyl estradiol and progestin components of oral contraceptives, reducing their plasma concentrations.
In an MTM session, a patient on digoxin reports starting clarithromycin for a respiratory infection. What is the interaction mechanism?
Answer: Clarithromycin inhibits P-glycoprotein and CYP3A4, increasing digoxin levels
Clarithromycin inhibits P-glycoprotein (which normally effluxes digoxin from intestinal cells and renal tubules), leading to increased digoxin absorption and decreased renal elimination.
A patient with heart failure has a serum potassium of 3.1 mEq/L and takes digoxin and furosemide. What is the primary concern?
Answer: Hypokalemia increases cardiac sensitivity to digoxin toxicity
Hypokalemia enhances digoxin binding to the Na+/K+-ATPase pump and increases myocardial sensitivity to digoxin, raising the risk of arrhythmias at normal or even subtherapeutic digoxin levels.
Which antidiabetic agent class carries the highest risk of hypoglycemia when used as monotherapy?
Answer: Sulfonylureas
Sulfonylureas stimulate insulin secretion independently of blood glucose levels, making hypoglycemia a significant risk even without co-administration of other agents.
Which pharmacokinetic change is most commonly observed in elderly patients and requires medication dose adjustment?
Answer: Decreased renal clearance due to reduced GFR
Age-related decline in glomerular filtration rate (GFR) decreases renal drug clearance, necessitating dose reductions for renally eliminated medications in elderly patients.
A patient on an MAOI is given meperidine for pain. What potentially fatal reaction may occur?
Answer: Serotonin syndrome
Meperidine inhibits serotonin reuptake; combined with an MAOI that prevents serotonin breakdown, this results in serotonin syndrome, characterized by hyperthermia, agitation, and neuromuscular abnormalities.