FPGEE FPGEE MCQ Exam 3 — Questions and Answers
Question 1: A 65-year-old patient requires a loading dose of digoxin. Which factor most significantly affects the volume of distribution (Vd) of digoxin?
- Hepatic function
- Serum albumin level
- Lean body weight and tissue binding (Correct answer)
- Renal tubular secretion
Correct answer: Lean body weight and tissue binding
Digoxin has a very large Vd (~7 L/kg) due to extensive binding to skeletal muscle and other tissues; lean body weight is used to dose it.
Question 2: Which enzyme is responsible for the first-pass metabolism of morphine to morphine-6-glucuronide?
- CYP3A4
- CYP2D6
- UGT2B7 (UDP-glucuronosyltransferase) (Correct answer)
- MAO-B
Correct answer: UGT2B7 (UDP-glucuronosyltransferase)
Morphine undergoes extensive glucuronidation by UGT2B7 in the liver and intestinal wall, producing morphine-6-glucuronide (active) and morphine-3-glucuronide.
Question 3: A patient taking phenytoin for seizures is started on valproic acid. What is the expected net effect on phenytoin?
- Decreased total phenytoin with possible increased free phenytoin levels (Correct answer)
- Increased total and free phenytoin
- Decreased total and free phenytoin
- No significant change
Correct answer: Decreased total phenytoin with possible increased free phenytoin levels
Valproic acid displaces phenytoin from protein binding (decreasing total levels) while also inhibiting its metabolism, often raising free (active) phenytoin.
Question 4: Under the OBRA '90 regulations, pharmacists are required to perform which activities when dispensing medications to Medicaid patients?
- Drug utilization review (DUR), patient counseling, and maintaining medication records (Correct answer)
- Only label verification and dispensing
- Therapeutic substitution and prior authorization
- Compounding and repackaging only
Correct answer: Drug utilization review (DUR), patient counseling, and maintaining medication records
OBRA '90 mandates prospective DUR, patient counseling offers, and maintenance of patient medication records for Medicaid outpatient prescriptions.
Question 5: Which antihypertensive agent is absolutely contraindicated in bilateral renal artery stenosis?
- Amlodipine
- Metoprolol
- Lisinopril (Correct answer)
- Hydrochlorothiazide
Correct answer: Lisinopril
ACE inhibitors like lisinopril block angiotensin II–mediated efferent arteriolar constriction, which is the compensatory mechanism maintaining GFR in bilateral renal artery stenosis.
Question 6: A patient develops QT prolongation after starting a new antibiotic. Which agent is MOST likely responsible?
- Amoxicillin-clavulanate
- Azithromycin (Correct answer)
- Doxycycline
- Trimethoprim-sulfamethoxazole
Correct answer: Azithromycin
Azithromycin (and other macrolides) block hERG potassium channels, prolonging the QT interval and increasing the risk of Torsades de Pointes.
Question 7: Which parameter describes the fraction of a drug excreted unchanged in the urine?
- Bioavailability (F)
- Extraction ratio (ER)
- Fraction excreted renally (fe) (Correct answer)
- Intrinsic clearance (CLint)
Correct answer: Fraction excreted renally (fe)
The fraction excreted renally (fe) represents the proportion of absorbed drug eliminated unchanged by the kidneys and determines how much renal impairment affects drug clearance.
FPGEE FPGEE MCQ Exam 3
A 65-year-old patient requires a loading dose of digoxin.
Which factor most significantly affects the volume of distribution (Vd) of digoxin?