Wilkes University Actual Exam Complete Questions &
Rationales | Advanced Drug Therapy | Pass Guaranteed -
A+ Graded
Pharmacokinetics & Pharmacodynamics
Q1: A 45-year-old patient asks why their phenytoin level keeps fluctuating despite taking
it at the same time daily. The NP explains that phenytoin exhibits which
pharmacokinetic characteristic?
A. Zero-order kinetics at all concentrations
B. First-order kinetics regardless of dose
C. Capacity-limited metabolism where small dose increases cause disproportionately
large serum level jumps [CORRECT]
D. Linear pharmacokinetics with predictable proportional increases
Correct Answer: C
Rationale: The best answer is C. Phenytoin follows Michaelis-Menten kinetics, meaning
once those hepatic enzymes get saturated, even tiny dose bumps can send levels
soaring unpredictably. This is why you titrate phenytoin slowly and monitor levels
closely, especially when you're getting near the therapeutic range.
Q2: A 62-year-old with atrial fibrillation is started on amiodarone 400 mg daily. The NP
knows amiodarone has an exceptionally long half-life. Approximately how long will it
take to reach steady-state plasma concentrations?
A. 1 to 2 days
B. 1 to 2 weeks
C. 1 to 3 months [CORRECT]
D. 6 to 12 hours
Correct Answer: C
,Rationale: The best answer is C. Amiodarone's half-life is roughly 40 to 55 days, so
you're looking at about five half-lives—or roughly two to three months—to reach steady
state. This is why loading doses are often used and why adverse effects can show up
long after starting or even stopping the drug.
Q3: A drug has a half-life of 6 hours. If a patient receives a single 200 mg dose,
approximately how much drug remains after 24 hours assuming first-order kinetics?
A. 6.25 mg
B. 12.5 mg [CORRECT]
C. 25 mg
D. 50 mg
Correct Answer: B
Rationale: The best answer is B. After 24 hours, you've gone through four half-lives. With
each half-life you cut the amount in half: 200 becomes 100, then 50, then 25, then 12.5
mg. This basic calculation is essential when you're thinking about drug accumulation,
dosing intervals, and how long a drug hangs around after the last dose.
Q4: A patient asks why they need a much lower dose of morphine than their sibling did
for the same surgery. The NP explains that morphine has high efficacy but that the
amount needed varies between individuals. Which pharmacodynamic concept best
explains this individual variation?
A. Efficacy is the dose needed to produce an effect; potency is the maximum effect
achievable
B. Efficacy is the maximum biological effect a drug can produce; potency is the amount
of drug needed to produce a given effect [CORRECT]
C. Efficacy and potency are interchangeable terms describing the same concept
D. Potency determines therapeutic index while efficacy determines bioavailability
Correct Answer: B
Rationale: The best answer is B. Efficacy is about how good the drug can get at its
best—think morphine's strong analgesic ceiling. Potency is about how little you need to
get there. A drug can be super potent but have low efficacy, or vice versa, and knowing
the difference matters when you're choosing between agents and explaining dose
variability to patients.
, Q5: A patient on chronic warfarin therapy is started on metronidazole for a bacterial
infection. The NP anticipates an increased INR because metronidazole inhibits which
primary metabolic pathway?
A. Glucuronidation via UGT enzymes
B. The CYP2C9 enzyme system [CORRECT]
C. Renal tubular secretion
D. Hydrolysis by plasma esterases
Correct Answer: B
Rationale: The best answer is B. Metronidazole is a potent CYP2C9 inhibitor, and since
warfarin's S-isomer is primarily metabolized by 2C9, adding metronidazole can send the
INR climbing fast. You'll want to check an INR within a few days and be ready to adjust
the warfarin dose downward.
Q6: A new antihypertensive drug has a therapeutic index of 2, while an established drug
in the same class has a therapeutic index of 15. What does this tell the prescriber about
the new drug?
A. The new drug is more potent than the established drug
B. The new drug has a much narrower margin of safety and requires closer monitoring
[CORRECT]
C. The new drug is less efficacious than the established drug
D. The new drug has better oral bioavailability
Correct Answer: B
Rationale: The best answer is B. Therapeutic index is the ratio of toxic dose to effective
dose—a smaller number means the effective dose and toxic dose are close together.
With a TI of 2, you've got very little wiggle room, so monitoring drug levels or clinical
effects closely is essential to avoid tipping into toxicity.
Q7: A patient with chronic kidney disease (eGFR 28 mL/min) is prescribed a drug that is
80% renally excreted unchanged. The NP should anticipate which adjustment?
A. No adjustment needed since hepatic metabolism will compensate
B. A dose reduction or extended dosing interval to prevent accumulation and toxicity
[CORRECT]
C. An increased dose to overcome reduced renal clearance
D. Switching to the IV route to bypass renal excretion
Correct Answer: B