NURS 6521 ADVANCED PHARMACOLOGY FINAL EXAM
NURS 6521N Week 11 | Latest Version B | 100 Questions with Correct Answers
Walden University | 2026-2027 Curriculum Standards
Section 1: Pharmacokinetics, Pharmacodynamics, and Pharmacogenomics (Q1-15)
Q1: A nurse practitioner is reviewing the pharmacokinetics of a newly prescribed medication. The drug has a bioavailability
of 30% after oral administration. Which of the following best explains why the bioavailability is low?
A. The drug is highly protein-bound in the plasma
B. The drug undergoes extensive first-pass metabolism in the liver [CORRECT]
C. The drug has a very large volume of distribution
D. The drug is primarily excreted unchanged by the kidneys
Correct Answer: B
Rationale: First-pass metabolism occurs when a drug is absorbed from the GI tract and passes through the liver before reaching
systemic circulation, where a significant portion may be metabolized, reducing bioavailability. Protein binding (A) affects distribution,
not absorption. A large volume of distribution (C) indicates extensive tissue binding but does not reduce bioavailability. Renal
excretion (D) affects elimination, not the fraction absorbed.
Q2: A patient with chronic kidney disease has a creatinine clearance (CrCl) of 25 mL/min. The nurse practitioner is
prescribing a drug that is primarily eliminated unchanged by the kidneys. Which adjustment is most appropriate?
A. Increase the dose to compensate for reduced efficacy
B. Extend the dosing interval to prevent drug accumulation [CORRECT]
C. Switch to a drug metabolized by CYP3A4
D. Administer the drug intravenously to bypass first-pass metabolism
Correct Answer: B
Rationale: When a drug is renally eliminated and CrCl is significantly reduced (25 mL/min indicates moderate-severe impairment),
extending the dosing interval prevents drug accumulation and toxicity. Increasing the dose (A) would worsen toxicity. Simply
switching to a CYP3A4-metabolized drug (C) does not address the patient's renal impairment. IV administration (D) bypasses
first-pass metabolism but does not solve the clearance problem.
Q3: A patient is prescribed a drug with a half-life of 12 hours. Approximately how long will it take to reach steady-state
concentration?
A. 12 hours
B. 24 hours
C. 48 to 60 hours [CORRECT]
D. 120 hours
Correct Answer: C
Rationale: Steady-state concentration is achieved after approximately 4-5 half-lives. With a half-life of 12 hours, 4 half-lives equals
48 hours and 5 half-lives equals 60 hours, making 48-60 hours the correct range. A single half-life (A) reaches only 50% of steady
state. Two half-lives (B) reaches 75%. Ten half-lives (D) far exceeds what is needed.
Q4: A patient taking warfarin has genetic testing that reveals they are a CYP2C9 poor metabolizer. What is the clinical
implication?
A. The patient will require a higher warfarin dose to achieve therapeutic INR
B. The patient is at increased risk for bleeding at standard doses [CORRECT]
, C. The patient should be switched to a direct oral anticoagulant immediately
D. CYP2C9 has no effect on warfarin metabolism
Correct Answer: B
Rationale: CYP2C9 is the primary enzyme responsible for metabolizing S-warfarin, the more active enantiomer. Poor metabolizers
have reduced metabolic capacity, leading to higher serum warfarin levels and increased bleeding risk at standard doses. These patients
typically require lower initial doses. Option A is the opposite of the correct response. While switching to a DOAC (C) may be
considered, it is not the immediate implication of the genotype result. Option D is factually incorrect.
Q5: A nurse practitioner is counseling a patient who is taking a drug that is a CYP3A4 substrate. Which of the following
substances would most likely increase the plasma concentration of this drug?
A. St. John's Wort
B. Phenytoin
C. Grapefruit juice [CORRECT]
D. Carbamazepine
Correct Answer: C
Rationale: Grapefruit juice inhibits intestinal CYP3A4, reducing first-pass metabolism and increasing the bioavailability of CYP3A4
substrates. St. John's Wort (A), phenytoin (B), and carbamazepine (D) are all CYP3A4 inducers, which would decrease plasma drug
concentrations by increasing metabolism.
Q6: A patient with epilepsy who has been stable on phenytoin is prescribed erythromycin for a respiratory infection. What
is the most likely clinical outcome?
A. Increased phenytoin levels leading to nystagmus and ataxia [CORRECT]
B. Decreased phenytoin levels causing breakthrough seizures
C. No significant interaction between these two medications
D. Enhanced antibiotic efficacy due to enzyme induction
Correct Answer: A
Rationale: Erythromycin is a CYP3A4 inhibitor, and phenytoin is metabolized by CYP3A4 (among other CYP enzymes). Inhibition
of metabolism leads to increased phenytoin serum levels, which can cause dose-dependent toxicity including nystagmus, ataxia, and
gingival hyperplasia. Option B describes the effect of an inducer, not an inhibitor. The interaction is clinically significant (C is
incorrect). The interaction affects phenytoin levels, not antibiotic efficacy (D).
Q7: Which of the following best describes the concept of volume of distribution (Vd)?
A. The total volume of blood in the body
B. The theoretical volume that relates the amount of drug in the body to the measured plasma concentration
[CORRECT]
C. The rate at which a drug is eliminated from the body
D. The fraction of an administered dose that reaches systemic circulation unchanged
Correct Answer: B
Rationale: Volume of distribution (Vd) is a pharmacokinetic parameter representing the theoretical space in the body available to
contain the drug, calculated as the amount of drug in the body divided by the plasma concentration. It reflects the extent of drug
distribution into tissues versus plasma. Option A describes blood volume. Option C describes clearance. Option D describes
bioavailability.
Q8: A drug has a therapeutic index (TI) of 2. Which of the following is the most accurate interpretation?
A. The drug is very safe with a wide margin between effective and toxic doses
B. The drug has a narrow therapeutic window requiring close monitoring [CORRECT]
C. The drug is ineffective at any dose
D. The drug has no adverse effects
Correct Answer: B
, Rationale: The therapeutic index is calculated as LD50/ED50. A TI of 2 indicates that the toxic dose is only twice the effective dose,
representing a narrow therapeutic window. Drugs with a low TI require careful monitoring and dose adjustments. A high TI (e.g., >10)
would indicate a wide safety margin (A). Options C and D are incorrect interpretations.
Q9: A patient is prescribed clopidogrel for secondary prevention after a myocardial infarction. Genetic testing reveals the
patient is a CYP2C19 poor metabolizer. What is the most appropriate clinical action?
A. Continue clopidogrel at the standard dose since genetics do not affect response
B. Double the clopidogrel dose to overcome the metabolic deficit
C. Consider an alternative antiplatelet agent such as prasugrel or ticagrelor [CORRECT]
D. Add omeprazole to enhance clopidogrel activation
Correct Answer: C
Rationale: CYP2C19 is essential for converting clopidogrel to its active metabolite. Poor metabolizers have significantly reduced
antiplatelet effect and higher rates of cardiovascular events. Current guidelines recommend considering alternative antiplatelet agents
such as prasugrel (which has less CYP2C19 dependence) or ticagrelor (a direct-acting agent) in these patients. Continuing
standard-dose clopidogrel (A) leaves the patient inadequately protected. Doubling the dose (B) does not overcome the genetic
metabolic deficit. Omeprazole (D) further inhibits CYP2C19, worsening the problem.
Q10: A competitive antagonist is administered alongside an agonist. Which of the following describes the effect on the
agonist dose-response curve?
A. The curve shifts to the left with no change in maximal response
B. The curve shifts to the right with no change in maximal response [CORRECT]
C. The maximal response is decreased without a shift in the curve
D. There is no effect on the dose-response curve
Correct Answer: B
Rationale: A competitive antagonist binds to the same receptor site as the agonist and can be overcome by increasing the agonist
concentration, resulting in a rightward parallel shift of the dose-response curve with no change in maximal response (Emax). A
leftward shift (A) would indicate sensitization or an allosteric enhancer. Decreased maximal response (C) describes a non-competitive
or irreversible antagonist. Option D is incorrect because competitive antagonism does alter the curve.
Q11: A patient with a known HLA-B*5701 allele is being considered for HIV treatment. Which medication is
contraindicated?
A. Tenofovir
B. Abacavir [CORRECT]
C. Dolutegravir
D. Emtricitabine
Correct Answer: B
Rationale: HLA-B*5701 is strongly associated with abacavir hypersensitivity syndrome, a potentially fatal systemic reaction. Current
guidelines mandate HLA-B*5701 screening before initiating abacavir, and the drug is absolutely contraindicated in patients who test
positive. Tenofovir (A), dolutegravir (C), and emtricitabine (D) are not associated with this genetic risk.
Q12: Enterohepatic recirculation of a drug will have which of the following effects on the drug's pharmacokinetics?
A. Decreased half-life and faster elimination
B. Increased half-life and prolonged duration of action [CORRECT]
C. No effect on half-life or duration
D. Increased first-pass metabolism
Correct Answer: B
Rationale: Enterohepatic recirculation occurs when a drug is conjugated in the liver, excreted into bile, deconjugated by intestinal
bacteria, and reabsorbed. This recycling prolongs the drug's presence in the body, resulting in an increased apparent half-life and
extended duration of action. It decreases the rate of overall elimination (opposite of A). It certainly affects half-life (C is wrong).
First-pass metabolism (D) is a separate concept related to initial oral absorption.
NURS 6521N Week 11 | Latest Version B | 100 Questions with Correct Answers
Walden University | 2026-2027 Curriculum Standards
Section 1: Pharmacokinetics, Pharmacodynamics, and Pharmacogenomics (Q1-15)
Q1: A nurse practitioner is reviewing the pharmacokinetics of a newly prescribed medication. The drug has a bioavailability
of 30% after oral administration. Which of the following best explains why the bioavailability is low?
A. The drug is highly protein-bound in the plasma
B. The drug undergoes extensive first-pass metabolism in the liver [CORRECT]
C. The drug has a very large volume of distribution
D. The drug is primarily excreted unchanged by the kidneys
Correct Answer: B
Rationale: First-pass metabolism occurs when a drug is absorbed from the GI tract and passes through the liver before reaching
systemic circulation, where a significant portion may be metabolized, reducing bioavailability. Protein binding (A) affects distribution,
not absorption. A large volume of distribution (C) indicates extensive tissue binding but does not reduce bioavailability. Renal
excretion (D) affects elimination, not the fraction absorbed.
Q2: A patient with chronic kidney disease has a creatinine clearance (CrCl) of 25 mL/min. The nurse practitioner is
prescribing a drug that is primarily eliminated unchanged by the kidneys. Which adjustment is most appropriate?
A. Increase the dose to compensate for reduced efficacy
B. Extend the dosing interval to prevent drug accumulation [CORRECT]
C. Switch to a drug metabolized by CYP3A4
D. Administer the drug intravenously to bypass first-pass metabolism
Correct Answer: B
Rationale: When a drug is renally eliminated and CrCl is significantly reduced (25 mL/min indicates moderate-severe impairment),
extending the dosing interval prevents drug accumulation and toxicity. Increasing the dose (A) would worsen toxicity. Simply
switching to a CYP3A4-metabolized drug (C) does not address the patient's renal impairment. IV administration (D) bypasses
first-pass metabolism but does not solve the clearance problem.
Q3: A patient is prescribed a drug with a half-life of 12 hours. Approximately how long will it take to reach steady-state
concentration?
A. 12 hours
B. 24 hours
C. 48 to 60 hours [CORRECT]
D. 120 hours
Correct Answer: C
Rationale: Steady-state concentration is achieved after approximately 4-5 half-lives. With a half-life of 12 hours, 4 half-lives equals
48 hours and 5 half-lives equals 60 hours, making 48-60 hours the correct range. A single half-life (A) reaches only 50% of steady
state. Two half-lives (B) reaches 75%. Ten half-lives (D) far exceeds what is needed.
Q4: A patient taking warfarin has genetic testing that reveals they are a CYP2C9 poor metabolizer. What is the clinical
implication?
A. The patient will require a higher warfarin dose to achieve therapeutic INR
B. The patient is at increased risk for bleeding at standard doses [CORRECT]
, C. The patient should be switched to a direct oral anticoagulant immediately
D. CYP2C9 has no effect on warfarin metabolism
Correct Answer: B
Rationale: CYP2C9 is the primary enzyme responsible for metabolizing S-warfarin, the more active enantiomer. Poor metabolizers
have reduced metabolic capacity, leading to higher serum warfarin levels and increased bleeding risk at standard doses. These patients
typically require lower initial doses. Option A is the opposite of the correct response. While switching to a DOAC (C) may be
considered, it is not the immediate implication of the genotype result. Option D is factually incorrect.
Q5: A nurse practitioner is counseling a patient who is taking a drug that is a CYP3A4 substrate. Which of the following
substances would most likely increase the plasma concentration of this drug?
A. St. John's Wort
B. Phenytoin
C. Grapefruit juice [CORRECT]
D. Carbamazepine
Correct Answer: C
Rationale: Grapefruit juice inhibits intestinal CYP3A4, reducing first-pass metabolism and increasing the bioavailability of CYP3A4
substrates. St. John's Wort (A), phenytoin (B), and carbamazepine (D) are all CYP3A4 inducers, which would decrease plasma drug
concentrations by increasing metabolism.
Q6: A patient with epilepsy who has been stable on phenytoin is prescribed erythromycin for a respiratory infection. What
is the most likely clinical outcome?
A. Increased phenytoin levels leading to nystagmus and ataxia [CORRECT]
B. Decreased phenytoin levels causing breakthrough seizures
C. No significant interaction between these two medications
D. Enhanced antibiotic efficacy due to enzyme induction
Correct Answer: A
Rationale: Erythromycin is a CYP3A4 inhibitor, and phenytoin is metabolized by CYP3A4 (among other CYP enzymes). Inhibition
of metabolism leads to increased phenytoin serum levels, which can cause dose-dependent toxicity including nystagmus, ataxia, and
gingival hyperplasia. Option B describes the effect of an inducer, not an inhibitor. The interaction is clinically significant (C is
incorrect). The interaction affects phenytoin levels, not antibiotic efficacy (D).
Q7: Which of the following best describes the concept of volume of distribution (Vd)?
A. The total volume of blood in the body
B. The theoretical volume that relates the amount of drug in the body to the measured plasma concentration
[CORRECT]
C. The rate at which a drug is eliminated from the body
D. The fraction of an administered dose that reaches systemic circulation unchanged
Correct Answer: B
Rationale: Volume of distribution (Vd) is a pharmacokinetic parameter representing the theoretical space in the body available to
contain the drug, calculated as the amount of drug in the body divided by the plasma concentration. It reflects the extent of drug
distribution into tissues versus plasma. Option A describes blood volume. Option C describes clearance. Option D describes
bioavailability.
Q8: A drug has a therapeutic index (TI) of 2. Which of the following is the most accurate interpretation?
A. The drug is very safe with a wide margin between effective and toxic doses
B. The drug has a narrow therapeutic window requiring close monitoring [CORRECT]
C. The drug is ineffective at any dose
D. The drug has no adverse effects
Correct Answer: B
, Rationale: The therapeutic index is calculated as LD50/ED50. A TI of 2 indicates that the toxic dose is only twice the effective dose,
representing a narrow therapeutic window. Drugs with a low TI require careful monitoring and dose adjustments. A high TI (e.g., >10)
would indicate a wide safety margin (A). Options C and D are incorrect interpretations.
Q9: A patient is prescribed clopidogrel for secondary prevention after a myocardial infarction. Genetic testing reveals the
patient is a CYP2C19 poor metabolizer. What is the most appropriate clinical action?
A. Continue clopidogrel at the standard dose since genetics do not affect response
B. Double the clopidogrel dose to overcome the metabolic deficit
C. Consider an alternative antiplatelet agent such as prasugrel or ticagrelor [CORRECT]
D. Add omeprazole to enhance clopidogrel activation
Correct Answer: C
Rationale: CYP2C19 is essential for converting clopidogrel to its active metabolite. Poor metabolizers have significantly reduced
antiplatelet effect and higher rates of cardiovascular events. Current guidelines recommend considering alternative antiplatelet agents
such as prasugrel (which has less CYP2C19 dependence) or ticagrelor (a direct-acting agent) in these patients. Continuing
standard-dose clopidogrel (A) leaves the patient inadequately protected. Doubling the dose (B) does not overcome the genetic
metabolic deficit. Omeprazole (D) further inhibits CYP2C19, worsening the problem.
Q10: A competitive antagonist is administered alongside an agonist. Which of the following describes the effect on the
agonist dose-response curve?
A. The curve shifts to the left with no change in maximal response
B. The curve shifts to the right with no change in maximal response [CORRECT]
C. The maximal response is decreased without a shift in the curve
D. There is no effect on the dose-response curve
Correct Answer: B
Rationale: A competitive antagonist binds to the same receptor site as the agonist and can be overcome by increasing the agonist
concentration, resulting in a rightward parallel shift of the dose-response curve with no change in maximal response (Emax). A
leftward shift (A) would indicate sensitization or an allosteric enhancer. Decreased maximal response (C) describes a non-competitive
or irreversible antagonist. Option D is incorrect because competitive antagonism does alter the curve.
Q11: A patient with a known HLA-B*5701 allele is being considered for HIV treatment. Which medication is
contraindicated?
A. Tenofovir
B. Abacavir [CORRECT]
C. Dolutegravir
D. Emtricitabine
Correct Answer: B
Rationale: HLA-B*5701 is strongly associated with abacavir hypersensitivity syndrome, a potentially fatal systemic reaction. Current
guidelines mandate HLA-B*5701 screening before initiating abacavir, and the drug is absolutely contraindicated in patients who test
positive. Tenofovir (A), dolutegravir (C), and emtricitabine (D) are not associated with this genetic risk.
Q12: Enterohepatic recirculation of a drug will have which of the following effects on the drug's pharmacokinetics?
A. Decreased half-life and faster elimination
B. Increased half-life and prolonged duration of action [CORRECT]
C. No effect on half-life or duration
D. Increased first-pass metabolism
Correct Answer: B
Rationale: Enterohepatic recirculation occurs when a drug is conjugated in the liver, excreted into bile, deconjugated by intestinal
bacteria, and reabsorbed. This recycling prolongs the drug's presence in the body, resulting in an increased apparent half-life and
extended duration of action. It decreases the rate of overall elimination (opposite of A). It certainly affects half-life (C is wrong).
First-pass metabolism (D) is a separate concept related to initial oral absorption.
