NURS 5433 MIDTERM EXAM ACTUAL 2025/2026
QUESTIONS AND 100% CORRECT ANSWERS
Section 1: Pharmacokinetics and Pharmacodynamics (Q 1-10)
Q1: A 78-year-old patient with chronic heart failure and an eGFR of 35 mL/min is prescribed
digoxin 0.25 mg daily. After 5 days, the patient presents with nausea, visual disturbances, and a
serum digoxin level of 2.8 ng/mL (therapeutic: 0.5-0.9 ng/mL). Which pharmacokinetic principle
best explains this toxicity?
A. Decreased hepatic first-pass metabolism in elderly patients
B. Reduced renal clearance leading to drug accumulation [CORRECT]
C. Increased volume of distribution in heart failure
D. Enhanced P-glycoprotein efflux in the gut
Correct Answer: B
Rationale:
• Digoxin is primarily eliminated unchanged by the kidneys (60-80%)
• The patient's eGFR of 35 mL/min indicates Stage 3b CKD, significantly reducing clearance
• Loading doses should be reduced by 50% and maintenance doses by 25-50% in this
population
• Per 2025 AHA/ACC guidelines, digoxin levels >2.0 ng/mL significantly increase toxicity
risk without additional therapeutic benefit
Q2: A 45-year-old patient with HIV on ritonavir-boosted atazanavir requires simvastatin for
hyperlipidemia. Which statin and dosing strategy is safest given the pharmacokinetic
interaction?
A. Simvastatin 40 mg daily
B. Atorvastatin 80 mg daily [CORRECT]
C. Lovastatin 20 mg daily
D. Pravastatin 10 mg daily
Correct Answer: B
Rationale:
, • Ritonavir is a potent CYP3A4 inhibitor that increases statin levels 2-30 fold
• Simvastatin and lovastatin are CYP3A4 substrates with high interaction risk
(contraindicated with protease inhibitors per FDA 2024 labeling)
• Atorvastatin has less CYP3A4 dependence and can be used cautiously at reduced doses
• Pravastatin is not metabolized by CYP3A4 but 10 mg is subtherapeutic for most adults
Q3: A 62-year-old with atrial fibrillation on warfarin (INR stable at 2.5) starts amiodarone. Two
weeks later, INR is 4.8 without bleeding. Which mechanism explains this interaction?
A. Amiodarone induces CYP2C9, increasing warfarin metabolism
B. Amiodarone inhibits CYP2C9 and CYP1A2, reducing S-warfarin clearance [CORRECT]
C. Amiodarone displaces warfarin from albumin binding sites
D. Amiodarone increases vitamin K absorption
Correct Answer: B
Rationale:
• Amiodarone is a potent inhibitor of multiple CYP450 enzymes including CYP2C9 and
CYP1A2
• S-warfarin (2-5x more potent than R-warfarin) is metabolized primarily by CYP2C9
• FDA guidelines recommend reducing warfarin dose by 30-50% when initiating
amiodarone
• The interaction has a delayed onset (1-2 weeks) due to amiodarone's long half-life (40-
55 days)
Q4: A 28-year-old pregnant patient (32 weeks gestation) requires treatment for community-
acquired pneumonia. Which antibiotic requires dose adjustment due to altered
pharmacokinetics in pregnancy?
A. Azithromycin 500 mg daily
B. Ceftriaxone 1g IV daily
C. Piperacillin-tazobactam 3.375g IV q6h [CORRECT]
D. Doxycycline 100 mg BID
Correct Answer: C
, Rationale:
• Pregnancy increases GFR by 40-50%, increasing renal clearance of hydrophilic drugs
• Piperacillin is primarily renally eliminated and requires more frequent dosing (q4-6h vs
q6-8h) in pregnancy
• Azithromycin has minimal renal clearance; ceftriaxone dose is unchanged for pneumonia
• Doxycycline is contraindicated in pregnancy (teratogenic), not merely dose-adjusted
Q5: A patient with metastatic breast cancer receiving paclitaxel develops severe peripheral
neuropathy. Genetic testing reveals a CYP2C8*3 variant. Which statement best describes this
pharmacogenomic finding?
A. The patient is a rapid metabolizer requiring dose escalation
B. Reduced paclitaxel metabolism increases neurotoxicity risk [CORRECT]
C. The variant affects paclitaxel protein binding
D. CYP2C8 variants have no clinical significance for taxane therapy
Correct Answer: B
Rationale:
• CYP2C8 is the primary enzyme metabolizing paclitaxel
• The *3 variant (R139K, K399R) reduces enzyme activity, increasing drug exposure
• Per 2025 CPIC guidelines, CYP2C8 poor metabolizers have 2-3x increased risk of grade ≥3
neuropathy
• Dose reduction or alternative taxanes (docetaxel - less CYP2C8 dependent) should be
considered
Q6: A 55-year-old with cirrhosis (Child-Pugh Class C) requires analgesia post-operatively. Which
opioid requires the most significant dose reduction due to altered pharmacokinetics?
A. Morphine [CORRECT]
B. Fentanyl
C. Oxycodone
D. Hydromorphone
Correct Answer: A
QUESTIONS AND 100% CORRECT ANSWERS
Section 1: Pharmacokinetics and Pharmacodynamics (Q 1-10)
Q1: A 78-year-old patient with chronic heart failure and an eGFR of 35 mL/min is prescribed
digoxin 0.25 mg daily. After 5 days, the patient presents with nausea, visual disturbances, and a
serum digoxin level of 2.8 ng/mL (therapeutic: 0.5-0.9 ng/mL). Which pharmacokinetic principle
best explains this toxicity?
A. Decreased hepatic first-pass metabolism in elderly patients
B. Reduced renal clearance leading to drug accumulation [CORRECT]
C. Increased volume of distribution in heart failure
D. Enhanced P-glycoprotein efflux in the gut
Correct Answer: B
Rationale:
• Digoxin is primarily eliminated unchanged by the kidneys (60-80%)
• The patient's eGFR of 35 mL/min indicates Stage 3b CKD, significantly reducing clearance
• Loading doses should be reduced by 50% and maintenance doses by 25-50% in this
population
• Per 2025 AHA/ACC guidelines, digoxin levels >2.0 ng/mL significantly increase toxicity
risk without additional therapeutic benefit
Q2: A 45-year-old patient with HIV on ritonavir-boosted atazanavir requires simvastatin for
hyperlipidemia. Which statin and dosing strategy is safest given the pharmacokinetic
interaction?
A. Simvastatin 40 mg daily
B. Atorvastatin 80 mg daily [CORRECT]
C. Lovastatin 20 mg daily
D. Pravastatin 10 mg daily
Correct Answer: B
Rationale:
, • Ritonavir is a potent CYP3A4 inhibitor that increases statin levels 2-30 fold
• Simvastatin and lovastatin are CYP3A4 substrates with high interaction risk
(contraindicated with protease inhibitors per FDA 2024 labeling)
• Atorvastatin has less CYP3A4 dependence and can be used cautiously at reduced doses
• Pravastatin is not metabolized by CYP3A4 but 10 mg is subtherapeutic for most adults
Q3: A 62-year-old with atrial fibrillation on warfarin (INR stable at 2.5) starts amiodarone. Two
weeks later, INR is 4.8 without bleeding. Which mechanism explains this interaction?
A. Amiodarone induces CYP2C9, increasing warfarin metabolism
B. Amiodarone inhibits CYP2C9 and CYP1A2, reducing S-warfarin clearance [CORRECT]
C. Amiodarone displaces warfarin from albumin binding sites
D. Amiodarone increases vitamin K absorption
Correct Answer: B
Rationale:
• Amiodarone is a potent inhibitor of multiple CYP450 enzymes including CYP2C9 and
CYP1A2
• S-warfarin (2-5x more potent than R-warfarin) is metabolized primarily by CYP2C9
• FDA guidelines recommend reducing warfarin dose by 30-50% when initiating
amiodarone
• The interaction has a delayed onset (1-2 weeks) due to amiodarone's long half-life (40-
55 days)
Q4: A 28-year-old pregnant patient (32 weeks gestation) requires treatment for community-
acquired pneumonia. Which antibiotic requires dose adjustment due to altered
pharmacokinetics in pregnancy?
A. Azithromycin 500 mg daily
B. Ceftriaxone 1g IV daily
C. Piperacillin-tazobactam 3.375g IV q6h [CORRECT]
D. Doxycycline 100 mg BID
Correct Answer: C
, Rationale:
• Pregnancy increases GFR by 40-50%, increasing renal clearance of hydrophilic drugs
• Piperacillin is primarily renally eliminated and requires more frequent dosing (q4-6h vs
q6-8h) in pregnancy
• Azithromycin has minimal renal clearance; ceftriaxone dose is unchanged for pneumonia
• Doxycycline is contraindicated in pregnancy (teratogenic), not merely dose-adjusted
Q5: A patient with metastatic breast cancer receiving paclitaxel develops severe peripheral
neuropathy. Genetic testing reveals a CYP2C8*3 variant. Which statement best describes this
pharmacogenomic finding?
A. The patient is a rapid metabolizer requiring dose escalation
B. Reduced paclitaxel metabolism increases neurotoxicity risk [CORRECT]
C. The variant affects paclitaxel protein binding
D. CYP2C8 variants have no clinical significance for taxane therapy
Correct Answer: B
Rationale:
• CYP2C8 is the primary enzyme metabolizing paclitaxel
• The *3 variant (R139K, K399R) reduces enzyme activity, increasing drug exposure
• Per 2025 CPIC guidelines, CYP2C8 poor metabolizers have 2-3x increased risk of grade ≥3
neuropathy
• Dose reduction or alternative taxanes (docetaxel - less CYP2C8 dependent) should be
considered
Q6: A 55-year-old with cirrhosis (Child-Pugh Class C) requires analgesia post-operatively. Which
opioid requires the most significant dose reduction due to altered pharmacokinetics?
A. Morphine [CORRECT]
B. Fentanyl
C. Oxycodone
D. Hydromorphone
Correct Answer: A
