NR 565 ADVANCED PHARMACOLOGY FINAL EXAM REVIEW
2026/2027 | Latest Highly Rated Guide | Chamberlain College
| Pass Guaranteed - A+ Graded
Unit 1: Pharmacokinetics & Pharmacodynamics (15 Questions)
Q1: A 68-year-old male with heart failure and renal impairment (CrCl 35 mL/min) is
prescribed digoxin 0.25 mg daily. His serum digoxin level after 5 days is 2.8 ng/mL
(therapeutic 0.5-0.9 ng/mL for heart failure). He reports nausea and visual disturbances.
Which pharmacokinetic principle best explains this toxicity?
A. Increased volume of distribution in elderly patients
B. Decreased renal elimination prolonging half-life and causing accumulation
[CORRECT]
C. Increased hepatic metabolism due to enzyme induction
D. Increased protein binding in renal impairment
Correct Answer: B
Rationale: Digoxin is primarily eliminated unchanged by the kidneys (60-80%). In renal
impairment (CrCl 35 mL/min), elimination is significantly reduced, prolonging the
half-life from 36-48 hours (normal) to 3.5-5 days. Steady state, achieved in 4-5 half-lives,
takes 2-3 weeks in this patient instead of 1 week. The maintenance dose should be
reduced by 50% when CrCl is 30-50 mL/min. The narrow therapeutic index (0.5-0.9
,ng/mL for heart failure, higher for atrial fibrillation) makes accumulation dangerous.
Symptoms (nausea, visual changes—yellow-green halos) are classic for digoxin toxicity.
Distractor Analysis:
● A (Increased Vd): Digoxin Vd actually decreases in renal impairment due to
reduced tissue binding; this would increase serum concentration but is not the
primary mechanism of toxicity.
● C (Hepatic metabolism): Digoxin is not significantly metabolized by the liver;
enzyme induction does not affect its clearance.
● D (Increased protein binding): Digoxin is only 20-30% protein bound; renal
impairment does not significantly alter protein binding.
Q2: A 45-year-old female requires treatment with a drug that has a half-life of 8 hours.
She needs to achieve therapeutic levels rapidly. Which loading dose strategy is most
appropriate?
A. Give the maintenance dose every 8 hours until steady state is achieved
B. Calculate loading dose using the formula: LD = Vd × Cp(target), then begin
maintenance dose [CORRECT]
C. Double the maintenance dose for the first 24 hours only
D. Give the drug by continuous infusion at twice the standard rate for 24 hours
Correct Answer: B
Rationale: The loading dose (LD) formula LD = Vd × Cp(target) calculates the dose
needed to achieve target plasma concentration (Cp) immediately, accounting for the
drug's volume of distribution (Vd). This is essential for drugs with long half-lives (e.g.,
,digoxin, amiodarone, lidocaine) where waiting 4-5 half-lives (32-40 hours for this drug)
to reach steady state would delay therapeutic effect. After the loading dose, the
maintenance dose (MD = CL × Css) maintains the concentration. This approach avoids
toxicity from arbitrary dose doubling while achieving rapid therapeutic levels.
Distractor Analysis:
● A (Maintenance only): Would take 4-5 half-lives (32-40 hours) to reach 97% of
steady state; unacceptable delay for serious conditions.
● C (Double dose): Arbitrary doubling does not account for pharmacokinetic
parameters; risks toxicity without guaranteeing target concentration.
● D (Continuous infusion): Still requires 4-5 half-lives to reach steady state;
doubling rate temporarily overshoots target then requires adjustment.
Q3: A patient on warfarin (highly protein-bound, 99%) is started on phenytoin (also
highly protein-bound, 90%). After 1 week, the patient's INR decreases despite stable
warfarin dose. Which mechanism explains this interaction?
A. Phenytoin inhibits warfarin metabolism by CYP2C9
B. Phenytoin displaces warfarin from albumin binding sites, increasing free warfarin
clearance [CORRECT]
C. Phenytoin induces CYP1A2, increasing warfarin metabolism
D. Phenytoin decreases warfarin absorption from the GI tract
Correct Answer: B
Rationale: This is a classic example of protein binding displacement. Phenytoin
displaces warfarin from albumin binding sites, transiently increasing free (active)
, warfarin. However, free drug is available for metabolism and excretion, so clearance
increases and total drug concentration decreases. The net effect is decreased INR
despite increased free fraction transiently. Importantly, the free concentration eventually
normalizes, but total concentration remains lower. This interaction is less clinically
significant than enzyme induction (phenytoin also induces CYP2C9, which would
increase warfarin metabolism over days-weeks), but the question describes the acute
protein displacement effect.
Distractor Analysis:
● A (CYP2C9 inhibition): Phenytoin is an inducer, not inhibitor, of CYP2C9; would
increase, not decrease, INR if inhibition occurred.
● C (CYP1A2 induction): Warfarin is metabolized primarily by CYP2C9 (S-warfarin)
and CYP1A2/CYP3A4 (R-warfarin); induction would decrease INR but the
mechanism described is protein binding displacement, not metabolism.
● D (Decreased absorption): No interaction at absorption level; both drugs have
excellent oral bioavailability.
Q4: A 72-year-old male with liver cirrhosis (Child-Pugh Class B) requires analgesia.
Which opioid requires the most significant dose reduction due to altered
pharmacokinetics?
A. Morphine (high hepatic extraction, active metabolites)
B. Fentanyl (high hepatic extraction, no active metabolites)
C. Hydromorphone (intermediate hepatic extraction, no active metabolites)
D. Oxycodone (intermediate hepatic extraction, active metabolites) [CORRECT]
Correct Answer: D
2026/2027 | Latest Highly Rated Guide | Chamberlain College
| Pass Guaranteed - A+ Graded
Unit 1: Pharmacokinetics & Pharmacodynamics (15 Questions)
Q1: A 68-year-old male with heart failure and renal impairment (CrCl 35 mL/min) is
prescribed digoxin 0.25 mg daily. His serum digoxin level after 5 days is 2.8 ng/mL
(therapeutic 0.5-0.9 ng/mL for heart failure). He reports nausea and visual disturbances.
Which pharmacokinetic principle best explains this toxicity?
A. Increased volume of distribution in elderly patients
B. Decreased renal elimination prolonging half-life and causing accumulation
[CORRECT]
C. Increased hepatic metabolism due to enzyme induction
D. Increased protein binding in renal impairment
Correct Answer: B
Rationale: Digoxin is primarily eliminated unchanged by the kidneys (60-80%). In renal
impairment (CrCl 35 mL/min), elimination is significantly reduced, prolonging the
half-life from 36-48 hours (normal) to 3.5-5 days. Steady state, achieved in 4-5 half-lives,
takes 2-3 weeks in this patient instead of 1 week. The maintenance dose should be
reduced by 50% when CrCl is 30-50 mL/min. The narrow therapeutic index (0.5-0.9
,ng/mL for heart failure, higher for atrial fibrillation) makes accumulation dangerous.
Symptoms (nausea, visual changes—yellow-green halos) are classic for digoxin toxicity.
Distractor Analysis:
● A (Increased Vd): Digoxin Vd actually decreases in renal impairment due to
reduced tissue binding; this would increase serum concentration but is not the
primary mechanism of toxicity.
● C (Hepatic metabolism): Digoxin is not significantly metabolized by the liver;
enzyme induction does not affect its clearance.
● D (Increased protein binding): Digoxin is only 20-30% protein bound; renal
impairment does not significantly alter protein binding.
Q2: A 45-year-old female requires treatment with a drug that has a half-life of 8 hours.
She needs to achieve therapeutic levels rapidly. Which loading dose strategy is most
appropriate?
A. Give the maintenance dose every 8 hours until steady state is achieved
B. Calculate loading dose using the formula: LD = Vd × Cp(target), then begin
maintenance dose [CORRECT]
C. Double the maintenance dose for the first 24 hours only
D. Give the drug by continuous infusion at twice the standard rate for 24 hours
Correct Answer: B
Rationale: The loading dose (LD) formula LD = Vd × Cp(target) calculates the dose
needed to achieve target plasma concentration (Cp) immediately, accounting for the
drug's volume of distribution (Vd). This is essential for drugs with long half-lives (e.g.,
,digoxin, amiodarone, lidocaine) where waiting 4-5 half-lives (32-40 hours for this drug)
to reach steady state would delay therapeutic effect. After the loading dose, the
maintenance dose (MD = CL × Css) maintains the concentration. This approach avoids
toxicity from arbitrary dose doubling while achieving rapid therapeutic levels.
Distractor Analysis:
● A (Maintenance only): Would take 4-5 half-lives (32-40 hours) to reach 97% of
steady state; unacceptable delay for serious conditions.
● C (Double dose): Arbitrary doubling does not account for pharmacokinetic
parameters; risks toxicity without guaranteeing target concentration.
● D (Continuous infusion): Still requires 4-5 half-lives to reach steady state;
doubling rate temporarily overshoots target then requires adjustment.
Q3: A patient on warfarin (highly protein-bound, 99%) is started on phenytoin (also
highly protein-bound, 90%). After 1 week, the patient's INR decreases despite stable
warfarin dose. Which mechanism explains this interaction?
A. Phenytoin inhibits warfarin metabolism by CYP2C9
B. Phenytoin displaces warfarin from albumin binding sites, increasing free warfarin
clearance [CORRECT]
C. Phenytoin induces CYP1A2, increasing warfarin metabolism
D. Phenytoin decreases warfarin absorption from the GI tract
Correct Answer: B
Rationale: This is a classic example of protein binding displacement. Phenytoin
displaces warfarin from albumin binding sites, transiently increasing free (active)
, warfarin. However, free drug is available for metabolism and excretion, so clearance
increases and total drug concentration decreases. The net effect is decreased INR
despite increased free fraction transiently. Importantly, the free concentration eventually
normalizes, but total concentration remains lower. This interaction is less clinically
significant than enzyme induction (phenytoin also induces CYP2C9, which would
increase warfarin metabolism over days-weeks), but the question describes the acute
protein displacement effect.
Distractor Analysis:
● A (CYP2C9 inhibition): Phenytoin is an inducer, not inhibitor, of CYP2C9; would
increase, not decrease, INR if inhibition occurred.
● C (CYP1A2 induction): Warfarin is metabolized primarily by CYP2C9 (S-warfarin)
and CYP1A2/CYP3A4 (R-warfarin); induction would decrease INR but the
mechanism described is protein binding displacement, not metabolism.
● D (Decreased absorption): No interaction at absorption level; both drugs have
excellent oral bioavailability.
Q4: A 72-year-old male with liver cirrhosis (Child-Pugh Class B) requires analgesia.
Which opioid requires the most significant dose reduction due to altered
pharmacokinetics?
A. Morphine (high hepatic extraction, active metabolites)
B. Fentanyl (high hepatic extraction, no active metabolites)
C. Hydromorphone (intermediate hepatic extraction, no active metabolites)
D. Oxycodone (intermediate hepatic extraction, active metabolites) [CORRECT]
Correct Answer: D
