MVU NURS 629 EXAM 4 COMPLETE SOLUTION 2026/2027 |
Advanced Pharmacology | 75 Questions | 6 Core Domains |
Mountain View University Graduate Nursing | A+ Verified |
Pass Guaranteed
Domain 1: Principles of Pharmacokinetics, Pharmacodynamics, and Therapeutic Drug
Monitoring (Questions 1-12)
Q1: A 68-year-old male with heart failure is prescribed lisinopril 10 mg daily and
furosemide 40 mg daily. After 1 week, his serum creatinine increased from 1.2 mg/dL to
2.1 mg/dL, and BUN rose from 18 mg/dL to 35 mg/dL. His blood pressure is 98/62
mmHg, and he reports dizziness upon standing. Which
pharmacokinetic/pharmacodynamic principle best explains this clinical scenario?
A. Lisinopril inhibits cytochrome P450 3A4, causing furosemide accumulation and
nephrotoxicity
B. The combination creates a synergistic hypotensive effect, reducing renal perfusion
and causing prerenal azotemia [CORRECT]
C. Furosemide increases lisinopril bioavailability through reduced first-pass metabolism
D. Lisinopril induces P-glycoprotein, reducing furosemide renal clearance
Correct Answer: B
Rationale: This scenario demonstrates synergistic pharmacodynamic interaction
between ACE inhibitors and loop diuretics. Both drugs lower blood pressure through
different mechanisms: lisinopril inhibits angiotensin II formation (reducing afterload and
aldosterone-mediated sodium retention), while furosemide inhibits the Na-K-2Cl
cotransporter in the thick ascending loop of Henle. The combined effect can cause
excessive hypotension, particularly orthostatic hypotension in elderly patients with
,reduced baroreceptor sensitivity. Reduced renal perfusion pressure leads to prerenal
azotemia (elevated BUN:creatinine ratio >20:1, here approximately 17:1 but trending
upward, with BUN rising disproportionately).
Distractor Analysis: Option A is incorrect because lisinopril is not a CYP3A4 inhibitor; it
is primarily excreted unchanged and does not significantly affect hepatic metabolism.
ACE inhibitors can cause acute kidney injury through hemodynamic mechanisms, not
CYP inhibition. Option C is incorrect because furosemide does not affect lisinopril's
first-pass metabolism; lisinopril is a prodrug converted to active form in the liver, but
furosemide doesn't alter this process. Option D is incorrect because lisinopril does not
induce P-glycoprotein; this transporter affects drugs like digoxin and certain
chemotherapeutics, not furosemide which is filtered and secreted in the proximal tubule
via organic anion transporters.
Clinical Action: Hold the next dose, assess volume status, consider reducing furosemide
dose or holding if hypovolemic, monitor renal function closely, and restart at lower
doses with slower titration once stabilized.
Q2: A 45-year-old female with epilepsy has been seizure-free on phenytoin 300 mg daily
for 5 years. Her recent phenytoin level is 18 mcg/mL (therapeutic range 10-20 mcg/mL).
She is started on oral contraceptives containing ethinyl estradiol and norethindrone. Six
weeks later, she reports increased seizure frequency and her phenytoin level is 12
mcg/mL. Which mechanism explains this change?
A. Oral contraceptives inhibit phenytoin metabolism through CYP2C9 inhibition
B. Phenytoin induces hepatic enzymes that increase contraceptive metabolism, leading
to reciprocal autoinduction of its own metabolism
C. Estrogen induces CYP1A2 and CYP3A4, increasing phenytoin clearance [CORRECT]
D. Progestin competes with phenytoin for albumin binding, increasing free phenytoin
fraction
,Correct Answer: C
Rationale: Estrogen-containing oral contraceptives are known inducers of hepatic
cytochrome P450 enzymes, particularly CYP1A2 and CYP3A4. Phenytoin is metabolized
primarily by CYP2C9 and CYP2C19, but CYP3A4 also contributes to its metabolism.
Estrogen induction increases hepatic metabolic capacity, leading to increased clearance
of phenytoin and decreased serum concentrations. This is a pharmacokinetic
interaction at the metabolic level. The patient now has subtherapeutic phenytoin levels
(12 mcg/mL is borderline low, and with breakthrough seizures, likely insufficient for her
individual therapeutic need), explaining the increased seizure frequency.
Distractor Analysis: Option A is incorrect because oral contraceptives do not inhibit
phenytoin metabolism; they induce it. Option B is incorrect because while phenytoin is
an enzyme inducer, it does not cause "reciprocal autoinduction" in this context. The
interaction is unidirectional: contraceptives induce phenytoin metabolism, not vice versa
in a feedback loop. Additionally, phenytoin's autoinduction occurs early in therapy (first
2-4 weeks), not after 5 years. Option D is incorrect because progestin does not
significantly compete with phenytoin for albumin binding sites; phenytoin is highly
protein-bound (90%), but displacement by progestin is not clinically significant, and
increased free fraction would increase metabolism/elimination, not decrease total
levels.
Clinical Action: Increase phenytoin dose by 25-30%, monitor levels in 2-4 weeks,
consider alternative contraception (progestin-only or non-hormonal methods), and
counsel patient on breakthrough seizure precautions.
Q3: [Select-All-That-Apply] A 72-year-old female with atrial fibrillation on warfarin (INR
stable at 2.5) is started on amiodarone for rhythm control. Which parameters require
monitoring due to this drug interaction? (Select all that apply)
, A. INR should be monitored within 3-5 days of starting amiodarone [CORRECT]
B. Thyroid function tests should be checked at baseline and every 6 months [CORRECT]
C. Liver function tests should be monitored monthly for the first 3 months [CORRECT]
D. Digoxin levels should be checked even if the patient is not taking digoxin
E. QTc interval should be assessed on ECG at baseline and after dose changes
[CORRECT]
F. Potassium levels should be monitored weekly for the first month
Correct Answer: A, B, C, E
Rationale: Amiodarone-warfarin interaction occurs through multiple mechanisms:
amiodarone inhibits CYP2C9 (primary warfarin metabolic pathway) and CYP3A4, and
displaces warfarin from protein binding sites. This increases warfarin levels and INR
significantly within 3-5 days, requiring close monitoring. Amiodarone contains iodine
(37% by weight) and causes thyroid dysfunction in 15-20% of patients—both
hypothyroidism (more common) and hyperthyroidism—requiring baseline TSH and
periodic monitoring. Hepatotoxicity occurs in 1-3% of patients, with hepatocellular
necrosis possible; monitoring LFTs at baseline, monthly for 3 months, then periodically
is standard. Amiodarone prolongs QTc (class III antiarrhythmic effect), increasing
torsades de pointes risk; baseline ECG and monitoring after dose changes are essential.
Why Incorrect: Option D is incorrect because digoxin level monitoring is only required if
the patient is actually taking digoxin. While amiodarone does increase digoxin levels (by
reducing clearance and volume of distribution), this patient is not on digoxin, making
this monitoring irrelevant. Option F is incorrect because while electrolyte monitoring is
important with antiarrhythmics, weekly potassium monitoring for a month is excessive
unless the patient is on diuretics or has renal dysfunction; standard monitoring is at
baseline and periodically.
Q4: A 55-year-old male with type 2 diabetes, BMI 34, and eGFR 45 mL/min/1.73m² is
started on metformin 1000 mg twice daily. Three days later, he presents with severe
Advanced Pharmacology | 75 Questions | 6 Core Domains |
Mountain View University Graduate Nursing | A+ Verified |
Pass Guaranteed
Domain 1: Principles of Pharmacokinetics, Pharmacodynamics, and Therapeutic Drug
Monitoring (Questions 1-12)
Q1: A 68-year-old male with heart failure is prescribed lisinopril 10 mg daily and
furosemide 40 mg daily. After 1 week, his serum creatinine increased from 1.2 mg/dL to
2.1 mg/dL, and BUN rose from 18 mg/dL to 35 mg/dL. His blood pressure is 98/62
mmHg, and he reports dizziness upon standing. Which
pharmacokinetic/pharmacodynamic principle best explains this clinical scenario?
A. Lisinopril inhibits cytochrome P450 3A4, causing furosemide accumulation and
nephrotoxicity
B. The combination creates a synergistic hypotensive effect, reducing renal perfusion
and causing prerenal azotemia [CORRECT]
C. Furosemide increases lisinopril bioavailability through reduced first-pass metabolism
D. Lisinopril induces P-glycoprotein, reducing furosemide renal clearance
Correct Answer: B
Rationale: This scenario demonstrates synergistic pharmacodynamic interaction
between ACE inhibitors and loop diuretics. Both drugs lower blood pressure through
different mechanisms: lisinopril inhibits angiotensin II formation (reducing afterload and
aldosterone-mediated sodium retention), while furosemide inhibits the Na-K-2Cl
cotransporter in the thick ascending loop of Henle. The combined effect can cause
excessive hypotension, particularly orthostatic hypotension in elderly patients with
,reduced baroreceptor sensitivity. Reduced renal perfusion pressure leads to prerenal
azotemia (elevated BUN:creatinine ratio >20:1, here approximately 17:1 but trending
upward, with BUN rising disproportionately).
Distractor Analysis: Option A is incorrect because lisinopril is not a CYP3A4 inhibitor; it
is primarily excreted unchanged and does not significantly affect hepatic metabolism.
ACE inhibitors can cause acute kidney injury through hemodynamic mechanisms, not
CYP inhibition. Option C is incorrect because furosemide does not affect lisinopril's
first-pass metabolism; lisinopril is a prodrug converted to active form in the liver, but
furosemide doesn't alter this process. Option D is incorrect because lisinopril does not
induce P-glycoprotein; this transporter affects drugs like digoxin and certain
chemotherapeutics, not furosemide which is filtered and secreted in the proximal tubule
via organic anion transporters.
Clinical Action: Hold the next dose, assess volume status, consider reducing furosemide
dose or holding if hypovolemic, monitor renal function closely, and restart at lower
doses with slower titration once stabilized.
Q2: A 45-year-old female with epilepsy has been seizure-free on phenytoin 300 mg daily
for 5 years. Her recent phenytoin level is 18 mcg/mL (therapeutic range 10-20 mcg/mL).
She is started on oral contraceptives containing ethinyl estradiol and norethindrone. Six
weeks later, she reports increased seizure frequency and her phenytoin level is 12
mcg/mL. Which mechanism explains this change?
A. Oral contraceptives inhibit phenytoin metabolism through CYP2C9 inhibition
B. Phenytoin induces hepatic enzymes that increase contraceptive metabolism, leading
to reciprocal autoinduction of its own metabolism
C. Estrogen induces CYP1A2 and CYP3A4, increasing phenytoin clearance [CORRECT]
D. Progestin competes with phenytoin for albumin binding, increasing free phenytoin
fraction
,Correct Answer: C
Rationale: Estrogen-containing oral contraceptives are known inducers of hepatic
cytochrome P450 enzymes, particularly CYP1A2 and CYP3A4. Phenytoin is metabolized
primarily by CYP2C9 and CYP2C19, but CYP3A4 also contributes to its metabolism.
Estrogen induction increases hepatic metabolic capacity, leading to increased clearance
of phenytoin and decreased serum concentrations. This is a pharmacokinetic
interaction at the metabolic level. The patient now has subtherapeutic phenytoin levels
(12 mcg/mL is borderline low, and with breakthrough seizures, likely insufficient for her
individual therapeutic need), explaining the increased seizure frequency.
Distractor Analysis: Option A is incorrect because oral contraceptives do not inhibit
phenytoin metabolism; they induce it. Option B is incorrect because while phenytoin is
an enzyme inducer, it does not cause "reciprocal autoinduction" in this context. The
interaction is unidirectional: contraceptives induce phenytoin metabolism, not vice versa
in a feedback loop. Additionally, phenytoin's autoinduction occurs early in therapy (first
2-4 weeks), not after 5 years. Option D is incorrect because progestin does not
significantly compete with phenytoin for albumin binding sites; phenytoin is highly
protein-bound (90%), but displacement by progestin is not clinically significant, and
increased free fraction would increase metabolism/elimination, not decrease total
levels.
Clinical Action: Increase phenytoin dose by 25-30%, monitor levels in 2-4 weeks,
consider alternative contraception (progestin-only or non-hormonal methods), and
counsel patient on breakthrough seizure precautions.
Q3: [Select-All-That-Apply] A 72-year-old female with atrial fibrillation on warfarin (INR
stable at 2.5) is started on amiodarone for rhythm control. Which parameters require
monitoring due to this drug interaction? (Select all that apply)
, A. INR should be monitored within 3-5 days of starting amiodarone [CORRECT]
B. Thyroid function tests should be checked at baseline and every 6 months [CORRECT]
C. Liver function tests should be monitored monthly for the first 3 months [CORRECT]
D. Digoxin levels should be checked even if the patient is not taking digoxin
E. QTc interval should be assessed on ECG at baseline and after dose changes
[CORRECT]
F. Potassium levels should be monitored weekly for the first month
Correct Answer: A, B, C, E
Rationale: Amiodarone-warfarin interaction occurs through multiple mechanisms:
amiodarone inhibits CYP2C9 (primary warfarin metabolic pathway) and CYP3A4, and
displaces warfarin from protein binding sites. This increases warfarin levels and INR
significantly within 3-5 days, requiring close monitoring. Amiodarone contains iodine
(37% by weight) and causes thyroid dysfunction in 15-20% of patients—both
hypothyroidism (more common) and hyperthyroidism—requiring baseline TSH and
periodic monitoring. Hepatotoxicity occurs in 1-3% of patients, with hepatocellular
necrosis possible; monitoring LFTs at baseline, monthly for 3 months, then periodically
is standard. Amiodarone prolongs QTc (class III antiarrhythmic effect), increasing
torsades de pointes risk; baseline ECG and monitoring after dose changes are essential.
Why Incorrect: Option D is incorrect because digoxin level monitoring is only required if
the patient is actually taking digoxin. While amiodarone does increase digoxin levels (by
reducing clearance and volume of distribution), this patient is not on digoxin, making
this monitoring irrelevant. Option F is incorrect because while electrolyte monitoring is
important with antiarrhythmics, weekly potassium monitoring for a month is excessive
unless the patient is on diuretics or has renal dysfunction; standard monitoring is at
baseline and periodically.
Q4: A 55-year-old male with type 2 diabetes, BMI 34, and eGFR 45 mL/min/1.73m² is
started on metformin 1000 mg twice daily. Three days later, he presents with severe
