DAVIS'S DRUG GUIDE FOR NURSES
19TH EDITION
• AUTHOR(S)APRIL HAZARD
VALLERAND; CYNTHIA SANOSKI
TEST BANK
1
Drug Reference
Warfarin — Vitamin K antagonist — Pharmacogenomics &
Special Dosing Considerations
Clinical stem
A 55-year-old man with new atrial fibrillation is started on
warfarin. His chart contains a pharmacogenomic report showing
VKORC1 and CYP2C9 variants associated with increased
warfarin sensitivity. Which nursing action is most appropriate
when administering the initial doses?
A. Administer standard starting dose and schedule INR in 7
days.
B. Question/hold standard dose and notify prescriber to
,consider a lower starting dose with earlier INR monitoring.
C. Give a loading dose of warfarin to reach therapeutic
anticoagulation faster.
D. Start standard dose and add low-molecular-weight heparin
without additional INR checks.
Correct answer: B
Rationale (correct)
With VKORC1 and CYP2C9 variants the patient is likely more
sensitive to warfarin; anticipating a lower maintenance dose
and earlier INR checks reduces bleeding risk. Nursing
implication: notify prescriber and arrange more frequent INR
monitoring per drug-guide pharmacogenomics guidance.
Rationale (incorrect)
A. Standard dosing risks over-anticoagulation in genetically
sensitive patients and delayed INR checking increases bleeding
risk.
C. Loading doses increase early bleeding risk in sensitive
genotypes — inappropriate without personalized dosing.
D. Adding heparin without adjusting warfarin or monitoring
INRs may create overlapping anticoagulation risk and is not a
safe nursing action.
Teaching point:
Genetic variants may require lower warfarin doses and earlier
INR monitoring.
,Citation:
Vallerand, A. H., & Sanoski, C. (2025). Davis's Drug Guide for
Nurses (19th ed.). [Pharmacogenomics].
2
Drug Reference
Clopidogrel — P2Y₁₂ ADP receptor inhibitor — Drug Interactions
& The Cytochrome P450 System
Clinical stem
A 62-year-old woman on clopidogrel for recent stent placement
reports that her primary care provider started omeprazole for
GERD three days ago. She asks whether she should take both.
What is the nurse’s best response/action?
A. Instruct the patient to stop clopidogrel immediately and
continue omeprazole.
B. Explain a possible interaction and notify the prescriber to
consider alternative acid suppression (e.g., H₂ blocker) or
alternate PPI, and reinforce adherence until prescriber
responds.
C. Advise taking omeprazole in the morning and clopidogrel at
night to avoid interaction.
D. Tell the patient there is no interaction; continue both as
ordered.
Correct answer: B
, Rationale (correct)
Omeprazole (a CYP2C19 inhibitor) can reduce clopidogrel
activation and efficacy; nursing best practice is to inform
prescriber and consider alternatives rather than unilaterally
stopping therapy. Reinforce adherence while prescriber
evaluates risk.
Rationale (incorrect)
A. Stopping antiplatelet therapy without prescriber approval
risks stent thrombosis.
C. Timing changes do not eliminate CYP-mediated interaction—
this is pharmacokinetic, not timing dependent.
D. There is evidence of interaction; dismissing it ignores risk of
reduced antiplatelet effect.
Teaching point:
CYP2C19 inhibitors (some PPIs) may reduce clopidogrel
activation—consult prescriber.
Citation:
Vallerand, A. H., & Sanoski, C. (2025). Davis's Drug Guide for
Nurses (19th ed.). [Drug Interactions; CYP450].
3
Drug Reference
Insulin (regular/rapid-acting) — Antidiabetic — Medication
Errors: Improving Practices & Patient Education
19TH EDITION
• AUTHOR(S)APRIL HAZARD
VALLERAND; CYNTHIA SANOSKI
TEST BANK
1
Drug Reference
Warfarin — Vitamin K antagonist — Pharmacogenomics &
Special Dosing Considerations
Clinical stem
A 55-year-old man with new atrial fibrillation is started on
warfarin. His chart contains a pharmacogenomic report showing
VKORC1 and CYP2C9 variants associated with increased
warfarin sensitivity. Which nursing action is most appropriate
when administering the initial doses?
A. Administer standard starting dose and schedule INR in 7
days.
B. Question/hold standard dose and notify prescriber to
,consider a lower starting dose with earlier INR monitoring.
C. Give a loading dose of warfarin to reach therapeutic
anticoagulation faster.
D. Start standard dose and add low-molecular-weight heparin
without additional INR checks.
Correct answer: B
Rationale (correct)
With VKORC1 and CYP2C9 variants the patient is likely more
sensitive to warfarin; anticipating a lower maintenance dose
and earlier INR checks reduces bleeding risk. Nursing
implication: notify prescriber and arrange more frequent INR
monitoring per drug-guide pharmacogenomics guidance.
Rationale (incorrect)
A. Standard dosing risks over-anticoagulation in genetically
sensitive patients and delayed INR checking increases bleeding
risk.
C. Loading doses increase early bleeding risk in sensitive
genotypes — inappropriate without personalized dosing.
D. Adding heparin without adjusting warfarin or monitoring
INRs may create overlapping anticoagulation risk and is not a
safe nursing action.
Teaching point:
Genetic variants may require lower warfarin doses and earlier
INR monitoring.
,Citation:
Vallerand, A. H., & Sanoski, C. (2025). Davis's Drug Guide for
Nurses (19th ed.). [Pharmacogenomics].
2
Drug Reference
Clopidogrel — P2Y₁₂ ADP receptor inhibitor — Drug Interactions
& The Cytochrome P450 System
Clinical stem
A 62-year-old woman on clopidogrel for recent stent placement
reports that her primary care provider started omeprazole for
GERD three days ago. She asks whether she should take both.
What is the nurse’s best response/action?
A. Instruct the patient to stop clopidogrel immediately and
continue omeprazole.
B. Explain a possible interaction and notify the prescriber to
consider alternative acid suppression (e.g., H₂ blocker) or
alternate PPI, and reinforce adherence until prescriber
responds.
C. Advise taking omeprazole in the morning and clopidogrel at
night to avoid interaction.
D. Tell the patient there is no interaction; continue both as
ordered.
Correct answer: B
, Rationale (correct)
Omeprazole (a CYP2C19 inhibitor) can reduce clopidogrel
activation and efficacy; nursing best practice is to inform
prescriber and consider alternatives rather than unilaterally
stopping therapy. Reinforce adherence while prescriber
evaluates risk.
Rationale (incorrect)
A. Stopping antiplatelet therapy without prescriber approval
risks stent thrombosis.
C. Timing changes do not eliminate CYP-mediated interaction—
this is pharmacokinetic, not timing dependent.
D. There is evidence of interaction; dismissing it ignores risk of
reduced antiplatelet effect.
Teaching point:
CYP2C19 inhibitors (some PPIs) may reduce clopidogrel
activation—consult prescriber.
Citation:
Vallerand, A. H., & Sanoski, C. (2025). Davis's Drug Guide for
Nurses (19th ed.). [Drug Interactions; CYP450].
3
Drug Reference
Insulin (regular/rapid-acting) — Antidiabetic — Medication
Errors: Improving Practices & Patient Education
