DAVIS'S DRUG GUIDE FOR NURSES
19TH EDITION
• AUTHOR(S)APRIL HAZARD
VALLERAND; CYNTHIA SANOSKI
TEST BANK
1)
Drug Reference
Warfarin — Vitamin K antagonist anticoagulant —
Pharmacogenomics & Nursing Implications (Monitoring)
Clinical stem
A 68-year-old man with new deep vein thrombosis is prescribed
warfarin 5 mg PO nightly. Current meds: amiodarone (chronic),
TMP-SMX started yesterday for UTI. Baseline INR 1.1; renal
function normal. Which nursing action is best before
administering the first dose of warfarin?
A. Give the 5 mg dose as ordered and obtain INR in 3 days.
B. Hold the dose, notify prescriber about interacting drugs, and
,request INR today.
C. Administer 2.5 mg instead and schedule INR in 7 days.
D. Give 5 mg and schedule vitamin K on standby if INR rises.
Correct answer: B
Rationale — Correct (B)
Holding and notifying the prescriber recognizes significant
drug–drug interactions (amiodarone and TMP-SMX increase
warfarin effect via CYP2C9 inhibition) and the need for
immediate INR monitoring prior to dosing. This prevents
overshoot of anticoagulation and bleeding in line with drug-
guide monitoring recommendations.
Rationale — Incorrect
A. Unsafe — giving full dose without checking INR or addressing
interactions risks major bleeding.
C. Giving a reduced empiric dose without consulting prescriber
still ignores interactions and lacks baseline INR follow-up.
D. Scheduling vitamin K “on standby” is not a substitution for
prevention and immediate INR evaluation; reactive
management is lower priority.
Teaching point:
Check INR and address interacting meds before initial warfarin
dosing.
Citation:
Vallerand, A. H., & Sanoski, C. (2025). Davis's Drug Guide for
,Nurses (19th ed.). [Warfarin — Pharmacogenomics &
Monitoring].
2)
Drug Reference
Clopidogrel — P2Y12 platelet inhibitor (prodrug) —
Pharmacogenomics & Patient/Family Teaching
Clinical stem
A 56-year-old woman is started on clopidogrel after PCI. She
reports recently having genetic testing showing reduced
CYP2C19 activity. Which nursing intervention is most
appropriate?
A. Reinforce clopidogrel adherence and proceed—no change
needed.
B. Document the finding and ask prescriber if alternative
antiplatelet therapy is indicated.
C. Advise doubling the clopidogrel dose to overcome reduced
activation.
D. Hold clopidogrel and substitute aspirin monotherapy.
Correct answer: B
Rationale — Correct (B)
Reduced CYP2C19 decreases conversion of clopidogrel to its
active metabolite, reducing effectiveness; the nurse should
notify the prescriber so an alternative (e.g.,
, ticagrelor/prasugrel) can be considered per pharmacogenomic
guidance in the drug guide.
Rationale — Incorrect
A. Unsafe — ignoring genotype could risk stent thrombosis.
C. Doubling dose is unsupported and may increase bleeding
without ensuring activation.
D. Substituting aspirin alone is not prescriber-directed and may
provide insufficient antiplatelet effect post-PCI.
Teaching point:
Report reduced CYP2C19 activity—alternative P2Y12 agents
may be needed.
Citation:
Vallerand, A. H., & Sanoski, C. (2025). Davis's Drug Guide for
Nurses (19th ed.). [Clopidogrel — Pharmacogenomics &
Teaching].
3)
Drug Reference
Codeine — Opioid analgesic (CYP2D6 substrate) — Adverse
Reactions & Pharmacogenomics
Clinical stem
A 10-year-old girl with recent tonsillectomy has been prescribed
codeine for pain. Her parent asks about testing for codeine
safety. Which nursing action best addresses safety?
19TH EDITION
• AUTHOR(S)APRIL HAZARD
VALLERAND; CYNTHIA SANOSKI
TEST BANK
1)
Drug Reference
Warfarin — Vitamin K antagonist anticoagulant —
Pharmacogenomics & Nursing Implications (Monitoring)
Clinical stem
A 68-year-old man with new deep vein thrombosis is prescribed
warfarin 5 mg PO nightly. Current meds: amiodarone (chronic),
TMP-SMX started yesterday for UTI. Baseline INR 1.1; renal
function normal. Which nursing action is best before
administering the first dose of warfarin?
A. Give the 5 mg dose as ordered and obtain INR in 3 days.
B. Hold the dose, notify prescriber about interacting drugs, and
,request INR today.
C. Administer 2.5 mg instead and schedule INR in 7 days.
D. Give 5 mg and schedule vitamin K on standby if INR rises.
Correct answer: B
Rationale — Correct (B)
Holding and notifying the prescriber recognizes significant
drug–drug interactions (amiodarone and TMP-SMX increase
warfarin effect via CYP2C9 inhibition) and the need for
immediate INR monitoring prior to dosing. This prevents
overshoot of anticoagulation and bleeding in line with drug-
guide monitoring recommendations.
Rationale — Incorrect
A. Unsafe — giving full dose without checking INR or addressing
interactions risks major bleeding.
C. Giving a reduced empiric dose without consulting prescriber
still ignores interactions and lacks baseline INR follow-up.
D. Scheduling vitamin K “on standby” is not a substitution for
prevention and immediate INR evaluation; reactive
management is lower priority.
Teaching point:
Check INR and address interacting meds before initial warfarin
dosing.
Citation:
Vallerand, A. H., & Sanoski, C. (2025). Davis's Drug Guide for
,Nurses (19th ed.). [Warfarin — Pharmacogenomics &
Monitoring].
2)
Drug Reference
Clopidogrel — P2Y12 platelet inhibitor (prodrug) —
Pharmacogenomics & Patient/Family Teaching
Clinical stem
A 56-year-old woman is started on clopidogrel after PCI. She
reports recently having genetic testing showing reduced
CYP2C19 activity. Which nursing intervention is most
appropriate?
A. Reinforce clopidogrel adherence and proceed—no change
needed.
B. Document the finding and ask prescriber if alternative
antiplatelet therapy is indicated.
C. Advise doubling the clopidogrel dose to overcome reduced
activation.
D. Hold clopidogrel and substitute aspirin monotherapy.
Correct answer: B
Rationale — Correct (B)
Reduced CYP2C19 decreases conversion of clopidogrel to its
active metabolite, reducing effectiveness; the nurse should
notify the prescriber so an alternative (e.g.,
, ticagrelor/prasugrel) can be considered per pharmacogenomic
guidance in the drug guide.
Rationale — Incorrect
A. Unsafe — ignoring genotype could risk stent thrombosis.
C. Doubling dose is unsupported and may increase bleeding
without ensuring activation.
D. Substituting aspirin alone is not prescriber-directed and may
provide insufficient antiplatelet effect post-PCI.
Teaching point:
Report reduced CYP2C19 activity—alternative P2Y12 agents
may be needed.
Citation:
Vallerand, A. H., & Sanoski, C. (2025). Davis's Drug Guide for
Nurses (19th ed.). [Clopidogrel — Pharmacogenomics &
Teaching].
3)
Drug Reference
Codeine — Opioid analgesic (CYP2D6 substrate) — Adverse
Reactions & Pharmacogenomics
Clinical stem
A 10-year-old girl with recent tonsillectomy has been prescribed
codeine for pain. Her parent asks about testing for codeine
safety. Which nursing action best addresses safety?
