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 & Nursing Implications
Stem: A 68-year-old man with atrial fibrillation is started on
warfarin. His INR today is 1.8 (goal 2–3). He takes amiodarone
chronically and reports new bruising on his legs. Genetic testing
is pending. What is the most appropriate nursing action now?
A. Increase the warfarin dose to achieve INR >2.0.
B. Hold the morning dose and notify the prescriber about the
low-therapeutic INR and concurrent amiodarone.
C. Continue current dose and request recheck in 2 weeks since
,genetic testing will guide changes.
D. Teach the patient to avoid leafy greens to increase INR.
Correct answer: B
Rationale — Correct: Holding the dose and notifying prescriber
is safest: amiodarone inhibits warfarin metabolism (CYP
interactions), increases bleeding risk despite INR slightly low;
dose adjustments require prescriber input and closer
monitoring. Nursing implication: consider drug interactions and
recent bleeding/bruising before empiric dose increase.
Rationales — Incorrect:
A. Increasing dose risks overshoot once interaction or genetics
change INR — unsafe without prescriber.
C. Waiting 2 weeks is unsafe given new bruising and known
amiodarone interaction.
D. Avoiding leafy greens would raise INR (less vitamin K) — this
is not immediate priority and could worsen bleeding risk.
Teaching point: Notify prescriber for dose decision when
interacting drugs or bleeding are present.
Citation: Vallerand, A. H., & Sanoski, C. (2025). Davis's Drug
Guide for Nurses (19th ed.). [Warfarin — Pharmacogenomics &
Nursing Implications].
2
,Drug reference: Clopidogrel — P2Y₁₂ ADP Receptor Antagonist
— Pharmacogenomics & Drug Interactions
Stem: A 55-year-old woman received a drug-eluting stent and is
prescribed clopidogrel. She tests positive for a CYP2C19 loss-of-
function allele. Which nursing action is most appropriate?
A. Continue clopidogrel and instruct to stop aspirin to reduce
bleeding risk.
B. Notify the cardiologist; recommend alternative antiplatelet
therapy is considered.
C. Double the clopidogrel dose to overcome reduced
metabolism.
D. Encourage grapefruit juice to increase clopidogrel activation.
Correct answer: B
Rationale — Correct: Loss-of-function CYP2C19 reduces
activation of clopidogrel and decreases antiplatelet effect;
notifying prescriber for an alternative (e.g., prasugrel or
ticagrelor) is appropriate. Nursing role: integrate
pharmacogenomic result into medication plan.
Rationales — Incorrect:
A. Stopping aspirin is inappropriate—dual antiplatelet therapy is
indicated post-stent.
C. Doubling dose is not recommended without prescriber and
evidence; risk of bleeding unclear.
D. Grapefruit juice inhibits CYP3A4 and is unlikely to increase
clopidogrel activation; it may cause other interactions.
, Teaching point: Pharmacogenomic results should prompt
prescriber review for alternative antiplatelet therapy.
Citation: Vallerand, A. H., & Sanoski, C. (2025). Davis's Drug
Guide for Nurses (19th ed.). [Clopidogrel — Pharmacogenomics
& Drug Interactions].
3
Drug reference: Isotretinoin — Retinoid — REMS & Females of
Reproductive Potential (Patient/Family Teaching)
Stem: A 22-year-old woman starting isotretinoin reports she
uses an oral contraceptive but missed her last refill. She is
sexually active. Which action should the nurse prioritize?
A. Reinforce starting isotretinoin immediately; arrange
contraceptive counseling later.
B. Ask about pregnancy test results and ensure she understands
REMS pregnancy prevention requirements before dispensing.
C. Advise her to use condoms only since oral contraceptives are
unavailable.
D. Obtain a negative urine pregnancy test within 3 months after
starting isotretinoin.
Correct answer: B
Rationale — Correct: Isotretinoin has a strict REMS program
requiring documented negative pregnancy tests and
contraception counseling before dispensing; nurse must ensure
19TH EDITION
• AUTHOR(S)APRIL HAZARD
VALLERAND; CYNTHIA SANOSKI
TEST BANK
1
Drug reference: Warfarin — Vitamin K Antagonist —
Pharmacogenomics & Nursing Implications
Stem: A 68-year-old man with atrial fibrillation is started on
warfarin. His INR today is 1.8 (goal 2–3). He takes amiodarone
chronically and reports new bruising on his legs. Genetic testing
is pending. What is the most appropriate nursing action now?
A. Increase the warfarin dose to achieve INR >2.0.
B. Hold the morning dose and notify the prescriber about the
low-therapeutic INR and concurrent amiodarone.
C. Continue current dose and request recheck in 2 weeks since
,genetic testing will guide changes.
D. Teach the patient to avoid leafy greens to increase INR.
Correct answer: B
Rationale — Correct: Holding the dose and notifying prescriber
is safest: amiodarone inhibits warfarin metabolism (CYP
interactions), increases bleeding risk despite INR slightly low;
dose adjustments require prescriber input and closer
monitoring. Nursing implication: consider drug interactions and
recent bleeding/bruising before empiric dose increase.
Rationales — Incorrect:
A. Increasing dose risks overshoot once interaction or genetics
change INR — unsafe without prescriber.
C. Waiting 2 weeks is unsafe given new bruising and known
amiodarone interaction.
D. Avoiding leafy greens would raise INR (less vitamin K) — this
is not immediate priority and could worsen bleeding risk.
Teaching point: Notify prescriber for dose decision when
interacting drugs or bleeding are present.
Citation: Vallerand, A. H., & Sanoski, C. (2025). Davis's Drug
Guide for Nurses (19th ed.). [Warfarin — Pharmacogenomics &
Nursing Implications].
2
,Drug reference: Clopidogrel — P2Y₁₂ ADP Receptor Antagonist
— Pharmacogenomics & Drug Interactions
Stem: A 55-year-old woman received a drug-eluting stent and is
prescribed clopidogrel. She tests positive for a CYP2C19 loss-of-
function allele. Which nursing action is most appropriate?
A. Continue clopidogrel and instruct to stop aspirin to reduce
bleeding risk.
B. Notify the cardiologist; recommend alternative antiplatelet
therapy is considered.
C. Double the clopidogrel dose to overcome reduced
metabolism.
D. Encourage grapefruit juice to increase clopidogrel activation.
Correct answer: B
Rationale — Correct: Loss-of-function CYP2C19 reduces
activation of clopidogrel and decreases antiplatelet effect;
notifying prescriber for an alternative (e.g., prasugrel or
ticagrelor) is appropriate. Nursing role: integrate
pharmacogenomic result into medication plan.
Rationales — Incorrect:
A. Stopping aspirin is inappropriate—dual antiplatelet therapy is
indicated post-stent.
C. Doubling dose is not recommended without prescriber and
evidence; risk of bleeding unclear.
D. Grapefruit juice inhibits CYP3A4 and is unlikely to increase
clopidogrel activation; it may cause other interactions.
, Teaching point: Pharmacogenomic results should prompt
prescriber review for alternative antiplatelet therapy.
Citation: Vallerand, A. H., & Sanoski, C. (2025). Davis's Drug
Guide for Nurses (19th ed.). [Clopidogrel — Pharmacogenomics
& Drug Interactions].
3
Drug reference: Isotretinoin — Retinoid — REMS & Females of
Reproductive Potential (Patient/Family Teaching)
Stem: A 22-year-old woman starting isotretinoin reports she
uses an oral contraceptive but missed her last refill. She is
sexually active. Which action should the nurse prioritize?
A. Reinforce starting isotretinoin immediately; arrange
contraceptive counseling later.
B. Ask about pregnancy test results and ensure she understands
REMS pregnancy prevention requirements before dispensing.
C. Advise her to use condoms only since oral contraceptives are
unavailable.
D. Obtain a negative urine pregnancy test within 3 months after
starting isotretinoin.
Correct answer: B
Rationale — Correct: Isotretinoin has a strict REMS program
requiring documented negative pregnancy tests and
contraception counseling before dispensing; nurse must ensure
