DAVIS'S DRUG GUIDE FOR NURSES
19TH EDITION
• AUTHOR(S)APRIL HAZARD
VALLERAND; CYNTHIA SANOSKI
TEST BANK
1
Drug Reference — Warfarin — Vitamin K Antagonist — Drug
Interactions & Renal Impairment
Stem: A 72-year-old man with atrial fibrillation is receiving
warfarin 5 mg PO nightly. His current INR is 1.8 (therapeutic
goal 2–3). He was admitted for a urinary tract infection and the
team started trimethoprim-sulfamethoxazole (TMP-SMX)
yesterday. The nurse notes decreased urine output and serum
creatinine increased from 1.0 to 1.8 mg/dL. What is the nurse’s
best action?
A. Administer warfarin as ordered and recheck INR in 24 hours.
,B. Hold warfarin and notify prescriber about TMP-SMX and
rising creatinine.
C. Give vitamin K 1 mg PO now to prevent bleeding.
D. Continue warfarin and add low-molecular-weight heparin
until creatinine stabilizes.
Correct Answer: B
Rationale — Correct (B): TMP-SMX interacts with warfarin and
can potentiate anticoagulation; renal impairment may alter
drug effects and increase bleeding risk. Holding warfarin and
notifying the prescriber allows evaluation of interaction, renal
dosing, and INR monitoring before further dosing. This
prioritizes patient safety.
Rationale — Incorrect:
A. Administering without prescriber notification ignores an
important drug interaction and rising creatinine that may
increase warfarin effect.
C. Prophylactic vitamin K is inappropriate without evidence of
high INR or bleeding risk; unnecessary reversal risks thrombosis.
D. Adding LMWH when renal impairment exists risks
accumulation (some LMWH require dose adjustment) and
doesn’t address the warfarin–TMP-SMX interaction.
Teaching Point: TMP-SMX can potentiate warfarin; alert
prescriber and monitor INR closely.
Citation: Vallerand, A. H., & Sanoski, C. (2025). Davis's Drug
Guide for Nurses (19th ed.). [Drug Interactions; Renal
Impairment].
,2
Drug Reference — Ciprofloxacin — Fluoroquinolone —
Cytochrome P450 System & Drug Interactions
Stem: A 28-year-old woman is prescribed ciprofloxacin 500 mg
PO BID for complicated UTI. She also takes sertraline 100 mg
daily for depression. She reports new lightheadedness and
palpitations after two doses. Her pulse is 110 bpm, BP 100/64
mm Hg. What should the nurse suspect and do first?
A. Suspect serotonin syndrome; hold sertraline and notify
prescriber.
B. Suspect QT prolongation interaction; obtain a 12-lead ECG
and notify prescriber.
C. Encourage increased oral fluids and continue therapy.
D. Administer IV fluids for suspected hypovolemia from UTI.
Correct Answer: B
Rationale — Correct (B): Some fluoroquinolones can prolong
QT interval and, combined with SSRIs or other QT-prolonging
drugs, increase risk of torsades. Palpitations and tachycardia
require ECG to assess QTc prior to continuing drug. Prompt
notification allows medication review.
Rationale — Incorrect:
A. Serotonin syndrome typically features hyperreflexia,
hyperthermia, and altered mental status; lightheaded
palpitations without neuromuscular findings are less consistent.
C. Fluid encouragement alone misses potential cardiac
, conduction risk.
D. IV fluids for hypovolemia are premature without signs of
volume depletion.
Teaching Point: Check ECG if patient on QT-prolonging drugs
develops palpitations.
Citation: Vallerand, A. H., & Sanoski, C. (2025). Davis's Drug
Guide for Nurses (19th ed.). [The Cytochrome P450 System;
Drug Interactions].
3
Drug Reference — Carbamazepine — Anticonvulsant —
Pharmacogenomics & Special Dosing Considerations
Stem: A 35-year-old Southeast Asian patient is to start
carbamazepine for trigeminal neuralgia. The prescriber orders
no genetic testing. The nurse knows a genetic test for HLA-
B15:02 is available. What is the nurse’s best action?
A. Administer the first dose and schedule HLA testing later.
B. Inform the prescriber that HLA-B15:02 testing is indicated
before starting carbamazepine.
C. Ask the patient about family history of liver disease and
proceed without testing.
D. Substitute carbamazepine with gabapentin without
contacting prescriber.
Correct Answer: B
19TH EDITION
• AUTHOR(S)APRIL HAZARD
VALLERAND; CYNTHIA SANOSKI
TEST BANK
1
Drug Reference — Warfarin — Vitamin K Antagonist — Drug
Interactions & Renal Impairment
Stem: A 72-year-old man with atrial fibrillation is receiving
warfarin 5 mg PO nightly. His current INR is 1.8 (therapeutic
goal 2–3). He was admitted for a urinary tract infection and the
team started trimethoprim-sulfamethoxazole (TMP-SMX)
yesterday. The nurse notes decreased urine output and serum
creatinine increased from 1.0 to 1.8 mg/dL. What is the nurse’s
best action?
A. Administer warfarin as ordered and recheck INR in 24 hours.
,B. Hold warfarin and notify prescriber about TMP-SMX and
rising creatinine.
C. Give vitamin K 1 mg PO now to prevent bleeding.
D. Continue warfarin and add low-molecular-weight heparin
until creatinine stabilizes.
Correct Answer: B
Rationale — Correct (B): TMP-SMX interacts with warfarin and
can potentiate anticoagulation; renal impairment may alter
drug effects and increase bleeding risk. Holding warfarin and
notifying the prescriber allows evaluation of interaction, renal
dosing, and INR monitoring before further dosing. This
prioritizes patient safety.
Rationale — Incorrect:
A. Administering without prescriber notification ignores an
important drug interaction and rising creatinine that may
increase warfarin effect.
C. Prophylactic vitamin K is inappropriate without evidence of
high INR or bleeding risk; unnecessary reversal risks thrombosis.
D. Adding LMWH when renal impairment exists risks
accumulation (some LMWH require dose adjustment) and
doesn’t address the warfarin–TMP-SMX interaction.
Teaching Point: TMP-SMX can potentiate warfarin; alert
prescriber and monitor INR closely.
Citation: Vallerand, A. H., & Sanoski, C. (2025). Davis's Drug
Guide for Nurses (19th ed.). [Drug Interactions; Renal
Impairment].
,2
Drug Reference — Ciprofloxacin — Fluoroquinolone —
Cytochrome P450 System & Drug Interactions
Stem: A 28-year-old woman is prescribed ciprofloxacin 500 mg
PO BID for complicated UTI. She also takes sertraline 100 mg
daily for depression. She reports new lightheadedness and
palpitations after two doses. Her pulse is 110 bpm, BP 100/64
mm Hg. What should the nurse suspect and do first?
A. Suspect serotonin syndrome; hold sertraline and notify
prescriber.
B. Suspect QT prolongation interaction; obtain a 12-lead ECG
and notify prescriber.
C. Encourage increased oral fluids and continue therapy.
D. Administer IV fluids for suspected hypovolemia from UTI.
Correct Answer: B
Rationale — Correct (B): Some fluoroquinolones can prolong
QT interval and, combined with SSRIs or other QT-prolonging
drugs, increase risk of torsades. Palpitations and tachycardia
require ECG to assess QTc prior to continuing drug. Prompt
notification allows medication review.
Rationale — Incorrect:
A. Serotonin syndrome typically features hyperreflexia,
hyperthermia, and altered mental status; lightheaded
palpitations without neuromuscular findings are less consistent.
C. Fluid encouragement alone misses potential cardiac
, conduction risk.
D. IV fluids for hypovolemia are premature without signs of
volume depletion.
Teaching Point: Check ECG if patient on QT-prolonging drugs
develops palpitations.
Citation: Vallerand, A. H., & Sanoski, C. (2025). Davis's Drug
Guide for Nurses (19th ed.). [The Cytochrome P450 System;
Drug Interactions].
3
Drug Reference — Carbamazepine — Anticonvulsant —
Pharmacogenomics & Special Dosing Considerations
Stem: A 35-year-old Southeast Asian patient is to start
carbamazepine for trigeminal neuralgia. The prescriber orders
no genetic testing. The nurse knows a genetic test for HLA-
B15:02 is available. What is the nurse’s best action?
A. Administer the first dose and schedule HLA testing later.
B. Inform the prescriber that HLA-B15:02 testing is indicated
before starting carbamazepine.
C. Ask the patient about family history of liver disease and
proceed without testing.
D. Substitute carbamazepine with gabapentin without
contacting prescriber.
Correct Answer: B
