KEISER UNIVERSITY
Course Code: NUR1140C
Course Title: Nursing Pharmacology
Credit Hours:4.0
Exam: Final Exam
Date:2026
A 68-year-old male with chronic atrial fibrillation is prescribed warfarin 5 mg daily. On his follow-
up visit, his INR is 4.9. He denies any bleeding episodes but reports recently starting a course of
metronidazole for a dental infection. Which of the following is the most appropriate nursing
action?
A. Administer vitamin K 10 mg IV immediately B. Hold the next dose of warfarin, recheck INR in 24-48
hours, and notify the prescriber C. Continue warfarin and advise the patient to watch for signs of
bleeding D. Switch the patient to aspirin until metronidazole is completed
Correct Answer: B
Rationale: Metronidazole inhibits CYP2C9, the primary enzyme responsible for warfarin metabolism,
significantly potentiating its anticoagulant effect and elevating INR. An INR of 4.9 in a patient
without active bleeding does not require immediate reversal with vitamin K; however, withholding
the next warfarin dose and rechecking INR within 24-48 hours is the safest and most clinically
appropriate step. Vitamin K is reserved for INR greater than 10 or active bleeding. Switching to
aspirin is inappropriate and dangerous.
A 52-year-old woman with type 2 diabetes is admitted with a serum creatinine of 3.1 mg/dL and an
eGFR of 22 mL/min/1.73m². She is currently on metformin 1000 mg twice daily. Which
statement best explains why metformin must be discontinued in this patient?
A. Metformin causes direct nephrotoxicity at high creatinine levels B. Reduced renal clearance leads to
metformin accumulation and risk of fatal lactic acidosis C. Metformin causes hypoglycemia when
renal function is impaired D. Metformin is converted to a toxic metabolite in renal failure
Correct Answer: B
Rationale: Metformin is excreted unchanged by the kidneys via tubular secretion. When eGFR falls below
30 mL/min/1.73m², renal clearance is critically impaired, causing metformin to accumulate in tissues.
This accumulation inhibits mitochondrial oxidative phosphorylation, promoting anaerobic
metabolism and the accumulation of lactate, resulting in potentially fatal lactic acidosis. Metformin
does not cause nephrotoxicity, does not cause hypoglycemia, and is not hepatically metabolized to
toxic compounds.
A patient in the ICU is receiving vancomycin for MRSA bacteremia. The trough level drawn 30
minutes before the fourth dose returns at 28 mcg/mL (therapeutic range: 15-20 mcg/mL for
serious infections, though AUC-guided dosing is now preferred). The patient's serum creatinine
has risen from 0.9 to 1.8 mg/dL over 48 hours. What is the nurse's priority intervention?
A. Administer the next dose as scheduled and recheck trough after the fifth dose B. Increase the infusion
rate to clear the drug faster C. Hold the dose, notify the pharmacist and prescriber, and assess for
nephrotoxicity D. Switch to oral vancomycin to reduce systemic accumulation
Correct Answer: C
Rationale: A supratherapeutic vancomycin trough combined with rising serum creatinine is a hallmark of
vancomycin-associated nephrotoxicity (VAN). Vancomycin is renally eliminated, and impaired renal
function further reduces clearance, creating a dangerous cycle of accumulation. The nurse must hold
the dose to prevent worsening toxicity, notify the prescriber and clinical pharmacist for dose
recalculation, and thoroughly assess renal function indicators. Oral vancomycin is not absorbed
, systemically and is only used for Clostridioides difficile colitis.
A 44-year-old man with hypertension is started on lisinopril 10 mg daily. After two weeks, he
presents to the emergency department with angioedema of the lips and tongue. The nurse
should recognize this reaction as:
A. A dose-dependent allergic reaction manageable by reducing the dose B. A class effect of ACE
inhibitors mediated by bradykinin accumulation and not dose-related C. An anaphylactic reaction
requiring epinephrine and future low-dose rechallenge D. An expected side effect of all
antihypertensive agents
Correct Answer: B
Rationale: ACE inhibitor-induced angioedema is a bradykinin-mediated phenomenon. ACE normally
degrades bradykinin; when inhibited, bradykinin accumulates and promotes vascular permeability,
particularly in the face, lips, tongue, and larynx. This is not an IgE-mediated allergy, is not dose-
dependent, and can occur at any point during therapy, even after years of uneventful use. The patient
must never be rechallenged with any ACE inhibitor. ARBs are a safer alternative but carry a small
cross-reactivity risk and must be used with caution.
A nurse is preparing to administer digoxin 0.25 mg IV to a 77-year-old woman with heart failure
and atrial fibrillation. Her potassium level is 3.1 mEq/L. What is the most critical nursing
concern before administration?
A. Hypokalemia potentiates digoxin toxicity by competing with digoxin for Na/K-ATPase binding sites
B. Hyperkalemia is more dangerous with digoxin and must be assessed first C. Potassium has no
clinically significant interaction with digoxin D. The dose should be doubled because elderly patients
absorb digoxin poorly
Correct Answer: A
Rationale: Digoxin exerts its therapeutic effect by inhibiting the Na/K-ATPase pump. Potassium and
digoxin compete for the same binding site on this pump. When serum potassium is low (hypokalemia),
digoxin binds more readily to the pump, dramatically increasing its pharmacological effect and
toxicity risk, even at therapeutic serum digoxin concentrations. In elderly patients, reduced renal
clearance already prolongs digoxin's half-life. The nurse must withhold the dose, correct the
hypokalemia, and notify the prescriber. Digoxin dose is typically reduced, not increased, in elderly
patients.
A patient with a deep vein thrombosis is initiated on heparin infusion per weight-based protocol.
Four hours after initiation, the aPTT is 28 seconds (therapeutic range: 60-100 seconds). The
nurse correctly interprets this as:
A. Therapeutic and the infusion should continue unchanged B. Subtherapeutic, requiring a bolus dose and
rate increase per protocol C. Supratherapeutic, requiring the infusion to be held D. Indicative of
heparin-induced thrombocytopenia (HIT)
Correct Answer: B
Rationale: An aPTT of 28 seconds is below the therapeutic range of 60-100 seconds, indicating
subtherapeutic anticoagulation. In the context of DVT treatment, inadequate anticoagulation
increases the risk of thrombus extension and pulmonary embolism. Weight-based heparin protocols
typically direct nurses to administer an additional bolus dose and increase the infusion rate when
aPTT is below therapeutic range. HIT presents with thrombocytopenia and paradoxical thrombosis,
not simply a low aPTT.
A 38-year-old woman being treated for tuberculosis is also on oral contraceptives. She reports that
her periods have become irregular. The pharmacist flags a drug interaction. Which TB
medication is most responsible for this interaction and why?
A. Isoniazid, by inhibiting hepatic enzymes and increasing estrogen levels B. Rifampin, by inducing
CYP3A4 and accelerating the metabolism of oral contraceptives C. Ethambutol, by directly
competing with estrogen for receptor binding D. Pyrazinamide, by reducing GI absorption of oral
contraceptives
Correct Answer: B
,Rationale: Rifampin is one of the most potent inducers of cytochrome P450 enzymes, particularly
CYP3A4, which is the primary enzyme responsible for the metabolism of ethinyl estradiol and
progestin in combined oral contraceptives. Induction of CYP3A4 significantly accelerates the
breakdown of these hormones, reducing their plasma concentrations below therapeutic levels and
resulting in contraceptive failure. Women on rifampin-based TB regimens must be counseled to use a
non-hormonal barrier contraceptive method throughout treatment.
A patient receiving chemotherapy with cisplatin is prescribed ondansetron for nausea. She also has
a history of long QT syndrome and is on amiodarone. Which of the following best describes the
nurse's primary concern?
A. Ondansetron is contraindicated with amiodarone due to additive QT prolongation risk B. Ondansetron
will reduce the efficacy of amiodarone C. Amiodarone increases ondansetron levels by inhibiting its
renal excretion D. There is no clinically significant interaction between these drugs
Correct Answer: A
Rationale: Both ondansetron (a 5-HT3 antagonist) and amiodarone independently prolong the cardiac
QT interval by blocking cardiac potassium channels (hERG/IKr channels). When combined,
particularly in a patient with pre-existing long QT syndrome, the risk of potentially fatal ventricular
arrhythmias such as Torsades de Pointes is substantially increased. The nurse should alert the
prescriber, obtain a baseline ECG, and monitor the QTc interval closely. An alternative antiemetic
such as metoclopramide or dexamethasone may be safer in this clinical context.
A 60-year-old man with heart failure is started on carvedilol. The nurse should explain that unlike
selective beta-1 blockers, carvedilol is preferred in heart failure patients with diabetes because:
A. It stimulates insulin secretion directly through beta-2 receptors B. Its alpha-1 blocking activity
improves insulin sensitivity and reduces hypoglycemia masking C. It has no effect on glucose
metabolism whatsoever D. It blocks all adrenergic receptors equally, eliminating all metabolic side
effects
Correct Answer: B
Rationale: Carvedilol is a non-selective beta blocker (blocks beta-1 and beta-2) with additional alpha-1
blocking properties. While beta-2 blockade can mask hypoglycemic tachycardia in diabetics (a known
concern with all non-selective agents), carvedilol's alpha-1 activity improves peripheral insulin
sensitivity and is associated with a more favorable metabolic profile compared to selective agents like
metoprolol. Studies including COPERNICUS and US Carvedilol trials showed it improves mortality
in heart failure with reduced ejection fraction. The alpha-1 blockade also causes vasodilation,
reducing afterload.
A nurse administers IV phenytoin too rapidly (greater than 50 mg/min) during status epilepticus
management. The patient suddenly develops severe hypotension and bradycardia. The nurse
recognizes this is due to:
A. An allergic reaction to the phenytoin molecule itself B. The propylene glycol diluent causing
cardiovascular depression at rapid infusion rates C. Phenytoin directly stimulating vagal tone in the
brainstem D. Phenytoin-induced hyperkalemia causing myocardial depression
Correct Answer: B
Rationale: IV phenytoin is formulated in a vehicle containing propylene glycol, ethanol, and sodium
hydroxide to maintain solubility. Propylene glycol is cardiotoxic when infused rapidly, causing
myocardial depression, hypotension, bradycardia, and heart block. The maximum safe infusion rate
for phenytoin is 50 mg/min in adults (25 mg/min in elderly or cardiac-compromised patients).
Fosphenytoin, a water-soluble prodrug, was developed specifically to avoid this complication and
can be infused at 150 mg PE/min with significantly less cardiovascular risk.
A post-surgical patient on patient-controlled analgesia (PCA) with morphine is found unresponsive
with a respiratory rate of 6 breaths/min and miosis. The nurse administers naloxone 0.4 mg IV.
Within 2 minutes, the patient is awake and in severe pain. What is the nurse's next concern?
A. The naloxone dose was too high and may cause seizures B. Re-narcotization may occur because
naloxone's duration of action is shorter than morphine's C. The patient will develop permanent opioid
, tolerance from this reversal D. Administering naloxone in a post-surgical patient is contraindicated
Correct Answer: B
Rationale: Naloxone has a half-life of approximately 30-90 minutes, significantly shorter than most
opioids including morphine (half-life 2-4 hours). Once naloxone's effect wanes, unopposed opioid
activity will resume, potentially causing re-narcotization (return of respiratory depression). Nurses
must monitor the patient continuously for at least 2-4 hours after naloxone administration, have
repeat doses or a naloxone infusion ready, and avoid over-reversal which can precipitate acute
opioid withdrawal, severe pain, tachycardia, hypertension, and pulmonary edema.
A 55-year-old woman with rheumatoid arthritis on methotrexate 15 mg weekly is prescribed
trimethoprim-sulfamethoxazole (TMP-SMX) for a UTI. What potentially life-threatening
interaction must the nurse recognize?
A. TMP-SMX reduces methotrexate absorption from the GI tract B. Both drugs inhibit dihydrofolate
reductase, causing additive folate antagonism and risk of severe bone marrow suppression C. TMP-
SMX accelerates methotrexate excretion through renal tubular secretion D. Methotrexate inhibits
TMP-SMX metabolism, causing sulfonamide toxicity
Correct Answer: B
Rationale: Methotrexate inhibits dihydrofolate reductase (DHFR), preventing conversion of folate to its
active form, thereby suppressing rapidly dividing cells including immune cells. TMP (the
trimethoprim component of TMP-SMX) also inhibits DHFR. When combined, the additive inhibition
of folate metabolism can cause profound bone marrow suppression, pancytopenia, mucositis, and
potentially fatal hematologic toxicity. TMP-SMX also competes with methotrexate for renal tubular
secretion, increasing methotrexate plasma levels. An alternative antibiotic such as nitrofurantoin
should be used for UTI management in patients on methotrexate.
A patient with Parkinson's disease on levodopa/carbidopa is admitted for a psychiatric episode and
the on-call physician orders haloperidol. The nurse should:
A. Administer haloperidol as ordered since it is safe in all neurological conditions B. Question the order
because haloperidol blocks dopamine D2 receptors and will worsen Parkinsonism C. Administer
haloperidol and increase the levodopa dose simultaneously D. Hold all medications until neurology is
consulted
Correct Answer: B
Rationale: Levodopa/carbidopa works by increasing central dopamine availability to compensate for the
dopaminergic deficit in Parkinson's disease. Haloperidol is a typical (first-generation) antipsychotic
that acts by blocking dopamine D2 receptors. Administering haloperidol will directly antagonize the
therapeutic effect of levodopa, precipitate or dramatically worsen Parkinsonian symptoms (rigidity,
bradykinesia, tremor), and can cause neuroleptic malignant syndrome in this population. For
psychosis in Parkinson's disease, quetiapine or clozapine (which have low D2 affinity) are the
preferred alternatives.
A patient on long-term corticosteroid therapy for Crohn's disease is scheduled for elective knee
surgery. The anesthesiologist orders a perioperative stress dose of hydrocortisone. This is
necessary because:
A. Corticosteroids improve wound healing and should be continued at higher doses B. Exogenous
corticosteroids suppress the hypothalamic-pituitary-adrenal axis, impairing the body's ability to
mount a physiological cortisol stress response C. Surgical patients always need corticosteroids to
prevent anaphylaxis D. Corticosteroids prevent postoperative nausea and are given for antiemetic
purposes
Correct Answer: B
Rationale: Chronic exogenous corticosteroid use suppresses the hypothalamic-pituitary-adrenal (HPA)
axis through negative feedback. The adrenal glands atrophy from disuse and lose the capacity to
produce the surge of cortisol (up to 75-150 mg/day) required during physiological stress such as
surgery. Without stress dosing, the patient risks adrenal crisis, characterized by refractory
hypotension, cardiovascular collapse, hyponatremia, and hypoglycemia. Standard practice involves
hydrocortisone 50-100 mg IV at induction, then every 8 hours for 24-48 hours post-surgery, tapering
Course Code: NUR1140C
Course Title: Nursing Pharmacology
Credit Hours:4.0
Exam: Final Exam
Date:2026
A 68-year-old male with chronic atrial fibrillation is prescribed warfarin 5 mg daily. On his follow-
up visit, his INR is 4.9. He denies any bleeding episodes but reports recently starting a course of
metronidazole for a dental infection. Which of the following is the most appropriate nursing
action?
A. Administer vitamin K 10 mg IV immediately B. Hold the next dose of warfarin, recheck INR in 24-48
hours, and notify the prescriber C. Continue warfarin and advise the patient to watch for signs of
bleeding D. Switch the patient to aspirin until metronidazole is completed
Correct Answer: B
Rationale: Metronidazole inhibits CYP2C9, the primary enzyme responsible for warfarin metabolism,
significantly potentiating its anticoagulant effect and elevating INR. An INR of 4.9 in a patient
without active bleeding does not require immediate reversal with vitamin K; however, withholding
the next warfarin dose and rechecking INR within 24-48 hours is the safest and most clinically
appropriate step. Vitamin K is reserved for INR greater than 10 or active bleeding. Switching to
aspirin is inappropriate and dangerous.
A 52-year-old woman with type 2 diabetes is admitted with a serum creatinine of 3.1 mg/dL and an
eGFR of 22 mL/min/1.73m². She is currently on metformin 1000 mg twice daily. Which
statement best explains why metformin must be discontinued in this patient?
A. Metformin causes direct nephrotoxicity at high creatinine levels B. Reduced renal clearance leads to
metformin accumulation and risk of fatal lactic acidosis C. Metformin causes hypoglycemia when
renal function is impaired D. Metformin is converted to a toxic metabolite in renal failure
Correct Answer: B
Rationale: Metformin is excreted unchanged by the kidneys via tubular secretion. When eGFR falls below
30 mL/min/1.73m², renal clearance is critically impaired, causing metformin to accumulate in tissues.
This accumulation inhibits mitochondrial oxidative phosphorylation, promoting anaerobic
metabolism and the accumulation of lactate, resulting in potentially fatal lactic acidosis. Metformin
does not cause nephrotoxicity, does not cause hypoglycemia, and is not hepatically metabolized to
toxic compounds.
A patient in the ICU is receiving vancomycin for MRSA bacteremia. The trough level drawn 30
minutes before the fourth dose returns at 28 mcg/mL (therapeutic range: 15-20 mcg/mL for
serious infections, though AUC-guided dosing is now preferred). The patient's serum creatinine
has risen from 0.9 to 1.8 mg/dL over 48 hours. What is the nurse's priority intervention?
A. Administer the next dose as scheduled and recheck trough after the fifth dose B. Increase the infusion
rate to clear the drug faster C. Hold the dose, notify the pharmacist and prescriber, and assess for
nephrotoxicity D. Switch to oral vancomycin to reduce systemic accumulation
Correct Answer: C
Rationale: A supratherapeutic vancomycin trough combined with rising serum creatinine is a hallmark of
vancomycin-associated nephrotoxicity (VAN). Vancomycin is renally eliminated, and impaired renal
function further reduces clearance, creating a dangerous cycle of accumulation. The nurse must hold
the dose to prevent worsening toxicity, notify the prescriber and clinical pharmacist for dose
recalculation, and thoroughly assess renal function indicators. Oral vancomycin is not absorbed
, systemically and is only used for Clostridioides difficile colitis.
A 44-year-old man with hypertension is started on lisinopril 10 mg daily. After two weeks, he
presents to the emergency department with angioedema of the lips and tongue. The nurse
should recognize this reaction as:
A. A dose-dependent allergic reaction manageable by reducing the dose B. A class effect of ACE
inhibitors mediated by bradykinin accumulation and not dose-related C. An anaphylactic reaction
requiring epinephrine and future low-dose rechallenge D. An expected side effect of all
antihypertensive agents
Correct Answer: B
Rationale: ACE inhibitor-induced angioedema is a bradykinin-mediated phenomenon. ACE normally
degrades bradykinin; when inhibited, bradykinin accumulates and promotes vascular permeability,
particularly in the face, lips, tongue, and larynx. This is not an IgE-mediated allergy, is not dose-
dependent, and can occur at any point during therapy, even after years of uneventful use. The patient
must never be rechallenged with any ACE inhibitor. ARBs are a safer alternative but carry a small
cross-reactivity risk and must be used with caution.
A nurse is preparing to administer digoxin 0.25 mg IV to a 77-year-old woman with heart failure
and atrial fibrillation. Her potassium level is 3.1 mEq/L. What is the most critical nursing
concern before administration?
A. Hypokalemia potentiates digoxin toxicity by competing with digoxin for Na/K-ATPase binding sites
B. Hyperkalemia is more dangerous with digoxin and must be assessed first C. Potassium has no
clinically significant interaction with digoxin D. The dose should be doubled because elderly patients
absorb digoxin poorly
Correct Answer: A
Rationale: Digoxin exerts its therapeutic effect by inhibiting the Na/K-ATPase pump. Potassium and
digoxin compete for the same binding site on this pump. When serum potassium is low (hypokalemia),
digoxin binds more readily to the pump, dramatically increasing its pharmacological effect and
toxicity risk, even at therapeutic serum digoxin concentrations. In elderly patients, reduced renal
clearance already prolongs digoxin's half-life. The nurse must withhold the dose, correct the
hypokalemia, and notify the prescriber. Digoxin dose is typically reduced, not increased, in elderly
patients.
A patient with a deep vein thrombosis is initiated on heparin infusion per weight-based protocol.
Four hours after initiation, the aPTT is 28 seconds (therapeutic range: 60-100 seconds). The
nurse correctly interprets this as:
A. Therapeutic and the infusion should continue unchanged B. Subtherapeutic, requiring a bolus dose and
rate increase per protocol C. Supratherapeutic, requiring the infusion to be held D. Indicative of
heparin-induced thrombocytopenia (HIT)
Correct Answer: B
Rationale: An aPTT of 28 seconds is below the therapeutic range of 60-100 seconds, indicating
subtherapeutic anticoagulation. In the context of DVT treatment, inadequate anticoagulation
increases the risk of thrombus extension and pulmonary embolism. Weight-based heparin protocols
typically direct nurses to administer an additional bolus dose and increase the infusion rate when
aPTT is below therapeutic range. HIT presents with thrombocytopenia and paradoxical thrombosis,
not simply a low aPTT.
A 38-year-old woman being treated for tuberculosis is also on oral contraceptives. She reports that
her periods have become irregular. The pharmacist flags a drug interaction. Which TB
medication is most responsible for this interaction and why?
A. Isoniazid, by inhibiting hepatic enzymes and increasing estrogen levels B. Rifampin, by inducing
CYP3A4 and accelerating the metabolism of oral contraceptives C. Ethambutol, by directly
competing with estrogen for receptor binding D. Pyrazinamide, by reducing GI absorption of oral
contraceptives
Correct Answer: B
,Rationale: Rifampin is one of the most potent inducers of cytochrome P450 enzymes, particularly
CYP3A4, which is the primary enzyme responsible for the metabolism of ethinyl estradiol and
progestin in combined oral contraceptives. Induction of CYP3A4 significantly accelerates the
breakdown of these hormones, reducing their plasma concentrations below therapeutic levels and
resulting in contraceptive failure. Women on rifampin-based TB regimens must be counseled to use a
non-hormonal barrier contraceptive method throughout treatment.
A patient receiving chemotherapy with cisplatin is prescribed ondansetron for nausea. She also has
a history of long QT syndrome and is on amiodarone. Which of the following best describes the
nurse's primary concern?
A. Ondansetron is contraindicated with amiodarone due to additive QT prolongation risk B. Ondansetron
will reduce the efficacy of amiodarone C. Amiodarone increases ondansetron levels by inhibiting its
renal excretion D. There is no clinically significant interaction between these drugs
Correct Answer: A
Rationale: Both ondansetron (a 5-HT3 antagonist) and amiodarone independently prolong the cardiac
QT interval by blocking cardiac potassium channels (hERG/IKr channels). When combined,
particularly in a patient with pre-existing long QT syndrome, the risk of potentially fatal ventricular
arrhythmias such as Torsades de Pointes is substantially increased. The nurse should alert the
prescriber, obtain a baseline ECG, and monitor the QTc interval closely. An alternative antiemetic
such as metoclopramide or dexamethasone may be safer in this clinical context.
A 60-year-old man with heart failure is started on carvedilol. The nurse should explain that unlike
selective beta-1 blockers, carvedilol is preferred in heart failure patients with diabetes because:
A. It stimulates insulin secretion directly through beta-2 receptors B. Its alpha-1 blocking activity
improves insulin sensitivity and reduces hypoglycemia masking C. It has no effect on glucose
metabolism whatsoever D. It blocks all adrenergic receptors equally, eliminating all metabolic side
effects
Correct Answer: B
Rationale: Carvedilol is a non-selective beta blocker (blocks beta-1 and beta-2) with additional alpha-1
blocking properties. While beta-2 blockade can mask hypoglycemic tachycardia in diabetics (a known
concern with all non-selective agents), carvedilol's alpha-1 activity improves peripheral insulin
sensitivity and is associated with a more favorable metabolic profile compared to selective agents like
metoprolol. Studies including COPERNICUS and US Carvedilol trials showed it improves mortality
in heart failure with reduced ejection fraction. The alpha-1 blockade also causes vasodilation,
reducing afterload.
A nurse administers IV phenytoin too rapidly (greater than 50 mg/min) during status epilepticus
management. The patient suddenly develops severe hypotension and bradycardia. The nurse
recognizes this is due to:
A. An allergic reaction to the phenytoin molecule itself B. The propylene glycol diluent causing
cardiovascular depression at rapid infusion rates C. Phenytoin directly stimulating vagal tone in the
brainstem D. Phenytoin-induced hyperkalemia causing myocardial depression
Correct Answer: B
Rationale: IV phenytoin is formulated in a vehicle containing propylene glycol, ethanol, and sodium
hydroxide to maintain solubility. Propylene glycol is cardiotoxic when infused rapidly, causing
myocardial depression, hypotension, bradycardia, and heart block. The maximum safe infusion rate
for phenytoin is 50 mg/min in adults (25 mg/min in elderly or cardiac-compromised patients).
Fosphenytoin, a water-soluble prodrug, was developed specifically to avoid this complication and
can be infused at 150 mg PE/min with significantly less cardiovascular risk.
A post-surgical patient on patient-controlled analgesia (PCA) with morphine is found unresponsive
with a respiratory rate of 6 breaths/min and miosis. The nurse administers naloxone 0.4 mg IV.
Within 2 minutes, the patient is awake and in severe pain. What is the nurse's next concern?
A. The naloxone dose was too high and may cause seizures B. Re-narcotization may occur because
naloxone's duration of action is shorter than morphine's C. The patient will develop permanent opioid
, tolerance from this reversal D. Administering naloxone in a post-surgical patient is contraindicated
Correct Answer: B
Rationale: Naloxone has a half-life of approximately 30-90 minutes, significantly shorter than most
opioids including morphine (half-life 2-4 hours). Once naloxone's effect wanes, unopposed opioid
activity will resume, potentially causing re-narcotization (return of respiratory depression). Nurses
must monitor the patient continuously for at least 2-4 hours after naloxone administration, have
repeat doses or a naloxone infusion ready, and avoid over-reversal which can precipitate acute
opioid withdrawal, severe pain, tachycardia, hypertension, and pulmonary edema.
A 55-year-old woman with rheumatoid arthritis on methotrexate 15 mg weekly is prescribed
trimethoprim-sulfamethoxazole (TMP-SMX) for a UTI. What potentially life-threatening
interaction must the nurse recognize?
A. TMP-SMX reduces methotrexate absorption from the GI tract B. Both drugs inhibit dihydrofolate
reductase, causing additive folate antagonism and risk of severe bone marrow suppression C. TMP-
SMX accelerates methotrexate excretion through renal tubular secretion D. Methotrexate inhibits
TMP-SMX metabolism, causing sulfonamide toxicity
Correct Answer: B
Rationale: Methotrexate inhibits dihydrofolate reductase (DHFR), preventing conversion of folate to its
active form, thereby suppressing rapidly dividing cells including immune cells. TMP (the
trimethoprim component of TMP-SMX) also inhibits DHFR. When combined, the additive inhibition
of folate metabolism can cause profound bone marrow suppression, pancytopenia, mucositis, and
potentially fatal hematologic toxicity. TMP-SMX also competes with methotrexate for renal tubular
secretion, increasing methotrexate plasma levels. An alternative antibiotic such as nitrofurantoin
should be used for UTI management in patients on methotrexate.
A patient with Parkinson's disease on levodopa/carbidopa is admitted for a psychiatric episode and
the on-call physician orders haloperidol. The nurse should:
A. Administer haloperidol as ordered since it is safe in all neurological conditions B. Question the order
because haloperidol blocks dopamine D2 receptors and will worsen Parkinsonism C. Administer
haloperidol and increase the levodopa dose simultaneously D. Hold all medications until neurology is
consulted
Correct Answer: B
Rationale: Levodopa/carbidopa works by increasing central dopamine availability to compensate for the
dopaminergic deficit in Parkinson's disease. Haloperidol is a typical (first-generation) antipsychotic
that acts by blocking dopamine D2 receptors. Administering haloperidol will directly antagonize the
therapeutic effect of levodopa, precipitate or dramatically worsen Parkinsonian symptoms (rigidity,
bradykinesia, tremor), and can cause neuroleptic malignant syndrome in this population. For
psychosis in Parkinson's disease, quetiapine or clozapine (which have low D2 affinity) are the
preferred alternatives.
A patient on long-term corticosteroid therapy for Crohn's disease is scheduled for elective knee
surgery. The anesthesiologist orders a perioperative stress dose of hydrocortisone. This is
necessary because:
A. Corticosteroids improve wound healing and should be continued at higher doses B. Exogenous
corticosteroids suppress the hypothalamic-pituitary-adrenal axis, impairing the body's ability to
mount a physiological cortisol stress response C. Surgical patients always need corticosteroids to
prevent anaphylaxis D. Corticosteroids prevent postoperative nausea and are given for antiemetic
purposes
Correct Answer: B
Rationale: Chronic exogenous corticosteroid use suppresses the hypothalamic-pituitary-adrenal (HPA)
axis through negative feedback. The adrenal glands atrophy from disuse and lose the capacity to
produce the surge of cortisol (up to 75-150 mg/day) required during physiological stress such as
surgery. Without stress dosing, the patient risks adrenal crisis, characterized by refractory
hypotension, cardiovascular collapse, hyponatremia, and hypoglycemia. Standard practice involves
hydrocortisone 50-100 mg IV at induction, then every 8 hours for 24-48 hours post-surgery, tapering
