HESI RN Pharmacology Final Exam 2025/2026 –
Verified 100% Correct Answers
1. A patient is prescribed warfarin 5 mg PO daily. Which laboratory value
requires immediate provider notification before administering the
dose?INR 4.2 Rationale: Mechanism: Warfarin inhibits vitamin K-dependent
clotting factors (II, VII, IX, X). Therapeutic INR: 2.0–3.0 (or 2.5–3.5 for
mechanical valves). INR >4 increases bleeding risk. Hold dose and notify
provider.
2. The nurse is preparing to administer furosemide 40 mg IV push. Which
action is most important before administration?Check serum potassium level
Rationale: Mechanism: Loop diuretic inhibits Na-K-2Cl cotransporter in
ascending loop of Henle. Side effect: Hypokalemia → arrhythmias. Monitor K⁺;
supplement if <3.5 mEq/L.
3. A patient receiving gentamicin develops tinnitus and vertigo. What is the
nurse’s priority action?Stop the infusion and notify the provider immediately
Rationale: Mechanism: Aminoglycoside binds 30S ribosomal subunit →
bactericidal. Side effect: Ototoxicity (cochlear/vestibular damage). Irreversible;
discontinue drug.
4. Which medication requires the nurse to monitor for signs of cinchonism
(tinnitus, headache, nausea)?Quinidine Rationale: Mechanism: Class IA
antiarrhythmic; blocks Na⁺ channels → prolongs QRS/QT. Side effect:
Cinchonism from quinine-like structure. Reduce dose if symptoms occur.
5. A patient on digoxin has a serum level of 2.8 ng/mL. Which symptom is
most concerning?Visual halos and yellow tint Rationale: Mechanism: Inhibits
Na/K-ATPase → ↑ intracellular Ca²⁺ → positive inotrope. Toxicity: >2.0 ng/mL →
GI upset, visual changes, arrhythmias. Antidote: Digoxin immune Fab.
6. The nurse administers epinephrine 0.3 mg IM to a patient in anaphylaxis.
How soon should reassessment occur?Within 5–15 minutes Rationale:
Mechanism: α/β agonist → vasoconstriction, bronchodilation. Administration: IM
into vastus lateralis; peak 10 min. Repeat q5–15min if no response.
7. Which electrolyte imbalance must be corrected before administering
amphotericin B?Hypokalemia and hypomagnesemia Rationale: Mechanism:
Binds ergosterol in fungal membrane → pores → cell death. Side effect:
Nephrotoxicity, electrolyte wasting. Pre-medicate: saline, K⁺, Mg²⁺.
8. A patient on heparin infusion has aPTT of 110 seconds (control 30 sec).
What is the priority action?Stop infusion and prepare protamine sulfate
Rationale: Mechanism: Binds antithrombin III → inhibits Xa/IIa. Therapeutic
, aPTT: 1.5–2.5× control. Antidote: Protamine 1 mg per 100 units heparin (max 50
mg).
9. Which medication should be held prior to surgery due to risk of serotonin
syndrome when combined with anesthetics?Fluoxetine (SSRI) Rationale:
Mechanism: Inhibits serotonin reuptake. Side effect: Serotonin syndrome
(hyperthermia, rigidity, autonomic instability). Hold 2–5 weeks pre-op depending
on half-life.
10.The nurse is teaching a patient on metformin. Which statement indicates
understanding?"I should hold the dose if I feel nauseated before a CT with
contrast." Rationale: Mechanism: ↓ hepatic glucose production, ↑ insulin
sensitivity. Side effect: Lactic acidosis (rare). Hold 48h before/after iodinated
contrast.
11.A patient receiving vancomycin develops red man syndrome during
infusion. What is the immediate action?Slow infusion rate to over 2 hours and
pre-medicate with antihistamine Rationale: Mechanism: Bactericidal; inhibits cell
wall synthesis. Side effect: Histamine release → flushing, pruritus. Prevention:
1–2 hr infusion.
12.Which lab value indicates phenytoin toxicity (>20 mcg/mL)?Nystagmus,
ataxia, slurred speech Rationale: Mechanism: Blocks Na⁺ channels → stabilizes
neuronal membranes. Toxicity: >20 → horizontal nystagmus; >30 → ataxia.
Monitor levels.
13.A patient on lithium has a level of 1.6 mEq/L. Which symptom requires
immediate intervention?Coarse hand tremor and confusion Rationale:
Mechanism: Mood stabilizer; alters Na⁺ transport. Therapeutic: 0.6–1.2 mEq/L.
Toxicity: >1.5 → tremor, confusion; >2.0 → seizures. Hydrate, hemodialysis if
severe.
14.The nurse administers morphine 4 mg IV for pain. When should peak effect
be expected?15–30 minutes Rationale: Mechanism: Mu-opioid agonist →
analgesia, sedation. Onset IV: 5–10 min; peak: 20 min; duration: 3–4 hr. Monitor
RR.
15.Which medication is contraindicated in a patient with prolonged QTc
interval?Ondansetron Rationale: Mechanism: 5-HT₃ antagonist → antiemetic.
Side effect: QT prolongation → torsades. Avoid with other QT-prolonging drugs
(e.g., haloperidol).
16.A patient on levothyroxine reports palpitations and weight loss. What lab
should be checked?Free T4 and TSH Rationale: Mechanism: Synthetic T4 → ↑
metabolism. Toxicity: Hyperthyroidism symptoms. ↓ TSH, ↑ Free T4 → reduce
dose.
17.The nurse is preparing to give succinylcholine. Which condition is an
absolute contraindication?History of malignant hyperthermia Rationale:
Verified 100% Correct Answers
1. A patient is prescribed warfarin 5 mg PO daily. Which laboratory value
requires immediate provider notification before administering the
dose?INR 4.2 Rationale: Mechanism: Warfarin inhibits vitamin K-dependent
clotting factors (II, VII, IX, X). Therapeutic INR: 2.0–3.0 (or 2.5–3.5 for
mechanical valves). INR >4 increases bleeding risk. Hold dose and notify
provider.
2. The nurse is preparing to administer furosemide 40 mg IV push. Which
action is most important before administration?Check serum potassium level
Rationale: Mechanism: Loop diuretic inhibits Na-K-2Cl cotransporter in
ascending loop of Henle. Side effect: Hypokalemia → arrhythmias. Monitor K⁺;
supplement if <3.5 mEq/L.
3. A patient receiving gentamicin develops tinnitus and vertigo. What is the
nurse’s priority action?Stop the infusion and notify the provider immediately
Rationale: Mechanism: Aminoglycoside binds 30S ribosomal subunit →
bactericidal. Side effect: Ototoxicity (cochlear/vestibular damage). Irreversible;
discontinue drug.
4. Which medication requires the nurse to monitor for signs of cinchonism
(tinnitus, headache, nausea)?Quinidine Rationale: Mechanism: Class IA
antiarrhythmic; blocks Na⁺ channels → prolongs QRS/QT. Side effect:
Cinchonism from quinine-like structure. Reduce dose if symptoms occur.
5. A patient on digoxin has a serum level of 2.8 ng/mL. Which symptom is
most concerning?Visual halos and yellow tint Rationale: Mechanism: Inhibits
Na/K-ATPase → ↑ intracellular Ca²⁺ → positive inotrope. Toxicity: >2.0 ng/mL →
GI upset, visual changes, arrhythmias. Antidote: Digoxin immune Fab.
6. The nurse administers epinephrine 0.3 mg IM to a patient in anaphylaxis.
How soon should reassessment occur?Within 5–15 minutes Rationale:
Mechanism: α/β agonist → vasoconstriction, bronchodilation. Administration: IM
into vastus lateralis; peak 10 min. Repeat q5–15min if no response.
7. Which electrolyte imbalance must be corrected before administering
amphotericin B?Hypokalemia and hypomagnesemia Rationale: Mechanism:
Binds ergosterol in fungal membrane → pores → cell death. Side effect:
Nephrotoxicity, electrolyte wasting. Pre-medicate: saline, K⁺, Mg²⁺.
8. A patient on heparin infusion has aPTT of 110 seconds (control 30 sec).
What is the priority action?Stop infusion and prepare protamine sulfate
Rationale: Mechanism: Binds antithrombin III → inhibits Xa/IIa. Therapeutic
, aPTT: 1.5–2.5× control. Antidote: Protamine 1 mg per 100 units heparin (max 50
mg).
9. Which medication should be held prior to surgery due to risk of serotonin
syndrome when combined with anesthetics?Fluoxetine (SSRI) Rationale:
Mechanism: Inhibits serotonin reuptake. Side effect: Serotonin syndrome
(hyperthermia, rigidity, autonomic instability). Hold 2–5 weeks pre-op depending
on half-life.
10.The nurse is teaching a patient on metformin. Which statement indicates
understanding?"I should hold the dose if I feel nauseated before a CT with
contrast." Rationale: Mechanism: ↓ hepatic glucose production, ↑ insulin
sensitivity. Side effect: Lactic acidosis (rare). Hold 48h before/after iodinated
contrast.
11.A patient receiving vancomycin develops red man syndrome during
infusion. What is the immediate action?Slow infusion rate to over 2 hours and
pre-medicate with antihistamine Rationale: Mechanism: Bactericidal; inhibits cell
wall synthesis. Side effect: Histamine release → flushing, pruritus. Prevention:
1–2 hr infusion.
12.Which lab value indicates phenytoin toxicity (>20 mcg/mL)?Nystagmus,
ataxia, slurred speech Rationale: Mechanism: Blocks Na⁺ channels → stabilizes
neuronal membranes. Toxicity: >20 → horizontal nystagmus; >30 → ataxia.
Monitor levels.
13.A patient on lithium has a level of 1.6 mEq/L. Which symptom requires
immediate intervention?Coarse hand tremor and confusion Rationale:
Mechanism: Mood stabilizer; alters Na⁺ transport. Therapeutic: 0.6–1.2 mEq/L.
Toxicity: >1.5 → tremor, confusion; >2.0 → seizures. Hydrate, hemodialysis if
severe.
14.The nurse administers morphine 4 mg IV for pain. When should peak effect
be expected?15–30 minutes Rationale: Mechanism: Mu-opioid agonist →
analgesia, sedation. Onset IV: 5–10 min; peak: 20 min; duration: 3–4 hr. Monitor
RR.
15.Which medication is contraindicated in a patient with prolonged QTc
interval?Ondansetron Rationale: Mechanism: 5-HT₃ antagonist → antiemetic.
Side effect: QT prolongation → torsades. Avoid with other QT-prolonging drugs
(e.g., haloperidol).
16.A patient on levothyroxine reports palpitations and weight loss. What lab
should be checked?Free T4 and TSH Rationale: Mechanism: Synthetic T4 → ↑
metabolism. Toxicity: Hyperthyroidism symptoms. ↓ TSH, ↑ Free T4 → reduce
dose.
17.The nurse is preparing to give succinylcholine. Which condition is an
absolute contraindication?History of malignant hyperthermia Rationale:
