NCLEX Pharmacology Questions: High-Alert Meds & Dosage Calculations
NCLEX pharmacology practice questions on high-alert medications, dosage calculations, and adverse effects, with rationales explaining the correct nursing action.
Pharmacology questions are woven throughout every NCLEX content category, and high-alert medications (insulin, heparin, opioids, potassium) are tested disproportionately because errors with these drugs are the most dangerous in real practice. Here's a sample of the question style used in the full pharmacology set.
Practice questions
1. A client receiving IV heparin has an aPTT of 110 seconds (control 30 seconds). What should the nurse do first?
- A. Increase the infusion rate
- B. Stop the infusion and notify the provider
- C. Administer vitamin K
- D. Document the finding and reassess in 4 hours
Show answer & rationale
Correct answer: B
An aPTT more than 2.5x the control indicates the client is over-anticoagulated and at risk for bleeding; the infusion must be stopped and the provider notified. Vitamin K reverses warfarin, not heparin — protamine sulfate is the heparin antidote.
2. The nurse is preparing to administer regular insulin and NPH insulin to a client. Which action is correct?
- A. Draw up NPH first, then regular insulin
- B. Draw up regular insulin first, then NPH
- C. Mix them in equal proportions only
- D. Administer them in two separate syringes only
Show answer & rationale
Correct answer: B
When mixing insulins, always draw up the clear (regular) insulin before the cloudy (NPH) insulin to avoid contaminating the regular insulin vial with the longer-acting insulin.
3. A client is prescribed digoxin 0.125 mg PO daily. Before administration, which assessment is priority?
- A. Blood pressure
- B. Apical pulse for one full minute
- C. Respiratory rate
- D. Temperature
Show answer & rationale
Correct answer: B
Digoxin toxicity can cause bradycardia; the nurse must count the apical pulse for a full minute and hold the dose if it is below 60 bpm (adult) before administering.
4. A client asks why they must take their oral potassium chloride with food. What is the nurse's best response?
- A. "It improves absorption."
- B. "It reduces the risk of GI irritation and ulceration."
- C. "It prevents hyperkalemia."
- D. "It speeds the onset of action."
Show answer & rationale
Correct answer: B
Oral potassium is highly irritating to the GI mucosa and can cause ulceration; taking it with food or a full glass of water reduces this risk.
5. A prescription reads: Give 500 mL NS IV over 4 hours. The IV tubing delivers 15 gtt/mL. What is the correct flow rate in gtt/min?
- A. 21 gtt/min
- B. 31 gtt/min
- C. 42 gtt/min
- D. 125 gtt/min
Show answer & rationale
Correct answer: B
500 mL ÷ 240 min = 2.08 mL/min × 15 gtt/mL = 31.25, rounded to 31 gtt/min.
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Frequently asked questions
Do I need to memorize dosage calculation formulas for the NCLEX?
Yes — the NCLEX regularly tests IV flow rate, weight-based dosing, and safe dosage range calculations. Practicing the same formula repeatedly until it's automatic is more effective than memorizing multiple formulas.
Which drug classes get tested the most?
Anticoagulants, insulin, opioids, cardiac glycosides (digoxin), and antihypertensives are the most heavily tested because of their high-alert status and narrow therapeutic windows.