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NCLEX Pharmacology Practice Questions

Medically reviewed by Douglas Carollo, MSN, APRN, FNP-BC Updated September 2026 10 practice questions

Quick answer: Pharmacology is tested mainly under Pharmacological and Parenteral Therapies, 13-19% of the 2026 NCLEX-RN test plan, a category that includes dosage calculation, mixing medications from two vials, and handling high-risk medications safely. The 10 practice questions below cover insulin, heparin, warfarin, digoxin, IV potassium, opioids, lithium, furosemide, ACE inhibitors, and beta blockers, each with a full rationale.

Pharmacology is one of the highest-yield and most feared sections of the NCLEX. Work through these 10 practice questions — insulin timing and mixing, anticoagulant monitoring and antidotes, digoxin and lithium safety, high-alert IV potassium, opioids, loop diuretics, ACE inhibitors, and beta blockers — each with a full rationale that explains why every option is right or wrong.

High-Alert Meds, Ranges & Antidotes: High-Yield Review

Pharmacology is one of the highest-yield areas on the NCLEX because safe medication administration questions test clinical judgment, not memorization alone. Many of these drugs are high-alert medications, meaning an error carries a high risk of serious harm. Master a short list of exact therapeutic ranges and antidotes: heparin is monitored by aPTT (therapeutic ~1.5 to 2.5 times the control) with the antidote protamine sulfate, while warfarin is monitored by PT/INR (therapeutic INR 2 to 3 for most indications) with the antidote vitamin K (phytonadione); enoxaparin, a low-molecular-weight heparin, is generally given without routine aPTT monitoring. Digoxin has a therapeutic level of 0.5 to 2 ng/mL, and hypokalemia potentiates its toxicity (antidote: digoxin immune Fab). Lithium has a narrow therapeutic range of 0.6 to 1.2 mEq/L. Phenytoin runs 10 to 20 mcg/mL. Aminoglycosides (such as gentamicin) require peak and trough monitoring and carry nephrotoxicity and ototoxicity risk, while vancomycin is monitored by trough level (AUC-guided in current practice), with nephrotoxicity as the primary concern.

Insulin timing is a classic exam target. Rapid-acting lispro and aspart begin working in about 15 minutes (give with the meal); regular (short-acting) insulin has an onset of about 30 to 60 minutes and a peak of 2 to 3 hours; NPH (intermediate) peaks around 4 to 12 hours; and glargine or detemir are essentially peakless over about 24 hours. Hypoglycemia is most likely at a drug's peak. When mixing regular and NPH in one syringe, always draw up the clear regular insulin before the cloudy NPH: remember "clear before cloudy." Potassium chloride is never given IV push (it causes fatal dysrhythmias); always dilute it and infuse by pump, with a peripheral maximum around 10 mEq/hr, and give oral forms with food.

Anchor a few more safety rules. For opioids, monitor respiratory rate and hold or reassess if it falls below 12; the antidote is naloxone, and constipation is an expected effect that needs a bowel regimen. Loop diuretics such as furosemide cause hypokalemia, dehydration, and ototoxicity with rapid IV push, so teach potassium-rich foods and push slowly. ACE inhibitors (the "-pril" drugs) cause a dry nonproductive cough, first-dose hypotension, hyperkalemia, and angioedema, which is a reason to STOP the drug. Beta blockers (the "-olol" drugs) require an apical pulse check, are held for a rate below 60, must not be stopped abruptly (rebound), and can mask the signs of hypoglycemia.

NCLEX Pharmacology Practice Questions

Question 1 · Insulin administration and mixing

The nurse is preparing to administer 10 units of regular insulin and 15 units of NPH insulin in a single syringe subcutaneously before breakfast. Which action is correct?

  • A Draw up the NPH (cloudy) insulin into the syringe before the regular (clear) insulin
  • B Withdraw the NPH insulin first and then add the regular insulin to the same syringe
  • C Draw up the regular (clear) insulin into the syringe before the NPH (cloudy) insulin
  • D Administer the two insulins in two separate syringes at two different injection sites
Show answer & rationale
Correct answer: C
When mixing regular and NPH in one syringe, always draw up the clear regular insulin before the cloudy NPH: the memory aid is "clear before cloudy" (or "RN" for Regular then NPH). Technique: inject air into the NPH (cloudy) vial first without touching the solution, then inject air into the regular vial, withdraw the regular insulin, and finally withdraw the NPH. Drawing up NPH first, or withdrawing NPH before regular, risks contaminating the clear regular vial with the intermediate-acting NPH suspension, which alters the rapid onset of the regular insulin and is why those two orderings are wrong. Giving the two insulins in separate syringes and sites is unnecessary here and adds a second injection; separate syringes are reserved for insulins that cannot be mixed, such as glargine, which is never combined with other insulins. Know the timing that makes this dangerous if done wrong: regular (short-acting) insulin has an onset of about 30 to 60 minutes and a peak of 2 to 3 hours, while NPH (intermediate) peaks around 4 to 12 hours. For comparison, rapid-acting lispro and aspart begin in about 15 minutes and are given with the meal, and glargine and detemir are essentially peakless over about 24 hours. Hypoglycemia is most likely at each insulin's peak, so accurate mixing preserves the intended action profile. Insulin is a high-alert medication requiring an independent double-check per facility policy.
Question 2 · Anticoagulant monitoring and antidotes

A client receiving a continuous IV heparin infusion has an aPTT that is 3.5 times the control value and develops new hematuria. Which medication should the nurse anticipate administering?

  • A Protamine sulfate
  • B Digoxin immune Fab
  • C Vitamin K (phytonadione)
  • D Naloxone
Show answer & rationale
Correct answer: A
Heparin is monitored by the aPTT, with a therapeutic goal of about 1.5 to 2.5 times the control value. An aPTT of 3.5 times control is supratherapeutic and, combined with new hematuria (bleeding), signals heparin excess. The specific antidote for heparin is protamine sulfate, which binds heparin and neutralizes its anticoagulant effect. Vitamin K (phytonadione) is the antidote for warfarin, not heparin; warfarin is monitored by PT/INR with a therapeutic INR of 2 to 3 for most indications, so vitamin K is the wrong reversal agent here. Digoxin immune Fab is the antidote for digoxin toxicity and has no role in anticoagulation. Naloxone reverses opioids and would do nothing for heparin-related bleeding. A helpful memory aid: heParin pairs with Protamine and the aPTT, while warFarin pairs with the INR and vitamin K. Note that enoxaparin, a low-molecular-weight heparin, is generally dosed by weight and given without routine aPTT monitoring, though protamine provides partial reversal if needed. The nurse should also stop the infusion, apply pressure to any bleeding sites, and notify the provider while anticipating the protamine order.
Question 3 · Digoxin safety and toxicity

Before administering the morning dose of digoxin to a client with heart failure, the nurse notes an apical heart rate of 52 beats per minute and the client reports nausea and seeing yellow-green halos around lights. Which action is the priority?

  • A Administer the dose and recheck the apical pulse in one hour
  • B Hold the dose and notify the provider
  • C Give the dose with orange juice to prevent GI upset
  • D Document the findings as expected and give half the dose
Show answer & rationale
Correct answer: B
Digoxin is held when the apical pulse is below 60 beats per minute; an apical rate of 52 alone is a reason to hold. In addition, nausea/anorexia and visual disturbances such as yellow-green halos are hallmark early signs of digoxin toxicity. The correct action is to hold the dose and notify the provider, then anticipate a serum digoxin level (therapeutic range 0.5 to 2 ng/mL) and a potassium level. Administering the dose and rechecking later ignores both the low pulse and the toxicity signs and could worsen bradycardia or heart block. Giving the drug with orange juice treats the symptom as ordinary GI upset and still delivers a dangerous dose. Giving half the dose is never a nursing decision; the nurse does not alter a prescribed dose independently. Clinical pearl: hypokalemia potentiates digoxin toxicity, so watch clients on loop diuretics closely, and the antidote for severe toxicity is digoxin immune Fab. Remember the early toxicity triad: anorexia/nausea and vomiting, visual changes (halos, blurred or yellow-green vision), and bradycardia.
Question 4 · High-alert IV potassium safety

A provider prescribes potassium chloride 20 mEq IV for a client with a serum potassium of 2.9 mEq/L. Which action by the nurse is safest?

  • A Administer the potassium chloride by slow IV push over two minutes on a cardiac monitor
  • B Give the potassium chloride undiluted through a large-bore peripheral IV line
  • C Add the potassium chloride to the maintenance IV bag already hanging at the bedside
  • D Dilute the potassium chloride and infuse by pump at 10 mEq/hr or less peripherally
Show answer & rationale
Correct answer: D
Potassium chloride is a high-alert medication and is NEVER given by IV push; a concentrated bolus can cause fatal cardiac dysrhythmias, including cardiac arrest. The safe practice is to use a premixed, diluted solution and infuse it via an IV pump, with a peripheral rate that usually does not exceed 10 mEq/hr (higher rates or more concentrated solutions require central access and continuous cardiac monitoring). That makes the diluted, pump-controlled, rate-limited option correct. Slow IV push over two minutes, even on a cardiac monitor, is still an IV push and is contraindicated. Giving it undiluted, even through a large-bore peripheral line, is dangerously irritating to the vein and unsafe. Adding potassium to a bag already hanging risks uneven distribution ('bolusing') and dosing error; potassium should be added before hanging or, preferably, come premixed from the pharmacy. Clinical pearl: oral potassium forms should be taken with food or a full glass of water to reduce GI irritation. Always verify the client has adequate urine output before infusing potassium, and monitor the ECG and IV site for irritation during the infusion.
Question 5 · Opioid respiratory monitoring and antidote

One hour after receiving IV morphine for postoperative pain, a client has a respiratory rate of 8 breaths per minute and is difficult to arouse. Which action is the priority?

  • A Administer naloxone as prescribed
  • B Encourage the client to cough and deep breathe
  • C Administer the next scheduled dose of morphine
  • D Document the finding and reassess in 30 minutes
Show answer & rationale
Correct answer: A
Opioids are held or reassessed when the respiratory rate falls below 12 breaths per minute. A rate of 8 with a client who is difficult to arouse indicates opioid-induced respiratory depression and oversedation, a medical emergency. The priority is to administer the opioid antagonist naloxone as prescribed, while supporting airway and breathing and stimulating the client. Encouraging coughing and deep breathing does not reverse the opioid effect and is inadequate for a sedated client with a rate of 8. Giving the next dose of morphine would deepen the respiratory depression and could be fatal. Documenting and waiting 30 minutes delays urgent treatment and is unsafe. Clinical pearl: naloxone has a shorter half-life than many opioids, so the nurse must keep monitoring for re-sedation and repeat dosing may be required. Also remember that constipation is an expected opioid effect that does not lessen with tolerance and requires a proactive bowel regimen (stool softener plus stimulant laxative, fluids, and fiber), whereas respiratory depression is the effect that demands immediate intervention.
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Question 6 · Lithium therapeutic range and toxicity

A client who takes lithium for bipolar disorder has a serum lithium level of 1.8 mEq/L and reports coarse hand tremors, vomiting, and new confusion. How should the nurse interpret these findings?

  • A The level is subtherapeutic and the dose should be increased
  • B The level is within the normal therapeutic range
  • C These are expected first-week side effects that need no action
  • D The client is showing signs of lithium toxicity
Show answer & rationale
Correct answer: D
Lithium has a narrow therapeutic range of 0.6 to 1.2 mEq/L. A level of 1.8 mEq/L is elevated, and the combination of coarse tremors (versus the fine tremor sometimes seen at therapeutic levels), vomiting, and confusion reflects lithium toxicity. Toxic manifestations progress from GI upset and coarse tremor to ataxia, confusion, seizures, and cardiovascular collapse as levels climb. Calling the level subtherapeutic and increasing the dose would worsen the toxicity and is dangerous. Calling 1.8 mEq/L normal is incorrect because it exceeds the 1.2 upper limit. Dismissing these as harmless first-week side effects ignores a level that is clearly out of range and symptoms that demand action; the nurse should hold the drug and notify the provider. Clinical pearl: lithium is handled by the kidneys like sodium, so dehydration and low sodium intake raise the lithium level and precipitate toxicity. Teach clients to maintain consistent, adequate sodium intake and fluids (about 2 to 3 liters per day), avoid becoming dehydrated (illness, heavy sweating, diuretics), and have levels monitored regularly.
Question 7 · ACE inhibitor angioedema

A client who started lisinopril three days ago telephones the clinic reporting new swelling of the lips and tongue and difficulty breathing. Which is the priority nursing response?

  • A Reassure the client that this is a harmless expected dry cough
  • B Tell the client to take the next dose with food to reduce symptoms
  • C Instruct the client to stop the drug and seek emergency care immediately
  • D Advise the client to double the daily water intake
Show answer & rationale
Correct answer: C
Swelling of the lips and tongue with difficulty breathing is angioedema, a potentially life-threatening reaction to ACE inhibitors (the '-pril' drugs). Angioedema can compromise the airway, so the priority is to have the client stop the drug and seek emergency care immediately; the ACE inhibitor should be discontinued and not restarted. Calling this a harmless dry cough is wrong: ACE inhibitors do cause a dry, nonproductive cough, but a cough is not lip and tongue swelling with breathing difficulty, and confusing the two could cost the client an airway. Taking the dose with food does nothing for angioedema and delays care. Doubling water intake is irrelevant and dangerous when the airway is threatened. Clinical pearl: memorize the key '-pril' effects as a cluster: dry cough, first-dose hypotension, hyperkalemia, and angioedema. Angioedema is the one that means STOP the drug. Because ACE inhibitors raise potassium, also teach clients to avoid salt substitutes (which are potassium-based) and excessive potassium-rich foods unless directed otherwise.
Question 8 · Warfarin patient teaching

The nurse is teaching a client who is newly prescribed warfarin. Which statements by the client indicate correct understanding? Select all that apply.

  • A "I can take ibuprofen freely whenever I have a headache."
  • B "I will keep my intake of green leafy vegetables about the same amount each week."
  • C "My blood will be checked with an INR, and 2 to 3 is the usual target."
  • D "I should use a soft toothbrush and an electric razor."
  • E "An INR of 5 just means the medicine is working really well and is safe."
  • F "If I bleed too much, vitamin K can be given to reverse this drug."
Show answer & rationale
Correct answer: B, C, D, F
Warfarin blocks vitamin K-dependent clotting factors, so consistency, not avoidance, is the teaching point: the client should keep green leafy vegetable (vitamin K) intake about the same each week so the dose stays balanced, making that statement correct. Warfarin is monitored by PT/INR, with a therapeutic INR of 2 to 3 for most indications, so understanding that goal is correct. Bleeding precautions such as a soft toothbrush and electric razor are appropriate because warfarin increases bleeding risk. Recognizing that vitamin K (phytonadione) is the antidote for warfarin is also correct. The statement about taking ibuprofen freely is wrong: NSAIDs like ibuprofen increase bleeding risk and can displace warfarin from protein binding, raising the effect; clients should check before using any NSAID or aspirin and generally use acetaminophen for pain instead. The statement that an INR of 5 is safe is wrong and dangerous: an INR above the 2 to 3 target markedly increases bleeding risk and should be reported, not celebrated. Clinical pearl: warFarin goes with the INR and vitamin K, while heParin goes with the aPTT and Protamine. Teach clients to report unusual bruising, blood in urine or stool, or bleeding gums, and to maintain consistent diet and medication timing.
Question 9 · Loop diuretic (furosemide) monitoring

A client is receiving IV furosemide for fluid overload. Which interventions and teaching points should the nurse include? Select all that apply.

  • A Monitor for hypokalemia and report muscle weakness or leg cramps
  • B Encourage potassium-rich foods such as bananas, oranges, and potatoes
  • C Expect the medication to cause hyperkalemia
  • D Monitor for hearing changes, especially with rapid IV administration
  • E Push the IV dose rapidly to achieve a faster diuretic response
  • F Teach the client to change positions slowly to prevent dizziness
Show answer & rationale
Correct answer: A, B, D, F
Furosemide is a loop diuretic that causes potassium loss, so monitoring for hypokalemia and its signs (muscle weakness, cramps, fatigue, cardiac dysrhythmias) is essential, and teaching potassium-rich foods such as bananas, oranges, and potatoes helps offset that loss. Because loop diuretics are ototoxic, especially when given by rapid IV push, the nurse monitors for hearing changes and tinnitus and administers IV doses slowly (generally no faster than about 20 mg/min or per policy); this is exactly why the statement about pushing the dose rapidly is wrong and unsafe. Furosemide also causes fluid and volume loss, so teaching the client to change positions slowly reduces the risk of orthostatic hypotension and falls. The statement expecting hyperkalemia is wrong: loop diuretics cause hypokalemia, not hyperkalemia (potassium-sparing diuretics like spironolactone are the ones that raise potassium). Clinical pearl: monitor daily weights (a change of about 1 kg reflects roughly 1 liter of fluid), intake and output, blood pressure, and electrolytes. Watch closely when a client also takes digoxin, because furosemide-induced hypokalemia potentiates digoxin toxicity.
Question 10 · Beta blocker patient teaching

The nurse is teaching a client who is prescribed metoprolol for hypertension. Which statements by the client indicate correct understanding? Select all that apply.

  • A "Once my pulse has been normal for a few days, I can just stop taking it."
  • B "I will check my pulse and hold the dose if it is below 60."
  • C "I should not stop this medication suddenly."
  • D "It is fine to skip doses whenever I think my blood pressure is okay."
  • E "This drug can hide the warning signs of low blood sugar, like a fast heartbeat."
  • F "I should stand up slowly because I might feel dizzy."
Show answer & rationale
Correct answer: B, C, E, F
Beta blockers (the '-olol' drugs) slow the heart rate, so teaching the client to check the pulse and hold the dose for a rate below 60 beats per minute is correct. They must not be stopped abruptly, because abrupt discontinuation can cause rebound hypertension, tachycardia, angina, or even myocardial infarction; the client who says he should not stop suddenly understands this. Beta blockers can mask the adrenergic warning signs of hypoglycemia (such as tachycardia and tremor), which is an important teaching point for clients with diabetes, so that statement is correct. Because beta blockers can cause orthostatic hypotension, rising slowly to prevent dizziness is appropriate. The statement about simply stopping the drug once the pulse is normal is wrong, as is skipping doses when the client feels fine: both reflect self-discontinuation, which risks rebound effects, and hypertension is often asymptomatic, so 'feeling okay' is not a reason to skip doses. Clinical pearl: beta blockers should be tapered, never stopped cold. Non-selective beta blockers can also cause bronchospasm, so use caution in clients with asthma or COPD. Teach clients to report weight gain, shortness of breath, or swelling, which may signal worsening heart failure.

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NCLEX Pharmacology FAQ

What are the must-know therapeutic drug ranges for the NCLEX?

Memorize a short high-yield list: digoxin 0.5 to 2 ng/mL, lithium 0.6 to 1.2 mEq/L, and phenytoin 10 to 20 mcg/mL. For anticoagulants, warfarin targets an INR of 2 to 3 for most indications, while therapeutic heparin keeps the aPTT about 1.5 to 2.5 times the control value. Aminoglycosides are dosed to peak and trough levels and carry nephrotoxicity and ototoxicity risk, while vancomycin is monitored by trough level (AUC-guided in current practice), with nephrotoxicity as the main concern. Knowing the number lets you recognize both toxicity (above range) and ineffective dosing (below range).

What are the key medication antidotes I need to memorize?

Pair each high-alert drug with its reversal agent: heparin is reversed by protamine sulfate; warfarin is reversed by vitamin K (phytonadione); opioids (like morphine) are reversed by naloxone; digoxin toxicity is treated with digoxin immune Fab; benzodiazepines are reversed by flumazenil; and acetaminophen overdose is treated with acetylcysteine. A quick memory aid links the anticoagulants: heParin goes with Protamine and the aPTT, while warFarin goes with vitamin K and the INR.

How do I remember insulin onset, peak, and mixing rules?

Rapid-acting lispro and aspart start in about 15 minutes and are given with the meal. Regular (short-acting) insulin has an onset of about 30 to 60 minutes and peaks in 2 to 3 hours. NPH (intermediate) peaks around 4 to 12 hours. Glargine and detemir (long-acting) are essentially peakless over about 24 hours. Hypoglycemia is most likely at a drug's peak. When mixing regular and NPH in one syringe, draw up the clear regular before the cloudy NPH: remember 'clear before cloudy.'

Why is IV potassium chloride considered so dangerous?

Concentrated potassium given by IV push can trigger fatal cardiac dysrhythmias, so potassium chloride is NEVER pushed IV. It must always be diluted and infused with an IV pump, with a peripheral rate that usually does not exceed 10 mEq/hr; faster rates or higher concentrations require central access and continuous cardiac monitoring. Verify adequate urine output before infusing, monitor the ECG and the IV site for irritation, and give oral potassium with food or a full glass of water to reduce GI upset.

Sources

Sources checked September 2026.

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