🏥 NCLEX Pharmacology MCQs (Set 1: Q1–50)
Pharmacology is one of the most challenging parts of the NCLEX exam. Nurses are expected to know not only the names of drugs but also their mechanisms, side effects, and safe administration practices. To help you prepare effectively, we’ve compiled 50 NCLEX Pharmacology MCQs with answers and explanations.
These questions cover essential topics like insulin therapy, cardiac drugs, antibiotics, antiepileptics, and emergency medications. Each question is explained in simple language so that you not only memorize the answer but also understand the concept behind it.
Whether you are a nursing student preparing for the NCLEX-RN in the USA, NCLEX-PN in Canada, or other nursing licensing exams worldwide, these practice questions will help strengthen your knowledge and test-taking skills.
Q1. Which of the following is a common side effect of beta-blockers?
A) Hypoglycemia
B) Bradycardia
C) Hyperthermia
D) Constipation
✅ Correct Answer: B) Bradycardia
Explanation: Beta-blockers (e.g., propranolol, atenolol) work by blocking beta-adrenergic receptors, reducing heart rate and blood pressure. This often results in bradycardia. Nurses should always check the patient’s pulse before administration and withhold the dose if the heart rate is below 60 bpm.
Q2. A nurse is administering digoxin. Which electrolyte imbalance increases the risk of digoxin toxicity?
A) Hypernatremia
B) Hypokalemia
C) Hypercalcemia
D) Hypermagnesemia
✅ Correct Answer: B) Hypokalemia
Explanation: Low potassium levels enhance digoxin’s effects, leading to toxicity. Symptoms include nausea, vomiting, visual disturbances (yellow-green halos), and arrhythmias. Monitoring potassium and digoxin levels is crucial in patients on diuretics.
Q3. Which of the following antibiotics can cause permanent discoloration of teeth in children?
A) Penicillin
B) Tetracycline
C) Amoxicillin
D) Erythromycin
✅ Correct Answer: B) Tetracycline
Explanation: Tetracyclines bind to calcium, leading to yellow-gray-brown discoloration of teeth in children and affecting bone growth. They should be avoided in children under 8 and in pregnant women.
Q4. A nurse is caring for a patient prescribed warfarin. Which laboratory test is most important to monitor?
A) Hemoglobin
B) INR (International Normalized Ratio)
C) Platelet count
D) aPTT (Activated Partial Thromboplastin Time)
✅ Correct Answer: B) INR
Explanation: Warfarin’s effectiveness is measured by the INR, with a therapeutic range of 2.0–3.0 for most conditions. Elevated INR increases bleeding risk. Vitamin K is the antidote for warfarin overdose.
Q5. Which insulin type has the fastest onset of action?
A) Regular insulin
B) NPH insulin
C) Lispro insulin
D) Glargine insulin
✅ Correct Answer: C) Lispro insulin
Explanation: Lispro (Humalog) is a rapid-acting insulin with an onset of about 15 minutes, peak at 1 hour, and duration of 3–4 hours. It should be administered with meals to control postprandial glucose spikes.
Q6. Which adverse effect is commonly associated with aminoglycosides (e.g., gentamicin)?
A) Hepatotoxicity
B) Ototoxicity
C) Hypertension
D) Constipation
✅ Correct Answer: B) Ototoxicity
Explanation: Aminoglycosides can damage the inner ear, leading to hearing loss or balance problems. They are also nephrotoxic, so renal function and hearing must be monitored closely during treatment.
Q7. Which medication is commonly used as the first-line treatment for anaphylaxis?
A) Diphenhydramine
B) Epinephrine
C) Hydrocortisone
D) Ranitidine
✅ Correct Answer: B) Epinephrine
Explanation: Epinephrine is the drug of choice in anaphylaxis. It rapidly reverses airway obstruction, hypotension, and bronchospasm by stimulating alpha and beta adrenergic receptors. It is usually administered intramuscularly into the thigh.
Q8. Which class of drugs is most commonly used for the management of hypertension?
A) Antacids
B) Antidepressants
C) ACE inhibitors
D) Anticoagulants
✅ Correct Answer: C) ACE inhibitors
Explanation: ACE inhibitors (e.g., enalapril, lisinopril) are widely used for hypertension. They reduce angiotensin II production, lowering blood pressure. A notable side effect is a persistent dry cough due to increased bradykinin levels.
Q9. Which vitamin deficiency is associated with prolonged use of isoniazid (INH)?
A) Vitamin C
B) Vitamin B6 (Pyridoxine)
C) Vitamin D
D) Vitamin K
✅ Correct Answer: B) Vitamin B6 (Pyridoxine)
Explanation: INH interferes with pyridoxine metabolism, leading to peripheral neuropathy. Supplementation with Vitamin B6 is recommended for all patients receiving isoniazid.
Q10. Which drug is contraindicated in patients with a history of peptic ulcer disease due to its risk of GI bleeding?
A) Acetaminophen
B) Aspirin
C) Omeprazole
D) Ranitidine
✅ Correct Answer: B) Aspirin
Explanation: Aspirin is an NSAID that inhibits prostaglandin synthesis, leading to gastric mucosal irritation and risk of GI bleeding. Patients with peptic ulcer disease should avoid aspirin unless prescribed under strict medical supervision.
Q11. Which drug is the antidote for opioid overdose?
A) Flumazenil
B) Naloxone
C) Atropine
D) Protamine sulfate
✅ Correct Answer: B) Naloxone
Explanation: Naloxone is an opioid antagonist that rapidly reverses respiratory depression and CNS depression caused by opioid overdose (e.g., morphine, heroin). It works within minutes and is life-saving in emergency care.
Q12. Which of the following is a serious side effect of long-term corticosteroid use?
A) Hypoglycemia
B) Osteoporosis
C) Bradycardia
D) Hypotension
✅ Correct Answer: B) Osteoporosis
Explanation: Chronic corticosteroid therapy (e.g., prednisone) can lead to bone demineralization, muscle wasting, hyperglycemia, immunosuppression, and Cushingoid features. Nurses must educate patients about calcium and vitamin D intake.
Q13. A patient is prescribed heparin. Which laboratory test should the nurse monitor?
A) INR
B) aPTT
C) Hematocrit
D) Platelet aggregation
✅ Correct Answer: B) aPTT
Explanation: Heparin therapy is monitored by activated partial thromboplastin time (aPTT). The therapeutic range is usually 1.5–2.5 times the normal control value. Protamine sulfate is the antidote for heparin toxicity.
Q14. Which drug is classified as a proton pump inhibitor (PPI)?
A) Omeprazole
B) Ranitidine
C) Sucralfate
D) Misoprostol
✅ Correct Answer: A) Omeprazole
Explanation: Omeprazole is a PPI that suppresses gastric acid secretion by inhibiting the proton pump in stomach parietal cells. It is widely used in GERD, peptic ulcers, and Zollinger-Ellison syndrome.
Q15. Which of the following drugs is used to treat tuberculosis (TB)?
A) Rifampin
B) Ciprofloxacin
C) Amoxicillin
D) Clarithromycin
✅ Correct Answer: A) Rifampin
Explanation: Rifampin is a first-line anti-TB drug. It is often used in combination with isoniazid, pyrazinamide, and ethambutol. A common side effect is orange-red discoloration of body fluids (urine, sweat, tears).
Q16. Which adverse effect is commonly associated with ACE inhibitors?
A) Dry cough
B) Constipation
C) Hypoglycemia
D) Hearing loss
✅ Correct Answer: A) Dry cough
Explanation: ACE inhibitors increase bradykinin levels, leading to a persistent dry cough in some patients. Angioedema is a rare but dangerous reaction. If cough is intolerable, patients may be switched to ARBs (losartan).
Q17. Which drug is considered the first-line treatment for status epilepticus?
A) Lorazepam
B) Phenytoin
C) Carbamazepine
D) Gabapentin
✅ Correct Answer: A) Lorazepam
Explanation: Benzodiazepines like lorazepam or diazepam are the first-line drugs for status epilepticus because of their rapid onset in stopping seizures. Phenytoin may be given later for long-term seizure control.
Q18. Which medication is used as an antidote for benzodiazepine overdose?
A) Protamine sulfate
B) Flumazenil
C) Atropine
D) Naloxone
✅ Correct Answer: B) Flumazenil
Explanation: Flumazenil is a benzodiazepine receptor antagonist that reverses sedation and respiratory depression caused by benzodiazepines (e.g., diazepam, lorazepam). It must be used cautiously as it may trigger seizures in chronic users.
Q19. Which drug class is commonly prescribed to lower cholesterol levels?
A) Beta-blockers
B) Statins
C) Diuretics
D) Antacids
✅ Correct Answer: B) Statins
Explanation: Statins (e.g., atorvastatin, simvastatin) lower LDL cholesterol by inhibiting HMG-CoA reductase. They also reduce cardiovascular risks. A serious side effect is rhabdomyolysis, so patients must report muscle pain or weakness.
Q20. Which drug is commonly used as a bronchodilator in asthma patients?
A) Metformin
B) Salbutamol (Albuterol)
C) Atenolol
D) Digoxin
✅ Correct Answer: B) Salbutamol (Albuterol)
Explanation: Salbutamol is a short-acting beta-2 agonist (SABA) that relaxes bronchial smooth muscles, providing quick relief in asthma attacks. Overuse can cause tachycardia, tremors, and palpitations.
Q21. Which of the following is a side effect of beta-blockers (e.g., propranolol, atenolol)?
A) Tachycardia
B) Bradycardia
C) Hyperglycemia
D) Bronchodilation
✅ Correct Answer: B) Bradycardia
Explanation: Beta-blockers slow the heart rate and reduce blood pressure by blocking beta-adrenergic receptors. They are used in hypertension, arrhythmias, and heart failure. Nurses should monitor pulse and blood pressure before giving the drug.
Q22. Which antibiotic may cause permanent discoloration of teeth in children?
A) Amoxicillin
B) Ciprofloxacin
C) Tetracycline
D) Azithromycin
✅ Correct Answer: C) Tetracycline
Explanation: Tetracycline binds to calcium in developing teeth and bones, leading to yellow-gray-brown discoloration. It should not be used in children under 8 years old or during pregnancy.
Q23. Which of the following is a common side effect of furosemide (Lasix)?
A) Hyperkalemia
B) Hypokalemia
C) Hypercalcemia
D) Hyponatremia
✅ Correct Answer: B) Hypokalemia
Explanation: Furosemide is a loop diuretic that increases excretion of sodium, potassium, and water. Nurses should monitor electrolyte levels and teach patients about potassium-rich foods to prevent hypokalemia.
Q24. Which drug is the first-line treatment for anaphylaxis?
A) Hydrocortisone
B) Epinephrine
C) Diphenhydramine
D) Prednisone
✅ Correct Answer: B) Epinephrine
Explanation: Epinephrine is life-saving in anaphylactic shock. It works by bronchodilation, vasoconstriction, and increasing heart rate, reversing the effects of severe allergic reactions. It is administered via intramuscular injection (EpiPen).
Q25. Which of the following drugs is used to manage hypothyroidism?
A) Methimazole
B) Levothyroxine
C) Propranolol
D) Propylthiouracil
✅ Correct Answer: B) Levothyroxine
Explanation: Levothyroxine is a synthetic form of thyroxine (T4). It is the standard treatment for hypothyroidism. Nurses should educate patients to take it in the morning on an empty stomach for best absorption.
Q26. Which medication is used to prevent organ transplant rejection?
A) Aspirin
B) Cyclosporine
C) Digoxin
D) Metformin
✅ Correct Answer: B) Cyclosporine
Explanation: Cyclosporine is an immunosuppressant that prevents rejection after organ transplantation. It suppresses T-cell activity but increases risk of infection and nephrotoxicity. Regular monitoring is essential.
Q27. Which of the following medications is classified as a benzodiazepine?
A) Diazepam
B) Zolpidem
C) Haloperidol
D) Lithium
✅ Correct Answer: A) Diazepam
Explanation: Diazepam is a benzodiazepine used for anxiety, seizures, and muscle spasms. It enhances the effect of GABA (an inhibitory neurotransmitter), producing calming effects. Risk of dependence and withdrawal exists.
Q28. Which medication is commonly prescribed for type 2 diabetes mellitus?
A) Insulin glargine
B) Metformin
C) Prednisone
D) Furosemide
✅ Correct Answer: B) Metformin
Explanation: Metformin is the first-line oral drug for type 2 diabetes. It decreases hepatic glucose production and improves insulin sensitivity. It does not usually cause hypoglycemia. Major risk: lactic acidosis (rare).
Q29. Which drug is considered a calcium channel blocker?
A) Lisinopril
B) Amlodipine
C) Atenolol
D) Losartan
✅ Correct Answer: B) Amlodipine
Explanation: Amlodipine is a calcium channel blocker that relaxes blood vessels, lowering blood pressure and preventing angina. Common side effects: dizziness, peripheral edema, flushing.
Q30. Which drug is given to patients with bipolar disorder for mood stabilization?
A) Lithium
B) Fluoxetine
C) Clozapine
D) Diazepam
✅ Correct Answer: A) Lithium
Explanation: Lithium is a mood stabilizer used in bipolar disorder. Therapeutic levels must be closely monitored (0.6–1.2 mEq/L). Toxicity signs include tremors, confusion, and seizures. Patients must maintain adequate hydration and sodium intake.
31. Which drug is commonly used as an anticoagulant for prevention of blood clots?
A) Aspirin
B) Heparin
C) Ibuprofen
D) Paracetamol
Answer: B) Heparin
Explanation: Heparin is an anticoagulant that prevents clot formation by inhibiting clotting factors. Aspirin also has antiplatelet activity but is not the primary choice for rapid anticoagulation. Ibuprofen and paracetamol are analgesics, not anticoagulants.
32. A nurse should monitor potassium levels when a patient is prescribed which drug?
A) Digoxin
B) Furosemide
C) Paracetamol
D) Amoxicillin
Answer: B) Furosemide
Explanation: Furosemide is a loop diuretic that can cause hypokalemia due to excessive potassium excretion. Regular potassium monitoring is crucial. Digoxin requires potassium monitoring as well, but mainly because hypokalemia increases its toxicity.
33. Which drug is classified as a proton pump inhibitor (PPI)?
A) Omeprazole
B) Ranitidine
C) Loperamide
D) Sucralfate
Answer: A) Omeprazole
Explanation: Omeprazole is a PPI that reduces gastric acid secretion by blocking H⁺/K⁺ ATPase. Ranitidine is an H2 blocker, loperamide is an antidiarrheal, and sucralfate is a mucosal protective agent.
34. Which of the following is a common side effect of morphine?
A) Hypertension
B) Constipation
C) Polyuria
D) Hyperglycemia
Answer: B) Constipation
Explanation: Morphine, like most opioids, slows gastrointestinal motility, leading to constipation. Nurses should encourage fluids, fiber intake, and possibly stool softeners.
35. What is the antidote for benzodiazepine overdose?
A) Naloxone
B) Flumazenil
C) Atropine
D) Protamine sulfate
Answer: B) Flumazenil
Explanation: Flumazenil is the specific antidote for benzodiazepine overdose. Naloxone is for opioid overdose, atropine treats bradycardia, and protamine sulfate reverses heparin.
36. Which vitamin deficiency is most likely in patients on long-term isoniazid therapy?
A) Vitamin B6 (Pyridoxine)
B) Vitamin B12
C) Vitamin D
D) Vitamin C
Answer: A) Vitamin B6 (Pyridoxine)
Explanation: Isoniazid interferes with vitamin B6 metabolism, leading to neuropathy. Supplementation with pyridoxine is usually prescribed to prevent side effects.
37. Which medication is classified as a calcium channel blocker?
A) Atenolol
B) Diltiazem
C) Lisinopril
D) Furosemide
Answer: B) Diltiazem
Explanation: Diltiazem is a calcium channel blocker used for hypertension and angina. Atenolol is a beta-blocker, lisinopril is an ACE inhibitor, and furosemide is a diuretic.
38. A patient taking warfarin should be advised to avoid excessive intake of which vitamin?
A) Vitamin A
B) Vitamin K
C) Vitamin D
D) Vitamin B12
Answer: B) Vitamin K
Explanation: Warfarin inhibits vitamin K-dependent clotting factors. High vitamin K intake (green leafy vegetables) can reduce its effectiveness, leading to clot risk.
39. Which drug is commonly prescribed for the treatment of hypothyroidism?
A) Levothyroxine
B) Methimazole
C) Carbimazole
D) Propranolol
Answer: A) Levothyroxine
Explanation: Levothyroxine is a synthetic form of thyroxine (T4) used to treat hypothyroidism. Methimazole and carbimazole are used in hyperthyroidism, while propranolol is used for symptom control in hyperthyroidism.
40. Which of the following drugs is an antiplatelet agent?
A) Warfarin
B) Clopidogrel
C) Heparin
D) Dabigatran
Answer: B) Clopidogrel
Explanation: Clopidogrel inhibits platelet aggregation by blocking ADP receptors, preventing clot formation. Warfarin, heparin, and dabigatran are anticoagulants, not antiplatelet drugs.
41. Which insulin is considered rapid-acting?
A) Glargine
B) Lispro
C) NPH
D) Detemir
Answer: B) Lispro
Explanation: Insulin lispro is a rapid-acting insulin that starts working within 15 minutes, making it suitable for use just before meals. Glargine and detemir are long-acting, while NPH is intermediate-acting.
42. Which antibiotic can cause permanent discoloration of teeth if given to children under 8 years?
A) Amoxicillin
B) Tetracycline
C) Erythromycin
D) Ciprofloxacin
Answer: B) Tetracycline
Explanation: Tetracyclines bind to calcium in developing teeth and bones, causing permanent yellow-brown discoloration. Hence, they are avoided in young children and pregnant women.
43. Which drug is a selective beta-1 blocker commonly used in hypertension?
A) Propranolol
B) Atenolol
C) Labetalol
D) Carvedilol
Answer: B) Atenolol
Explanation: Atenolol is a cardio-selective beta-1 blocker, effective in lowering blood pressure with fewer respiratory side effects compared to non-selective agents like propranolol.
44. What is the therapeutic drug level of digoxin?
A) 0.1 – 0.5 ng/mL
B) 0.5 – 2.0 ng/mL
C) 2.5 – 4.0 ng/mL
D) 4.5 – 6.0 ng/mL
Answer: B) 0.5 – 2.0 ng/mL
Explanation: Digoxin has a narrow therapeutic window. Levels above 2.0 ng/mL increase the risk of toxicity, which may present with nausea, confusion, and visual disturbances (yellow vision).
45. Which drug is used in the emergency treatment of anaphylaxis?
A) Atropine
B) Epinephrine
C) Diphenhydramine
D) Hydrocortisone
Answer: B) Epinephrine
Explanation: Epinephrine (IM injection) is the first-line treatment for anaphylaxis as it rapidly reverses airway obstruction, hypotension, and shock. Antihistamines and corticosteroids are supportive but not immediate lifesaving.
46. A nurse should advise a patient on lithium therapy to avoid excessive intake of which drink?
A) Coffee
B) Alcohol
C) Milk
D) Water
Answer: A) Coffee
Explanation: Lithium excretion is influenced by sodium and hydration. Excessive caffeine (coffee) acts as a diuretic and can cause dehydration, increasing lithium levels and toxicity risk. Adequate water intake is essential.
47. Which medication is most commonly used to treat absence seizures?
A) Phenytoin
B) Valproic acid
C) Ethosuximide
D) Carbamazepine
Answer: C) Ethosuximide
Explanation: Ethosuximide is the drug of choice for absence seizures. Valproic acid is an alternative, while phenytoin and carbamazepine are ineffective in this seizure type.
48. What is the mechanism of action of ACE inhibitors like enalapril?
A) Block calcium channels in smooth muscles
B) Inhibit conversion of angiotensin I to angiotensin II
C) Increase sodium reabsorption in kidneys
D) Stimulate beta-adrenergic receptors
Answer: B) Inhibit conversion of angiotensin I to angiotensin II
Explanation: ACE inhibitors prevent the formation of angiotensin II, a potent vasoconstrictor, thereby lowering blood pressure. They also reduce aldosterone secretion, promoting sodium excretion.
49. Which common side effect is associated with ACE inhibitors?
A) Constipation
B) Dry cough
C) Blurred vision
D) Hypoglycemia
Answer: B) Dry cough
Explanation: ACE inhibitors often cause a persistent dry cough due to accumulation of bradykinin. If intolerable, patients may be switched to ARBs (angiotensin receptor blockers).
50. Which drug is classified as a statin and used to lower cholesterol?
A) Metformin
B) Simvastatin
C) Nitroglycerin
D) Furosemide
Answer: B) Simvastatin
Explanation: Statins like simvastatin inhibit HMG-CoA reductase, reducing cholesterol synthesis. Metformin is for diabetes, nitroglycerin for angina, and furosemide for fluid overload.
You’ve completed the first 50 NCLEX Pharmacology MCQs with explanations. These questions are designed to build your understanding of core nursing concepts and drug safety — two areas highly emphasized in the NCLEX.
👉 Here is the next part, NCLEX Pharmacology MCQs 51–100, including more advanced questions.
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