NAPLEX Exam 2026–2027 Latest Comprehensive Pharmacy
Review with Practice Questions, Clinical Cases & Detailed
Answer Explanations
1. A prescription calls for 500 mg of amoxicillin in 5 mL of suspension. How many milligrams
of amoxicillin are in 3.75 mL of this suspension?
• A. 325 mg
• B. 375 mg
• C. 400 mg
• D. 425 mg
• E. 450 mg
Correct Answer: B. 375 mg
Rationale: This is a ratio-proportion problem. Set up: 500 mg / 5 mL = x mg / 3.75 mL.
Cross-multiply: 5x = 500 × 3.75 = 1,875. x = 1, = 375 mg.
2. A patient requires 40 mEq of potassium chloride. The available concentration is 20 mEq
per 15 mL. How many milliliters should be administered?
• A. 15 mL
• B. 30 mL
• C. 40 mL
• D. 45 mL
• E. 60 mL
Correct Answer: B. 30 mL
,Rationale: Set up proportion: 20 mEq / 15 mL = 40 mEq / x mL. Cross-multiply: 20x = 40 ×
15 = 600. x = = 30 mL.
3. A 180-lb patient is to receive a medication at 5 mg/kg/day divided into 3 doses. What is
the dose per administration?
• A. 100 mg
• B. 120 mg
• C. 136 mg
• D. 150 mg
• E. 180 mg
Correct Answer: C. 136 mg
Rationale: Convert weight: 180 lb ÷ 2.2 = 81.8 kg. Daily dose = 81.8 kg × 5 mg/kg = 409
mg. Per dose = 409 mg ÷ 3 ≈ 136 mg.
4. A 10 mL vial of insulin contains 100 units/mL. How many units are in 0.85 mL?
• A. 75 units
• B. 85 units
• C. 95 units
• D. 100 units
• E. 110 units
Correct Answer: B. 85 units
Rationale: 100 units/mL × 0.85 mL = 85 units.
5. A medication has a half-life of 4 hours. What percentage of the original dose remains
after 12 hours?
• A. 6.25%
, • B. 12.5%
• C. 25%
• D. 37.5%
• E. 50%
Correct Answer: B. 12.5%
Rationale: After 12 hours, 3 half-lives have elapsed (12 ÷ 4 = 3). After 1 half-life: 50%; after
2: 25%; after 3: 12.5%.
6. An IV infusion is ordered at 0.5 mcg/kg/min for a 70 kg patient. The concentration is 400
mg in 250 mL. What is the infusion rate in mL/hour?
• A. 1.3 mL/hr
• B. 2.6 mL/hr
• C. 3.3 mL/hr
• D. 4.2 mL/hr
• E. 5.0 mL/hr
Correct Answer: C. 3.3 mL/hr
Rationale: Dose = 0.5 mcg/kg/min × 70 kg = 35 mcg/min = 2,100 mcg/hr = 2.1 mg/hr.
Concentration = 400 mg / 250 mL = 1.6 mg/mL. Rate = 2.1 mg/hr ÷ 1.6 mg/mL = 1.31
mL/hr. Wait, recalculate: 2.1 mg/hr ÷ 1.6 = 1.31 mL/hr. Let me re-check: 35 mcg/min × 60 =
2,100 mcg/hr = 2.1 mg/hr. 2.1 ÷ 1.6 = 1.31 mL/hr. The correct answer is A. 1.3 mL/hr.
Correction: The correct answer is A. 1.3 mL/hr.
7. A child weighing 22 kg requires amoxicillin at 40 mg/kg/day divided into 2 doses. The
suspension is 250 mg/5 mL. How many mL should be given per dose?
• A. 4.4 mL
• B. 8.8 mL
, • C. 10 mL
• D. 12 mL
• E. 17.6 mL
Correct Answer: B. 8.8 mL
Rationale: Daily dose = 22 kg × 40 mg/kg = 880 mg/day. Per dose = 880 ÷ 2 = 440 mg.
Volume = 440 mg × (5 mL / 250 mg) = 8.8 mL.
8. What is the osmolarity (mOsm/L) of a 3% NaCl solution? (MW NaCl = 58.5, each
molecule provides 2 particles)
• A. 513 mOsm/L
• B. 1,026 mOsm/L
• C. 1,500 mOsm/L
• D. 2,052 mOsm/L
• E. 3,000 mOsm/L
Correct Answer: B. 1,026 mOsm/L
Rationale: 3% = 30 g/L. Moles = .5 = 0.513 mol/L. Particles = 0.513 × 2 = 1.026
Osm/L = 1,026 mOsm/L.
9. A prescription reads: "Hydrocortisone 2.5% cream, 30 g." How many milligrams of
hydrocortisone are in the total preparation?
• A. 250 mg
• B. 500 mg
• C. 750 mg
• D. 1,000 mg
• E. 1,500 mg
Correct Answer: C. 750 mg
Review with Practice Questions, Clinical Cases & Detailed
Answer Explanations
1. A prescription calls for 500 mg of amoxicillin in 5 mL of suspension. How many milligrams
of amoxicillin are in 3.75 mL of this suspension?
• A. 325 mg
• B. 375 mg
• C. 400 mg
• D. 425 mg
• E. 450 mg
Correct Answer: B. 375 mg
Rationale: This is a ratio-proportion problem. Set up: 500 mg / 5 mL = x mg / 3.75 mL.
Cross-multiply: 5x = 500 × 3.75 = 1,875. x = 1, = 375 mg.
2. A patient requires 40 mEq of potassium chloride. The available concentration is 20 mEq
per 15 mL. How many milliliters should be administered?
• A. 15 mL
• B. 30 mL
• C. 40 mL
• D. 45 mL
• E. 60 mL
Correct Answer: B. 30 mL
,Rationale: Set up proportion: 20 mEq / 15 mL = 40 mEq / x mL. Cross-multiply: 20x = 40 ×
15 = 600. x = = 30 mL.
3. A 180-lb patient is to receive a medication at 5 mg/kg/day divided into 3 doses. What is
the dose per administration?
• A. 100 mg
• B. 120 mg
• C. 136 mg
• D. 150 mg
• E. 180 mg
Correct Answer: C. 136 mg
Rationale: Convert weight: 180 lb ÷ 2.2 = 81.8 kg. Daily dose = 81.8 kg × 5 mg/kg = 409
mg. Per dose = 409 mg ÷ 3 ≈ 136 mg.
4. A 10 mL vial of insulin contains 100 units/mL. How many units are in 0.85 mL?
• A. 75 units
• B. 85 units
• C. 95 units
• D. 100 units
• E. 110 units
Correct Answer: B. 85 units
Rationale: 100 units/mL × 0.85 mL = 85 units.
5. A medication has a half-life of 4 hours. What percentage of the original dose remains
after 12 hours?
• A. 6.25%
, • B. 12.5%
• C. 25%
• D. 37.5%
• E. 50%
Correct Answer: B. 12.5%
Rationale: After 12 hours, 3 half-lives have elapsed (12 ÷ 4 = 3). After 1 half-life: 50%; after
2: 25%; after 3: 12.5%.
6. An IV infusion is ordered at 0.5 mcg/kg/min for a 70 kg patient. The concentration is 400
mg in 250 mL. What is the infusion rate in mL/hour?
• A. 1.3 mL/hr
• B. 2.6 mL/hr
• C. 3.3 mL/hr
• D. 4.2 mL/hr
• E. 5.0 mL/hr
Correct Answer: C. 3.3 mL/hr
Rationale: Dose = 0.5 mcg/kg/min × 70 kg = 35 mcg/min = 2,100 mcg/hr = 2.1 mg/hr.
Concentration = 400 mg / 250 mL = 1.6 mg/mL. Rate = 2.1 mg/hr ÷ 1.6 mg/mL = 1.31
mL/hr. Wait, recalculate: 2.1 mg/hr ÷ 1.6 = 1.31 mL/hr. Let me re-check: 35 mcg/min × 60 =
2,100 mcg/hr = 2.1 mg/hr. 2.1 ÷ 1.6 = 1.31 mL/hr. The correct answer is A. 1.3 mL/hr.
Correction: The correct answer is A. 1.3 mL/hr.
7. A child weighing 22 kg requires amoxicillin at 40 mg/kg/day divided into 2 doses. The
suspension is 250 mg/5 mL. How many mL should be given per dose?
• A. 4.4 mL
• B. 8.8 mL
, • C. 10 mL
• D. 12 mL
• E. 17.6 mL
Correct Answer: B. 8.8 mL
Rationale: Daily dose = 22 kg × 40 mg/kg = 880 mg/day. Per dose = 880 ÷ 2 = 440 mg.
Volume = 440 mg × (5 mL / 250 mg) = 8.8 mL.
8. What is the osmolarity (mOsm/L) of a 3% NaCl solution? (MW NaCl = 58.5, each
molecule provides 2 particles)
• A. 513 mOsm/L
• B. 1,026 mOsm/L
• C. 1,500 mOsm/L
• D. 2,052 mOsm/L
• E. 3,000 mOsm/L
Correct Answer: B. 1,026 mOsm/L
Rationale: 3% = 30 g/L. Moles = .5 = 0.513 mol/L. Particles = 0.513 × 2 = 1.026
Osm/L = 1,026 mOsm/L.
9. A prescription reads: "Hydrocortisone 2.5% cream, 30 g." How many milligrams of
hydrocortisone are in the total preparation?
• A. 250 mg
• B. 500 mg
• C. 750 mg
• D. 1,000 mg
• E. 1,500 mg
Correct Answer: C. 750 mg
