NAPLEX Quiz: Quantities To Be Dispensed Or Administered

What this quiz covers

This quiz focuses on Quantities To Be Dispensed Or Administered, giving you a quick way to practice the rules, question types, and explanations that matter most for NAPLEX.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. 102 mL
2. 203 mL (correct answer)
3. 225 mL
4. 180 mL

Explanation: This question tests pediatric weight-based antibiotic dosing calculations and volume determination. The key patient-specific factor is the child's weight of 18 kg, which determines the total daily dose. The correct answer (B, 203 mL) is calculated as follows: 90 mg/kg/day × 18 kg = 1,620 mg/day; 1,620 mg ÷ 2 doses = 810 mg per dose; 810 mg ÷ (400 mg/5 mL) = 10.125 mL per dose; 10.125 mL × 2 doses/day × 10 days = 202.5 mL, rounded to 203 mL. Option A (102 mL) represents approximately half the needed volume, possibly calculating for once-daily dosing. Option C (225 mL) and Option D (180 mL) represent calculation errors in either the dose or volume conversion. When calculating pediatric liquid medications: first determine total daily dose (mg/kg/day × weight), divide by number of doses, convert to volume using the concentration, then multiply by total doses for the treatment course.

Question 2

1. 7 capsules
2. 10 capsules
3. 14 capsules (correct answer)
4. 28 capsules

Explanation: This question tests the calculation of total quantity for doxycycline over 7 days. The key patient-specific factor is the fixed 100 mg every 12 hours dose. Option C is correct because 2 capsules/day × 7 days = 14 capsules. Option A (7) once daily, B (10) misdays, D (28) 14 days. Formula: total = doses/day × days. For tetracyclines.

Question 3

1. 30 tablets
2. 90 tablets
3. 60 tablets (correct answer)
4. 120 tablets

Explanation: This question tests the calculation of tablet quantities for chronic medication therapy with twice-daily dosing. The key factor is the fixed dosing regimen of 5 mg twice daily, with no dose adjustments needed based on the patient's renal function (SCr 1.1 mg/dL is within acceptable range for full-dose apixaban). The correct answer (C, 60 tablets) is calculated as: 2 tablets/day × 30 days = 60 tablets. Option A (30 tablets) incorrectly calculates for once-daily dosing. Option B (90 tablets) may represent a calculation error or confusion with three-times-daily dosing. Option D (120 tablets) doubles the correct quantity, possibly confusing a 30-day supply with a 60-day supply. For chronic medications, always multiply the daily tablet count by the number of days supplied, and verify that no dose adjustments are needed based on organ function or drug interactions.

Question 4

1. 10 capsules (correct answer)
2. 14 capsules
3. 20 capsules
4. 5 capsules

Explanation: This question tests the calculation of total capsules needed for a fixed-dose antibiotic regimen. The key factor is the straightforward dosing schedule of 100 mg twice daily for 5 days, with no weight-based adjustments needed. The correct answer (A, 10 capsules) is calculated by multiplying: 2 capsules/day × 5 days = 10 capsules total. Option B (14 capsules) incorrectly calculates for a 7-day course instead of 5 days. Option C (20 capsules) doubles the correct answer, possibly confusing twice-daily dosing with the total number of capsules. Option D (5 capsules) represents only one capsule per day instead of two. For fixed-dose medications, the formula is simple: doses per day × number of days = total doses needed. Always verify the duration of therapy and frequency to avoid dispensing errors.

Question 5

1. 7 syringes
2. 14 syringes (correct answer)
3. 28 syringes
4. 10 syringes

Explanation: This question tests the calculation of total medication quantity needed for a weight-based dosing regimen over a specified treatment duration. The key patient-specific factor is the patient's weight of 78 kg, which determines the daily enoxaparin dose. The correct answer (B, 14 syringes) is calculated as follows: 78 kg × 1 mg/kg = 78 mg per dose; 78 mg × 2 doses/day × 7 days = 1,092 mg total; 1,092 mg ÷ 80 mg/syringe = 13.65 syringes, rounded up to 14 syringes. Option A (7 syringes) incorrectly calculates for once-daily dosing instead of twice-daily. Option C (28 syringes) doubles the correct answer, possibly confusing the number of doses with the number of syringes. Option D (10 syringes) underestimates the total quantity needed. When calculating quantities for weight-based medications, always multiply: weight × dose/kg × doses/day × days, then divide by the strength per unit to determine units needed, rounding up to ensure adequate supply.

Question 6

1. 10 tablets
2. 14 tablets
3. 20 tablets (correct answer)
4. 28 tablets

Explanation: This question tests the concept of calculating the total quantity of medication to dispense based on the prescribed dosing frequency and treatment duration. The key patient-specific factors include normal renal function (SCr 0.9 mg/dL) and body weight (88 kg), but no dose adjustments are required for amoxicillin/clavulanate in this adult patient with acute bacterial sinusitis. The correct answer, 20 tablets, is calculated as follows: the prescription is for one 875 mg/125 mg tablet every 12 hours (twice daily) for 10 days, so total doses = 2 doses/day × 10 days = 20 tablets. Option A (10 tablets) is incorrect as it underestimates the quantity by assuming once-daily dosing for 10 days or twice-daily for only 5 days. Option B (14 tablets) is wrong because it might mistakenly calculate for a 7-day course instead of 10 days, and option D (28 tablets) overestimates by assuming a 14-day course. A transferable principle is to always multiply the daily dose frequency by the total treatment days to determine the quantity needed, ensuring no adjustments unless indicated by patient factors like renal impairment. For similar scenarios, use the formula: total quantity = (doses per day) × (number of days), and verify against the stocked formulation to confirm dispensing accuracy.

Question 7

1. 30 capsules
2. 60 capsules
3. 90 capsules (correct answer)
4. 120 capsules

Explanation: This question tests the calculation of total quantity for a 30-day supply of thrice-daily gabapentin. The key patient-specific factor is renal function, but dose is given as 300 mg TID without adjustment noted. Option C is correct because 3 capsules/day × 30 days = 90 capsules. Option A (30) assumes daily, B (60) twice daily, D (120) four times. Formula: total = doses/day × days. Essential for neuropathic pain meds like pregabalin.

Question 8

1. 30 tablets
2. 45 tablets
3. 60 tablets (correct answer)
4. 90 tablets

Explanation: This question tests the calculation of total quantity for a 30-day supply of twice-daily furosemide. The key patient-specific factor is the fixed 40 mg twice daily dose, independent of weight. Option C is correct because 2 tablets/day × 30 days = 60 tablets. Option A (30) is incorrect, assuming once daily. Options B (45) and D (90) wrong; B might use 1.5/day, D triples. Formula: total = doses/day × days. Transferable to loop diuretics like torsemide.

Question 9

1. 7 tablets
2. 10 tablets
3. 14 tablets (correct answer)
4. 21 tablets

Explanation: This question tests the calculation of total quantity for metronidazole over 7 days. The key patient-specific factor is the fixed 500 mg every 12 hours dose. Option C is correct because 2 tablets/day × 7 days = 14 tablets. Option A (7) once daily, B (10) miscalculates days, D (21) three times daily. Formula: total = doses/day × days. Applies to anaerobe coverage drugs.

Question 10

1. 1.4 mL per dose
2. 2.8 mL per dose (correct answer)
3. 4.2 mL per dose
4. 5.6 mL per dose

Explanation: This question tests the calculation of volume for a weight-based dose of ondansetron oral solution. The key patient-specific factor is the child's weight of 15 kg. Option B is correct because 0.15 mg/kg × 15 kg = 2.25 mg/dose, and at 4 mg/5 mL, volume = (2.25 / 4) × 5 = 2.8125 ≈ 2.8 mL. Option A (1.4 mL) is incorrect, likely from halving the dose. Options C (4.2 mL) and D (5.6 mL) are wrong; C uses 0.225 mg/kg, D doubles weight. For oral solutions, use: dose (mg) = rate (mg/kg) × weight (kg), volume (mL) = (dose / concentration mg) × unit mL. This method applies to antiemetics like promethazine.

Question 11

1. 20 tablets
2. 24 tablets
3. 30 tablets (correct answer)
4. 40 tablets

Explanation: This question tests the calculation of total quantity for a tapering regimen of prednisone tablets. The key patient-specific factor is the stepwise dosing schedule over 12 days, independent of weight. Option C is correct because (4 tabs × 3 days) + (3 × 3) + (2 × 3) + (1 × 3) = 12 + 9 + 6 + 3 = 30 tablets. Option A (20 tablets) is incorrect, likely from summing only the daily tabs without multiplying by days. Options B (24 tablets) and D (40 tablets) are wrong; B might omit one step, while D could extend days per step. For tapering regimens, sum quantities as: total = Σ (daily tabs × days per step). This principle applies to steroid tapers like methylprednisolone, ensuring safe de-escalation.

Question 12

1. 6.2 mL/hour
2. 12.4 mL/hour
3. 15.5 mL/hour (correct answer)
4. 18.0 mL/hour

Explanation: This question tests the calculation of infusion rate for weight-based heparin continuous infusion. The key patient-specific factor is the patient's weight of 86 kg. Option C is correct because 18 units/kg/hour × 86 kg = 1548 units/hour, bag is 25,000 units/250 mL = 100 units/mL, rate = 1548 / 100 = 15.48 ≈15.5 mL/hour. Option A (6.2) incorrect, perhaps quarter rate. B (12.4) uses 14 units/kg, D (18.0) ignores weight precision. Formula: hourly dose = rate × weight, rate (mL/hour) = hourly dose / concentration. Applies to anticoagulants like argatroban.

Question 13

1. 5 capsules
2. 10 capsules (correct answer)
3. 14 capsules
4. 20 capsules

Explanation: This question tests the calculation of total quantity for pediatric oseltamivir treatment. The key patient-specific factor is the weight-based dose of 75 mg twice daily for 5 days (for >23 kg). Option B is correct because 2 capsules/day × 5 days = 10 capsules. Option A (5) incorrect, half duration. C (14) adds days, D (20) doubles doses. Formula: total = doses/day × days. Transferable to antivirals like valacyclovir.

Question 14

1. 10 capsules (correct answer)
2. 5 capsules
3. 14 capsules
4. 20 capsules

Explanation: This question tests the calculation of total quantity to dispense for a fixed-dose antibiotic regimen over a specified duration. The key patient-specific factor is the absence of weight-based dosing, as nitrofurantoin is prescribed at a standard 100 mg twice daily for 5 days. Option A is correct because twice daily for 5 days requires 2 doses/day × 5 days = 10 capsules. Option B (5 capsules) is incorrect, likely from calculating for only one dose per day or half the duration. Options C (14 capsules) and D (20 capsules) are wrong; C might add extra days, while D could double the daily doses or duration. For dispensing quantities in short courses, use the formula: total quantity = doses per day × number of days. This principle helps verify prescriptions for antibiotics like azithromycin and ensures complete therapy without excess.

Question 15

1. 0.41 mL per dose
2. 0.82 mL per dose (correct answer)
3. 1.64 mL per dose
4. 82 mL per dose

Explanation: This question tests the calculation of volume for a weight-based dose of enoxaparin administered subcutaneously. The key patient-specific factor is the patient's weight of 82 kg. Option B is correct because the dose is 1 mg/kg × 82 kg = 82 mg, and with a concentration of 100 mg/mL, the volume per dose is 82 mg / 100 mg/mL = 0.82 mL. Option A (0.41 mL) is incorrect as it represents half the required dose, possibly from mistakenly using 0.5 mg/kg or dividing by 200 mg/mL. Option C (1.64 mL) and D (82 mL) are wrong; C likely doubles the dose to 2 mg/kg, while D omits dividing by the concentration. For weight-based injectable doses, use the formula: dose (mg) = dosing rate (mg/kg) × weight (kg), then volume (mL) = dose (mg) / concentration (mg/mL). This method ensures accurate administration and can be applied to other parenteral medications like heparin.

Question 16

1. 1.2 mL per dose
2. 2.3 mL per dose (correct answer)
3. 3.8 mL per dose
4. 4.7 mL per dose

Explanation: This question tests the calculation of volume for weight-based acetaminophen dose in infants. The key patient-specific factor is the infant's weight of 5 kg. Option B is correct because 15 mg/kg × 5 kg = 75 mg/dose, 160 mg/5 mL, volume = (75 / 160) × 5 ≈ 2.34 mL, rounded to 2.3 mL. Option A (1.2) halves, C (3.8) uses 24 mg/kg, D (4.7) doubles. Formula: dose = rate × weight, volume = (dose / conc) × unit. For antipyretics like ibuprofen.

Question 17

1. 3 mL/hour
2. 6 mL/hour
3. 9 mL/hour
4. 12 mL/hour (correct answer)

Explanation: This question tests the calculation of infusion rates based on drug concentration and desired delivery rate. The key factor is converting the prescribed dose rate (10 mg/hour) to the corresponding volume rate using the available concentration. The correct answer (D, 12 mL/hour) is calculated using the formula: (Desired dose rate ÷ Concentration) = Volume rate; (10 mg/hour) ÷ (2.5 mg/3 mL) = (10 mg/hour) × (3 mL/2.5 mg) = 12 mL/hour. Option A (3 mL/hour) would only deliver 2.5 mg/hour. Option B (6 mL/hour) would deliver 5 mg/hour. Option C (9 mL/hour) would deliver 7.5 mg/hour. When calculating continuous infusion rates, always use dimensional analysis to ensure units cancel appropriately: (mg/hour) × (mL/mg) = mL/hour. This principle applies to all continuous infusions including nebulizations.

Question 18

1. 7.2 mL/hour
2. 10.8 mL/hour
3. 14.4 mL/hour (correct answer)
4. 18 mL/hour

Explanation: This question tests the calculation of IV infusion rates for weight-based heparin dosing. The key patient-specific factor is the patient's weight of 80 kg, which determines the hourly heparin dose. The correct answer (C, 14.4 mL/hour) is calculated using: 18 units/kg/hour × 80 kg = 1,440 units/hour; 1,440 units/hour ÷ 100 units/mL = 14.4 mL/hour. Option A (7.2 mL/hour) represents half the correct rate. Option B (10.8 mL/hour) appears to use an incorrect weight or dose calculation. Option D (18 mL/hour) may confuse the units/kg/hour rate with the mL/hour rate. When calculating weight-based continuous infusions, use the formula: (units/kg/hour × weight in kg) ÷ concentration = mL/hour. Always double-check that the final rate seems reasonable for the clinical scenario.

Question 19

1. Continue 300 mg three times daily
2. Adjust to 300 mg once daily (correct answer)
3. Adjust to 900 mg once daily
4. Adjust to 300 mg twice daily

Explanation: This question tests renal dose adjustment for gabapentin based on creatinine clearance. The key patient-specific factor is the severely reduced renal function with CrCl of 25 mL/min, requiring significant dose reduction. The correct answer (B, 300 mg once daily) falls within the recommended range of 200-700 mg/day given once daily for CrCl 15-29 mL/min, representing an appropriate reduction from the original 900 mg/day (300 mg TID). Option A (continuing 300 mg TID) ignores the renal impairment and would result in drug accumulation. Option C (900 mg once daily) maintains the total daily dose but doesn't reduce it for renal impairment. Option D (300 mg BID) provides 600 mg/day, which while within range, doesn't follow the once-daily recommendation for this CrCl range. For renally-eliminated drugs like gabapentin, always consult dosing guidelines based on CrCl ranges and adjust both the dose amount and frequency as specified.

Question 20

1. 30 tablets
2. 60 tablets (correct answer)
3. 90 tablets
4. 120 tablets

Explanation: This question tests the calculation of total quantity for a 30-day supply of twice-daily potassium chloride. The key patient-specific factor is the fixed 20 mEq twice daily dose. Option B is correct because 2 tablets/day × 30 days = 60 tablets. Option A (30) once daily, C (90) three times, D (120) double supply. Formula: total = doses/day × days. For electrolytes like magnesium.