NAPLEX Quiz: Quantities To Be Dispensed Or Administered
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Quantities To Be Dispensed Or AdministeredQuestion 1 of 20

A 4-year-old male (weight 18 kg) is diagnosed with acute otitis media. Medical history: none significant; allergies: none known. Current medications: none. Labs: not available/required. The pediatrician prescribes amoxicillin 90 mg/kg/day by mouth divided every 12 hours for 10 days. The suspension available is amoxicillin 400 mg/5 mL. Calculate the volume to be dispensed to complete the full 10-day course (in mL, rounded to the nearest mL).

102 mL
203 mL
225 mL
180 mL
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NAPLEX Quiz

NAPLEX Quiz: Quantities To Be Dispensed Or Administered

Practice Quantities To Be Dispensed Or Administered in NAPLEX with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

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.

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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.

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Question 1

A 4-year-old male (weight 18 kg) is diagnosed with acute otitis media. Medical history: none significant; allergies: none known. Current medications: none. Labs: not available/required. The pediatrician prescribes amoxicillin 90 mg/kg/day by mouth divided every 12 hours for 10 days. The suspension available is amoxicillin 400 mg/5 mL. Calculate the volume to be dispensed to complete the full 10-day course (in mL, rounded to the nearest mL).

  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

Heparin 25,000 units/250 mL. Order 18 units/kg/hr; patient weighs 75 kg. What rate (mL/hr)?

  1. 2.7 mL/hr
  2. 5.4 mL/hr
  3. 13.5 mL/hr (correct answer)
  4. 27.0 mL/hr
Explanation: Heparin concentration is 25,000 units / 250 mL = 100 units/mL. You need 18 units/kg/hr x 75 kg = 1,350 units/hr. Divide 1,350 units/hr by 100 units/mL to get 13.5 mL/hr. The tempting 5.4 mL/hr comes from dividing by 250 mL total volume instead of the concentration, which gives the wrong units.

Question 3

Dexamethasone 4 mg tablets: 6 mg days 1-2, 4 mg days 3-4, 2 mg days 5-6. Total tablets?

  1. 5 tablets
  2. 6 tablets (correct answer)
  3. 7 tablets
  4. 8 tablets
Explanation: During days 1-2, 6 mg of a 4 mg tablet is 1.5 tablets each day, so you need 3 tablets total. Days 3-4 use 1 tablet daily, adding 2. Days 5-6 use 0.5 tablet daily, adding 1. Total is 3 + 2 + 1 = 6 tablets. The tempting 8-tablet count rounds up every half-tablet, but split 4 mg tablets are allowed.

Question 4

Albuterol 2 puffs q6h; canister contains 200 puffs; 90-day supply. How many canisters?

  1. 3 canisters
  2. 4 canisters (correct answer)
  3. 5 canisters
  4. 6 canisters
Explanation: Use 8 puffs per day (2 puffs x 4 doses daily), over 90 days = 720 puffs. One 200-puff canister lasts 25 days, so 90 days needs 3.6 canisters; round up to 4. Don't pick 3 canisters: 3 canisters provide only 600 puffs, short by 120 puffs.

Question 5

Augmentin 600 mg/5 mL; dose 90 mg/kg/day divided q12h; child weighs 22 lb; 10-day course. Total mL?

  1. 7.5 mL
  2. 37.5 mL
  3. 150 mL
  4. 75 mL (correct answer)
Explanation: 22 lb = 10 kg, so the daily dose is 90 x 10 = 900 mg/day. The concentration is 600 mg/5 mL = 120 mg/mL, so one day needs 900 / 120 = 7.5 mL. Over 10 days that is 7.5 x 10 = 75 mL. The tempting 7.5 mL is only one day's volume, not the full course.

Question 6

A 61-year-old woman (weight 74 kg) is prescribed doxycycline 100 mg by mouth every 12 hours for 7 days for sinusitis. Medical history: seasonal allergies; current medications: cetirizine 10 mg daily. Allergies: none known. Labs: SCr 0.9 mg/dL, AST/ALT within normal limits. Doxycycline is available as 100 mg capsules. Calculate the total quantity to be dispensed.

  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 7

A 72-year-old female (weight 60 kg) with atrial fibrillation is prescribed apixaban 5 mg by mouth twice daily. Medical history: hypertension, osteoarthritis; allergies: sulfonamides (hives). Current medications: hydrochlorothiazide 25 mg daily, acetaminophen 650 mg every 6 hours as needed. Labs: SCr 1.1 mg/dL, AST/ALT within normal limits. Calculate the total quantity to be dispensed for a 30-day supply (number of 5 mg tablets).

  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 8

A 45-year-old female (weight 62 kg) presents with an uncomplicated urinary tract infection. Past medical history: type 2 diabetes mellitus; allergies: none known. Current medications: metformin 1000 mg twice daily, empagliflozin 10 mg daily. Labs: hemoglobin A1c 7.4%, SCr 0.8 mg/dL, AST/ALT within normal limits. She is prescribed nitrofurantoin monohydrate/macrocrystals 100 mg by mouth twice daily for 5 days. Calculate the total quantity to be dispensed for this prescription (number of capsules).

  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 9

A 67-year-old male (weight 78 kg) is being treated for acute deep vein thrombosis and is prescribed enoxaparin 1 mg/kg subcutaneously every 12 hours for 7 days. Medical history includes hypertension and hyperlipidemia; allergies: penicillin (rash). Current medications: lisinopril 20 mg daily, atorvastatin 40 mg nightly, aspirin 81 mg daily. Labs: serum creatinine (SCr) 0.9 mg/dL, AST/ALT within normal limits. Enoxaparin is supplied as 80 mg/0.8 mL prefilled syringes. Calculate the total quantity to be dispensed for the full 7-day course (number of 80 mg/0.8 mL syringes).

  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 10

A 47-year-old man (weight 88 kg) is prescribed amoxicillin/clavulanate 875 mg/125 mg by mouth every 12 hours for 10 days for acute bacterial sinusitis. Medical history: hypertension; current medications: hydrochlorothiazide 25 mg daily. Allergies: none known. Labs: SCr 0.9 mg/dL, AST/ALT within normal limits. The pharmacy stocks amoxicillin/clavulanate 875/125 mg tablets. Calculate the total quantity to be dispensed.

  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 11

A 63-year-old man (weight 72 kg) with chronic kidney disease is prescribed gabapentin 300 mg by mouth three times daily. Medical history: diabetic neuropathy, CKD; current medications: insulin lispro with meals, insulin glargine 24 units nightly. Allergies: none known. Labs: SCr 2.4 mg/dL (elevated; normal ~0.6–1.2). The prescriber requests a 30-day supply. Gabapentin is available as 300 mg capsules. Calculate the total quantity to be dispensed for 30 days.

  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 12

A 66-year-old woman (weight 55 kg) with heart failure is prescribed furosemide 40 mg by mouth twice daily. Medical history: heart failure with reduced ejection fraction, hypertension; current medications: carvedilol 25 mg twice daily, losartan 50 mg daily, spironolactone 25 mg daily. Allergies: none known. Labs: SCr 1.1 mg/dL, potassium 4.6 mEq/L (normal ~3.5–5.0). Calculate the total quantity of furosemide 40 mg tablets to dispense for a 30-day supply.

  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 13

A 50-year-old woman (weight 62 kg) is prescribed metronidazole 500 mg by mouth every 12 hours for 7 days for bacterial vaginosis. Medical history: none significant; current medications: none. Allergies: none known. Labs: AST/ALT within normal limits, SCr 0.8 mg/dL. The pharmacy has metronidazole 500 mg tablets. Calculate the total quantity to be dispensed.

  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 14

A 3-year-old girl (weight 15 kg) has nausea and vomiting and is prescribed ondansetron 0.15 mg/kg per dose by mouth every 8 hours as needed. Medical history: none significant; current medications: none. Allergies: none known. Labs: not applicable. Ondansetron oral solution concentration is 4 mg/5 mL. What volume (mL) should be administered per dose?

  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 15

A 32-year-old woman (weight 68 kg) is prescribed prednisone 10 mg tablets with directions: take 4 tablets daily for 3 days, then 3 tablets daily for 3 days, then 2 tablets daily for 3 days, then 1 tablet daily for 3 days, then stop. Medical history: asthma; current medications: albuterol inhaler as needed, budesonide/formoterol 2 inhalations twice daily. Allergies: none known. Labs: not applicable. What total quantity of prednisone 10 mg tablets should be dispensed?

  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 16

A 58-year-old man (weight 86 kg) is prescribed heparin for venous thromboembolism treatment: a bolus of 80 units/kg IV once, then continuous infusion at 18 units/kg/hour. Medical history: atrial fibrillation; current medications: none currently. Allergies: none known. Labs: SCr 1.0 mg/dL, AST/ALT within normal limits. The heparin premix bag concentration is 25,000 units in 250 mL. Determine the infusion rate in mL/hour.

  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 17

A 9-year-old boy (weight 30 kg) is prescribed oseltamivir for influenza treatment at 75 mg by mouth twice daily for 5 days. Medical history: asthma; current medications: albuterol inhaler as needed. Allergies: none known. Labs: not applicable. Oseltamivir is available as 75 mg capsules. Calculate the total quantity to be dispensed to complete therapy.

  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 18

A 45-year-old woman (weight 70 kg) presents with uncomplicated urinary tract infection and is prescribed nitrofurantoin monohydrate/macrocrystals 100 mg by mouth twice daily for 5 days. Medical history: none significant; current medications: ethinyl estradiol/levonorgestrel 1 tablet daily. Allergies: none known. Labs: SCr 0.8 mg/dL, AST/ALT within normal limits. The pharmacy stocks nitrofurantoin 100 mg capsules. Calculate the total quantity to be dispensed to complete the course.

  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 19

A 67-year-old man (weight 82 kg) is being treated for acute deep vein thrombosis and is prescribed enoxaparin 1 mg/kg subcutaneously every 12 hours for 7 days. Medical history includes hypertension and type 2 diabetes; current medications: lisinopril 20 mg daily, metformin 1000 mg twice daily, atorvastatin 40 mg nightly. Allergies: penicillin (rash). Labs: SCr 0.9 mg/dL, AST/ALT within normal limits, A1c 7.4%. Enoxaparin is supplied as 100 mg/mL in a prefilled syringe; what volume (mL) should be administered per dose?

  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 20

A 2-month-old male infant (weight 5 kg) is prescribed acetaminophen 15 mg/kg per dose by mouth every 6 hours as needed for fever. Medical history: none significant; current medications: none. Allergies: none known. Labs: not applicable. Acetaminophen liquid concentration is 160 mg/5 mL. What volume (mL) should be administered per dose?

  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.