Ptcb Quiz: Quantity Interpretation
19 questions · exam conditions
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Quantity InterpretationQuestion 1 of 19

A prescription for losartan 50 mg is written for a quantity of 90 tablets with 2 refills. What is the total number of tablets authorized by the prescriber for the entire duration of the prescription?

90
180
270
360
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Ptcb Quiz

Ptcb Quiz: Quantity Interpretation

Practice Quantity Interpretation in Ptcb 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 Quantity Interpretation, giving you a quick way to practice the rules, question types, and explanations that matter most for Ptcb.

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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 prescription for losartan 50 mg is written for a quantity of 90 tablets with 2 refills. What is the total number of tablets authorized by the prescriber for the entire duration of the prescription?

  1. 90
  2. 180
  3. 270 (correct answer)
  4. 360
Explanation: The total authorized quantity includes the initial fill plus all refills. The initial fill is 90 tablets. There are 2 refills, each for 90 tablets. The total is calculated as: Initial Fill+(Number of Refills×Quantity per Fill)=90+(2×90)=90+180=270\text{Initial Fill} + (\text{Number of Refills} \times \text{Quantity per Fill}) = 90 + (2 \times 90) = 90 + 180 = 270 tablets.
  • A is incorrect; 90 is the quantity for the initial fill only.
  • B is incorrect; 180 is the quantity for the refills only.
  • D is incorrect; 360 would be the total quantity if there were 3 refills.

Question 2

A prescription for potassium chloride 10 mEq tablets is written with the sig "Mitte #LX". How many tablets should be dispensed?

  1. 30
  2. 40
  3. 50
  4. 60 (correct answer)
Explanation: "Mitte" is a Latin term meaning "send" or "dispense". It is followed by the quantity to be dispensed, often in Roman numerals. The Roman numeral 'L' represents 50 and 'X' represents 10. When a smaller numeral follows a larger one, they are added. Therefore, LX = 50 + 10 = 60. The pharmacy should dispense 60 tablets.
  • A is incorrect; 30 is represented by XXX.
  • B is incorrect; 40 is represented by XL.
  • C is incorrect; 50 is represented by L.

Question 3

A prescription for atorvastatin 20 mg is written with the quantity indicated as "#XC". How many tablets should be dispensed?

  1. 40
  2. 60
  3. 90 (correct answer)
  4. 110
Explanation: Roman numerals are used on prescriptions. The numeral 'X' represents 10 and 'C' represents 100. When a smaller numeral is placed before a larger numeral, it is subtracted from the larger one. Therefore, XC = 100 - 10 = 90.
  • A is incorrect; 40 is represented by XL (50 - 10).
  • B is incorrect; 60 is represented by LX (50 + 10).
  • D is incorrect; 110 is represented by CX (100 + 10).

Question 4

A prescription for alprazolam 0.5 mg is written with "5 refills" and is dated March 1st. According to federal law for a C-IV substance, what is the last possible date this prescription can be refilled?

  1. March 31st of the same year
  2. September 1st of the same year
  3. March 1st of the next year
  4. August 31st of the same year (correct answer)
Explanation: According to federal law, prescriptions for schedule III and IV controlled substances are valid for a maximum of 6 months from the date written and may not be refilled more than 5 times. Six months from March 1st would be September 1st. The prescription expires at 6 months, so the last day to fill it is August 31st.
  • A is incorrect as it is only one month from the date written.
  • B is incorrect because the prescription expires on this date; it cannot be filled on this date.
  • C is incorrect because non-controlled substance prescriptions are typically valid for one year; this is a C-IV.

Question 5

A prescription for latanoprost eye drops directs the patient to instill 1 drop (gtt) into each eye once daily. The medication is available in a 2.5 mL bottle, which contains approximately 20 drops per mL. How many days will the bottle last?

  1. 25 days (correct answer)
  2. 30 days
  3. 50 days
  4. 100 days
Explanation: First, calculate the total number of drops in the bottle: 2.5 mL×20 drops/mL=50 drops2.5 \text{ mL} \times 20 \text{ drops/mL} = 50 \text{ drops}. The patient uses 1 drop in each eye (OU), which is 2 drops per day. The days' supply is the total number of drops divided by the daily usage: 50 drops÷2 drops/day=25 days50 \text{ drops} \div 2 \text{ drops/day} = 25 \text{ days}.
  • B is a common days' supply but is not the correct calculation for this specific medication and usage.
  • C is incorrect; this would be the days' supply if only one eye was being treated.
  • D is incorrect as it miscalculates the total drops or daily usage.

Question 6

A prescription for prednisone 10 mg tablets has the following tapering schedule:

  • 3 tabs po daily x 3 days
  • 2 tabs po daily x 3 days
  • 1 tab po daily x 3 days
  • 1/2 tab po daily x 3 days How many tablets should be dispensed?
  1. 19
  2. 19.5
  3. 20 (correct answer)
  4. 21
Explanation: Calculate the number of tablets for each step of the taper and sum them: Step 1: 3 tabs/day×3 days=9 tablets3 \text{ tabs/day} \times 3 \text{ days} = 9 \text{ tablets} Step 2: 2 tabs/day×3 days=6 tablets2 \text{ tabs/day} \times 3 \text{ days} = 6 \text{ tablets} Step 3: 1 tab/day×3 days=3 tablets1 \text{ tab/day} \times 3 \text{ days} = 3 \text{ tablets} Step 4: 0.5 tab/day×3 days=1.5 tablets0.5 \text{ tab/day} \times 3 \text{ days} = 1.5 \text{ tablets} Total: 9+6+3+1.5=19.5 tablets9 + 6 + 3 + 1.5 = 19.5 \text{ tablets}. Since the patient needs 1.5 tablets for the final step and prednisone tablets are scored, 20 tablets must be dispensed to ensure adequate supply for the complete taper.
  • A is insufficient to complete the prescribed taper.
  • B is the exact calculated amount but insufficient since partial tablets for the final step require dispensing whole tablets.
  • D exceeds the required amount for this specific taper schedule.

Question 7

A prescription for gabapentin 300 mg has the directions "Take 1 cap PO at bedtime for 3 days, then 1 cap PO BID for 3 days, then 1 cap PO TID thereafter." How many capsules are needed for the first 30 days of therapy?

  1. 69
  2. 75
  3. 81 (correct answer)
  4. 90
Explanation: This is a titration schedule. Calculate the quantity for each step:
  • Step 1 (3 days): 1 cap/day×3 days=3 capsules1 \text{ cap/day} \times 3 \text{ days} = 3 \text{ capsules}
  • Step 2 (3 days): 1 cap×2 times/day×3 days=6 capsules1 \text{ cap} \times 2 \text{ times/day} \times 3 \text{ days} = 6 \text{ capsules}
  • Step 3 (Maintenance): The first 6 days are used for titration. The remaining duration is 30−6=24 days30 - 6 = 24 \text{ days}. The dose is 1 cap TID (3 times/day). Quantity for this step is 1 cap×3 times/day×24 days=72 capsules1 \text{ cap} \times 3 \text{ times/day} \times 24 \text{ days} = 72 \text{ capsules}.
  • Total: 3+6+72=81 capsules3 + 6 + 72 = 81 \text{ capsules}.
  • A and B are incorrect due to miscalculation of one of the steps.
  • D is incorrect; 90 would be the quantity for a 30-day supply at the final maintenance dose of 1 cap TID.

Question 8

A prescription for methotrexate 2.5 mg tablets has the sig: "Take 4 tablets by mouth once weekly on Saturdays." What quantity should be dispensed for a 30-day supply?

  1. 4
  2. 12
  3. 16 (correct answer)
  4. 30
Explanation: The patient takes 4 tablets once per week. A 30-day supply will typically contain 4 weeks (as 30 / 7 ≈ 4.28). However, it's standard practice to account for the number of dose-days (Saturdays) in a month, which can be 4 or 5. To be safe and ensure uninterrupted therapy, a 4-week supply is often considered 28 days and a one-month supply is based on the number of dose days. In a typical 4-week period, there are 4 Saturdays. Therefore, the quantity is 4 tablets/week×4 weeks=16 tablets4 \text{ tablets/week} \times 4 \text{ weeks} = 16 \text{ tablets}.
  • A is incorrect; 4 is the quantity for a single week's dose.
  • B is incorrect; this would be the quantity if the patient took 3 tablets weekly.
  • D is incorrect; 30 would be the quantity for a daily medication.

Question 9

A patient has a prescription for zolpidem 10 mg, "#30, i tab po qhs prn sleep." The patient last filled this C-IV prescription 21 days ago. The patient requests a refill today. What should the technician do?

  1. Refill the prescription for 30 tablets.
  2. Tell the patient it is too soon to refill. (correct answer)
  3. Dispense a partial supply of 9 tablets.
  4. Refill the prescription since it has refills.
Explanation: Most insurance plans and pharmacy policies will not allow a refill for a 30-day supply of a controlled substance until at least 75-85% of the medication has been used. At 21 days, the patient has used 21/30=7021/30 = 70% of the supply. This is generally considered too early to refill, especially for a controlled substance used for sleep. The technician should inform the patient it is too soon and check the pharmacy's policy or ask the pharmacist.
  • A and D are incorrect because refilling early without a valid reason could be a sign of misuse or diversion.
  • C is incorrect; dispensing a partial fill in this situation is not standard practice unless there is a specific reason or override provided.

Question 10

A prescription is written for warfarin 5 mg with the sig "take as directed per anticoagulation clinic." The quantity is #30. The patient states the clinic told them to take 1.5 tablets daily. Based on the patient's report, what is the days' supply?

  1. 15 days
  2. 20 days (correct answer)
  3. 30 days
  4. 45 days
Explanation: The technician must calculate the days' supply based on the current directions, which are reported by the patient to be 1.5 tablets daily. The total quantity dispensed is 30 tablets. The calculation is 30 tablets÷1.5 tablets/day=20 days30 \text{ tablets} \div 1.5 \text{ tablets/day} = 20 \text{ days}. The technician should confirm these directions with the pharmacist before dispensing.
  • A is incorrect; 15 days would be the supply for 2 tablets daily.
  • C is incorrect; 30 days would be the supply for 1 tablet daily.
  • D is incorrect; 45 days would be the supply if 45 tablets were dispensed.

Question 11

A prescription for oxycodone 5mg/acetaminophen 325mg reads "Dispense #120, 1-2 tabs po q4-6h prn pain." It has zero refills. What is the maximum number of tablets the patient could take per day according to these instructions?

  1. 8
  2. 12 (correct answer)
  3. 16
  4. 24
Explanation: To determine the maximum daily dose, use the highest dose (2 tablets) at the most frequent interval (every 4 hours). The number of doses in a 24-hour period is 24 hours÷4 hours/dose=6 doses/day24 \text{ hours} \div 4 \text{ hours/dose} = 6 \text{ doses/day}. The maximum number of tablets per day is 2 tablets/dose×6 doses/day=12 tablets/day2 \text{ tablets/dose} \times 6 \text{ doses/day} = 12 \text{ tablets/day}. It is also important to note the maximum daily limit of acetaminophen, which is typically 3000-4000 mg. 12 tablets would be 12×325 mg=3900 mg12 \times 325 \text{ mg} = 3900 \text{ mg}, which is within the acceptable limit.
  • A is incorrect. This would be 2 tablets every 6 hours.
  • C is incorrect. This would be over the maximum daily dose and could result from miscalculation.
  • D is incorrect and would far exceed the maximum daily dose of both oxycodone and acetaminophen.

Question 12

A patient presents a new prescription for hydromorphone 2 mg tablets, a C-II medication. The quantity is #60 and the refills field states "2". How should the technician interpret the refill information?

  1. The patient can receive two additional fills of 60 tablets within 6 months.
  2. The prescription allows for a total of three fills.
  3. The prescription cannot be refilled. (correct answer)
  4. The technician should call the prescriber to verify the quantity.
Explanation: According to federal law, Schedule II (C-II) controlled substance prescriptions cannot have refills. The "2" in the refill field is legally invalid. The technician must process the prescription for the initial quantity with zero refills. The pharmacist may need to contact the prescriber to clarify their intent, but the legal interpretation is that no refills are permitted.
  • A and B are incorrect because C-II prescriptions are not refillable.
  • D is incorrect because while the pharmacist may call for clarification, the legal standing is clear: no refills are allowed. The quantity does not need verification, but the refill information is invalid.

Question 13

A patient presents a prescription for amoxicillin 500 mg capsules with the instructions: "Take 1 capsule by mouth three times daily for 10 days." How many capsules should be dispensed to fulfill the prescription?

  1. 10
  2. 20
  3. 30 (correct answer)
  4. 60
Explanation: The correct quantity is calculated by multiplying the dose frequency by the duration of therapy. The patient takes 1 capsule 3 times a day for 10 days. The calculation is 1 capsule×3 times/day×10 days=30 capsules1 \text{ capsule} \times 3 \text{ times/day} \times 10 \text{ days} = 30 \text{ capsules}.
  • A is incorrect because 10 is the number of days, not the total quantity.
  • B is incorrect because 20 would be the quantity for taking 1 capsule twice a day (b.i.d.) for 10 days.
  • D is incorrect as it does not correspond to the prescribed directions.

Question 14

A prescription for hydrochlorothiazide 25 mg reads: "Take 1 tablet by mouth every morning." The quantity is listed as "#90" with 3 refills. This prescription is considered valid for what duration from the date it was written?

  1. 3 months
  2. 6 months
  3. 1 year (correct answer)
  4. 2 years
Explanation: For non-controlled substances, a prescription is federally valid for one year from the date it was written. Even though the quantity and refills would last for more than a year (90 days + 3*90 days = 360 days total), the prescription itself expires after 12 months (1 year). No refills can be dispensed after the one-year expiration date.
  • A is incorrect; 3 months is the duration of a single fill.
  • B is incorrect; 6 months is the expiration date for Schedule III-V controlled substances.
  • D is incorrect; no standard prescription is valid for two years.

Question 15

A patient has a prescription for an albuterol HFA inhaler with the instructions "Inhale 2 puffs every 4 to 6 hours as needed for shortness of breath." Each inhaler contains 200 actuations. If the patient uses the maximum daily dose, what is the days' supply?

  1. 16 days (correct answer)
  2. 25 days
  3. 33 days
  4. 50 days
Explanation: To calculate the days' supply for a PRN (as needed) medication, use the maximum frequency allowed. The maximum frequency is every 4 hours. There are 24 hours in a day, so the maximum number of doses per day is 24÷4=624 \div 4 = 6 doses. The patient takes 2 puffs per dose, so the maximum daily usage is 6 doses/day×2 puffs/dose=12 puffs/day6 \text{ doses/day} \times 2 \text{ puffs/dose} = 12 \text{ puffs/day}. The inhaler contains 200 puffs (actuations). The days' supply is 200 puffs÷12 puffs/day≈16.67200 \text{ puffs} \div 12 \text{ puffs/day} \approx 16.67 days. The days' supply is rounded down to 16.
  • B is incorrect; 25 days would be the supply if the patient used 8 puffs per day.
  • C is incorrect; 33 days would be the supply if the patient used 6 puffs per day (e.g., 2 puffs tid).
  • D is incorrect; 50 days would be the supply if the patient used 4 puffs per day.

Question 16

A patient uses 25 units of Lantus insulin every evening. How many 10 mL vials will be needed for a 90-day supply? (Lantus = 100 units/mL)

  1. 1
  2. 2
  3. 3 (correct answer)
  4. 4
Explanation: First, calculate the total units needed for 90 days: 25 units/day×90 days=2250 units25 \text{ units/day} \times 90 \text{ days} = 2250 \text{ units}. Next, calculate the number of units in one 10 mL vial: 100 units/mL×10 mL/vial=1000 units/vial100 \text{ units/mL} \times 10 \text{ mL/vial} = 1000 \text{ units/vial}. Finally, determine how many vials are needed: 2250 total units÷1000 units/vial=2.25 vials2250 \text{ total units} \div 1000 \text{ units/vial} = 2.25 \text{ vials}. Since vials cannot be dispensed in fractions, the pharmacy must dispense 3 full vials to cover the 90-day supply.
  • A is incorrect; one vial provides 1000 units, which is only a 40-day supply.
  • B is incorrect; two vials provide 2000 units, which is only an 80-day supply.
  • D is incorrect as it is more than the required amount.

Question 17

A prescription for azithromycin 250 mg tablets is written as "Z-Pak". How many tablets should be dispensed?

  1. 5
  2. 6 (correct answer)
  3. 10
  4. 12
Explanation: A "Z-Pak" is the brand name for a common pre-packaged course of azithromycin therapy. It contains a blister card with 6 tablets of 250 mg azithromycin. The standard dosing is to take two tablets on day 1, followed by one tablet daily for days 2 through 5, for a total of 6 tablets over 5 days.
  • A is incorrect; 5 represents the number of days of therapy, not the number of tablets.
  • C and D are incorrect quantities for a standard Z-Pak.

Question 18

A prescription for fentanyl 25 mcg/hr patches has the instructions: "Apply 1 patch every 72 hours." A box contains 5 patches. What is the days' supply for one box?

  1. 5 days
  2. 10 days
  3. 15 days (correct answer)
  4. 30 days
Explanation: Each patch is effective for 72 hours. To convert hours to days, divide by 24: 72 hours÷24 hours/day=3 days72 \text{ hours} \div 24 \text{ hours/day} = 3 \text{ days}. Therefore, each patch lasts for 3 days. Since the box contains 5 patches, the total days' supply is 5 patches×3 days/patch=15 days5 \text{ patches} \times 3 \text{ days/patch} = 15 \text{ days}.
  • A is incorrect; this assumes one patch is used daily.
  • B is incorrect and represents a calculation error.
  • D is incorrect; a 30-day supply would require a box of 10 patches.

Question 19

A prescription for cephalexin 250 mg/5 mL suspension has the directions "Take two teaspoonfuls by mouth twice daily for 7 days." What is the total volume in mL that should be dispensed?

  1. 70 mL
  2. 100 mL
  3. 140 mL (correct answer)
  4. 280 mL
Explanation: First, convert teaspoonfuls to mL: 1 teaspoonful (tsp) = 5 mL. The patient takes two teaspoonfuls, which is 2×5 mL=10 mL2 \times 5 \text{ mL} = 10 \text{ mL} per dose. The dose is given twice daily, for a total of 10 mL/dose×2 doses/day=20 mL/day10 \text{ mL/dose} \times 2 \text{ doses/day} = 20 \text{ mL/day}. The duration is 7 days, so the total volume is 20 mL/day×7 days=140 mL20 \text{ mL/day} \times 7 \text{ days} = 140 \text{ mL}.
  • A is incorrect; 70 mL would be the volume if the patient took only one teaspoonful twice daily.
  • B is a common bottle size but is not the calculated volume.
  • D is incorrect; 280 mL would be the volume if the dose were four teaspoonfuls twice daily or two teaspoonfuls four times daily.