Ptcb Quiz: Duration Of Therapy
20 questions · exam conditions
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Duration Of TherapyQuestion 1 of 20

A patient is prescribed an albuterol HFA inhaler containing 200 metered inhalations. The directions are "Inhale 2 puffs every 4 hours as needed for shortness of breath." What is the minimum days supply for one inhaler?

8 days
16 days
33 days
100 days
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Ptcb Quiz

Ptcb Quiz: Duration Of Therapy

Practice Duration Of Therapy in Ptcb with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

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This quiz focuses on Duration Of Therapy, 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 patient is prescribed an albuterol HFA inhaler containing 200 metered inhalations. The directions are "Inhale 2 puffs every 4 hours as needed for shortness of breath." What is the minimum days supply for one inhaler?

  1. 8 days
  2. 16 days (correct answer)
  3. 33 days
  4. 100 days
Explanation: For "as needed" (PRN) medications, the days supply is calculated based on the maximum possible daily usage. The patient can take a dose every 4 hours, which is 24 hours÷4 hours/dose=6 doses/day24 \text{ hours} \div 4 \text{ hours/dose} = 6 \text{ doses/day}. Each dose is 2 puffs, 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 days supply is 200 puffs÷12 puffs/day=16.66 days200 \text{ puffs} \div 12 \text{ puffs/day} = 16.66 \text{ days}. The supply will last for 16 full days.

Question 2

A prescription for Lantus SoloStar pens (100 units/mL, 3 mL per pen) has the directions "Inject 20 units subcutaneously every evening at bedtime." If a box of 5 pens is dispensed, what is the days supply?

  1. 15 days
  2. 30 days
  3. 75 days (correct answer)
  4. 150 days
Explanation: First, calculate the total units dispensed. Each pen has 100 units/mL×3 mL=300 units100 \text{ units/mL} \times 3 \text{ mL} = 300 \text{ units}. A box of 5 pens has 300 units/pen×5 pens=1500 total units300 \text{ units/pen} \times 5 \text{ pens} = 1500 \text{ total units}. The patient uses 20 units per day. The days supply is 1500 units÷20 units/day=75 days1500 \text{ units} \div 20 \text{ units/day} = 75 \text{ days}.

Question 3

A prescription for cefdinir 250 mg/5 mL requires reconstitution to a final volume of 100 mL. The directions are "Take 5 mL by mouth twice daily until gone." What is the duration of therapy for one reconstituted bottle?

  1. 5 days
  2. 7 days
  3. 10 days (correct answer)
  4. 14 days
Explanation: The total volume after reconstitution is 100 mL. The patient takes 5 mL twice daily, for a total of 5 mL/dose×2 doses/day=10 mL/day5 \text{ mL/dose} \times 2 \text{ doses/day} = 10 \text{ mL/day}. To find the duration of therapy (days supply), divide the total volume by the daily volume: 100 mL÷10 mL/day=10 days100 \text{ mL} \div 10 \text{ mL/day} = 10 \text{ days}.

Question 4

A patient is prescribed levothyroxine 100 mcg tablets with the sig "Take 1 tablet on Monday, Wednesday, Friday and 1/2 tablet on Tuesday, Thursday, Saturday, Sunday." If 90 tablets are dispensed, what is the days supply?

  1. 90 days
  2. 108 days
  3. 126 days (correct answer)
  4. 140 days
Explanation: Calculate the number of tablets used per week. There are 3 days at 1 tablet/day and 4 days at 0.5 tablets/day. Total weekly usage: (3×1)+(4×0.5)=3+2=5(3 \times 1) + (4 \times 0.5) = 3 + 2 = 5 tablets per week. Next, find how many weeks the supply will last: 90 tablets÷5 tablets/week=18 weeks90 \text{ tablets} \div 5 \text{ tablets/week} = 18 \text{ weeks}. Finally, convert weeks to days: 18 weeks×7 days/week=126 days18 \text{ weeks} \times 7 \text{ days/week} = 126 \text{ days}.

Question 5

A prescription for clindamycin 150 mg capsules reads: "Take 2 capsules by mouth 4 times a day." If 112 capsules are dispensed, what is the days supply?

  1. 7 days
  2. 14 days (correct answer)
  3. 28 days
  4. 56 days
Explanation: First, calculate the total number of capsules taken per day. The patient takes 2 capsules per dose, 4 times a day. The daily amount is 2 capsules/dose×4 doses/day=8 capsules/day2 \text{ capsules/dose} \times 4 \text{ doses/day} = 8 \text{ capsules/day}. The total quantity dispensed is 112 capsules. The days supply is 112 capsules÷8 capsules/day=14 days112 \text{ capsules} \div 8 \text{ capsules/day} = 14 \text{ days}.

Question 6

A pharmacy receives a prescription for metformin 500 mg tablets. The directions are "Take 1 tablet by mouth twice daily." If the pharmacy dispenses 60 tablets, what is the days supply?

  1. 15 days
  2. 30 days (correct answer)
  3. 60 days
  4. 90 days
Explanation: The patient takes 1 tablet twice daily, for a total of 2 tablets per day. The total quantity dispensed is 60 tablets. To find the days supply, divide the total quantity by the number of tablets per day: 60 tablets÷2 tablets/day=30 days60 \text{ tablets} \div 2 \text{ tablets/day} = 30 \text{ days}.

Question 7

A prescription for amoxicillin 250 mg/5 mL suspension has the directions "Take one teaspoonful by mouth three times a day." If the pharmacy dispenses a 150 mL bottle, what is the duration of therapy?

  1. 5 days
  2. 7 days
  3. 10 days (correct answer)
  4. 15 days
Explanation: First, convert teaspoonfuls to mL: 1 tsp = 5 mL. The patient takes 5 mL three times a day, for a total of 5 mL/dose×3 doses/day=15 mL/day5 \text{ mL/dose} \times 3 \text{ doses/day} = 15 \text{ mL/day}. The total volume dispensed is 150 mL. The days supply is calculated as: 150 mL÷15 mL/day=10 days150 \text{ mL} \div 15 \text{ mL/day} = 10 \text{ days}.

Question 8

A 5 mL bottle of timolol 0.5% ophthalmic solution is prescribed with the directions "Instill 1 drop in both eyes twice daily." Assuming there are 20 drops per mL, what is the days supply?

  1. 12 days
  2. 25 days (correct answer)
  3. 50 days
  4. 100 days
Explanation: First, calculate the total number of drops in the bottle: 5 mL×20 drops/mL=100 drops5 \text{ mL} \times 20 \text{ drops/mL} = 100 \text{ drops}. Next, calculate the number of drops used per day: 1 drop/eye×2 eyes×2 times/day=4 drops/day1 \text{ drop/eye} \times 2 \text{ eyes} \times 2 \text{ times/day} = 4 \text{ drops/day}. Finally, calculate the days supply: 100 drops÷4 drops/day=25 days100 \text{ drops} \div 4 \text{ drops/day} = 25 \text{ days}.

Question 9

A prescription is written for a Medrol Dosepak, which contains 21 tablets. The patient is instructed to follow the directions on the package. What is the duration of therapy for this medication?

  1. 6 days (correct answer)
  2. 7 days
  3. 14 days
  4. 21 days
Explanation: A Medrol Dosepak is a pre-packaged tapering dose of methylprednisolone. The standard dosing schedule involves taking a decreasing number of tablets each day (6, 5, 4, 3, 2, 1) over a period of 6 days. Therefore, the duration of therapy is a fixed 6 days.

Question 10

A prescription for methotrexate 2.5 mg tablets has the directions "Take 4 tablets by mouth once weekly." If the pharmacy dispenses 24 tablets, what is the days supply?

  1. 6 days
  2. 24 days
  3. 42 days (correct answer)
  4. 168 days
Explanation: The patient takes 4 tablets per dose, and each dose is taken once a week. First, determine how many weekly doses are dispensed: 24 tablets÷4 tablets/dose=6 doses24 \text{ tablets} \div 4 \text{ tablets/dose} = 6 \text{ doses}. Since each dose covers one week, the supply will last for 6 weeks. To find the days supply, convert weeks to days: 6 weeks×7 days/week=42 days6 \text{ weeks} \times 7 \text{ days/week} = 42 \text{ days}.

Question 11

A prescription for fluticasone propionate nasal spray provides 120 metered sprays. The directions are "Use 2 sprays in each nostril once daily." What is the days supply?

  1. 15 days
  2. 30 days (correct answer)
  3. 60 days
  4. 120 days
Explanation: The patient uses 2 sprays in each nostril, for a total of 2 sprays/nostril×2 nostrils=4 sprays2 \text{ sprays/nostril} \times 2 \text{ nostrils} = 4 \text{ sprays} per day. The container has 120 sprays. The days supply is calculated as: 120 sprays÷4 sprays/day=30 days120 \text{ sprays} \div 4 \text{ sprays/day} = 30 \text{ days}.

Question 12

A patient is prescribed warfarin 5 mg tablets with the following directions: "Take 1 tablet daily, except on Sunday take 1/2 tablet." If 30 tablets are dispensed, what is the days supply?

  1. 28 days
  2. 30 days
  3. 32 days (correct answer)
  4. 35 days
Explanation: First, calculate the number of tablets used per week. The patient takes 1 tablet for 6 days and 0.5 tablets for 1 day: (6×1)+(1×0.5)=6.5(6 \times 1) + (1 \times 0.5) = 6.5 tablets per week. Next, determine how many full weeks the supply will last: 30 tablets÷6.5 tablets/week≈4.615 weeks30 \text{ tablets} \div 6.5 \text{ tablets/week} \approx 4.615 \text{ weeks}. This is 4.615×7=32.34.615 \times 7 = 32.3 days. To verify, after 4 weeks (28 days), 4×6.5=264 \times 6.5 = 26 tablets are used, leaving 4 tablets. These will last 4 more days (Day 29, 30, 31, 32), for a total of 32 days.

Question 13

A prescription for ciprofloxacin/dexamethasone otic suspension (7.5 mL bottle) has the directions "Instill 4 drops into the right ear twice daily." Assuming 20 drops per mL, what is the days supply?

  1. 9 days
  2. 18 days (correct answer)
  3. 25 days
  4. 37 days
Explanation: First, calculate the total drops in the bottle: 7.5 mL×20 drops/mL=150 drops7.5 \text{ mL} \times 20 \text{ drops/mL} = 150 \text{ drops}. Next, calculate daily usage. The directions specify the right ear (AD), so it is one ear: 4 drops/ear×1 ear×2 times/day=8 drops/day4 \text{ drops/ear} \times 1 \text{ ear} \times 2 \text{ times/day} = 8 \text{ drops/day}. The days supply is 150 drops÷8 drops/day=18.75150 \text{ drops} \div 8 \text{ drops/day} = 18.75. The supply will last for 18 full days.

Question 14

A patient receives a box of 5 Humalog KwikPens (3 mL/pen, 100 units/mL). The directions are "Inject 12 units subcutaneously three times daily with meals." What is the days supply?

  1. 8 days
  2. 41 days (correct answer)
  3. 83 days
  4. 125 days
Explanation: First, calculate total units dispensed. Each pen has 3 mL×100 units/mL=300 units3 \text{ mL} \times 100 \text{ units/mL} = 300 \text{ units}. The box has 5 pens×300 units/pen=1500 total units5 \text{ pens} \times 300 \text{ units/pen} = 1500 \text{ total units}. Next, calculate daily usage: 12 units/dose×3 doses/day=36 units/day12 \text{ units/dose} \times 3 \text{ doses/day} = 36 \text{ units/day}. The days supply is 1500 units÷36 units/day=41.66...1500 \text{ units} \div 36 \text{ units/day} = 41.66.... The supply will last 41 full days.

Question 15

A prescription for ondansetron 4 mg is written as "Take 1 tablet by mouth every 8 hours as needed for nausea." If 30 tablets are dispensed, what is the days supply?

  1. 10 days (correct answer)
  2. 15 days
  3. 24 days
  4. 30 days
Explanation: For insurance and refill purposes, the days supply for a PRN (as needed) medication is calculated based on the maximum frequency allowed. The maximum frequency is every 8 hours. The number of doses per day is 24 hours÷8 hours/dose=3 doses/day24 \text{ hours} \div 8 \text{ hours/dose} = 3 \text{ doses/day}. The patient takes 1 tablet per dose, so the maximum daily usage is 3 tablets. The days supply is 30 tablets÷3 tablets/day=10 days30 \text{ tablets} \div 3 \text{ tablets/day} = 10 \text{ days}.

Question 16

A prescription for azithromycin 250 mg tablets has the following directions: "Take tabs ii on day 1, then tab i daily for 4 days." What is the duration of therapy?

  1. 4 days
  2. 5 days (correct answer)
  3. 6 days
  4. 7 days
Explanation: This question requires interpreting the sig code to determine the total length of treatment. The patient takes medication on day 1 (the first day of therapy) and then for 4 additional days. The total duration is 1 day+4 days=5 days1 \text{ day} + 4 \text{ days} = 5 \text{ days}. This is the standard dosing for an Azithromycin Z-Pak.

Question 17

A 10 mL multi-dose vial of testosterone cypionate 200 mg/mL is dispensed. The directions are "Inject 0.5 mL intramuscularly once every week." What is the days supply?

  1. 20 days
  2. 70 days
  3. 100 days
  4. 140 days (correct answer)
Explanation: First, determine the number of doses in the vial: 10 mL÷0.5 mL/dose=20 doses10 \text{ mL} \div 0.5 \text{ mL/dose} = 20 \text{ doses}. Since each dose is given once per week, the vial will last for 20 weeks. To convert this to days, multiply by 7: 20 weeks×7 days/week=140 days20 \text{ weeks} \times 7 \text{ days/week} = 140 \text{ days}.

Question 18

A patient receives a prescription for fentanyl 25 mcg/hr patches with the sig "Apply 1 patch transdermally every 72 hours." If the quantity dispensed is 10 patches, what is the days supply?

  1. 10 days
  2. 30 days (correct answer)
  3. 72 days
  4. 240 days
Explanation: The directions state to apply one patch every 72 hours. First, convert 72 hours to days: 72 hours÷24 hours/day=3 days72 \text{ hours} \div 24 \text{ hours/day} = 3 \text{ days}. Each patch lasts for 3 days. The total days supply for 10 patches is 10 patches×3 days/patch=30 days10 \text{ patches} \times 3 \text{ days/patch} = 30 \text{ days}.

Question 19

A 60 mL bottle of nystatin oral suspension (100,000 units/mL) is dispensed with the directions "Swish and swallow 5 mL four times daily." What is the days supply?

  1. 3 days (correct answer)
  2. 5 days
  3. 12 days
  4. 15 days
Explanation: The patient uses 5 mL four times daily (QID), so the total daily volume is 5 mL/dose×4 doses/day=20 mL/day5 \text{ mL/dose} \times 4 \text{ doses/day} = 20 \text{ mL/day}. The total volume dispensed is 60 mL. The days supply is 60 mL÷20 mL/day=3 days60 \text{ mL} \div 20 \text{ mL/day} = 3 \text{ days}.

Question 20

A patient is prescribed a Symbicort 80/4.5 mcg inhaler, which contains 120 inhalations. The directions for use are "Inhale 2 puffs twice daily." What is the days supply?

  1. 15 days
  2. 30 days (correct answer)
  3. 60 days
  4. 120 days
Explanation: The patient takes 2 puffs twice daily (BID). The total number of puffs per day is 2 puffs/dose×2 doses/day=4 puffs/day2 \text{ puffs/dose} \times 2 \text{ doses/day} = 4 \text{ puffs/day}. The inhaler contains 120 puffs. To calculate the days supply, divide the total puffs by the daily usage: 120 puffs÷4 puffs/day=30 days120 \text{ puffs} \div 4 \text{ puffs/day} = 30 \text{ days}.