Order Entry and Processing is 22.5% of the scored PTCE (the PTCB exam). Answer 10 exam style questions on dosing and days supply calculations and see exactly which concepts would cost you points on test day.
Start the 10 questions →An adult weighing 176 lb is ordered a drug at 1.5 mg/kg as a single dose. Using 1 kg = 2.2 lb, how many milligrams should be given?
These questions cover dose by weight: adult mg/kg, pediatric dose: mg/kg/day to mL per dose, pediatric dose: mg/kg/dose to mL, days supply: insulin vial and days supply: metered-dose inhaler. Each one shows the correct answer and why every other option is wrong, so a miss tells you exactly what to review before the PTCE.
Prefer to read first? Every question from the practice set above, with the correct answer and why each wrong option is wrong.
Answer: C. Weight = 176 lb / 2.2 = 80 kg. Dose = 1.5 mg/kg x 80 kg = 120 mg.
Why not A: 264 mg multiplies 1.5 mg by 176, using pounds as if they were kilograms.
Why not B: 580.8 mg multiplies 176 by 2.2 (giving 387.2) before applying 1.5 mg/kg. lb to kg means dividing by 2.2.
Why not D: 53.3 mg divides the weight by the dose (80 / 1.5). A mg/kg dose is multiplied by the weight.
Exam tactic: Always convert to kg before applying a mg/kg dose.
Answer: B. Daily dose = 40 mg/kg/day x 22 kg = 880 mg/day. Every 12 hours = 2 doses, so 440 mg per dose. Concentration = 400 mg / 5 mL = 80 mg/mL. Volume = 440 mg / 80 mg/mL = 5.5 mL.
Why not A: 11 mL is the total daily volume (880 mg / 80 mg per mL). It must be split into 2 doses.
Why not C: 2.75 mL splits the daily dose into 4 doses (every 6 hours). Every 12 hours means 2 doses.
Why not D: 12.1 mL multiplies 22 kg by 2.2 as if converting to kg. The weight is already in kg.
Exam tactic: Daily total, then per dose, then mg to mL. Check the unit of the weight before converting.
Answer: A. Dose = 15 mg/kg x 12 kg = 180 mg. Concentration = 160 mg / 5 mL = 32 mg/mL. Volume = 180 / 32 = 5.625 mL, rounded to 5.6 mL.
Why not B: 1.1 mL divides 180 mg by 160 and forgets that 160 mg is contained in 5 mL, not 1 mL.
Why not C: 2.8 mL halves the correct volume, as if a mg/kg/day dose were divided into 2 doses. The order is per dose.
Why not D: 12.4 mL multiplies 12 by 2.2 (26.4) before applying 15 mg/kg. The weight is already in kg.
Exam tactic: Read whether the order is per dose or per day before dividing.
Answer: C. Total units = 10 mL x 100 units/mL = 1,000 units. Daily use = 22 + 18 = 40 units. Days supply = 1,000 / 40 = 25 days. This is also within the 28-day in-use limit of most opened insulin vials.
Why not A: 45 days counts only the 22-unit morning dose (1,000 / 22 = 45.5). Both daily doses must be added.
Why not B: 55 days counts only the 18-unit bedtime dose (1,000 / 18 = 55.6).
Why not D: 12 days uses 80 units per day, doubling the real daily total of 40 units (1,000 / 80 = 12.5).
Exam tactic: Insulin: mL x units/mL = total units, then divide by the total of all daily doses.
Answer: D. Puffs per day = 2 puffs x 2 times = 4. Days supply = 120 actuations / 4 per day = 30 days.
Why not A: 60 days uses 2 puffs per day, as if 1 puff twice daily. The sig is 2 puffs twice daily, 4 puffs per day.
Why not B: 15 days uses 8 puffs per day, as if 2 puffs four times daily.
Why not C: 120 is the number of actuations, which would last 120 days only at 1 puff per day.
Exam tactic: Inhaler days supply = actuations in the canister / puffs per day.
Answer: C. Maximum puffs per day = 12. Days supply = 200 / 12 = 16.7, rounded down to 16 days.
Why not A: 100 is the number of 2-puff doses in the canister (200 / 2), not the days supply.
Why not B: 33 days uses 6 puffs per day. The maximum stated in the sig is 12 puffs per day.
Why not D: 25 days uses 8 puffs per day, as if every 6 hours. The stated maximum is 12 puffs per day.
Exam tactic: For PRN orders, base days supply on the maximum daily use in the sig.
Answer: B. Total drops = 5 mL x 20 drops/mL = 100 drops. Daily use = 2 drops x 2 eyes x 3 times = 12 drops. Days supply = 100 / 12 = 8.3, rounded down to 8 days.
Why not A: 16 days counts only one eye (6 drops per day). Each eye means 12 drops per day.
Why not C: 50 days uses 2 drops per day, ignoring both eyes and the three daily doses.
Why not D: 12 days uses twice daily (8 drops per day). The sig says three times daily.
Exam tactic: Drops per day = drops per dose x number of eyes x doses per day.
Answer: A. Total drops = 10 mL x 20 drops/mL = 200 drops. Daily use = 4 drops x 2 = 8 drops. Days supply = 200 / 8 = 25 days.
Why not B: 50 days uses 4 drops per day, as if once daily. Twice daily means 8 drops per day.
Why not C: 12 days counts both ears (16 drops per day). The sig is for the affected ear only.
Why not D: 100 days uses 2 drops per day, as if 1 drop twice daily instead of 4 drops.
Exam tactic: Check whether the sig names one ear/eye or both before multiplying.
Answer: C. Each tablet covers 7 days. Days supply = 4 tablets x 7 days = 28 days.
Why not A: 4 days treats the drug as once daily. One tablet covers 7 days.
Why not B: 30 days assumes a month. 4 weekly tablets cover exactly 4 x 7 = 28 days.
Why not D: 7 days is the supply of a single tablet, not of all 4.
Exam tactic: For weekly drugs, days supply = number of doses x 7.
Answer: B. 72 hours = 3 days per patch. Days supply = 5 patches x 3 days = 15 days.
Why not A: 5 days assumes 1 patch per day. Each patch is worn for 72 hours (3 days).
Why not C: 10 days assumes a patch change every 48 hours (2 days).
Why not D: 30 days assumes the box is a monthly supply. 5 patches x 3 days = 15 days.
Exam tactic: Convert the change interval to days, then multiply by the number of patches.
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