PEBC PEBC Drug Dispensing and Compounding 4 — Questions and Answers
Question 1: A prescription calls for a 2% lidocaine solution. You have 4% lidocaine stock solution. How much 4% solution and sterile water are needed to prepare 200 mL of the 2% solution?
- 100 mL of 4% + 100 mL water (Correct answer)
- 50 mL of 4% + 150 mL water
- 150 mL of 4% + 50 mL water
- 80 mL of 4% + 120 mL water
Correct answer: 100 mL of 4% + 100 mL water
Using C1V1 = C2V2: 4% × V1 = 2% × 200 mL, so V1 = 100 mL of 4% solution; the remainder (100 mL) is sterile water.
Question 2: When compounding a topical ointment containing a drug that is classified as a hazardous substance, which primary engineering control is most appropriate?
- Laminar airflow workbench (LAFW)
- Containment primary engineering control (C-PEC) (Correct answer)
- Biological safety cabinet Class II Type A1
- Standard fume hood
Correct answer: Containment primary engineering control (C-PEC)
A containment primary engineering control (C-PEC) is required for hazardous drug compounding to protect the compounder and environment from exposure.
Question 3: A pharmacist receives a prescription for metformin 500 mg tablets with the sig 'i tab po BID ac'. What does 'ac' indicate?
- After meals
- Before meals (Correct answer)
- At bedtime
- With meals
Correct answer: Before meals
'ac' is the Latin abbreviation for 'ante cibum,' meaning before meals.
Question 4: During a compounding quality check, you discover that the beyond-use date (BUD) on a batch of sterile preparations was assigned based on manufacturer data rather than USP <797> guidelines. What is the most appropriate action?
- Keep the BUD as is since manufacturer data is acceptable
- Quarantine the batch and reassign BUD per USP <797> (Correct answer)
- Discard only the preparations dispensed that day
- Notify the prescriber and continue dispensing
Correct answer: Quarantine the batch and reassign BUD per USP <797>
USP <797> guidelines govern BUDs for sterile preparations; the batch must be quarantined and the BUD reassigned according to these standards before dispensing.
Question 5: A prescription is written for 'Tylenol #3'. Which controlled substance schedule does this combination product fall under in Canada?
- Schedule I
- Schedule II
- Schedule III (Correct answer)
- Schedule F
Correct answer: Schedule III
Tylenol #3 contains codeine 30 mg and falls under Schedule III (narcotic) in Canada due to its codeine content exceeding exempted thresholds.
Question 6: A pharmacist is preparing a batch of suppositories using cocoa butter as the base. Which mold displacement factor consideration is critical for accurate dosing?
- The API always weighs less than cocoa butter by volume
- The density factor of the API must be used to adjust base quantity (Correct answer)
- Cocoa butter expands on cooling, requiring overfill
- Aqueous APIs cannot be incorporated into cocoa butter
Correct answer: The density factor of the API must be used to adjust base quantity
The density (displacement) factor of the active ingredient relative to cocoa butter must be used to calculate how much base to subtract so each suppository contains the correct drug dose.
Question 7: A patient's warfarin dose is written as 'warfarin sodium 5 mg po od.' The dispenser notices the tablet on hand is 2.5 mg. What is the correct course of action?
- Dispense one 2.5 mg tablet and note the discrepancy
- Dispense two 2.5 mg tablets and counsel the patient (Correct answer)
- Call the prescriber to clarify before dispensing
- Dispense 5 mg tablets from a different manufacturer
Correct answer: Dispense two 2.5 mg tablets and counsel the patient
Two 2.5 mg tablets equal the prescribed 5 mg dose; the pharmacist should dispense two tablets and counsel the patient on proper administration.
PEBC PEBC Drug Dispensing and Compounding 4
A prescription calls for a 2% lidocaine solution.
You have 4% lidocaine stock solution.
How much 4% solution and sterile water are needed to prepare 200 mL of the 2% solution?