Common Registration Assessment, Part 1
Prochlorperazine tablet and buccal dose counts for the GPhC assessment
Three original practice questions, with the working shown. Read the stated prescription or plan before calculating.
Published 24 October 2026. Independent revision material, not GPhC questions, not for patient care.
For nausea and vomiting the BNF oral treatment is 20 mg at once, then 10 mg two hours later; prevention is 5 to 10 mg two or three times a day.
Buccal tablets of 3 mg dissolve between the upper lip and gum; the BNF buccal dose is 3 to 6 mg twice daily.
Each question fixes the values needed for its arithmetic. Write the unit beside every step and distinguish a single dose from a daily total or course supply. All prescriptions and patients here are fictional; these are revision materials, not for patient care.
The method
- Identify the exact formulation, strength, dose and frequency supplied in the question.
- Convert an X mg/5 mL strength to mg/mL if a dose-to-volume conversion is needed.
- Calculate one dose first; for tablets or capsules divide prescribed mg by mg per unit.
- Scale to the stated frequency and duration only when a total quantity is requested.
- Apply whole-container or complete-day rounding only if the question specifies it.
Three practice questions
Work each one on paper first, then open the answer. All patients and prescriptions are fictional.
Question 1
A fictional acute treatment is prochlorperazine 20 mg at once, then 10 mg two hours later. What is the total amount?
Show the answer
Answer: 30 mg
Working: 20 + 10 = 30 mg in total.
Question 2
A fictional prevention plan is prochlorperazine 10 mg three times a day, using 5 mg tablets. How many tablets is one day?
Show the answer
Answer: 6 tablets
Working: 10 ÷ 5 = 2 tablets per dose; 2 × 3 = 6 tablets per day.
Question 3
A fictional plan is prochlorperazine 6 mg twice daily, using 3 mg buccal tablets. How many tablets is one day?
Show the answer
Answer: 4 tablets
Working: 6 ÷ 3 = 2 tablets per dose; 2 × 2 = 4 tablets per day.
NHS: How and when to take prochlorperazine
https://www.nhs.uk/medicines/prochlorperazine/how-and-when-to-take-prochlorperazine/
Where marks are lost
- Using a remembered strength or schedule instead of the stated product.
- Reporting a daily total when the question asks for one dose or the course.
- Treating arithmetic as evidence that a real prescription is clinically suitable.
Frequently asked questions
Are these official assessment questions?
No. They are original revision exercises, not official GPhC questions and not for patient care.
Can a quantity calculation justify a formulation switch?
No. Follow the formulation and prescription in the exercise. Real switches and dose changes need clinical checks.
How should I check the answer?
Check the requested unit, then work backwards from the quantity to the stated dose and duration.
Sources
The questions above are original and use fictional patients and prescriptions. PreRegExamPrep is not affiliated with or endorsed by the General Pharmaceutical Council.
Practise until the method is automatic
Try 15 free questions with worked answers. No sign-up required.
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See also the formula sheet, the eight sample questions and the approved calculator page.