Common Registration Assessment, Part 1
Omeprazole capsule strengths and daily doses for the GPhC assessment
Three original practice questions, with the working shown. Read the stated prescription or plan before calculating.
Published 19 October 2026. Independent revision material, not GPhC questions, not for patient care.
The BNF lists omeprazole capsules in three strengths: 10 mg, 20 mg and 40 mg.
The BNF gives the usual adult dose for reflux as 20 mg once a day, and some conditions use 40 mg once a day.
Each question fixes the values needed for its arithmetic. Write the unit beside every step and keep a single dose separate from a supply total. All prescriptions and patients here are fictional; these are revision materials, not for patient care.
The method
- Identify the exact strength, dose and frequency supplied in the question.
- Calculate one dose first; divide prescribed mg by mg per capsule.
- Scale to the stated duration only when a supply is requested.
- Keep the once-daily frequency in view: one dose each day.
- Check the capsule count is a whole number before reporting it.
Three practice questions
Work each one on paper first, then open the answer. All patients and prescriptions are fictional.
Question 1
A fictional prescription specifies omeprazole 20 mg once a day using 10 mg capsules. How many capsules is one day, and how many for 28 days?
Show the answer
Answer: 2 capsules a day, 56 capsules for 28 days
Working: 20 ÷ 10 = 2 capsules a day. 2 × 28 = 56 capsules.
Question 2
A fictional prescription specifies omeprazole 40 mg once a day using 20 mg capsules. How many capsules are needed for 30 days?
Show the answer
Answer: 60 capsules
Working: 40 ÷ 20 = 2 capsules a day. 2 × 30 = 60 capsules.
Question 3
A fictional prescription specifies omeprazole 40 mg once a day using 40 mg capsules for 6 weeks. How many capsules is the course?
Show the answer
Answer: 42 capsules
Working: 40 ÷ 40 = 1 capsule a day. 6 weeks is 6 × 7 = 42 days, so 1 × 42 = 42 capsules.
Exam approach
Capsule arithmetic is one division per dose. Get the single dose right first, then multiply by the number of days.
Where marks are lost
- Mixing up 10 mg, 20 mg and 40 mg capsules when the strength is stated in the question.
- Reporting a daily total when the question asks for a supply, or the other way round.
- Forgetting to convert weeks to days before multiplying.
Frequently asked questions
Are these official assessment questions?
No. They are original revision exercises, not official GPhC questions and not for patient care.
Do I need to memorise the strengths?
The exercise supplies them. In the assessment, read any given product information exactly as written.
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.