Common Registration Assessment, Part 1
Lansoprazole capsule strengths and course lengths for the GPhC assessment
Three original practice questions, with the working shown. Read the stated prescription or plan before calculating.
Published 17 October 2026. Independent revision material, not GPhC questions, not for patient care.
The NHS states each lansoprazole capsule or dispersible tablet contains 15 mg or 30 mg. The usual dose for indigestion, acid reflux or stomach ulcers is 15 mg to 30 mg a day.
Higher doses exist for rarer conditions: the NHS describes a starting dose of 60 mg a day for Zollinger-Ellison syndrome, increasing up to 180 mg a day, with doses over 120 mg split into 2 doses.
Each question fixes the values needed for its arithmetic. Write the unit beside every step and keep a course total separate from a daily count. All prescriptions and patients here are fictional; these are revision materials, not for patient care.
The method
- Identify the exact strength, dose, frequency and course length supplied in the question.
- Calculate one day first, dividing prescribed mg by mg per capsule.
- Split into 2 doses only when the stated daily dose requires it.
- Scale to the stated course length for a total supply.
- Check the strengths used match the ones the question supplies.
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 lansoprazole 30 mg once a day for 4 weeks using 30 mg capsules. How many capsules is the course?
Show the answer
Answer: 28 capsules
Working: One 30 mg capsule a day for 4 × 7 = 28 days: 1 × 28 = 28 capsules.
Question 2
A fictional prescription specifies lansoprazole 45 mg once a day using 15 mg and 30 mg capsules. What is the fewest number of capsules for one dose?
Show the answer
Answer: 2 capsules
Working: One 30 mg plus one 15 mg capsule: 30 + 15 = 45 mg.
Question 3
A fictional prescription specifies lansoprazole 150 mg a day for Zollinger-Ellison syndrome, split into 2 doses, using 30 mg capsules. How many capsules is that per day?
Show the answer
Answer: 5 capsules
Working: 150 ÷ 30 = 5 capsules across the day. The daily dose is above 120 mg, so it is split into 2 doses, for example 90 mg (3 capsules) and 60 mg (2 capsules).
Exam approach
Daily count first, course length second. Above 120 mg a day the NHS schedule splits into 2 doses, which changes the per-dose count, not the daily total.
Where marks are lost
- Treating the 15 mg and 30 mg strengths as interchangeable per capsule.
- Forgetting the split when the stated daily dose is above the stated threshold.
- 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.
Does the course length change the daily count?
No. Work the daily count first, then multiply by the stated number of days.
How should I check the answer?
Check the requested unit, then work backwards from the quantity to the stated dose and duration.
Sources
- NHS: How and when to take lansoprazole
- GPhC, Common Registration Assessment specification and permitted items for 2026
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
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See also the formula sheet, the eight sample questions and the approved calculator page.