Common Registration Assessment, Part 1
Allopurinol tablet 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 18 October 2026. Independent revision material, not GPhC questions, not for patient care.
The NHS lists allopurinol as 100 mg and 300 mg tablets taken every day.
Treatment usually starts on a low dose, and the NHS notes the dose can be increased up to 900 mg daily in severe cases. Higher doses may be split and taken twice 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 daily 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 tablet.
- Scale to the daily total and duration only when requested.
- Split the daily total across the stated frequency for divided doses.
- Check any total against a stated maximum 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 allopurinol 300 mg once a day using 100 mg tablets. How many tablets is one day, and how many for 28 days?
Show the answer
Answer: 3 tablets a day, 84 tablets for 28 days
Working: 300 ÷ 100 = 3 tablets a day. 3 × 28 = 84 tablets.
Question 2
A fictional prescription specifies allopurinol 600 mg a day split into two doses, using 300 mg tablets. How many tablets is each dose, and how many each day?
Show the answer
Answer: 1 tablet per dose, 2 tablets a day
Working: 600 ÷ 2 = 300 mg per dose. 300 ÷ 300 = 1 tablet per dose. 1 × 2 = 2 tablets a day.
Question 3
A fictional plan specifies the severe-case maximum of allopurinol 900 mg a day using 300 mg tablets. How many tablets is one day?
Show the answer
Answer: 3 tablets
Working: 900 ÷ 300 = 3 tablets a day.
Exam approach
For divided doses, split the daily mg first, then divide by the tablet strength. Doing the two divisions in the wrong order is the classic slip.
Where marks are lost
- Forgetting to split the daily total before working out a divided dose.
- Mixing the 100 mg and 300 mg strengths within one line of working.
- Reporting tablets per dose when the question asks for the daily count.
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
- NHS: How and when to take allopurinol
- 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
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.