Common Registration Assessment, Part 1
Codeine tablet strengths and daily maximums for the GPhC assessment
Three original practice questions, with the working shown. Read the stated prescription or plan before calculating.
Published 20 October 2026. Independent revision material, not GPhC questions, not for patient care.
The NHS lists codeine tablets in three strengths: 15 mg, 30 mg and 60 mg.
The NHS gives the usual adult dose as one or two 30 mg tablets every 4 hours, up to a maximum of 8 tablets, that is 240 mg, in 24 hours.
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 any stated 24-hour maximum.
- Calculate one dose first; divide prescribed mg by mg per tablet.
- Apply the maximum: cap the count at the stated daily limit.
- Convert a tablet cap to mg by multiplying by the strength.
- Check the requested unit, tablets or mg, 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 adult takes two 30 mg codeine tablets per dose. The stated maximum is 8 tablets in 24 hours. What is the maximum amount of codeine in 24 hours, in mg?
Show the answer
Answer: 240 mg
Working: 8 × 30 = 240 mg. The per-dose amount does not change the stated daily cap.
Question 2
A fictional prescription allows one or two 30 mg codeine tablets every 4 hours, up to a maximum of 8 tablets in 24 hours. A fictional adult takes two tablets at each of three doses in one day. How many tablets remain within that day's maximum?
Show the answer
Answer: 2 tablets
Working: 3 doses × 2 tablets = 6 tablets taken. 8 - 6 = 2 tablets remain within the maximum.
Question 3
A fictional adult is prescribed codeine 60 mg per dose using 30 mg tablets, with a stated maximum of 240 mg in 24 hours. How many 60 mg doses fit within that maximum?
Show the answer
Answer: 4 doses
Working: 60 ÷ 30 = 2 tablets per dose. 240 ÷ 60 = 4 doses within the 24-hour maximum.
Exam approach
Maximum-dose questions are really two sums: work the dose, then test it against the cap. Show both before answering.
Where marks are lost
- Ignoring the stated 24-hour maximum when scaling up doses.
- Mixing up 15 mg, 30 mg and 60 mg tablets when the strength is stated in the question.
- Reporting tablets when the question asks for mg, or the other way round.
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 maximum?
The exercise supplies it. 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 maximum.
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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