Common Registration Assessment, Part 1
Co-amoxiclav tablet strengths and three daily doses for the GPhC assessment
Three original practice questions, with the working shown. Read the stated prescription or plan before calculating.
Published 23 October 2026. Independent revision material, not GPhC questions, not for patient care.
The BNF lists co-amoxiclav tablets as 250/125 mg and 500/125 mg strengths, written as 375 mg and 625 mg tablets respectively.
The BNF gives the usual adult and child over 12 dose for infection as 375 mg three times a day, or 625 mg three times a day for more severe infection.
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.
- Remember 375 mg means one 250/125 mg tablet and 625 mg means one 500/125 mg tablet.
- Apply the three-times-a-day frequency: three doses each day.
- Scale to the stated course length only when a supply is requested.
- Check the tablet 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 co-amoxiclav 375 mg three times a day using 250/125 mg tablets for 7 days. How many tablets is the course?
Show the answer
Answer: 21 tablets
Working: 375 mg is one 250/125 mg tablet per dose. Three times a day is 3 tablets a day. 3 × 7 = 21 tablets.
Question 2
A fictional prescription specifies co-amoxiclav 625 mg three times a day using 500/125 mg tablets for 5 days. How many tablets is the course?
Show the answer
Answer: 15 tablets
Working: 625 mg is one 500/125 mg tablet per dose. Three times a day is 3 tablets a day. 3 × 5 = 15 tablets.
Question 3
A fictional prescription specifies co-amoxiclav 375 mg three times a day using 250/125 mg tablets for 10 days. How many tablets is the course?
Show the answer
Answer: 30 tablets
Working: 375 mg is one 250/125 mg tablet per dose. Three times a day is 3 tablets a day. 3 × 10 = 30 tablets.
Exam approach
Frequency conversions cause most errors here. Turn three times a day into three doses before multiplying by the course length.
Where marks are lost
- Counting one dose a day when the question says three times a day.
- Mixing up the 375 mg and 625 mg labels with the 250/125 mg and 500/125 mg strengths.
- Reporting a daily total when the question asks for the whole course.
Frequently asked questions
Are these official assessment questions?
No. They are original revision exercises, not official GPhC questions and not for patient care.
Why two numbers in the strength?
Co-amoxiclav combines amoxicillin with clavulanic acid, so the strength names both parts. The exercise supplies the mapping to the tablet label.
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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