Common Registration Assessment, Part 1
Mirtazapine tablets, liquid and bedtime 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 BNF lists mirtazapine tablets in three strengths: 15 mg, 30 mg and 45 mg, and a liquid containing 15 mg in each 1 mL. The NHS notes the tablets also come as orodispersible tablets that melt in the mouth.
The NHS gives the usual starting dose as 15 mg to 30 mg a day, increased if needed up to 45 mg a day, usually taken once a day before bed.
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 formulation, strength, dose and frequency supplied in the question.
- Calculate one dose first; for tablets divide prescribed mg by mg per tablet.
- Convert the 15 mg per mL liquid to a volume when a liquid dose is requested.
- Scale to the stated duration only when a supply is requested.
- Check any total against the stated maximum of 45 mg a day.
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 mirtazapine 30 mg at bedtime using 15 mg tablets. How many tablets is one dose?
Show the answer
Answer: 2 tablets
Working: 30 ÷ 15 = 2 tablets at bedtime.
Question 2
A fictional prescription specifies mirtazapine 45 mg once a day using 45 mg tablets. How many tablets are needed for 28 days?
Show the answer
Answer: 28 tablets
Working: 45 ÷ 45 = 1 tablet a day. 1 × 28 = 28 tablets.
Question 3
A fictional prescription specifies mirtazapine 30 mg at bedtime using the liquid that contains 15 mg in 1 mL. What volume is one dose?
Show the answer
Answer: 2 mL
Working: 15 mg in 1 mL. 30 ÷ 15 = 2 mL.
Exam approach
Liquid concentrations are written per stated volume: 15 mg in 1 mL is not the same as 15 mg in 5 mL. Divide the prescribed mg by the mg per mL before reporting a volume.
Where marks are lost
- Treating 15 mg per mL as 15 mg per 5 mL; check the stated concentration.
- Splitting the bedtime dose across the day without being asked.
- Reporting a supply when the question asks for a single dose.
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.