Common Registration Assessment, Part 1

Methylphenidate immediate-release tablets and divided doses for the GPhC assessment

Three original practice questions, with the working shown. Read the stated prescription or plan before calculating.

Published 3 November 2026. Independent revision material, not GPhC questions, not for patient care.

A schoolboy sitting at a desk doing his homework
Photo from Pexels, used under the Pexels licence. It is a stock image and does not show the exercise.

The manufacturer's UK product information for Medikinet immediate-release tablets for children aged 6 years and over recommends a starting daily dose of 5 mg once daily or twice daily, for example at breakfast and lunch.

The same information recommends increasing, if necessary, by weekly increments of 5 to 10 mg in the daily dose, and states that doses above 60 mg daily are not recommended.

It also states the total daily dose should be administered in divided doses, usually 2 or 3. Medikinet immediate-release tablets are available in 5 mg, 10 mg and 20 mg strengths.

Each question fixes the values needed for its arithmetic. Write the unit beside every step and distinguish a single dose from a daily total or a weekly supply. All prescriptions and patients here are fictional; these are revision materials, not for patient care.

The method

  1. Identify the exact strength and frequency stated in the question.
  2. Add the stated doses to get the daily total before scaling up.
  3. Divide the daily total by the tablet strength to count tablets per day.
  4. Multiply each week's daily tablet count by 7 and add the weeks together.

Three practice questions

Work each one on paper first, then open the answer. All patients and prescriptions are fictional.

Question 1

A fictional patient starts methylphenidate 5 mg twice a day. How many milligrams is the daily total?

Show the answer

Answer: 10 mg

Working: 5 mg x 2 doses = 10 mg a day.

Question 2

A fictional prescription reads methylphenidate 20 mg a day in 2 divided doses using 10 mg tablets. How many tablets per dose?

Show the answer

Answer: 1 tablet

Working: 20 mg / 2 doses = 10 mg per dose; 10 mg / 10 mg = 1 tablet per dose.

Question 3

A fictional titration plan uses 10 mg a day in week 1, 15 mg a day in week 2 and 20 mg a day in week 3, all using 5 mg tablets. How many tablets does the 3 week plan need?

Show the answer

Answer: 63 tablets

Working: Week 1: 10 mg / 5 mg = 2 tablets a day, 2 x 7 = 14; week 2: 3 tablets a day, 3 x 7 = 21; week 3: 4 tablets a day, 4 x 7 = 28; 14 + 21 + 28 = 63 tablets.

eMC SmPC: Medikinet 10 mg tablets

https://www.medicines.org.uk/emc/product/8235/smpc

Where marks are lost

  • Forgetting the second daily dose when moving from a once daily start to a twice daily schedule.
  • Mixing the weekly increments with the daily total and double counting the increase.
  • 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.

Can a dose-total calculation justify changing a real dose?

No. Follow the steps in the exercise. Real titration is supervised by a specialist with regular monitoring.

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.

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More calculation topics

See also the formula sheet, the eight sample questions and the approved calculator page.