Common Registration Assessment, Part 1

Dydrogesterone 10 mg tablets and cycle-day doses for the GPhC assessment

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

Published 12 November 2026. Independent revision material, not GPhC questions, not for patient care.

Woman holding her lower abdomen in discomfort
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 Nalvee 10 mg film-coated tablets states that for dysmenorrhoea the dose is 10 mg twice a day from day 5 to day 25 of the cycle.

The same information states that for irregular menstrual cycles the dose is 10 mg twice a day from day 11 to day 25, and for pre-menstrual syndrome 10 mg twice a day from day 12 to day 26.

For continuous sequential hormone replacement therapy, the product information states that 10 mg of dydrogesterone is taken daily during the last 14 days of each 28-day cycle.

Each question fixes the values needed for its arithmetic. Count cycle days inclusively and distinguish a once-daily from a twice-daily schedule. All prescriptions and patients here are fictional; these are revision materials, not for patient care.

The method

  1. Identify the stated start and end cycle days for the indication.
  2. Count the treatment days inclusively: end day minus start day plus one.
  3. Multiply the treatment days by the stated tablets per day.
  4. Keep once-daily HRT dosing separate from the twice-daily gynaecological schedules.
  5. Keep days, tablets and milligrams in separate lines of working.

Three practice questions

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

Question 1

A fictional patient takes dydrogesterone 10 mg twice a day from day 5 to day 25 of each cycle for dysmenorrhoea. Using 10 mg tablets, how many tablets is one cycle?

Show the answer

Answer: 42 tablets

Working: Day 5 to day 25 inclusive is 25 - 5 + 1 = 21 days; 21 days x 2 tablets = 42 tablets.

Question 2

A fictional patient takes dydrogesterone 10 mg twice a day from day 11 to day 25 for irregular cycles. How many 10 mg tablets does one cycle need?

Show the answer

Answer: 30 tablets

Working: Day 11 to day 25 inclusive is 25 - 11 + 1 = 15 days; 15 days x 2 tablets = 30 tablets.

Question 3

A fictional patient on continuous sequential HRT takes 10 mg of dydrogesterone daily for the last 14 days of each 28-day cycle. How many 10 mg tablets is one cycle, and what is the daily dose in milligrams?

Show the answer

Answer: 14 tablets; 10 mg daily

Working: 14 days x 1 tablet = 14 tablets; the daily dose is 1 tablet x 10 mg = 10 mg.

eMC SmPC: Nalvee 10 mg film-coated tablets

https://www.medicines.org.uk/emc/product/101122/smpc

Where marks are lost

  • Counting cycle days exclusively and dropping one day from the total.
  • Applying the twice-daily schedule to the once-daily HRT regimen.
  • Confusing the 10 mg dose with the tablet count when each tablet is 10 mg.

Frequently asked questions

Are these official assessment questions?

No. They are original revision exercises, not official GPhC questions and not for patient care.

Does this calculation decide a real dydrogesterone course?

No. Follow the stated prescription in the exercise. Real treatment follows the prescriber and the product information for the named tablet.

How should I check the answer?

Fix the start and end cycle days, count the days inclusively, then multiply by the stated tablets per day for that indication.

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.