Common Registration Assessment, Part 1

Cabergoline twice-weekly doses and weekly step-up schedules 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.

Assorted capsules poured into an open palm
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 Dostinex 0.5 mg tablets states that for hyperprolactinaemic disorders the recommended starting dose is 0.5 mg per week, given in one or two doses a week, for example on Monday and Thursday.

The same information states that the weekly dose is increased gradually, preferably by adding 0.5 mg per week at monthly intervals, and that the usual therapeutic dosage is 1 mg per week, within a range of 0.25 mg to 2 mg per week.

For suppression of established lactation, the product information states 0.25 mg every 12 hours for 2 days, a 1 mg total course; for inhibition of lactation, a single 1 mg dose on the first day after delivery.

Each question fixes the values needed for its arithmetic. Keep weekly doses separate from per-dose figures and note that the tablets are scored. All prescriptions and patients here are fictional; these are revision materials, not for patient care.

The method

  1. Convert the stated weekly dose into doses on the stated days of the week.
  2. Halve the 0.5 mg tablet for each 0.25 mg dose.
  3. Multiply the weekly tablet count by the stated number of weeks for a supply.
  4. Keep the lactation regimens, which are one-off or 2-day courses, separate from the weekly hyperprolactinaemia schedule.
  5. Write microgram-level precision in milligrams: 0.25 mg, 0.5 mg, 1 mg.

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 cabergoline as 0.25 mg on Monday and 0.25 mg on Thursday. Using scored 0.5 mg tablets, how many tablets does one week of this starting schedule use?

Show the answer

Answer: 1 tablet per week

Working: 0.25 mg is half of one 0.5 mg tablet; half a tablet on Monday plus half a tablet on Thursday = 1 tablet a week, which is 0.5 mg a week as the product information states.

Question 2

A fictional patient is stabilised on the usual therapeutic dosage of cabergoline 1 mg per week, taken as 0.5 mg on Monday and 0.5 mg on Thursday. How many 0.5 mg tablets does a 4-week supply need?

Show the answer

Answer: 8 tablets

Working: 1 mg a week = 2 x 0.5 mg tablets a week; 2 tablets x 4 weeks = 8 tablets.

Question 3

A fictional patient takes cabergoline 0.25 mg every 12 hours for 2 days to suppress established lactation. Using scored 0.5 mg tablets, how many tablets is the whole course?

Show the answer

Answer: 2 tablets

Working: Every 12 hours for 2 days = 4 doses; 4 x 0.25 mg = 1 mg; 1 mg / 0.5 mg = 2 tablets.

eMC SmPC: Dostinex Tablets

https://www.medicines.org.uk/emc/product/1691/smpc

Where marks are lost

  • Reading the twice-weekly schedule as twice daily and inflating the weekly total.
  • Forgetting that 0.25 mg is half of one 0.5 mg scored tablet.
  • Mixing the single 1 mg lactation-inhibition dose with the 2-day 1 mg suppression course.

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 cabergoline dose?

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

How should I check the answer?

Split the weekly dose across the stated days, halve the 0.5 mg tablet for 0.25 mg doses, then multiply the weekly tablet count by the stated weeks.

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.