Common Registration Assessment, Part 1

Hyoscine hydrobromide 300 microgram tablets and daily maximums for the GPhC assessment

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

Published 29 October 2026. Independent revision material, not GPhC questions, not for patient care.

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The NHS lists hyoscine hydrobromide 300 microgram tablets for adults as 1 tablet every 6 hours as needed, with no more than 3 doses in 24 hours, taken at least 30 minutes before travel.

The NHS lists 150 microgram tablets for children: those aged 11 years or older take 1 or 2 tablets every 6 hours as needed, again with no more than 3 doses in 24 hours.

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 course supply. All prescriptions and patients here are fictional; these are revision materials, not for patient care.

The method

  1. Identify the exact strength, dose and maximum supplied in the question.
  2. Multiply tablets by the stated microgram strength when an answer is requested in micrograms.
  3. Convert micrograms to mg by dividing by 1,000 only when the answer is requested in mg.
  4. Check any schedule against the stated 3-dose 24-hour maximum before reporting a total.
  5. Apply whole-tablet rounding only if the question specifies it.

Three practice questions

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

Question 1

A fictional adult takes the stated maximum of 3 doses of hyoscine hydrobromide 300 microgram tablets in 24 hours, 1 tablet per dose. How many micrograms is that per day?

Show the answer

Answer: 900 micrograms

Working: 3 doses × 300 micrograms = 900 micrograms per day.

Question 2

A fictional adult takes 1 hyoscine hydrobromide 300 microgram tablet every 6 hours, within the stated maximum of 3 doses in 24 hours, starting at 06:00. At what times are the 3 doses taken?

Show the answer

Answer: 06:00, 12:00 and 18:00

Working: 6-hour gaps from 06:00 give 12:00 and 18:00; a 4th dose at 24:00 would exceed the stated maximum of 3 doses in 24 hours.

Question 3

A fictional child aged 12 takes 2 hyoscine hydrobromide 150 microgram tablets per dose for the stated maximum of 3 doses in 24 hours. How many tablets and how many micrograms is that per day?

Show the answer

Answer: 6 tablets (900 micrograms)

Working: 2 tablets × 3 doses = 6 tablets per day; 6 × 150 micrograms = 900 micrograms per day.

NHS: Hyoscine hydrobromide

https://www.nhs.uk/medicines/hyoscine-hydrobromide/

Where marks are lost

  • Using a remembered strength or schedule instead of the stated product.
  • Reporting a daily total when the question asks for one dose or the course.
  • 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 quantity calculation justify a formulation switch?

No. Follow the formulation and prescription in the exercise. Real switches and dose changes need clinical checks.

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

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More calculation topics

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