Common Registration Assessment, Part 1

Buprenorphine patch release rates and change intervals for the GPhC assessment

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

Published 30 October 2026. Independent revision material, not GPhC questions, not for patient care.

Adult holding their lower back in pain outdoors
Photo from Pexels, used under the Pexels licence. It is a stock image and does not show the exercise.

The NHS lists buprenorphine patches for pain that release 5 micrograms, 10 micrograms, 15 micrograms or 20 micrograms every hour, each worn for 7 days, and patches that release 35 micrograms, 52.5 micrograms or 70 micrograms every hour, each worn for 3 or 4 days.

The NHS lists buprenorphine tablets for pain containing 200 micrograms or 400 micrograms.

The NHS advises that doses vary from person to person and that a patch is usually started only after pain is controlled on another opioid.

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 patch strength and its wear interval (7 days, or 3 or 4 days) from the question.
  2. Convert the wear interval into hours by multiplying days by 24 before applying the hourly rate.
  3. Calculate one patch first, then scale to the stated period.
  4. Count patches by dividing total days by the wear interval; round up only if the question says so.
  5. Keep the two patch families apart: do not mix a 7-day interval with a 3 or 4-day strength.

Three practice questions

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

Question 1

A fictional patient wears a 10 micrograms per hour patch for 7 days. How many micrograms are released over the 7 days?

Show the answer

Answer: 1,680 micrograms

Working: 7 days x 24 hours = 168 hours; 10 micrograms x 168 hours = 1,680 micrograms.

Question 2

A fictional plan uses a 7-day patch, changed on the same day each week. How many patches are needed for 28 days?

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Answer: 4 patches

Working: 28 days / 7 days per patch = 4 patches.

Question 3

A fictional prescription uses a 70 micrograms per hour patch changed every 4 days. How many patches are needed for 28 days, and how many micrograms does one patch release?

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Answer: 7 patches; 6,720 micrograms per patch

Working: 28 days / 4 days per patch = 7 patches. One patch: 4 days x 24 hours = 96 hours; 70 micrograms x 96 hours = 6,720 micrograms.

NHS: How and when to use buprenorphine

https://www.nhs.uk/medicines/buprenorphine-for-pain/how-and-when-to-use-buprenorphine/

Where marks are lost

  • Mixing the 7-day patch interval with the 3 or 4-day patch strengths.
  • Applying the hourly rate to days without converting to hours.
  • 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 release-rate total justify swapping patch strengths?

No. Follow the strength and interval in the exercise. Real opioid switches need clinical checks and conversion guidance.

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.