Common Registration Assessment, Part 1

Colestyramine 4g sachets 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 7 November 2026. Independent revision material, not GPhC questions, not for patient care.

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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 colestyramine 4 g sachets states that, to reduce cholesterol, the dose is introduced over three to four weeks, and is then 3 to 6 sachets per day given as a single daily dose or in divided doses up to four times daily, which may be increased to 9 sachets per day if necessary.

The printed step-up schedule is: for a final dose of 3 sachets per day, 1 sachet daily in week 1, 2 in week 2 and 3 in week 3; for a final dose of 4 per day, 1, 2, 3 then 4 across weeks 1 to 4; and for a final dose of 6 per day, 1, 2, 3 then 6 across the four weeks.

The same information states that to relieve pruritus, one or two sachets daily are usually sufficient.

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

The method

  1. Identify the stated sachets per day for each week of the schedule.
  2. Multiply the daily sachet count by 7 days for each weekly total.
  3. Add the weekly totals for a supply quantity across the schedule.
  4. Keep sachets, grams and days separate; convert only when the question asks.

Three practice questions

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

Question 1

A fictional patient follows the printed step-up schedule to a final dose of 4 sachets per day: 1 sachet daily in week 1, 2 in week 2, 3 in week 3 and 4 in week 4. How many sachets are needed for the four weeks?

Show the answer

Answer: 70 sachets

Working: (1 + 2 + 3 + 4) sachets x 7 days = 10 x 7 = 70 sachets.

Question 2

A fictional patient takes the stated maximum of 9 sachets per day. How many sachets is this per week?

Show the answer

Answer: 63 sachets

Working: 9 sachets x 7 days = 63 sachets per week.

Question 3

A fictional patient takes colestyramine 2 sachets daily to relieve pruritus. How many sachets are needed for 30 days?

Show the answer

Answer: 60 sachets

Working: 2 sachets x 30 days = 60 sachets.

eMC SmPC: Questran Light 4g/sachet Powder for Oral Suspension

https://www.medicines.org.uk/emc/product/10588/smpc

Where marks are lost

  • Multiplying the final daily sachet count by 28 days instead of summing each week's own daily count.
  • Reading the schedule row for a final dose of 6 per day as 1, 2, 3, 4 when the printed fourth week is 6.
  • Confusing the 4 g sachet content with the number of sachets when the question asks only for sachet counts.

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 colestyramine dose?

No. Follow the stated schedule in the exercise. Real dosing is introduced gradually over three to four weeks and adjusted to response and acceptability.

How should I check the answer?

Check the requested unit, then sum the schedule week by week before multiplying by seven.

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.