Common Registration Assessment, Part 1

Chloramphenicol eye drops and ointment 5-day courses for the GPhC assessment

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

Published 31 October 2026. Independent revision material, not GPhC questions, not for patient care.

Woman applying eye drops to an elderly man indoors
Photo from Pexels, used under the Pexels licence. It is a stock image and does not show the exercise.

The BNF lists chloramphenicol 0.5% eye drops and 1% eye ointment for acute bacterial conjunctivitis, and the NHS advises applying the 1% ointment 3 to 4 times a day, leaving 4 to 6 hours between each dose, using about 1 centimetre of ointment each time.

The NHS advises using the eye drops or ointment for 5 days even if the eye seems better, and not using them for more than 5 days unless a prescriber says so.

The NHS advises discarding chloramphenicol within 4 weeks of opening, storing the eye drops in a fridge, and that more severe infections may use ointment at bedtime with drops during the day.

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 form, the applications per day and the spacing between them.
  2. Multiply the applications per day by the 5-day course for the course count.
  3. Multiply the centimetres per application by the application count for ointment totals.
  4. Count 28 days from the opening date for the discard date.
  5. Keep drops, applications and centimetres separate; convert only if 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 applies 1 cm of chloramphenicol 1% eye ointment 3 times a day for 5 days. How many centimetres of ointment is the full course?

Show the answer

Answer: 15 cm

Working: 1 cm x 3 applications = 3 cm per day; 3 cm x 5 days = 15 cm.

Question 2

A fictional patient uses chloramphenicol eye drops 4 times a day for 5 days. How many applications is the full course?

Show the answer

Answer: 20 applications

Working: 4 applications x 5 days = 20 applications.

Question 3

A fictional bottle of chloramphenicol eye drops is opened on 3 March and must be discarded 28 days after opening. On what date should it be discarded?

Show the answer

Answer: 31 March

Working: 3 March + 28 days = 31 March.

NHS: How and when to use chloramphenicol

https://www.nhs.uk/medicines/chloramphenicol/how-and-when-to-use-chloramphenicol/

Where marks are lost

  • Stopping the course early because symptoms have settled.
  • Continuing past the stated 5-day course without a prescriber.
  • Ignoring the 4-week discard date after opening.

Frequently asked questions

Are these official assessment questions?

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

Why count a discard date in a calculations exercise?

Counting days from an opening date is a date calculation; real expiry advice comes with the medicine.

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.

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More calculation topics

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