Common Registration Assessment, Part 1

Mebendazole 100mg tablets, single doses and two week repeats 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.

A mother and child washing their hands together at a sink
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 mebendazole 100 mg tablets states that adults and children over 2 years take one tablet, that all members of the family should be treated at the same time, and that a second tablet is recommended after two weeks if re-infection is suspected.

The same information states that the tablets may be chewed or swallowed whole, and can be crushed before being given to a young child, with supervision.

The manufacturer's UK product information for mebendazole suspension states that the dose for adults and children over 2 years is one 5 ml dose, and that the suspension should be shaken before use.

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. Count one dose for each person treated at the stated strength.
  2. Add a second dose for each person when a two week repeat is stated.
  3. For the suspension, multiply the 5 ml dose by the number of doses for a total volume.
  4. Keep tablets, millilitres and milligrams 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 family of 4 all take one mebendazole 100 mg tablet at the same time, then repeat the dose after two weeks. How many tablets are needed in total?

Show the answer

Answer: 8 tablets

Working: 4 people x 1 tablet = 4 tablets per round. 2 rounds x 4 tablets = 8 tablets.

Question 2

A fictional family of 3 each take one 5 ml dose of mebendazole suspension. How many millilitres is this in total?

Show the answer

Answer: 15 ml

Working: 3 people x 5 ml = 15 ml in total.

Question 3

A fictional patient takes one mebendazole 100 mg tablet, then a second 100 mg tablet two weeks later. How many milligrams of mebendazole is this in total?

Show the answer

Answer: 200 mg

Working: 100 mg + 100 mg = 200 mg in total.

eMC SmPC: Ovex (mebendazole 100 mg tablets)

https://www.medicines.org.uk/emc/product/1317/smpc

Where marks are lost

  • Dosing only the symptomatic person when the stated advice is to treat the whole family at the same time.
  • Forgetting the second dose after two weeks when the question includes suspected re-infection.
  • Mixing the 100 mg tablet and the 5 ml suspension measures in the same calculation.

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 mebendazole course?

No. Follow the stated plan in the exercise. Real treatment treats the household together and repeats the dose after two weeks if re-infection is suspected.

How should I check the answer?

Check the requested unit, keeping tablets and suspension millilitres separate before totalling people or rounds.

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.