Common Registration Assessment, Part 1

Atomoxetine capsule doses and mg per kg titration for the GPhC assessment

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

Published 3 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 atomoxetine hard capsules states that for children and adolescents up to 70 kg, treatment should be initiated at a total daily dose of approximately 0.5 mg/kg and maintained for a minimum of 7 days before any increase.

The same information gives a recommended maintenance dose of approximately 1.2 mg/kg/day, and states that no additional benefit has been demonstrated for doses higher than 1.2 mg/kg/day.

For children and adolescents over 70 kg, it states treatment should be initiated at 40 mg daily, with a recommended maintenance dose of 80 mg. For adults, it gives a 40 mg daily start and a maintenance range of 80 to 100 mg daily. In both groups, the initial dose is maintained for at least 7 days before an increase according to response and tolerability, and the maximum recommended total daily dose is 100 mg.

Each question fixes the values needed for its arithmetic. Write the unit beside every step and distinguish the initial dose from the maintenance dose. All prescriptions and patients here are fictional; these are revision materials, not for patient care.

The method

  1. Multiply the stated body weight by the stated mg per kg figure for weight-based doses.
  2. Hold the initial dose for the stated minimum period before any increase.
  3. Multiply the daily dose by the number of days at each step, then add the steps.
  4. Keep the 40 mg start, 80 mg maintenance and 100 mg maximum straight for patients over 70 kg.

Three practice questions

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

Question 1

A fictional child weighs 40 kg and starts atomoxetine at 0.5 mg/kg a day. How many milligrams is the daily dose?

Show the answer

Answer: 20 mg

Working: 40 kg x 0.5 mg/kg = 20 mg a day.

Question 2

A fictional child weighs 50 kg and takes the maintenance dose of 1.2 mg/kg a day. How many milligrams is the daily dose?

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Answer: 60 mg

Working: 50 kg x 1.2 mg/kg = 60 mg a day.

Question 3

A fictional adult takes atomoxetine 40 mg a day for 7 days, then 80 mg a day for the next 21 days. How many milligrams is the total over the 28 days?

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Answer: 1,960 mg

Working: 40 mg x 7 days = 280 mg; 80 mg x 21 days = 1,680 mg; 280 + 1,680 = 1,960 mg.

eMC SmPC: Atomoxetine 10 mg hard capsules

https://www.medicines.org.uk/emc/product/100466/smpc

Where marks are lost

  • Applying the mg per kg figures to a patient over 70 kg instead of the fixed 40 mg and 80 mg schedule.
  • Increasing the dose before the stated minimum 7 days on the initial dose.
  • 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 dose-total calculation justify changing a real dose?

No. Follow the steps in the exercise. Real titration depends on response and tolerability and needs 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.