Common Registration Assessment, Part 1

Nortriptyline tablet and liquid strengths and daily doses 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.

Senior man holding his shoulder in pain on a beach
Photo from Pexels, used under the Pexels licence. It is a stock image and does not show the exercise.

The NHS lists nortriptyline tablets as 10 mg, 25 mg and 50 mg, and a liquid containing 10 mg or 25 mg in a 5 ml spoonful.

The NHS states that for nerve pain the usual starting dose is 10 mg once a day, increased gradually if needed, with a maximum of 75 mg a day for pain under the supervision of a pain specialist.

The NHS states that for depression the dose is increased gradually to between 75 mg and 100 mg a day, and that older people usually take 30 mg to 50 mg a 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. Choose the tablet combination that makes the stated dose from the available strengths.
  2. Convert milligrams to millilitres using the stated liquid strength per 5 ml.
  3. Multiply the daily amount by the number of days for a course total.
  4. Keep the pain maximum and the depression range in separate lines of working.
  5. Check that a stepped dose stays within the stated maximum at every step.

Three practice questions

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

Question 1

A fictional patient takes nortriptyline 35 mg daily for nerve pain using 25 mg and 10 mg tablets. Which tablets make the dose, and how many tablets is that over 28 days?

Show the answer

Answer: One 25 mg tablet plus one 10 mg tablet daily; 56 tablets over 28 days

Working: 25 mg + 10 mg = 35 mg; 2 tablets x 28 days = 56 tablets.

Question 2

A fictional patient takes 25 mg daily using the liquid containing 10 mg in 5 ml. How many millilitres is each dose?

Show the answer

Answer: 12.5 ml

Working: 25 mg / 10 mg = 2.5; 2.5 x 5 ml = 12.5 ml.

Question 3

A fictional pain dose rises from 10 mg daily in week 1 to 20 mg daily in week 2 and 30 mg daily in week 3, staying within the 75 mg daily maximum. How many milligrams are taken across the 3 weeks?

Show the answer

Answer: 420 mg

Working: (10 mg + 20 mg + 30 mg) x 7 days = 60 mg x 7 days = 420 mg.

NHS: How and when to take nortriptyline

https://www.nhs.uk/medicines/nortriptyline/how-and-when-to-take-nortriptyline/

Where marks are lost

  • Exceeding the stated 75 mg daily maximum for pain.
  • Measuring liquid with a kitchen spoon instead of the supplied syringe or spoon.
  • 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-step calculation justify changing a real dose?

No. Follow the steps in the exercise. Real dose changes are gradual and need 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.

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More calculation topics

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