Common Registration Assessment, Part 1

Zonisamide capsule titration steps and weekly dose escalation for the GPhC assessment

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

Published 11 November 2026. Independent revision material, not GPhC questions, not for patient care.

A hand holding three plain green hard capsules
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 Zonegran (zonisamide) capsules states that for monotherapy in newly diagnosed adults the dose is 100 mg per day in weeks 1 and 2, 200 mg per day in weeks 3 and 4, and 300 mg per day from weeks 5 and 6, with further increases at two-weekly intervals in increments of 100 mg up to a maximum of 500 mg per day if a higher dose is required.

The same information states that for adjunctive therapy with CYP3A4-inducing agents the dose is 50 mg per day (in two divided doses) in week 1 and 100 mg per day (in two divided doses) in week 2, then increased at weekly intervals in increments of 100 mg to a usual maintenance of 300 to 500 mg per day.

It also states that when treatment is withdrawn it should be gradual, and that in clinical studies dose reductions of 100 mg at weekly intervals have been used.

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

The method

  1. Identify the stated regimen (monotherapy or adjunctive) and the stated week.
  2. Read the stepped daily dose for that week from the stated schedule.
  3. Divide the stated daily dose by the capsule strength for the capsule count, and by two for a divided dose.
  4. Keep mg per day, mg per dose, capsules and weeks 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 adult starts zonisamide monotherapy at the label schedule. What is the daily dose in week 4, and how many 100 mg capsules is that each day?

Show the answer

Answer: 200 mg per day; 2 capsules

Working: Monotherapy schedule: 100 mg/day in weeks 1-2, 200 mg/day in weeks 3-4. 200 / 100 = 2 capsules daily.

Question 2

A fictional adult starts zonisamide as adjunctive therapy with a CYP3A4-inducing agent. What is the week 1 daily dose, how is it divided, and what is each individual dose?

Show the answer

Answer: 50 mg per day in two divided doses; 25 mg per dose

Working: The label adjunctive schedule gives 50 mg/day in two divided doses in week 1. 50 / 2 = 25 mg per dose.

Question 3

A fictional patient on adjunctive zonisamide at 100 mg per day increases the dose at weekly intervals in increments of 100 mg, as the label describes. What is the daily dose after 4 weekly increases?

Show the answer

Answer: 500 mg per day

Working: 100 + 100 + 100 + 100 + 100 = 500 mg per day after 4 weekly increases, the top of the label's usual 300 to 500 mg maintenance range.

eMC SmPC: Zonegran 100 mg hard capsules

https://www.medicines.org.uk/emc/product/7870/smpc

Where marks are lost

  • Mixing the two schedules; monotherapy starts at 100 mg per day, adjunctive therapy at 50 mg per day in two divided doses.
  • Reading the week off by one; monotherapy holds 100 mg per day for weeks 1 and 2 and rises to 200 mg per day in weeks 3 and 4.
  • Halving the capsule count for a divided dose; divide the daily mg by the capsule strength for the daily count, then split the dose into two.

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 zonisamide titration?

No. Follow the stated regimen and week in the exercise. Real titration follows the prescriber and the product information.

How should I check the answer?

Identify the regimen, read the stepped daily dose for the stated week, then divide by the capsule strength and by two for a divided dose.

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.