Common Registration Assessment, Part 1

Labetalol twice daily doses and fortnightly titration steps for the GPhC assessment

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

Published 6 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 labetalol 100 mg film-coated tablets states that for hypertension in adults treatment should start with 100 mg twice daily, that increases of 100 mg twice daily should be made at fortnightly intervals, and that many patients' blood pressure is controlled by 200 mg twice daily.

The same information states that up to 800 mg daily may be given as a twice daily regimen, and that in severe, refractory hypertension daily doses up to 2,400 mg have been given, divided into a three or four times a day regimen.

It also states that in elderly patients an initial dose of 50 mg twice daily is recommended, and that the tablets should be taken orally with food.

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. Identify the dose per administration and the number of doses each day.
  2. Multiply the dose by the daily dose count for the daily milligram total.
  3. Multiply the daily tablet count by the stated number of days for a supply quantity.
  4. Keep milligrams, tablets 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 patient starts labetalol at 100 mg twice daily. How many milligrams is this each day?

Show the answer

Answer: 200 mg

Working: 100 mg x 2 doses each day = 200 mg a day.

Question 2

A fictional patient's blood pressure is controlled at 200 mg twice daily using 100 mg tablets. How many tablets are needed for a 28-day supply?

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Answer: 112 tablets

Working: 200 mg / 100 mg per tablet = 2 tablets each dose. 2 tablets x 2 doses = 4 tablets each day. 4 tablets x 28 days = 112 tablets.

Question 3

A fictional patient with severe, refractory hypertension takes the stated maximum daily dose of 2,400 mg divided into three equal doses. How many milligrams is each dose?

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Answer: 800 mg

Working: 2,400 mg a day / 3 doses = 800 mg each dose.

eMC SmPC: Labetalol 100 mg Film-coated Tablets

https://www.medicines.org.uk/emc/product/11602/smpc

Where marks are lost

  • Counting a twice daily dose as a once daily dose when finding the daily total.
  • Applying the fortnightly increase steps to a single day instead of across weeks.
  • Using the 2,400 mg severe-case figure when the question describes the usual twice daily regimen.

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 labetalol dose?

No. Follow the stated prescription in the exercise. Real dosing is titrated against blood pressure, with different starting doses in elderly patients and in pregnancy.

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.