Common Registration Assessment, Part 1

Hydralazine dose titration and daily maximums for the GPhC assessment

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

Published 13 November 2026. Independent revision material, not GPhC questions, not for patient care.

A doctor checking a patient's heart with a stethoscope
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 hydralazine 25 mg tablets states that for hypertension, treatment should begin with low doses, initially 25 mg twice a day, increased stepwise according to response.

The same information states the dose can be increased gradually to a level not exceeding 200 mg daily, and that it should not be increased beyond 100 mg daily without first checking the patient's acetylator status.

It also states the maximum dose in women should not exceed 100 mg.

Each question fixes the values needed for its arithmetic. Keep the starting dose, the acetylator check and the two different ceilings separate. All prescriptions and patients here are fictional; these are revision materials, not for patient care.

The method

  1. Start at 25 mg twice a day and titrate stepwise.
  2. Total the daily mg before applying any ceiling.
  3. Apply the acetylator-status check before any dose above 100 mg daily.
  4. Apply the printed ceilings: 100 mg daily for women, 200 mg daily overall.

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 hydralazine at the printed initial dose. What is the daily dose in mg, and how many 25 mg tablets is that per day?

Show the answer

Answer: 50 mg daily; two 25 mg tablets

Working: The initial dose is 25 mg twice a day, so 2 x 25 = 50 mg daily, which is 2 tablets.

Question 2

A fictional man's dose is titrated stepwise to 50 mg four times a day. What is the daily dose, how many 25 mg tablets is that, and does it stay within the printed maximum?

Show the answer

Answer: 200 mg daily; eight tablets; yes, at the printed maximum

Working: 50 mg four times a day is 4 x 50 = 200 mg daily, which is 200 / 25 = 8 tablets. That equals the printed maximum of 200 mg daily, and because it is above 100 mg, the product information requires the acetylator status to have been checked first.

Question 3

A fictional woman's dose is 100 mg daily and an increase is being considered. What does the product information say about doses above 100 mg daily for women?

Show the answer

Answer: The printed maximum for women is 100 mg daily, so an increase above that is outside the stated maximum

Working: The product information states the maximum dose in women should not exceed 100 mg, so the stated ceilings do not support a further increase.

eMC SmPC: Hydralazine 25 mg Tablets

https://www.medicines.org.uk/emc/product/6707/smpc

Where marks are lost

  • Jumping straight to a high dose instead of titrating stepwise from 25 mg twice a day.
  • Passing 100 mg daily without the acetylator-status check the product information requires.
  • Applying the 200 mg daily ceiling to women, whose printed maximum is 100 mg daily.

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 dose?

No. Follow the stated prescription in the exercise. Real dosing follows the prescriber and the product information for the named product.

How should I check the answer?

Total the daily mg from the stated schedule, then check the starting dose, the acetylator check above 100 mg, and the 100 mg (women) and 200 mg ceilings.

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.