Common Registration Assessment, Part 1

Sildenafil tablet timing and the one tablet daily limit for the GPhC assessment

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

Published 1 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 NHS advises people taking sildenafil for erection problems to take 1 tablet about 1 hour before sex.

The NHS also states not to take more than 1 tablet a day, and that sildenafil must not be taken with nitrates.

A daily maximum of 1 tablet caps how many tablets can be used across any number of days, whatever the stated strength.

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. Identify the stated frequency and any stated daily maximum before counting.
  2. Cap the counted doses at the stated maximum when actual use would exceed it.
  3. Calculate one day or one use first, then scale to the stated period.
  4. Keep tablet counts and days separate; convert only if the question asks.
  5. Check whether the question asks for tablets used or tablets to supply.

Three practice questions

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

Question 1

A fictional patient may take sildenafil at most 1 tablet a day. What is the maximum number of tablets that can be taken in 14 days?

Show the answer

Answer: 14 tablets

Working: 1 tablet x 14 days = 14 tablets at the stated daily maximum.

Question 2

A fictional pack contains 4 tablets of sildenafil. How many packs should be supplied to give 12 tablets?

Show the answer

Answer: 3 packs

Working: 12 tablets / 4 tablets per pack = 3 packs.

Question 3

A fictional patient uses 1 sildenafil tablet every 2 days. How many days will a supply of 8 tablets last, and does this stay within the stated daily maximum?

Show the answer

Answer: 16 days; yes, one tablet every 2 days is within 1 tablet a day

Working: 8 tablets x 2 days = 16 days; using 1 tablet over each 2-day period is below the maximum of 1 tablet a day.

NHS: Sildenafil

https://www.nhs.uk/medicines/sildenafil-viagra/

Where marks are lost

  • Ignoring a stated daily maximum and counting more than 1 tablet a day.
  • Confusing a count of tablets with a count of days when doses are not daily.
  • 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.

Why does the strength not appear in these questions?

These exercises practise timing and the stated daily limit. Strength only matters to the milligram amount, not to the tablet count.

How should I check the answer?

Check the requested unit, then work backwards from the quantity to the stated frequency 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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See also the formula sheet, the eight sample questions and the approved calculator page.