Common Registration Assessment, Part 1

Valaciclovir 500 mg tablets and shingles course counts for the GPhC assessment

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

Published 2 November 2026. Independent revision material, not GPhC questions, not for patient care.

Brown capsules arranged on a white surface
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 lists valaciclovir as 500 mg film-coated tablets.

For herpes zoster (shingles) in immunocompetent adults, that product information describes 1000 mg three times a day for 7 days. The dose is reduced according to creatinine clearance; immunocompromised patients have different duration requirements.

For herpes simplex infections in immunocompetent adults and adolescents aged 12 years and over, the same information describes 500 mg twice a day, for 3 to 5 days for recurrent episodes and up to 10 days for a first episode, with dose reduction according to creatinine clearance. Its separate cold-sore regimen is not the schedule used in these exercises.

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 exact strength and frequency stated in the question.
  2. Convert a gram dose into milligrams before counting 500 mg tablets.
  3. Triple a three times daily dose and double a twice daily dose to get each daily total.
  4. Multiply the daily tablet count by the stated number of days.
  5. Keep milligrams and tablets separate; convert only if 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 takes valaciclovir 1000 mg three times a day for shingles. How many milligrams a day is that, and how many 500 mg tablets is each day?

Show the answer

Answer: 3,000 mg a day; 6 tablets

Working: 1000 mg x 3 doses = 3,000 mg; 1000 mg / 500 mg = 2 tablets per dose; 2 tablets x 3 doses = 6 tablets a day.

Question 2

A fictional prescription reads valaciclovir 1000 mg three times a day for 7 days. How many 500 mg tablets should be supplied, and how many milligrams is the course?

Show the answer

Answer: 42 tablets; 21,000 mg

Working: 2 tablets x 3 doses = 6 tablets a day; 6 tablets x 7 days = 42 tablets; 3,000 mg x 7 days = 21,000 mg.

Question 3

A fictional prescription states valaciclovir 500 mg twice a day for 5 days, using 500 mg tablets. How many tablets is the course?

Show the answer

Answer: 10 tablets

Working: 1 tablet per dose x 2 doses = 2 tablets a day; 2 tablets x 5 days = 10 tablets.

eMC SmPC: Valaciclovir 500 mg film-coated tablets

https://www.medicines.org.uk/emc/product/4349/smpc

Where marks are lost

  • Counting 500 mg tablets for a 1000 mg dose without doubling.
  • Using the shingles frequency for a herpes simplex course when the question states the lower dose.
  • 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-total 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.

Practise until the method is automatic

Try 15 free questions with worked answers. No sign-up required.

Try 15 free questionsSee pricing

More calculation topics

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