Common Registration Assessment, Part 1
Spironolactone tablet strengths by condition for the GPhC assessment
Three original practice questions, with the working shown. Read the stated prescription or plan before calculating.
Published 18 October 2026. Independent revision material, not GPhC questions, not for patient care.
The NHS lists spironolactone tablets in four strengths: 12.5 mg, 25 mg, 50 mg and 100 mg.
The usual adult dose depends on the condition: heart failure starts at 25 mg once a day, ascites from liver disease is between 100 mg and 400 mg a day, and high blood pressure is 25 mg a day.
Each question fixes the values needed for its arithmetic. Write the unit beside every step and keep a single dose separate from a supply total. All prescriptions and patients here are fictional; these are revision materials, not for patient care.
The method
- Identify the exact strength, dose and frequency supplied in the question.
- Calculate one dose first; divide prescribed mg by mg per tablet.
- Scale to the stated duration only when a supply is requested.
- Keep alternate-day dosing distinct from daily dosing when stated.
- Check the arithmetic against the stated dose before reporting it.
Three practice questions
Work each one on paper first, then open the answer. All patients and prescriptions are fictional.
Question 1
A fictional prescription specifies spironolactone 25 mg once a day for heart failure using 25 mg tablets. How many tablets are needed for 28 days?
Show the answer
Answer: 28 tablets
Working: 25 ÷ 25 = 1 tablet a day. 1 × 28 = 28 tablets.
Question 2
A fictional prescription specifies spironolactone 200 mg a day for ascites using 100 mg tablets. How many tablets is one day?
Show the answer
Answer: 2 tablets
Working: 200 ÷ 100 = 2 tablets a day.
Question 3
A fictional prescription specifies spironolactone 50 mg once a day using 25 mg tablets. How many tablets are needed for 14 days?
Show the answer
Answer: 28 tablets
Working: 50 ÷ 25 = 2 tablets a day. 2 × 14 = 28 tablets.
Exam approach
Condition-based doses are given information, not recall. Use the dose written in the question, divide by the stated tablet strength, then multiply by the days.
Where marks are lost
- Applying the heart failure starting dose to a different stated condition.
- Forgetting that two 25 mg tablets make a 50 mg dose.
- Reporting a supply for the wrong number of days.
Frequently asked questions
Are these official assessment questions?
No. They are original revision exercises, not official GPhC questions and not for patient care.
Do I need to memorise the strengths?
The exercise supplies them. In the assessment, read any given product information exactly as written.
How should I check the answer?
Check the requested unit, then work backwards from the quantity to the stated dose and duration.
Sources
- NHS: How and when to take spironolactone
- GPhC, Common Registration Assessment specification and permitted items for 2026
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
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See also the formula sheet, the eight sample questions and the approved calculator page.