Common Registration Assessment, Part 1

Dalteparin weight-based units and once-daily syringe doses for the GPhC assessment

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

Published 12 November 2026. Independent revision material, not GPhC questions, not for patient care.

A nurse holding a tablet device while talking with a patient on a hospital bed
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 Fragmin (dalteparin) states that for extended treatment of symptomatic venous thromboembolism, month 1 dosing is 200 IU per kg of total body weight, injected under the skin once daily for the first 30 days.

The same information prints a weight-band table: under 46 kg gives 7,500 IU, 46 to 56 kg gives 10,000 IU, 57 to 68 kg gives 12,500 IU, 69 to 82 kg gives 15,000 IU, and 83 kg and over gives 18,000 IU.

The printed information caps the total daily dose at 18,000 IU, so a simple 200 IU per kg multiplication can overstate the dose for heavier patients.

Each question fixes the values needed for its arithmetic. Write the unit beside every step and distinguish a calculated dose from the printed band or cap. All prescriptions and patients here are fictional; these are revision materials, not for patient care.

The method

  1. Multiply the stated body weight in kg by 200 IU to get the calculated daily dose.
  2. Compare the calculated figure with the printed weight band for that weight.
  3. Apply the printed 18,000 IU daily maximum where the calculation exceeds it.
  4. Keep IU separate from mL; the questions here work in IU only.
  5. State the dose as a once-daily figure, not a divided one.

Three practice questions

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

Question 1

A fictional adult weighs 50 kg and is prescribed dalteparin at 200 IU per kg once daily for month 1. What is the daily dose in IU, and does it match the printed band for 46 to 56 kg?

Show the answer

Answer: 10,000 IU once daily; yes, it matches the printed 10,000 IU band

Working: 50 kg x 200 IU = 10,000 IU. The printed band for 46 to 56 kg is also 10,000 IU, so the calculation and the table agree.

Question 2

A fictional adult weighs 75 kg and is prescribed dalteparin at 200 IU per kg once daily. What daily dose does the calculation give, and what does the printed band for 69 to 82 kg say?

Show the answer

Answer: 15,000 IU once daily; the printed band is also 15,000 IU

Working: 75 kg x 200 IU = 15,000 IU. The printed band for 69 to 82 kg is 15,000 IU, so both routes give the same figure.

Question 3

A fictional adult weighs 100 kg. What does a plain 200 IU per kg calculation give, and what daily dose should the answer state once the printed maximum is applied?

Show the answer

Answer: 20,000 IU by calculation, capped at 18,000 IU once daily

Working: 100 kg x 200 IU = 20,000 IU. The product information limits the total daily dose to 18,000 IU, and the printed band for 83 kg and over is 18,000 IU, so the stated dose is 18,000 IU once daily.

eMC SmPC: Fragmin 12500 IU/0.5ml solution for injection

https://www.medicines.org.uk/emc/product/4241/smpc

Where marks are lost

  • Reporting the raw 200 IU per kg figure for a heavy patient and ignoring the printed 18,000 IU daily maximum.
  • Reading the wrong weight band, especially near the boundaries at 46, 56, 68 and 82 kg.
  • Writing the answer in mg or mL when the question works in international units (IU).

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 dalteparin 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?

Multiply the weight by 200 IU, then compare with the printed band for that weight and apply the 18,000 IU daily maximum if the calculation is higher.

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

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More calculation topics

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