Describe the stages involved in the clinical trial of a new medicine, from first use in humans to approval for widespread use.

WJEC GCSE Biology (Wales) — 2.6.3 Medicines and drugs · Describe · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

1. First, a small group of healthy volunteers receive the medicine to test safety and side effects.
2. Next, a larger group of patients with the target disease are given the medicine to assess its effectiveness.
3. A placebo is used as a control; some participants receive placebo while others receive the medicine.
4. The trial is double‑blind, so neither patients nor doctors know who receives the medicine or placebo, reducing bias.

Examiner tips

  • Use the exact wording from the mark scheme (e.g., "healthy volunteers", "placebo", "double‑blind").
  • Number the stages clearly to show you have covered all four points.

Common mistakes

  • Mixing up the order of the stages; the safety test comes first. Using a single‑blind trial instead of double‑blind. Omitting the placebo control or the patient group with the disease.

Mark scheme (4 marks)

  1. The medicine is first tested on a small number of healthy volunteers to check for safety / side effects
  2. The medicine is then tested on a larger group of patients who have the disease to check that it works / is effective
  3. A placebo is used as a control / some patients receive a placebo and others receive the medicine
  4. A double-blind trial is used so that neither the patient nor the doctor knows who received the medicine / placebo, to reduce bias

Key terms in this question

clinical trial

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