Drug Development and Clinical Trials — AQA GCSE Biology
New medicines must be thoroughly tested before they can be used, to make sure they are safe and effective.
Where drugs come from
Traditionally, drugs were extracted from plants and microorganisms:
- Digitalis (a heart drug) from foxgloves.
- Aspirin from willow bark.
- Penicillin discovered by Alexander Fleming from the Penicillium mould.
Most new drugs are now synthesised by chemists, though the starting point may still be a natural compound.
Testing new drugs
New drugs are tested for safety, efficacy (does it work), toxicity and dose:
- Preclinical testing — on cells, tissues and live animals in the lab.
- Clinical trials — using healthy volunteers first (very low doses, to test safety), then patients to find the optimum dose and check effectiveness.
Placebos and double-blind trials
- A placebo is a "dummy" treatment with no active drug.
- In a double-blind trial, neither the doctors nor the patients know who is receiving the real drug or the placebo. This removes bias from the results.
Peer review
Results are peer reviewed (checked by other scientists) and published before a drug is approved, to prevent false claims.
Exam tips
- Learn the three example drug origins (foxglove, willow, Penicillium).
- Know the testing order: preclinical (cells/tissues/animals) → healthy volunteers → patients.
- Explain why placebos and double-blind trials are used (to remove bias).
- Peer review checks the results before publication.