5.20 - Developing medicines
Follow a promising substance through discovery, development, preclinical tests and clinical trials. Explain why evidence of a useful effect must be considered alongside safety, dose and the quality of the comparison.
5.20 · From discovery to clinical testing
A substance that produces a clear zone in a bacterial culture may be worth investigating as an antibiotic, but this is only early evidence of inhibition in agar. Specification point 5.20 requires the ordered stages used to develop a new medicine, including a new antibiotic. Most candidate medicines are stopped during the process because the evidence is not good enough for them to progress.
| Stage | What happens | Evidence needed before progression |
|---|---|---|
| Discovery | Scientists identify a biological problem or target and screen chemical or biological substances for a useful effect. A substance that inhibits bacterial growth could become a candidate antibiotic. | Repeated laboratory evidence of the desired biological activity. |
| Development | The candidate is studied and may be modified. Scientists work out a stable formulation and how to produce consistent samples for testing. | A candidate that can be made reliably and is promising enough for more detailed safety and effectiveness tests. |
| Preclinical testing | Before testing in people, the candidate is tested using cells or tissues for activity and toxicity. Whole-organism testing, including animal studies where required, investigates effects and possible harm in a complete body. | Evidence that the candidate is potentially effective and acceptably safe to begin carefully controlled human testing. |
| Clinical testing | The medicine is tested in people. Early trials use small groups and low doses to examine safety, side effects and dose. Later trials use larger groups, including people with the condition, to test effectiveness and continue monitoring side effects. | Reliable evidence about safety, effective dose and whether the medicine works well enough for its intended use. |
5.20 · What each test can establish
In later clinical trials, a treatment group can be compared with a group receiving an existing treatment or a placebo where appropriate. Random allocation makes the groups less likely to differ systematically at the start. Blinding means participants, researchers or both do not know which treatment each person receives, reducing bias when effects are reported or measured.
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