Discovery and development of drugs — AQA GCSE Biology
Test yourself on Discovery and development of drugs with AQA GCSE practice questions.
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Discovery and development of drugs explained
New medicines are developed through a sequence of stages.
Read the full explanation
Potential drugs may be discovered from traditional plant or microorganism sources, or synthesised in the laboratory. Preclinical testing uses cells, tissues and live animals to assess toxicity, dosage and efficacy before any human trial. Clinical testing then proceeds in phases: a small number of healthy volunteers checks safety and side effects; a larger group of patients checks effectiveness and optimum dose; and larger-scale trials compare the new drug with existing treatments, often using placebos and randomisation to reduce bias. If results show the drug is safe and effective, it can be licensed and marketed. Students should describe this process in order and explain why each stage is needed.
Your focus
- Describe the stages in the discovery and development of a new medicine.
- Explain the purpose of preclinical testing and each phase of clinical testing.
- Outline how placebos and randomisation are used to make clinical trials valid.
Discovery and development of drugs exam tips
Marking Points
- Discovery: potential drugs are identified from plant or microorganism extracts, or designed and synthesised in the laboratory.
- Preclinical testing: the drug is tested on cells, tissues and live animals to assess toxicity, safety and effective dose before human trials.
- Clinical testing phase 1: a small number of healthy volunteers is used to check safety and side effects.
- Clinical testing phase 2: a larger group of patients is used to test effectiveness and find the optimum dose.
- Clinical testing phase 3: large-scale trials compare the new drug with existing treatments, often using placebos and random allocation.
- If the drug is shown to be safe and effective, it is licensed and can be prescribed; otherwise development stops.
Examiner Tips
- 💡Present the stages in a clear sequence: discovery, preclinical, clinical phases, licensing.
- 💡State the purpose of each stage, such as safety, dosage or effectiveness, rather than just naming it.
- 💡Mention placebos and randomisation when explaining how bias is reduced in clinical trials.
Common Mistakes
- Reversing preclinical and clinical testing: correct this by stating that preclinical testing occurs before any human testing.
- Thinking clinical trials use only healthy volunteers: correct this by explaining that healthy volunteers are used in early safety trials, while patients are used to test effectiveness.
- Believing a drug is tested on humans as soon as it is discovered: correct this by describing the prior preclinical safety and toxicity checks.