Describe that the process of developing new medicines, including…

The idea

New medicines, antibiotics included, are not simply found and then sold: they pass through a long sequence of stages. Discovery means identifying a candidate substance, for example a compound from a microorganism or a plant, that might treat a disease. Development covers the work of turning that candidate into a usable medicine, such as deciding a safe dose form and how it will be delivered. Preclinical testing happens before any person is involved: the substance is tested on cells and on animals to check for toxicity and to estimate safe doses. Clinical testing then involves people, usually in stages from a small group of healthy volunteers to larger groups of patients, to check safety, dosage and whether the medicine actually works. Only after these stages can a medicine be approved and used.

What earns the marks

• Discovery: identifying a potential new medicine, such as a compound produced by a microorganism or found in a plant.
• Development: turning the candidate into a usable medicine, including working out a suitable dose form and delivery.
• Preclinical testing: testing on cells and animals before humans, to check toxicity and estimate safe doses.
• Clinical testing: testing in humans, first small groups then larger groups, to check safety, dose and effectiveness.
• Antibiotics are included as medicines developed through the same staged process.
• The stages occur in order: discovery, development, preclinical testing, then clinical testing.

Common mistakes and how to put them right

• Thinking clinical testing comes before preclinical testing.

  Put it right by noting preclinical work on cells and animals must precede testing in people.

• Assuming a discovered substance is immediately a medicine.

  Put it right by explaining development and testing are needed first.

• Believing antibiotics are exempt from the staged process.

  Put it right by stating antibiotics are medicines developed through the same stages.

• Confusing 'development' with 'clinical testing'.

  Put it right by keeping development as preparing the medicine and clinical testing as the human trials.

Exam tips

• Learn the four named stages in order so you can pick the correct sequence in a multiple-choice option.
• Link each stage to who or what is tested: cells and animals for preclinical, people for clinical.
• Read every option fully; a distractor often swaps preclinical and clinical testing.