Discovery: from a target to a candidate
The whole journey is the drug pipeline, and the first half is drug discovery — the part medicinal chemists own most directly. It moves through recognizable stages.
- Pick and validate the target. Build confidence that hitting this target will actually help patients — that's target validation. Skipping it is the most expensive mistake in the field.
- Find hits. Test many compounds to find ones that touch the target. A common method is high-throughput screening, firing hundreds of thousands of compounds at the target to see what sticks.
- Optimize. Patiently improve the best lead through lead optimization — many design–make–test cycles balancing potency, safety, and drug-like properties.
- Choose a candidate. Nominate one molecule, the drug candidate, good enough to test in animals and, eventually, people.
Development: from a candidate to a medicine
Now the candidate enters the second half. Preclinical development tests it thoroughly outside humans — chemistry, manufacturing, and safety in animals — to earn permission to give it to people. Then come human trials, run in careful stages: a small first-in-human phase I trial focused on safety, followed by larger trials testing whether it actually works and how well. If everything holds up, the sponsor seeks regulatory approval from an agency, and only then can it be prescribed.