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[Pharmacology](https://durgical.com/en/pharmacology/) · Topic

# Drug discovery and development

The long path from an idea about a disease target to a medicine on the pharmacy shelf: laboratory work, clinical trials and regulatory review.

Updated 2026-11-01

New medicines go through discovery, preclinical research, clinical research in people, regulatory review and post-marketing safety monitoring. Each stage removes candidates that fail on safety or benefit, so only a small share of molecules that enter testing become approved medicines. Regulators such as the FDA (United States), the EMA (European Union) and INVIMA (Colombia) decide whether the benefits outweigh the risks.

## Key points

- Discovery: find a target (an enzyme, receptor or pathway linked to disease) and molecules that act on it, then optimise them.
- Preclinical research: laboratory and animal studies of pharmacology, pharmacokinetics and toxicity before the first human dose.
- Phase 1: first studies in people, usually small groups, focused on safety, tolerability and pharmacokinetics.
- Phase 2: patients with the condition; early evidence of efficacy, dose finding and short-term side effects.
- Phase 3: larger trials that confirm benefit against placebo or standard treatment and characterise adverse effects. Phase 4: studies and surveillance after approval.

## From target to candidate

Targets come from biology and genetics. Screening of compound libraries, structure-based design (using the 3D shape of the target, as for statins in the HMG-CoA reductase site or direct factor Xa inhibitors) and biologics (antibodies, proteins) produce leads, which chemists refine for potency, selectivity and drug-like properties.

## Preclinical work

Before testing in people, developers study what the molecule does to cells and animals, how it is absorbed and eliminated, and what organs it harms at high exposure. In the United States these data support an Investigational New Drug application that allows human trials.

## Clinical trials

- Phase 1: safety and pharmacokinetics in small groups, often healthy volunteers
- Phase 2: efficacy signals and dose selection in patients
- Phase 3: confirmatory, often randomised and blinded, in larger and more varied groups
- Ethics committee approval and informed consent are required at every phase

## Review and after approval

The regulator reviews all the data, the label and the manufacturing quality. Approval is not the end: rare or late adverse effects often appear only when many people use a drug, so post-marketing safety monitoring (pharmacovigilance) continues for the life of the product. In Colombia, INVIMA runs the national pharmacovigilance reporting system.

## Memory aid

Phase 1 asks «Is it safe?», Phase 2 «Does it work?», Phase 3 «Does it work better, in many people?», Phase 4 «What did we miss?»

## Test yourself

Think of the answer, then tap the question to see it.

## What is the main question of a phase 1 trial?

Whether the drug is safe and tolerated in people, and how it is absorbed, distributed and eliminated.

## Why do some adverse effects appear only after approval?

Trials include limited numbers of people for limited time; rare or delayed reactions show up only when many more people use the drug.

## Which agency approves medicines in Colombia?

INVIMA (Instituto Nacional de Vigilancia de Medicamentos y Alimentos), which also runs the national pharmacovigilance reporting system.

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## Related classes

- [Statins](https://durgical.com/en/pharmacology/classes/statins/)
- [Direct oral anticoagulants (DOACs)](https://durgical.com/en/pharmacology/classes/direct-oral-anticoagulants/)

## Example drugs

- [Atorvastatin](https://durgical.com/en/pharmacology/atorvastatin/)
- [Rivaroxaban](https://durgical.com/en/pharmacology/rivaroxaban/)
- [Dabigatran](https://durgical.com/en/pharmacology/dabigatran/)

[← All of pharmacology](https://durgical.com/en/pharmacology/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [The Drug Development Process](https://www.fda.gov/patients/learn-about-drug-and-device-approvals/drug-development-process) (U.S. Food and Drug Administration, 2026); [Servicios en Línea Farmacovigilancia - INVIMA](https://www.invima.gov.co/farmacovigilancia) (Instituto Nacional de Vigilancia de Medicamentos y Alimentos (INVIMA), Colombia, 2026); [MedWatch: The FDA Safety Information and Adverse Event Reporting Program](https://www.fda.gov/safety/medwatch-fda-safety-information-and-adverse-event-reporting-program) (U.S. Food and Drug Administration, 2026).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/topics/drug-discovery-and-development/