How the FDA Drug Approval Process Works, Step by Step
Understanding the FDA drug approval process helps investors read biotech news with more confidence and know which milestones move stocks. Here is the path a drug takes from the lab to the market, and where the catalysts are.
1. Preclinical research
Before testing in humans, a drug is studied in the lab and in animals for safety and biological activity. If results support human testing, the company files an Investigational New Drug (IND) application with the FDA.
2. Clinical trials: Phase 1, 2 and 3
Human testing runs in three main phases, each a potential catalyst:
- Phase 1 — small studies focused on safety and dosing.
- Phase 2 — medium studies testing whether the drug works and at what dose.
- Phase 3 — large, confirmatory studies that must show the drug is safe and effective, usually against a control arm.
Trial results are reported using endpoints such as median overall survival, progression-free survival and the hazard ratio. Many big biotech moves happen on Phase 3 readouts.
3. Filing: NDA or BLA
If the pivotal trials succeed, the company submits a marketing application: a New Drug Application (NDA) for small molecules or a Biologics License Application (BLA) for biologics. Filing — and the FDA accepting the application for review — is itself a positive milestone.
4. FDA review and the PDUFA date
Once accepted, the FDA assigns a PDUFA date — its target action date. Standard reviews target roughly ten months; priority reviews target about six. During review the FDA may convene an advisory committee of outside experts whose vote, while non-binding, can move the stock.
5. The decision: approval or CRL
On or before the PDUFA date, the FDA acts. It may approve the drug (sometimes with restrictions or post-marketing requirements) or issue a Complete Response Letter stating the application cannot be approved in its current form. A CRL is usually a major negative catalyst; approval is usually positive, though the reaction depends on what the market already expected.
Why this matters for investors
Each stage is a potential inflection point, and the risk profile changes as a drug advances. Special FDA designations — Orphan Drug, Fast Track, Breakthrough Therapy — can speed development but do not guarantee approval. And throughout, companies burn cash, so dilution risk runs alongside clinical risk. For definitions of the terms above, see the biotech investing glossary.
Frequently asked questions
How long does the FDA drug approval process take?
From first-in-human testing to approval typically takes many years, spanning Phase 1, 2 and 3 trials plus the FDA review. The FDA review stage itself targets roughly ten months for a standard review or about six months for a priority review, measured from when the application is filed and accepted.
What is the difference between an NDA and a BLA?
An NDA (New Drug Application) is used for small-molecule drugs, while a BLA (Biologics License Application) is used for biologics such as antibodies, cell and gene therapies and vaccines. Both are marketing applications submitted to the FDA and both receive a PDUFA target action date once accepted for review.
What happens if the FDA does not approve a drug?
The FDA issues a Complete Response Letter (CRL) explaining why the application cannot be approved in its current form. Depending on the issue, the company may fix a manufacturing problem in months or need another trial that takes years. A CRL is usually a significant negative catalyst for the stock.