How a drug approval differs from a trial result

A published trial shows what a study found. A regulatory approval is a separate decision, made later, on the data for a specific use. This guide explains the difference and gives five checks a reader can make.

This guide describes the US process only, using pages from the US Food and Drug Administration (FDA). In the UK, medicines are regulated by the Medicines and Healthcare products Regulatory Agency (MHRA). We have not checked UK or European rules for this guide, so do not assume the FDA's stages, terms or timelines apply in the UK.

This guide is general information, not medical advice. It does not tell anyone whether to take or stop a medicine.

What a trial result is

A trial result is what a study reports, from one study or a set of studies. The FDA describes testing in stages. Before a drug is tested in people, the drug company or sponsor performs laboratory and animal tests (FDA, development and approval process).

The FDA describes the clinical phases this way:

• Phase 1 tests safety and dosage, over several months, in healthy volunteers or people with the disease or condition (FDA, clinical research).
• Phase 2 looks at efficacy and side effects in people with the disease or condition, over several months to 2 years. The page says these studies are not large enough to show whether the drug will be beneficial (FDA, clinical research).
• Phase 3 is designed to show whether the product offers a treatment benefit to a specific population. The page gives 300 to 3,000 participants and 1 to 4 years (FDA, clinical research).
• Phase 4 trials run after FDA approval, during post-market safety monitoring (FDA, clinical research).

The same page gives approximate shares of drugs that move to the next phase: about 70% after Phase 1, about 33% after Phase 2 and about 25 to 30% after Phase 3 (FDA, clinical research). A good result at one phase does not mean the drug will be approved.

A result from one phase is evidence for a narrow question. It is not a decision.

What an approval is

At the FDA, a team of physicians, statisticians, chemists, pharmacologists and other scientists in its Center for Drug Evaluation and Research (CDER) reviews the company's data and proposed labelling (FDA, development and approval process).

The FDA says approval means that data on the drug's effects have been reviewed by CDER, and that the drug is determined to provide benefits that outweigh its known and potential risks for the intended population. The page also says the agency and the drug maker may reach different conclusions after analysing the same data (FDA, development and approval process).

The page says the agency "generally" expects results from two well-designed clinical trials, and that in some cases, especially for rare diseases, convincing evidence from one trial may be enough (FDA, development and approval process).

Five checks a reader can make

1. Which stage is the result from? Animal, Phase 1, Phase 2, Phase 3 and post-approval studies answer different questions (FDA, clinical research).
2. Is there a regulatory decision? A paper describes a study. An approval is a regulator's decision on the data (FDA, development and approval process). For a UK reader, the relevant decision is the MHRA's, which this guide does not cover.
3. Does the approved use match the study? The FDA judges benefits and risks "for the intended population" (FDA, development and approval process). A trial in one group does not by itself show the same result for another.
4. Does the result cover risk? The FDA test is whether benefits outweigh known and potential risks (FDA, development and approval process). A report of benefit alone does not meet it.
5. Which route was used? In the US, Accelerated Approval can rest on a "surrogate endpoint" reasonably likely to predict clinical benefit. The drug maker must then run further trials to confirm the benefit, and the FDA may withdraw approval if they fail. Priority Review means the FDA aims to act within six months, against 10 months under standard review (FDA, development and approval process). Check the regulator's own notice for the approved use and any conditions.

Limits of this guide

• The pages used describe the US process only. We have not read MHRA, European Medicines Agency or NICE pages for this guide, and their routes and terms may differ.
• The FDA development and approval page was marked as current as of 8 August 2022 when we read it.

How this fits Vrulum's labels

On Vrulum, "Demonstrated" means shown in a published experiment, test or shipping product, and company announcements are treated as reported claims until someone else confirms them. A trial result labelled Demonstrated is not the same as a regulatory approval.