Clinical trial phases, explained

Where clinical trials fit

FDA describes drug development in five steps: discovery and development, preclinical research (laboratory and animal testing), clinical research in people, FDA review, and post-market safety monitoring. Clinical trials are the third step.

ClinicalTrials.gov, run by the National Library of Medicine at NIH, defines a clinical trial as a study in which researchers assign participants to an intervention to test what happens. In an observational study, researchers collect information but don't assign anyone a treatment. Phases apply to clinical trials of drugs and biological products.

The IND: permission to start testing in people

Before a new drug can be tested in people, its sponsor (a drug company, a university, a government agency or an individual physician) submits an Investigational New Drug application, or IND, to FDA. It covers animal pharmacology and toxicology data, how the drug is made, and the study plans and the qualifications of the investigators.

Federal law requires a drug to have an approved marketing application before it is shipped across state lines. The IND is the exemption that lets a sponsor send a drug under study to researchers in other states. The sponsor then waits 30 calendar days before starting any trial, while FDA checks that participants won't face unreasonable risk. FDA can also place a "clinical hold" that delays or stops a study.

What "investigational" means in a trial

In FDA's regulations, an investigational drug is a new drug or biological drug that is used in a clinical investigation. ClinicalTrials.gov puts it plainly: an investigational intervention is "not approved for doctors to prescribe to people."

One thing to keep in mind: approved medicines are studied in trials too, after approval and for possible new uses. A trial listing on its own doesn't tell you whether a medicine is approved. For what "approved", "investigational", "compounded" and "Schedule III" each mean, see what FDA approved, investigational and compounded mean.

A phase isn't a forecast

FDA's overview estimates that about 70% of drugs move on from Phase 1, about 33% from Phase 2, and about 25 to 30% from Phase 3. A later phase means a drug has gone further in testing. It doesn't mean approval will follow.

How approval follows

When a sponsor believes its trials show a drug is safe and effective for its intended use, it applies to market it. For most drugs that's a New Drug Application (NDA). For biological products it's a Biologics License Application (BLA).

An NDA holds all the preclinical and clinical data, from early research through Phase 3, plus proposed labeling. FDA first decides whether it's complete enough to review; once it is, FDA's overview says the review team has "6 to 10 months" to decide. Along the way FDA inspects clinical study sites, may ask an advisory committee of outside experts for advice, and works with the applicant on the prescribing information. A senior FDA official makes the final decision.

The decision is about that product, for its intended use in the population studied, as its labeling describes. To read that labeling, see how to read an FDA drug label. After approval, FDA keeps monitoring safety, and Phase 4 studies may follow.

How to read a study record

At the top you'll find the study's status, its title, its ClinicalTrials.gov ID, the sponsor, who provided the information, and the Last Update Posted date. The status sits in a colored box: green if the study is looking for participants or soon will be, red if it isn't, and brown if its status is unknown.

In the Study Overview section:

• Conditions: what the study is about.
• Intervention/Treatment: what's being tested.
• Study Type: Interventional (a clinical trial) or Observational, among others.
• Phase: the stage, using FDA's definitions.
• Study dates and Enrollment: start and completion dates, and the number of participants. Either can be marked "estimated", meaning it's what the researchers expect, not what has happened.

What each recruitment status means, from ClinicalTrials.gov's glossary:

"Completed" means a study ended. It doesn't mean the drug was approved. "Terminated" on its own doesn't tell you why a study stopped.

The Record History tab shows every change to the record over time.

Keep in mind who wrote it. ClinicalTrials.gov says the US government "does not review or approve the safety and science of all studies" it lists. The sponsor or investigator supplies the information and is responsible for its accuracy; the site's staff check only for apparent errors. A listing isn't an endorsement or an approval. If you're considering joining a study, ClinicalTrials.gov suggests talking it over with your health care professional first.

Peptimes and your records

Peptimes is a private iPhone tracker for the peptides, GLP-1 medications, testosterone and other compounds you already use. You log each dose yourself, set reminders at your own times, and can export your records as CSV or JSON for an appointment (how to export your records). Library labels are reference information.