About Clinical Trials

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What is a clinical trial?

A clinical trial is a type of research study designed to learn if an investigational drug, device or procedure is safe, how it works in the body, and if it works to treat a specific disease. “Investigational” means that regulatory authorities, such as the FDA in the US or the EMA in Europe, have not yet approved it for use for a particular condition, disease, or patient population.

Without clinical trials, there would be no new medications.

Before a drug is made available to the general public, it must go through several phases of clinical research and regulatory approvals that show that it is safe and effective in treating a specific disease within the patient population that participated in the clinical trial. Most available medications are the result of past clinical research driven by patients’ unmet needs and lack of adequate treatment options. Without clinical trials and volunteer study participants, there would be no new medications.

Why diversity matters in clinical research.

Once approved, drugs are prescribed for people of all different ages, genders, races, and ethnicities. Unfortunately, minority groups are underrepresented in clinical trials. This is a problem because drugs can work differently in different people, depending on some of these individual characteristics. Increasing diversity in clinical research will lead to better research, treatments and health outcomes for all people.

The phases of clinical research

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Clinical trials for investigational drugs are done in steps or "phases." Each clinical phase has a different purpose and helps the study researchers answer specific questions about the drug being tested. These phases are designed to minimize risk to study participants and also advance clinical research. If an investigational drug fails during any clinical phase, it does not move into the next phase of research.

Pre-clinical trials

Conducted in a laboratory and evaluate safety and potential effectiveness. From there, the investigational drug may move into clinical trials in humans.


Phase I

Evaluate the potential safety profile and possible/likely side effects of an investigational drug in a small group of people.


Phase II

Further identify side effects and risks associated with the investigational drug and help to determine which dose of the drug works best. Phase II clinical trials are usually conducted with a larger group of people than Phase I clinical trials.


Phase III

Further evaluate an investigational drug’s safety, effectiveness, and side effects in an even larger group of people. Phase III clinical trials help to confirm the findings of earlier research and may compare the investigational drug to existing approved treatments or to no treatment, possibly using a placebo. A placebo looks like the investigational drug but does not have the active ingredient.


Phase IV

Refers to ongoing testing of a drug that occurs after that drug has been approved and made available to the general public, most often to evaluate its long-term effectiveness.

Who is involved?

Have questions? We’ve got answers.

Takeda's Commitment
Why do people choose to take part in clinical trials?
What are some of the risks in taking part in a clinical trial?
What should a person consider before taking part in a clinical trial?
What is informed consent?
What rights do participants have in a clinical trial?

Still have questions?

To learn more about clinical trials and whether participation might be right for you or someone close to you, please speak with your doctor.