What is a Clinical Trial?
- In Phase I trials, researchers test a new drug or treatment in a small group of usually healthy people (20-100) for the first time to evaluate its safety and determine a safe dosage -- or the amount or frequency of a drug.
- In Phase II trials, the drug or treatment is given to a larger group of people (generally 100-300) to see if it is effective and identify side effects -- or undesired reactions to a drug.
- In Phase III trials, the drug or treatment is given to large group of people (generally 1,000-3,000+) to confirm its effectiveness, monitor for less common side effects, and determine benefits for specific populations. If the drug proves safe and effective after Phase III trials, the FDA will often approve it for sale.
- In Phase IV trials, longer-term studies, conducted after medicine is approved, provide additional information across several thousand people on the drug or treatment's risks, benefits, and best use.
Sometimes researchers combine these phases in what is called a "seamless trial," but the study goals remain the same.
This video provides basic information about scientific research, the goals of research, and discusses how clinical research differs from medical care.