Clinical trials are conducted in a series of steps called “phases.” Each phase has a different purpose and helps researchers answer different questions.

Phase I trials:

• Researchers test a drug or treatment in a small group of healthy volunteers (20–80) for the first time.
• The purpose of Phase I is to study the drug or treatment to learn about safety and identify side effects.
• Investigators tend to look for the best way to administer the drug/therapy such as orally, intravenously, or topically.

Phase II trials:

• The new drug or treatment is given to a larger group of people (100–300) to determine its effectiveness and to further study its safety.
• Volunteers receiving the drug/therapy may be compared to similar volunteers receiving a different treatment, usually a placebo or other treatment.
• The drug is also given to volunteers with a certain condition/disease to determine its effectiveness.

Phase III trials:

• The experimental drug or treatment is administered to large groups of people (1,000–3,000) to confirm its effectiveness.
• Monitor side effects; compare it with standard or equivalent treatments.
• Clinical trials gather more information about a drug’s safety and effectiveness by studying different populations, and dosages by using the drug in combination with other drugs.

Phase IV trials:

• A phase of research to describe clinical trials occurring after the FDA has approved a drug for marketing.
• Phase IV studies include post-market requirements and commitment studies that are required or agreed to by the study sponsor.
• These trials gather additional information about a drug’s safety, efficacy, or optimal use.

• The reasons that a person can/cannot participate in a clinical trial.
• The sponsor usually are the ones who create these guidelines for safety reasons.
• These criteria are usually age, gender, health status, no abnormal findings of clinical relevance at screening.

Pre-clinical

• The sponsor develops a new therapy in their laboratory.
• They test the new therapy on animals for toxicities.
• Apply for an Investigational New Drug Application to the FDA.

Clinical

• The therapy will 1st go through Phase I and Phase II of a clinical trial for testing.
• At the end of Phase II, the FDA and sponsor discuss how large-scale the study will be in Phase III.
• Phase III of a clinical study will typically have thousands of participants to gather more robust data.

FDA New Drug Application

• The sponsor submits a New Drug Application to the FDA for approval.
• Once approved, the FDA inspects all the facilities where the new therapy will be manufactured.

Post-Marketing

• This occurs in Phase IV of a clinical trial.
• The sponsor continues to monitor all serious unexpected adverse events.
• Once the FDA approves a therapy, the post-marketing monitoring begins. Typically includes a requirement for the sponsor to submit a safety report to the FDA periodically.