What are the Clinical Trial Phases?
Watch this video to learn about the three phases of clinical trials.
While preclinical research answers basic questions about a drug’s safety, it is not a substitute for studies of ways the drug will interact with the human body. “Clinical research” refers to studies, or trials, that are done in people. As the developers design the clinical study, they will consider what they want to accomplish for each of the different Clinical Research Phases and begin the Investigational New Drug Process (IND), a process they must go through before clinical research begins.
On this page you will find information on:
Designing Clinical Trials
Designing Clinical Trials
Researchers design clinical trials to answer specific research questions related to a medical product. These trials follow a specific study plan, called a protocol, that is developed by the researcher or manufacturer. Before a clinical trial begins, researchers review prior information about the drug to develop research questions and objectives. Then, they decide:
Who qualifies to participate (selection criteria)
How many people will be part of the study
How long the study will last
Whether there will be a control group and other ways to limit research bias
How the drug will be given to patients and at what dosage
What assessments will be conducted, when, and what data will be collected
How the data will be reviewed and analyzed
Clinical Research Phase Studies
Learn more about Clinical Trials.
The Investigational New Drug Process
Drug developers, or sponsors, must submit an Investigational New Drug (IND) application to FDA before beginning clinical research.
In the IND application, developers must include:
Animal study data and toxicity (side effects that cause great harm) data
Clinical protocols (study plans) for studies to be conducted
Data from any prior human research
Asking for FDA Assistance
Drug developers are free to ask for help from FDA at any point in the drug development process, including:
Pre-IND application, to review FDA guidance documents and get answers to questions that may help enhance their research
After Phase 2, to obtain guidance on the design of large Phase 3 studies
Any time during the process, to obtain an assessment of the IND application
Even though FDA offers extensive technical assistance, drug developers are not required to take FDA’s suggestions. As long as clinical trials are thoughtfully designed, reflect what developers know about a product, safeguard participants, and otherwise meet Federal standards, FDA allows wide latitude in clinical trial design.
FDA IND Review Team
The review team consists of a group of specialists in different scientific fields. Each member has different responsibilities.
Project Manager: Coordinates the team’s activities throughout the review process, and is the primary contact for the sponsor.
Medical Officer: Reviews all clinical study information and data before, during, and after the trial is complete.
Statistician: Interprets clinical trial designs and data, and works closely with the medical officer to evaluate protocols and safety and efficacy data.
Pharmacologist: Reviews preclinical studies.
Pharmakineticist: Focuses on the drug’s absorption, distribution, metabolism, and excretion processes.Interprets blood-level data at different time intervals from clinical trials, as a way to assess drug dosages and administration schedules.
Chemist: Evaluates a drug’s chemical compounds. Analyzes how a drug was made and its stability, quality control, continuity, the presence of impurities, etc.
The FDA review team has 30 days to review the original IND submission. The process protects volunteers who participate in clinical trials from unreasonable and significant risk in clinical trials. FDA responds to IND applications in one of two ways:
Approval to begin clinical trials.
Clinical hold to delay or stop the investigation. FDA can place a clinical hold for specific reasons, including:
Participants are exposed to unreasonable or significant risk.
Investigators are not qualified.
Materials for the volunteer participants are misleading.
The IND application does not include enough information about the trial’s risks.
A clinical hold is rare; instead, FDA often provides comments intended to improve the quality of a clinical trial. In most cases, if FDA is satisfied that the trial meets Federal standards, the applicant is allowed to proceed with the proposed study.
The developer is responsible for informing the review team about new protocols, as well as serious side effects seen during the trial. This information ensures that the team can monitor the trials carefully for signs of any problems. After the trial ends, researchers must submit study reports.
This process continues until the developer decides to end clinical trials or files a marketing application. Before filing a marketing application, a developer must have adequate data from two large, controlled clinical trials.