source: Clinicaltrials.gov/ Glossary of Common Site Terms
Phase 1 : A phase of research to describe clinical trials that focus on the safety of a drug. They are usually conducted with healthy volunteers, and the goal is to determine the drug's most frequent and serious adverse events and, often, how the drug is broken down and excreted by the body. These trials usually involve a small number of participants.
Phase 2 : A phase of research to describe clinical trials that gather preliminary data on whether a drug works in people who have a certain condition/disease (that is, the drug's effectiveness). For example, participants receiving the drug may be compared to similar participants receiving a different treatment, usually an inactive substance (called a placebo) or a different drug. Safety continues to be evaluated, and short-term adverse events are studied.
Phase 3: A phase of research to describe clinical trials that gather more information about a drug's safety and effectiveness by studying different populations and different dosages and by using the drug in combination with other drugs. These studies typically involve more participants.
Phase 4: A phase of research to describe clinical trials occurring after FDA has approved a drug for marketing. They include postmarket requirement and commitment studies that are required of or agreed to by the study sponsor. These trials gather additional information about a drug's safety, efficacy, or optimal use.ype your paragraph here.
No Phase Specified: Interventional studies with no phase specified indicate the study investigator has not entered a phase when registering the study on ClinicalTrials.gov. This sometimes occurs for studies evaluating interventions such as exercise, physical therapy, speech therapy, and dietary supplements.
Analyzing the Parkinson's disease clinical trial pipeline to facilitate patient collaboration in research.