Phase 1 - 4 Clinical Study Trials - Research Centers & Doctors

In a Phase 1 study, humans are given a new drug for the first time. Usually, healthy people are enrolled in Phase 1 studies. Sometimes people with a certain disease may also be enrolled. Phase 1 studies help find out how a drug is broken down in the human body and how it interacts with the human body. Phase 1 studies reveal some of the side effects associated with a new drug. Information from Phase 1 studies is used to develop Phase 2 studies. Phase 1 studies can involve two groups, one group of people who get the new drug and another group which gets an inactive sugar-pill (placebo). About 20 to 80 people are included in a typical Phase 1 study, which lasts on the order of days to weeks.

In a Phase 2 study, a new drug is tested to see if it helps improve a particular illness. Researchers give the drug to people with the disease under study at the doses, and on the schedule, found to be safe in Phase 1 trials. During Phase 2, researchers collect additional data on the safety and efficacy of a drug, including short-term side effects and risks, and collect additional information about the proper dose and dosing schedule. Phase 2 studies often have at least two groups, people who get the new drug and people who get placebo; sometimes a standard treatment is also included for comparison. About 100 to 250 people are included in a typical Phase 2 study, which lasts on the order of weeks

In a Phase 3 study, research is expanded to longer, larger trials, after Phase 1 and Phase 2 studies have shown that the risk of side effects from a new drug is generally outweighed by its being helpful for the illness under study. However, since Phase 1 and Phase 2 studies include only a few hundred patients total, Phase 3 studies gather additional information needed to evaluate the overall benefit-risk relationship of a drug. Researchers collect additional information about drug-related side effects, including less common side effects. Several hundred to several thousand participants may be enrolled. Phase 3 studies commonly have at least two groups, people who get the new drug and people who get placebo, as well as a standard treatment group included for comparison. At the conclusion of a properly designed Phase 3 trial, the new drug will be found to be inferior, equivalent, or superior to placebo and/or the standard treatment. About 300 to 3,000 people are included in a typical Phase 3 study, which lasts on the order of weeks to months.

The intent of Phase 4, or post-marketing studies, is to learn more about the drug after it has been approved by government authorities. In Phase 4 studies, researchers gather information about an approved drug's risks, benefits, and best uses in ‘real-life’ conditions. These studies can also include trials of different doses or schedules of administration, other stages of disease or other disease and age groups, cost studies, quality-of-life studies, or use of the drug over a longer period of time.