Different Phases of Clinical Trials and What They Mean

April 17, 2018 6:00 AM

Carefully monitored tests to gauge the strengths and side effects of a new medical treatment are crucial to improving care. Learn about each stage in the process.


Before any new drug or treatment can be marketed to the masses, it must be tested to ensure safety and effectiveness.

The process is known as a clinical trial.

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These research studies, which only use volunteer participants, compare potential medications or procedures against current methods — or placebos if an existing treatment isn’t available. Clinical trials follow strict procedure to achieve their goals and ensure that everyone involved is safely monitored throughout.

“Clinical trials are important and necessary to help further the therapies that we have available for many different diseases,” says Vallerie McLaughlin, M.D., director of the Pulmonary Hypertension Program at the University of Michigan Frankel Cardiovascular Center.

“The only way to get a drug, device, or another intervention approved is to do a clinical trial to demonstrate that the therapy works.”

Many trials are underway at the U-M; some involve healthy people while others target those with advanced disease. Costs of the clinical trial and the experimental therapy are generally covered by the trial’s sponsor — and patients can withdraw at any time.

Each trial falls within a certain phase. McLaughlin explained the phases and what all participants should know:

What each type of clinical trial means

Phase I: A new medication or treatment is tested for the first time “usually a trial in healthy volunteers to get some information about the dosing of a drug and about the side effects that might be expected,” McLaughlin says. Often everyone involved, including participants, knows what medication is being tested a model known as a nonrandomized, nonblinded study.

SEE ALSO: How Clinical Trials Helped Three Cancer Patients Thrive

Phase II: Testing uses a larger group of patients, all with a specific condition or disease. The intent: “to get information about how effective the drug is to treat certain parameters of that disease,” McLaughlin says. That helps researchers determine how well a medication or treatment works in response. It’s an important step to gather information for the next phase of the development process.

Phase III: Also called a pivotal trial, this phase marks the formation of two groups: those on the new drug and those receiving a standard treatment or placebo. A larger number of participants is often involved. Neither the subjects, doctors or researchers know which option a patient gets. Drugs that reach this stage are typically on a path to FDA approval, McLaughlin notes.

Phase IV: Taking place after federal approval, this phase is meant to find “other indications or scenarios for the drug,” McLaughlin says. That could include new uses for a medication, different ways to administer it or additional safety precautions. It’s also a chance to study the drug on specific populations, such as the elderly and those with certain racial and ethnic backgrounds.

Video courtesy of phaware global association