Before a new drug or device can be sold to consumers, it must go through several phases of clinical research to ensure that it is safe and effective. There are typically four or five clinical research study phases, and each phase is considered a separate trial that builds upon the last. Upon the completion of a successful phase of research, scientists submit their data to the FDA for approval. If the FDA permits the researchers to continue, they may advance to the next phase of research.
If you’re considering participating in a clinical research study, you may find it helpful to learn more about the clinical research study phases, as each phase reveals where researchers are in the process of development and presents unique pros and cons for participants.
The clinical research study Phases
After conducting extensive laboratory research and receiving approval from the Food and Drug Administration (FDA), researchers may begin testing an experimental drug or device on humans. Each phase of a clinical research study accomplishes a different purpose and answers different questions.
Phase 0 Studies
Often skipped because they fail to provide data on safety or efficacy, phase 0 trials are exploratory studies in which a very small dose of a drug is given to a limited number of participants (typically fewer than 15). In these studies, the researchers are aiming to learn how participants’ bodies process the treatment and how the treatment affects their bodies. In addition, phase 0 studies can expedite and streamline the drug approval process by revealing any problems with the body’s reaction to the treatment upfront. While phase 0 studies pose little risk due to the low dosage of the treatment being studied, they are also very unlikely to benefit the participants.
Phase I Studies
In most research, a phase I study is the first involving people, but only a small number of participants are involved (usually between 20 and 100). This phase is used to assess the safety of the drug or device, so researchers closely watch participants for side effects. It is also used to determine what the drug or device does to the human body and what the body does with the drug, including absorption, metabolization, and excretion.
In the beginning, very low doses are given to very few participants, and researchers watch these participants closely for side effects. If the side effects are minimal or nonexistent, the researchers increase the dosage levels. This process continues until the side effects become too severe or the desired effect is produced. The aim is to find the ideal dose of the treatment that can be given safely without producing serious side effects. While this phase of clinical research is designed to test the drug’s safety and carries potential risks for participants, it may help some patients as well. If researchers determine that the new treatment is reasonably safe, it may progress to a phase II clinical research study.
Phase II Studies
Does the treatment work? Does it fulfill its intended purpose? How well does it work? Researchers aim to answer these questions in phase II studies, which test the efficacy of a new drug or device. Up to several hundred patients are involved at this stage of research, with larger groups of patients than in phase I. Although the focus is efficacy, researchers will also continue the safety assessment from phase I on the larger groups of participants and patients in phase II, looking for rare side effects and other safety concerns.
Phase II studies are often randomized trials, in which participants are divided by chance into separate groups that receive different treatments or interventions, allowing for comparison. In some studies, one group will receive the experimental treatment, while the other group (the “control” group) receives a standard treatment or placebo. Studies are often “double blind” as well, which means that neither the patients nor the researchers know who has received the experimental treatment. At the end of the study, if enough patients benefit from the treatment and the side effects aren’t unreasonably severe, the researchers may advance to a phase III clinical research study.
Phase III Studies
Further testing safety, efficacy, and effectiveness, phase III studies compare an experimental drug or device to the current standard treatment. Researchers examine each treatment’s side effects and efficacy to determine which treatment works better. Large-scale studies that may last several years in total, phase III studies typically involve at least several hundred patients. They are randomized and, when possible, incorporate double-blind testing. As with phase I and phase II trials, participants are watched closely for troubling side effects and the treatment is halted if the side effects become too severe.
Phase III studies aim to provide the pharmaceutical company and the FDA with a more thorough understanding of a new treatment, including its benefits and potential adverse reactions. Once this phase is completed with successful results, the pharmaceutical company may request FDA approval to market the new drug or device.
Phase IV Studies
After the FDA has approved a drug or device for consumer sale, the final phase of research commences. Also called Postmarketing Surveillance, phase IV studies are conducted to learn more about the long-term side effects and safety of approved drugs. They seek to answer an important question: What else do we need to know about this treatment? Often involving several hundreds or thousands of patients, and conducted for a minimum of two years, phase IV studies help doctors learn more about how well a treatment works, both on its own and when combined with other treatments. Pharmaceutical companies may also use phase IV studies for the following objectives:
- To compare the treatment with other treatments on the market
- To monitor the treatment’s long-term effectiveness
- To assess the treatment’s impact on patients’ quality of life
- To determine the cost-effectiveness of the treatment
At this late stage in the development process, the treatment has been studied extensively and is already available to doctors and patients. It is typically the safest of the clinical research study phases because the treatment has already received FDA approval. By taking part in the study, participants are simply helping researchers learn more about the drug or device, which can benefit people who might need the treatment in the future. Based on the findings of a phase IV trial, restrictions may be placed on the studied product or it may be taken off the market.
If you’re exploring the possibility of participating in a clinical research study, be sure to ask which phase you’ll be joining. Discuss the potential benefits and risks with your doctors, your family, and your friends to ensure you’re making a prudent decision for your health.
To learn more about participating in a clinical research study, contact QPS Missouri. Since opening its doors in 1994, QPS Missouri has conducted over 1,000 FDA-regulated studies, paying out over $35 million to local participants. Your local participation could have a global impact, as QPS is an international leader in contract research with facilities in North America, Europe, and Asia. Our mission is to accelerate the development of drugs worldwide by enabling breakthroughs in pharmaceutical innovation. If you would like to join us in this mission, consider applying for a clinical research study.
To get started, you simply need to fill out an online application. Within 48 business hours, a recruiting coordinator will contact you for your pre-screening assessment. To learn more, please visit the QPS Missouri website, review the study participation process, or check out our list of FAQ.