What Are the 4 Phases of Clinical Trials?

Calendar Icon June 17, 2021
Reading Time Icon Read Time: 3 min
By Ciitizen

The process through which a therapeutic alternative becomes available for mass use requires a great deal of time and hard work. The researchers who run clinical trials and the patients who participate in them make it possible for new therapies to be tested and licensed. These clinical trials progress from one phase to another as the benefits, therapeutic dose, safety, and long-term effects are verified. In total, there are four phases of clinical trials, each of which pursues well-defined objectives necessary for the approval and establishment of the new treatment.

Once the drug or therapy under study has been proven to have positive effects, it is ready to begin its journey through the four phases of clinical trials. Here is a brief account of these phases with their characteristics and objectives.

Phase 1

Phase 1 clinical trials seek to determine the safety of a drug and the most appropriate dosage to administer said drug. The total number of participants usually ranges between fifteen and thirty, with the particularity that people with different types of cancer can participate. The trial consists of administering low doses and observing if adverse effects arise, so participants are carefully monitored as doses are gradually increased. The purpose is to establish a safe dose for the drug. Patients who choose to participate in Phase 1 clinical trials have likely tried all other available options without benefit. It is important to note that placebos are not used in this phase. Although there are patients who benefit from Phase 1 clinical trials, these trials do not focus on the response of the disease to treatment, but rather on the safety of a possible treatment.

Phase 2

Once the safety has been proven, the drug can move on to Phase 2, in which therapeutic effects for certain pathology are tested. Phase 2 clinical trials are almost always conducted with fewer than 100 participants, though this time, they share the same diagnosis. Testing the drug on a slightly larger group makes it possible to observe any side effects that went unnoticed in Phase 1. In this phase, placebos are not used. The participants are randomly assigned to different groups, which allows comparisons to be made either in therapeutic effect, tumor size decrease, quality of life improvement, etc.

Phase 3

When a new therapy reaches Phase 3, it is because its safety and effectiveness have already been tested. At this time, researchers want to find out if this new therapy outperforms existing conventional therapy in benefits. Phase 3 clinical trials generally require hundreds to thousands of participants within and outside the country. In this phase, patients are randomly assigned to different groups; those in the experimental groups will receive the new treatment, while those in the control groups will receive the conventional therapy that is currently available. It is possible that some of the participants will receive placebos. However, those groups will also receive conventional therapy at some point, since this process is not only about trying a new treatment but also about providing care and attention to all participants involved.

After Phase 3 clinical trials, new drugs can be authorized for massive use. If the clinical trial proves a treatment to be effective and safe, a New Drug Application is submitted to the FDA for approval.

Phase 4

Now that the drug has been approved and can be used massively in patients with a specific type of cancer, it remains to prove what the long-term effects are, if any. Of all the phases of clinical trials, this is the safest because the drug has already been proven effective and has been authorized for massive use. It involves thousands of participants around the world. Since its objective is to determine long-term effects, clinical trials in Phase 4 tend to last longer than those of the other phases. It is worth noting that those who participate in Phase 4 clinical trials do not receive special care or attention and are not strictly monitored. It is a type of clinical trial with more freedom for participants, as the primary objective is to collect information about the long-term benefits of the drug and expand on its side effects. In Phase 4 clinical trials, there is no need to divide participants into groups or use placebos.

When considering the possibility of participating in a clinical trial, many questions arise regarding the benefits of the process: Is it a convenient option? Which one will best suit your particular case? It is a long process and sometimes exhausting. Knowing the details of the four phases of clinical trials can help you better understand what to expect in each trial so you can choose the ones that best suit your needs as a patient.

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