Describe the four phases of clinical testing in humans.

What will be an ideal response?

• Phase I: The first stage is carried out on a small number of healthy volunteer subjects (usually fewer than 100). The purpose is to observe how the drug works in humans, to determine general safety, and to see if there are any unexpected side effects.
• Phase II: The second stage involves a somewhat larger group of patients (250 subjects or more) with the target disease or illness. The purpose is to obtain a first reading about the potential effectiveness of the proposed drug and to determine whether it is appropriate for the trial to progress to the next stage of definitive testing. Phase II also provides additional information on safety and side effects.
• Phase III: The third stage involves larger groups of patients and is carried out with strict research protocols approved in advance by the FDA. Phase III trials are designed to determine the proposed drug’s effectiveness and also to see if there are significant side effects that will need to be considered by anyone using the drug in the future. The results of these trials are usually those that are eventually published in scientific literature, thereby providing researchers and potential users with scientific data about the proposed drug’s effectiveness in clinical settings with actual patients.
• Phase IV: If NDA status is granted, the FDA also mandates that the sponsor continue monitoring patient experiences with the new drug and report any adverse events through several reporting mechanisms. The purpose of this process is to pick up on any previously unexpected adverse reactions that may only appear with longer-term and more widespread use of the medication.