Which clinical trial phase is typically the last step before a drug is approved for public use?

Phase III is the final stage of clinical trials before a drug can be submitted for approval to the regulatory authorities. During this phase, the drug is tested on a larger group of patients to evaluate its effectiveness, monitor side effects, and compare it to commonly used treatments. This large-scale testing is essential for confirming the drug's benefits and risks in a wider population, which helps to ensure that it can be utilized safely in the general public. The data gathered from Phase III trials is critical for filing a New Drug Application (NDA) or Biologics License Application (BLA) with regulatory bodies such as the FDA.

Following Phase III, if the data is favorable, the drug can be approved for public use. Phase IV would occur post-approval to monitor long-term effects of the drug, while Phase I and Phase II focus on earlier stages of testing with smaller groups to primarily assess safety and efficacy.