What is the focus of Phase 4 trials in drug development?

Phase 4 trials, also known as post-marketing studies, primarily focus on long-term monitoring for safety and effectiveness after a drug has received regulatory approval. These trials aim to collect additional information about the drug's risks, benefits, and optimal use in the general population, which may not have been fully understood during earlier phases of clinical trials. In Phase 4, researchers may observe how the drug performs in a broader patient population, assess its impact in real-world settings, and identify any rare or long-term side effects that were not evident in Phase 1, 2, or 3 trials. This ongoing evaluation enhances the understanding of the drug’s performance over time and contributes to improved patient safety and treatment guidelines.

The other options involve earlier stages of clinical development or different assessments. Testing a drug in healthy volunteers and conducting initial feasibility studies are typically associated with earlier phases of clinical trials. Establishing a drug's market potential is more related to commercial strategies rather than the focus of Phase 4 clinical trials.