> ## Documentation Index
> Fetch the complete documentation index at: https://glossary.micahealth.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Phase 4

Studies conducted after FDA has approved a drug for marketing, including required postmarket studies that sponsors must perform or have agreed to conduct. These trials gather more data about the drug's safety, effectiveness, and best use in real-world conditions.

## Related terms

<CardGroup cols={3}>
  <Card title="Protocol" href="protocol" />
</CardGroup>

[*Source*](https://clinicaltrials.gov/study-basics/glossary)