Clinical trials, no matter how well designed, have inherent limitations:
- Limited population size: Even large Phase 3 trials rarely exceed 10,000 participants, making rare adverse events (occurring in fewer than 1 in 1,000 patients) difficult to detect
- Restricted populations: Trials often exclude elderly patients, children, pregnant women, and people with multiple health conditions, meaning drug behavior in these groups remains unknown at approval
- Controlled conditions: Trial participants receive careful monitoring that typical patients do not; interactions with other medications, dietary supplements, and real-world conditions may go undetected
- Limited duration: Most trials last months to a few years; long-term effects that take years to develop cannot be identified before approval
Post-marketing surveillance is not optional safety monitoring. It is essential protection for patients once a drug enters real-world use.
