How to Track Post-Marketing Studies for Drug Safety

When a new drug hits the market, the work isn’t done. In fact, the real safety test begins after approval. Pre-clinical trials involve a few thousand patients under controlled conditions. They rarely include older adults, pregnant women, or people with multiple chronic conditions. That’s where post-marketing surveillance comes in - tracking how drugs behave in the real world, where millions of people use them every day.

Why Post-Marketing Studies Matter

Before a drug is approved, clinical trials are limited. They’re short, tightly controlled, and exclude large segments of the population. But once that pill is in millions of medicine cabinets, rare side effects show up. Maybe it causes liver damage in people with a specific gene. Maybe it interacts dangerously with a common over-the-counter painkiller. These aren’t theoretical risks - they’re real, and they’ve led to black box warnings, label changes, and even withdrawals.

The U.S. Food and Drug Administration (FDA) requires drugmakers to track safety after approval. This isn’t optional. It’s the law. And the data collected isn’t just paperwork - it’s what keeps patients safe. Between 2018 and 2022, 87% of safety actions taken by the FDA were triggered by findings from post-marketing studies. That means most drug safety updates you see - like new warnings on packaging or changes to dosing instructions - came from real-world use, not lab tests.

The Three Pillars of Post-Marketing Surveillance

Tracking drug safety isn’t one system. It’s three interconnected systems working together.

First is spontaneous reporting. This is where doctors, pharmacists, nurses, and even patients report unexpected side effects. The FDA’s FAERS (FDA Adverse Event Reporting System) is the main hub. As of 2023, it held over 30 million reports. Anyone can submit one - a patient who felt dizzy after taking a new blood pressure med, a nurse who noticed unexplained bleeding in a patient on an anticoagulant. These reports are the earliest warning signs.

Second is active surveillance. Unlike spontaneous reports, this system proactively digs into real-world data. The FDA’s Sentinel System analyzes health records from over 300 million Americans. It looks at insurance claims, electronic health records (EHRs), and lab results. It doesn’t wait for someone to report a problem - it finds patterns automatically. For example, if a new diabetes drug shows up in 15% more heart failure cases than expected across a million patient records, Sentinel flags it. This system caught safety signals that spontaneous reports missed, especially for drugs used by older adults.

Third is mandated post-marketing studies. The FDA can require drugmakers to run specific studies after approval. These aren’t optional. They’re legally binding. For example, a new cancer drug might be required to track long-term kidney damage in patients over 70. Or a psychiatric medication might need a 5-year study on suicide risk in teenagers. These studies are often slow. In fact, between 2015 and 2022, 72% of these studies missed their deadlines. The median completion time was 5.3 years - over two years past the required 3-year window.

How to Track These Studies - Step by Step

If you’re a pharmacist, clinician, or someone managing drug safety for a healthcare system, here’s how to stay on top of it.

1. Know your drug’s safety plan. Every approved drug has a Risk Evaluation and Mitigation Strategy (REMS). This document lists required post-marketing studies, monitoring protocols, and reporting obligations. Check the FDA’s REMS database or the drugmaker’s website. If a drug has a REMS, you’re expected to follow its rules.
2. Subscribe to FDA Drug Safety Communications. The FDA publishes these every week. They’re short, clear alerts about new risks, label changes, or study results. Sign up for email alerts. Don’t wait for a patient to come in with a problem - be proactive.
3. Use your EHR alerts. Many electronic health record systems now integrate with FAERS and Sentinel data. If your system flags a new safety signal for a drug your patient is taking, act on it. These alerts aren’t perfect, but they’re better than nothing.
4. Track study deadlines. If your organization is running a post-marketing study, use a centralized tracker. Set reminders for enrollment targets, data submission dates, and final reports. Miss a deadline, and you risk regulatory penalties - or worse, delayed safety updates.
5. Report everything. Even if you think it’s minor. A headache after a new medication? A rash? A change in blood sugar? Report it. The more data, the better the signal detection. In 2022, the UK’s Yellow Card system received over 76,000 reports - and 12% more than the year before. That’s because people kept reporting.

What Happens When a Problem Is Found?

Finding a problem is just the start. The real work is responding.

The FDA doesn’t pull drugs off the market lightly. Most actions are changes to the label. That means adding new warnings, changing dosing instructions, or restricting use in certain groups. Between 2018 and 2022, 87% of safety actions were label updates. That’s the most common outcome.

Sometimes, it’s a Dear Health Care Professional letter - a direct message from the drugmaker or FDA to doctors and pharmacists. These often come when a risk is serious but not common enough to warrant a label change.

Rarely, it’s a REMS modification. That might mean requiring special training for prescribers, limiting distribution to certified pharmacies, or requiring regular blood tests.

Withdrawals happen less than 1% of the time. But they do happen - when the risk clearly outweighs the benefit, and no other solution works.

The Big Challenges

It’s not easy. There are major gaps.

One problem is data quality. The Sentinel System uses insurance claims and EHRs, but those records often lack details. Did the patient have kidney disease? Were they taking other meds? Were their lab values normal? Without this, it’s hard to tell if a side effect is truly caused by the drug or something else.

Another issue is speed. Post-marketing studies take years. By the time results come in, the drug may have been used by millions. That’s why the FDA is testing new tools. In 2023, pilot programs using Large Language Models (LLMs) to scan unstructured EHR notes improved signal detection by 42%. But they also generated 23% more false alarms. It’s a trade-off.

And then there’s global coordination. The U.S. has FAERS and Sentinel. The EU has EudraVigilance. Japan has its own system. But data doesn’t flow easily between them. That’s why the WHO is pushing for a global pharmacovigilance network by 2027 - to catch signals that one country might miss.

What’s Next?

The future of drug safety is smarter, faster, and more connected.

By 2026, the FDA’s Sentinel Common Data Model Plus (SCDM+) will include genomic data for 50 million patients. That means we’ll be able to see if a side effect is linked to a specific gene - not just age or gender.

The EU is launching an AI-powered signal detection system in 2025. It will analyze millions of reports automatically, reducing manual review time.

And drugmakers are finally getting better at tracking their own studies. Distributed data networks have cut study start times from 14 months to under 9 months. That’s progress.

But the most important tool hasn’t changed: people. Doctors reporting side effects. Pharmacists asking patients about new symptoms. Nurses noticing unusual patterns. Technology helps - but it doesn’t replace human vigilance.

What You Can Do Today

You don’t need to be a regulatory expert to make a difference.

- If you prescribe a new drug, check its REMS status.

- If you’re a pharmacist, encourage patients to report side effects - even small ones.

- If you’re a patient, keep a simple log: what you took, when, and how you felt. Bring it to your next appointment.

- If you’re in healthcare management, make sure your team has access to FDA safety alerts and knows how to report.

Drug safety isn’t a one-time check. It’s a continuous conversation - between patients, providers, regulators, and manufacturers. The more voices in that conversation, the safer we all are.

Final Thoughts

Drug safety doesn’t end at approval. It’s a living system - constantly updating, responding, and adapting. The tools are getting better. The data is growing. But the core remains the same: someone has to notice something unusual and speak up. Whether you’re a doctor, a pharmacist, a patient, or a researcher - your observations matter. The next safety alert might come from your report.