A PMR is required by law; a PMC is only promised

One word in the name decides the rest

A postmarketing requirement (PMR) is a study or clinical trial an applicant is required by statute or regulation to conduct after approval. A postmarketing commitment (PMC) is a study the applicant has agreed in writing to conduct, with no statute or regulation obligating it. Both can be imposed at the moment of approval or added afterward, and both can cover the same kinds of science — clinical safety, clinical efficacy, clinical pharmacology, nonclinical toxicology. The difference FDA's own reporting system tracks isn't what the study measures; it's whether FDA could have made the sponsor run it at all.

505(o)(3) only reaches four specific reasons

Section 505(o)(3) of the Act, added by the Food and Drug Administration Amendments Act of 2007, lets FDA require a postmarketing study or clinical trial for one of a closed set of purposes: assessing a known serious risk, assessing signals of a serious risk, or identifying an unexpected serious risk — and, after the SUPPORT Act added a fourth purpose in 2018, assessing a known serious risk of the drug failing to produce its expected pharmacological action. FDA can't reach for 505(o)(3) just because a question is scientifically interesting; the statute also requires the agency to first find that the two lighter-weight tools it already has — spontaneous adverse event reporting under 505(k)(1) and active risk-identification surveillance under 505(k)(3) — wouldn't be sufficient on their own. A PMR is what's left once those tools are ruled out, not a first choice.

A confirmatory trial runs on a different authority entirely

The postmarketing study tied to an accelerated approval — the trial meant to verify the clinical benefit a surrogate endpoint only predicted — isn't a 505(o)(3) PMR at all. It runs under section 506(c) of the Act and 21 CFR 314.510 for drugs, or 601.41 for biologics, with its own consequence for falling short: if the trial fails to verify clinical benefit, or the sponsor doesn't pursue it with due diligence, FDA can withdraw the approval after a hearing under 21 CFR 314.530. That's a different remedy than anything 505(o)(3) carries, which is why a sponsor juggling both kinds of postmarketing study on the same product is really juggling two separate legal regimes that happen to produce similarly shaped trial protocols.

Missing a PMR's deadline is misbranding, not just a late report

A sponsor that misses a PMR's required timetable without showing good cause has done more than fall behind on paperwork: FDA's position, applied in at least one public warning letter, is that the drug becomes misbranded under section 502(z) of the Act, 21 U.S.C. 352(z), and the violation can draw a civil monetary penalty of up to $250,000 under 21 U.S.C. 333(f)(4), with more for a violation that continues uncorrected. FDA's own draft guidance on determining PMR noncompliance carves out exactly the territory the last section described as separate — it doesn't apply to accelerated-approval confirmatory trials, pediatric PMRs, or PMRs based on animal-efficacy findings, because those already run on their own enforcement paths. Nothing in that penalty structure reaches a PMC. A sponsor that quietly drops a postmarketing commitment has broken a promise to FDA, which is its own kind of problem, but it hasn't misbranded anything.

Both still report through the same annual filing

The distinction doesn't carry through to how the two get tracked. 21 CFR 314.81(b)(2)(vii) requires the same annual report to cover the status of every PMR and every PMC — clinical safety, efficacy, pharmacology, and nonclinical toxicology studies in either category, with CMC-related commitments excluded from the count. FDA treats a complete annual report under that provision, or its biologics counterpart at 21 CFR 601.70, as satisfying the separate periodic-reporting duty that 505(o)(3)(E)(ii) imposes specifically on PMRs. A tracker that files both kinds of study in the same annual-report queue is handling the reporting mechanics correctly; it's the determination behind each entry — was this one ordered, or only offered — that the mechanics alone won't supply.

Where this meets the file

A postmarketing-study tracker that keeps the legal basis — 505(o)(3) purpose, accelerated-approval Subpart H or E, or commitment-only — as its own required field, separate from the study's protocol and due date, is previewed in the launch catalog alongside this week's other drug-lifecycle templates. If your program tracks that distinction differently, the shelf takes that correction directly.