The single largest change to peptide access in the last five years had nothing to do with new science. It was an inventory designation.
Under section 503A of the Food, Drug and Cosmetic Act, compounding pharmacies generally may not prepare copies of commercially available FDA-approved drugs. There is an exception: when a drug is on FDA's official shortage list, that restriction relaxes. It exists so patients aren't stranded when a manufacturer can't supply.
When demand for the incretin drugs outran manufacturing capacity, both tirzepatide and semaglutide landed on that list. The exception opened, and an entire industry — compounding pharmacies, telehealth prescribers, marketing operations — assembled inside it, at a scale the provision was never designed to accommodate.
Then the shortages resolved
Manufacturing caught up. FDA removed tirzepatide from the shortage list in late 2024, and semaglutide followed in early 2025. Both determinations were contested, and the tirzepatide decision in particular went through reconsideration before being reaffirmed.
Removal from the list closes the exception. FDA set transition windows rather than an overnight cutoff — different dates for 503A pharmacies and 503B outsourcing facilities — but the direction was one-way. The legal basis for mass compounding of those molecules ended with the shortage that created it.
What actually changed, and what didn't
Changed: the lawful supply of compounded copies of those specific molecules, at scale, through pharmacy channels. Businesses built entirely on that provision had no successor pathway.
Didn't change: anything about the molecules themselves, the trial evidence behind the branded products, or the status of research-use-only material — which was never operating under the shortage exception in the first place and is a separate category with separate rules.
The distinction matters because the two got conflated constantly during the boom. The shortage exception was a pharmacy provision governing prescription compounding for patients. It never legalised anything in the research-supply market, and its closure didn't change that market's status either.
Why this is still the most important story in the field
Because it demonstrates the actual mechanics of how access moves here. Not scientific breakthroughs — administrative determinations. A list, a designation, a transition window. Two years of market structure opened and closed on a supply-chain judgment most participants never read.
It's also the backdrop to the compounding-list vote now working its way through rulemaking. That process would create a durable lane for certain peptides in pharmacy compounding — one that doesn't evaporate when a manufacturer catches up. Whether it lands, and in what form, is the thing to watch through 2027.
The Assay covers the peptide news cycle from primary sources. Nothing here is legal or medical advice. Research use only.
For research use only · Not for human or veterinary use · No compound discussed here is FDA-approved for any indication