Section 503A lets a licensed pharmacy compound a drug for an identified patient without FDA approval, but not a copy of an approved drug unless the prescriber documents a significant difference for that patient. On 18 September 2026 FDA told Empower Pharmacy that its semaglutide/B12 and tirzepatide/niacinamide products were "essentially copies" and that the volume made the differences look "pretextual". FDA has also proposed keeping semaglutide, tirzepatide and liraglutide off the 503B bulks list; that decision is still pending.
What we read
Section 503A of the Federal Food, Drug, and Cosmetic Act (FDCA) as amended by the Drug Quality and Security Act of 2013; the publicly posted minutes from the FDA Pharmacy Compounding Advisory Committee meetings of October 2024 and April 2026; FDA shortage-status determinations for semaglutide and tirzepatide from 2023 through April 2026; and contemporaneous reporting on compounded-GLP-1 telehealth providers (Hims, Ro, Mochi, Henry, Eden) through the shortage-end transitions.
What Section 503A actually does — and what it doesn't
Section 503A is the part of US drug law that lets traditional compounding pharmacies prepare individualized prescriptions for specific patients without going through the full new-drug-application process. It exists because clinical practice sometimes requires formulations that brand-product manufacturers don't make — different strengths, allergen-free versions, alternative delivery formats.
The 503A exemption comes with conditions. Two of them matter for the GLP-1 story:
- The compound cannot be on the FDA's "do not compound" list. This list is maintained by the FDA based on PCAC recommendations, and it covers substances that the FDA has determined are unsafe, ineffective, or otherwise inappropriate for traditional compounding.
- The compound cannot be a copy of a commercially-available drug product. A 503A pharmacy cannot compound a near-identical version of an FDA-approved drug just because the patient prefers it; the compounded version must serve a clinical need the brand product doesn't meet.
There is a narrow exception to the second condition: if the brand product is in FDA-confirmed shortage, compounded versions become permissible during the shortage period. This shortage exemption is the door through which compounded semaglutide and tirzepatide entered the legal telehealth channel from 2022 onward.
The 2022 semaglutide and tirzepatide shortage that opened the door
Brand semaglutide (Wegovy) entered FDA-confirmed shortage in March 2022. Brand tirzepatide (Zepbound, Mounjaro) entered FDA-confirmed shortage in late 2022 and remained there through most of 2024. The shortage exemption under 503A made compounded versions of both compounds legally available — and a category of telehealth provider emerged to use that exemption commercially:
- Hims & Hers — compounded semaglutide via partner pharmacy network
- Ro Body — compounded semaglutide and tirzepatide
- Mochi Health — compounded tirzepatide at the lower price point
- Henry Meds — compounded semaglutide and tirzepatide
- Eden — compounded semaglutide and tirzepatide
The combined monthly active patient base across this category at peak in 2024 was reportedly in the hundreds of thousands. The legal basis for the entire category was the shortage-exemption door under 503A.
How the compounded-GLP-1 door closed — two stages, two PCAC votes
The shortage door closed in two stages, each approximately matching one of the PCAC meeting cycles.
October 2024 — tirzepatide added to the list
At the October 2024 PCAC meeting, the committee voted to recommend adding tirzepatide to the 503A do-not-compound list. The recommended addition was based on safety and efficacy concerns specific to compounded versions during the shortage period — the PCAC presentation cited dose-mismatch incidents and labeling-quality issues observed across the compounded-tirzepatide market.
The vote did not immediately bind compounding pharmacies. PCAC recommendations require formal FDA action to enter regulatory effect, and that process can take months. But the policy direction was set in October 2024, and the compounding-pharmacy and telehealth provider networks began planning for the wind-down accordingly.
Late 2024 to early 2025 — shortage status changes
Through late 2024 and into 2025, the FDA-confirmed shortage status for both semaglutide and tirzepatide began to wind down. Brand-product availability stabilized as Eli Lilly and Novo Nordisk completed manufacturing capacity expansions. With brand product available, the shortage-exemption door that had supported compounded versions began closing on the brand-availability side, independent of the PCAC process.
The combined effect: compounded telehealth providers faced two simultaneous pressures. The 503A do-not-compound list was moving toward formal restriction (PCAC track), and the shortage exemption that justified the compounded versions in the first place was being removed (brand-availability track).
April 2026 — PCAC reaffirms
At the April 2026 PCAC meeting, the committee reaffirmed the compounding restrictions on the GLP-1 class, extending and formalizing the regulatory direction set in October 2024. The reaffirmation closed the question of whether the October 2024 vote would face reversal under regulatory or political pressure: it did not, and the direction on the GLP-1 class has held since. That stability is specific to GLP-1s. Three months later the same committee moved the opposite way on a different set of peptides.
The practical effect on the legal compounded-GLP-1 market is severe. The category that existed at peak in 2024 has substantially contracted. Some telehealth providers have pivoted to brand-only prescription pathways (more expensive, slower reimbursement). Some have exited the GLP-1 line entirely. The compounded-tirzepatide category specifically is approaching closure.
July 2026 — the same committee moves the other way
On 23 and 24 July 2026 the PCAC met again, and this time the direction reversed. The agenda was seven non-GLP-1 peptides nominated for addition to the 503A Bulks List, and the committee recommended six of them.
| Peptide | Vote | Result |
|---|---|---|
| BPC-157 | 8-6, 1 abstention | Recommended |
| KPV | 8-6, 1 abstention | Recommended |
| TB-500 | 8-6, 1 abstention | Recommended |
| MOTS-c | 7-5, 2 abstentions | Recommended |
| Semax | 8-5, 1 abstention | Recommended |
| Epitalon | 7-4, 1 abstention | Recommended |
| Emideltide (DSIP) | 6-7, 1 abstention | Rejected |
Tallies as reported by trade press and law-firm summaries after the meeting. FDA has not posted minutes or official vote counts, and published summaries disagree on some margins (Frier Levitt, for example, reports Epitalon at 7–5 and DSIP rejected 7–6). We have not confirmed any tally against an FDA record.
Three months earlier, on 15 April 2026, FDA had already removed twelve substances from the Category 2 do-not-compound list, a superset of the seven later voted on.
Two things about this matter for reading the 503A picture correctly.
The two tracks are independent. Semaglutide and tirzepatide were not on the July agenda and their restrictions are unchanged. A committee tightening the GLP-1 class while loosening a separate peptide class is not inconsistent, because the questions in front of it were different ones.
Neither step legalised anything. Category 2 removal does not confer compounding eligibility, and an advisory recommendation is not a rule. FDA must complete notice-and-comment rulemaking, expected to reach 2027 or beyond, or separately grant interim Category 1 status. FDA's own review scientists recommended against all seven nominations. The detail, including what it does and does not mean for buyers, is in our FDA peptide vote explainer.
What did FDA's Empower letter change for 503A GLP-1 compounding?
The shortage exemption ended in 2025. Footnote 3 of the letter dates the end of FDA's enforcement discretion for copies at 5 March 2025 for tirzepatide and 24 April 2025 for semaglutide. After that, the 503A route for these drugs depended on one condition: the compounded product must not be "essentially a copy" of an approved drug, which in practice means a prescriber has to document a significant difference for the identified patient. Much of the market met that condition by adding an ingredient, usually vitamin B12 to semaglutide or niacinamide to tirzepatide.
FDA's warning letter 738238, dated 18 September 2026 after a November 2025 inspection of Empower's Houston facility, answers that model in three steps.
1. The add-on does not make it a different drug. FDA named "TIRZEPATIDE/NIACINAMIDE (4 ML)(17/2 MG/ML)", "SEMAGLUTIDE/CYANOCOBALAMIN (1 ML)(5/0.5 MG/ML)" and a second tirzepatide/niacinamide strength, which "appear to be essentially copies of FDA-approved semaglutide and tirzepatide products," compounded "regularly and in inordinate amounts."
2. Volume is evidence. "The volume of products you are producing suggests that differences between products you are compounding and the FDA-approved products are pretextual." The monthly order counts are redacted. Frier Levitt, a compounding-law firm, calls it the first time it has seen FDA use "pretextual" this way in a warning letter, and notes that the framing tracks arguments Lilly and Novo Nordisk have made in private suits against compounders.
3. A menu is not a clinical judgment. FDA found prescriptions with no significant-difference determination at all, and others where the statement appeared "repeated verbatim across many records, suggesting that they may be pre-generated." It singled out "third-party technology platforms that provide prescribers with pre-selected menu options for choosing a statement of significant difference." That sentence reaches past the pharmacy to the telehealth platforms that send it prescriptions.
The letter also cites sterility and CGMP problems (aseptic processing, media fills, environmental monitoring) and gave Empower 15 working days to respond. Empower told CBS it had "already remedied many of the issues outlined in the Warning Letter" (CBS, 24 September 2026).
The compounding trade group disagrees with one reading. The Alliance for Pharmacy Compounding wrote that "volume itself is not the violation" and that the letter does not declare all combination GLP-1s to be copies; FDA's concern, in its reading, is missing documentation of each prescriber's judgment. Both readings lead to the same practical test. A 503A GLP-1 prescription now needs a reason written for that patient, and a pharmacy filling thousands of identical "B12" prescriptions a month is the pattern FDA described.
For patients, r/tirzepatidecompound's "New FDA Warning Letter issued to Empower Pharmacy" thread shows the immediate question: will my pharmacy keep filling? A warning letter is not a shutdown order. It is the step before seizure or injunction if FDA judges the response inadequate.
Is the 503B route for semaglutide and tirzepatide still open?
It is narrowing, and the decision is pending. Outsourcing facilities under section 503B can compound from bulk ingredient only if the substance is on the 503B bulks list (or the drug is in shortage). On 30 April 2026 FDA proposed not to add semaglutide, tirzepatide or liraglutide, finding no clinical need. It extended the comment period to 30 July 2026 (docket FDA-2018-N-3240). FDA says it will publish a final determination in the Federal Register; we found none as of 5 October 2026.
| Route | Status, 5 October 2026 | Source |
|---|---|---|
| 503A, patient-specific with documented significant difference | Open, narrow | FD&C Act 503A; Empower letter |
| 503A, B12/niacinamide blends at volume | FDA says "essentially copies" | Letter 738238, 18 Sep 2026 |
| 503B from bulk semaglutide/tirzepatide | Proposed exclusion, final decision pending | FR 2026-08552, 2026-12937 |
| Shortage exemption | Closed (discretion ended 5 Mar 2025 tirzepatide, 24 Apr 2025 semaglutide) | Letter 738238, footnote 3 |
| Retatrutide | Not compoundable; not approved | Lilly, 12 Aug 2026 |
Why this matters for the research-peptide market (it's all demand-linked)
The compounding restrictions did not close any research-peptide vendor. The two markets are legally distinct: 503A governs prescription compounding by licensed pharmacies; research-peptide sales are unrelated to 503A and are governed by the FDA's misbranding and unapproved-drug authorities (the FDA Warning Letter track).
But the two markets are demand-linked. The closure of the legal compounded-GLP-1 channel removed a substantial fraction of legal buyer access to GLP-1 compounds without a brand-product prescription. A portion of that displaced demand migrated to the research-peptide channel, which exists in a different legal category but offers overlapping compounds (semaglutide, tirzepatide, retatrutide).
This migration is what made the research-peptide vendor market larger and more visible through 2024–2026. It is also what attracted the increased FDA Warning Letter enforcement in the September 2025 sweep and following actions: as the demand pressure pushed research-peptide vendors toward more aggressive marketing, the FDA's unapproved-drug-claims authority became the active enforcement tool.
The pattern: regulatory pressure on the legal channel produces demand pressure on the adjacent channel; the adjacent channel responds with marketing language that crosses into drug-claims territory; the FDA's misbranding authority responds in turn. The PCAC track, the shortage-status track, and the Warning Letter track are three separate regulatory mechanisms that have collectively reshaped what is buyable in the GLP-1 category. In August 2026 the warning letter track reached the code-named GLP-1 SKUs directly: five letters dated 24 August name semaglutide, tirzepatide and retatrutide products at research-peptide vendors as unapproved new drugs (see our enforcement timeline).
What the buyer should track from here — three forward indicators
Three forward indicators that will move the market further over 2026–2027.
The retatrutide approval timeline. If brand retatrutide receives FDA approval in 2027 (see our TRIUMPH-4 Phase 3 results read), it adds a brand prescription product to the legal channel. It does not open a compounded retatrutide channel — retatrutide is not in the existing shortage category and would not enter compounding eligibility on approval.
The semaglutide / tirzepatide brand-shortage status. If either brand product re-enters confirmed shortage (manufacturing disruptions, demand spikes), the 503A shortage exemption could re-open partially for that compound. The April 2026 PCAC reaffirmation makes a partial re-opening narrower than the 2022–2024 window, but the door is not permanently sealed.
The FDA Warning Letter cadence. The Warning Letter pace through late 2025 and early 2026 was the highest of the cycle. Whether this pace continues, accelerates, or slows is the leading indicator for research-peptide vendor exposure. The FDA Warning Letters database is the place to track this directly.
Sources
- Section 503A of the FDCA: FDA — 503A regulatory overview
- FDA Pharmacy Compounding Advisory Committee (PCAC) — meeting materials and minutes
- FDA drug shortage database — historical semaglutide and tirzepatide shortage status
- FDA Warning Letters database
- FDA warning letter 738238, Empower Pharmacy, 18 September 2026, posted 22 September 2026
- Frier Levitt on the Empower letter, 25 September 2026
- Alliance for Pharmacy Compounding, 25 September 2026
- CBS News, 24 September 2026
- 503B bulks proposal: FR 2026-08552 (1 May 2026); FR 2026-12937 (comment extension to 30 July 2026)
- Internal: FDA peptide enforcement, 2024–2026, TRIUMPH-4 Phase 3 retatrutide results, retatrutide vs tirzepatide research comparison, tirzepatide vs semaglutide, longevity telehealth platforms
Frequently asked
What is Section 503A of the FDCA?
Section 503A is the part of US drug law that lets traditional compounding pharmacies prepare individualized prescriptions for specific patients without going through the FDA's full new-drug-application process. It exists because clinical practice sometimes requires custom strengths, allergen-free versions, or alternative formats the brand product doesn't offer. The exemption comes with conditions — the compound can't be on the FDA's "do not compound" list, and can't be a copy of a commercially-available product (unless that product is in FDA-confirmed shortage).
Are compounded GLP-1 drugs still legal in 2026?
Only for patient-specific prescriptions. FDA's enforcement discretion for copies ended on 5 March 2025 for tirzepatide and 24 April 2025 for semaglutide. A 503A pharmacy now needs a prescriber's documented, patient-specific significant difference. FDA's 18 September 2026 Empower letter said B12 or niacinamide blends at volume do not meet that test.
What did FDA's Empower Pharmacy warning letter say?
Letter 738238, dated 18 September 2026, said Empower's tirzepatide/ niacinamide and semaglutide/cyanocobalamin products "appear to be essentially copies" of approved drugs, compounded "regularly and in inordinate amounts". FDA called the differences "pretextual" given the volume and questioned significant-difference statements selected from pre-set telehealth menus.
Can outsourcing facilities (503B) compound semaglutide or tirzepatide?
Not from bulk ingredient unless FDA adds them to the 503B bulks list, and FDA proposed on 30 April 2026 not to add semaglutide, tirzepatide or liraglutide. Comments closed on 30 July 2026 under docket FDA-2018-N-3240. As of 5 October 2026 we had found no final determination in the Federal Register.
Did the July 2026 PCAC vote reverse the GLP-1 compounding restrictions?
No. The July 23-24, 2026 PCAC meeting considered seven non-GLP-1 peptides - BPC-157, KPV, TB-500, MOTS-c, Semax, Epitalon and emideltide - and recommended six of them for the 503A Bulks List. Semaglutide and tirzepatide were not on that agenda and their restrictions are unchanged. The committee is moving in opposite directions on two separate peptide classes.
What did the April 2026 PCAC meeting decide?
The April 2026 Pharmacy Compounding Advisory Committee reaffirmed the compounding restrictions on the GLP-1 class first set in October 2024, formalizing the regulatory direction. The reaffirmation closed the question of whether the October 2024 vote would face reversal under regulatory or political pressure — it did not, and the policy direction is now stable.
Did the PCAC vote affect research-peptide vendors?
Not directly. The compounding market (503A pharmacies) and the research-peptide market (online vendors selling material as research-grade reagents) are legally distinct. 503A governs prescription compounding by licensed pharmacies; research-peptide sales are governed by FDA misbranding and unapproved-drug authorities. But the two markets are demand-linked — displaced compounded-GLP-1 buyers migrated to the research-peptide channel, which is the main reason FDA Warning Letter enforcement on peptide vendors accelerated through 2025–2026.
Will retatrutide be available through compounding pharmacies after FDA approval?
No. Retatrutide is not in the existing shortage category and would not enter compounding eligibility on approval. A brand-approved retatrutide in 2027 adds a brand prescription product to the legal channel — it does not open a compounded retatrutide channel under 503A.