The 503B Exclusion of Semaglutide, Tirzepatide, and Liraglutide — and the Three Lanes of Peptide Access

On April 30, 2026, the FDA proposed to exclude semaglutide, tirzepatide, and liraglutide from the 503B Bulks List — the roster of active ingredients that FDA-registered outsourcing facilities may use to compound in bulk on a finding of “clinical need.” After reviewing the nominations, the agency said it found no such need. The notice published in the Federal Register on May 1, 2026, opened a public comment window that was later extended to July 30, 2026. That window has closed; the FDA is weighing comments, and no final rule has issued. “Proposed” and “banned” remain different words.

The distinction to carry first: “the rules changed” is too coarse. Compounding runs through two separate federal channels — 503A (a licensed pharmacy compounding for one identified patient) and 503B (an outsourcing facility compounding in bulk). They sit under different statutory tests, touch different substances, and have moved on different timelines. This action touches the 503B lane only.

503A and 503B are not the same rulebook

A 503A pharmacy compounds a drug for a specific patient against a prescription; a 503B outsourcing facility registers with the FDA to make compounded drugs in larger batches, often without a patient-specific prescription. A 503B facility can generally only compound from a bulk substance if that substance is on the 503B Bulks List, or if the finished drug is on the FDA’s shortage list. The proposed exclusion removes these three GLP-1s from the first route. It does not, by its terms, rewrite what a 503A pharmacy may do, and it is not a statement about the broader research-chemical market at all.

The shortage route is the fine print. The tirzepatide shortage resolved in October 2024 and the semaglutide shortage on February 21, 2025, so for those two the bulks-list exclusion would close the last standing bulk-compounding pathway. Liraglutide injection remains on the shortage list, so it can still be compounded by 503B facilities for now despite its absence from the bulks list — a conditional door, not a sealed one, since a return to shortage would reopen the pathway for any of the three while the shortage lasted. The action has no bearing on retatrutide, which was never eligible for compounding: there is no approved version, so no shortage pathway ever applied.

The 503A peptide lane moved differently — and less than headlines suggest

While the GLP-1 news is about foreclosing a bulk route, the 503A peptide lane moved the other way this year — which is exactly why one word for “the rules” fails. In April 2026 the FDA removed twelve peptides from Category 2, the “significant safety concern” list, after their nominations were withdrawn (docket FDA-2025-N-6895). The step was one HHS Secretary Robert F. Kennedy Jr. had publicly pushed for; he has spoken of wanting to make “about 14” peptides more accessible.

The count matters, so be precise about it: the number of peptides now confirmed sitting in Category 1 as a result of these actions is none. Removal from Category 2 does not, on its own, authorize compounding or move a substance into Category 1 — per the FDA’s own category framework and independent legal analysis, the twelve are left in continued regulatory uncertainty, not a new pathway. Seven of the twelve went to the FDA’s Pharmacy Compounding Advisory Committee on July 23–24, 2026, which recommended six — BPC-157, KPV, TB-500, MOTS-c, Epitalon, and Semax — for the 503A Bulks List and rejected DSIP; the remaining five are slated for a later meeting. We covered the tallies in our vote recap. A PCAC recommendation is non-binding: the FDA must still act through rulemaking, a process observers expect to run into 2027.

The three lanes — which channel each rule touches

Sort the whole picture into three lanes and the confusion clears. Each rule this year lands in exactly one of them:

• Lane 1 — FDA-approved drugs. Semaglutide, tirzepatide, and liraglutide are approved medicines sold under brand names. The 503B proposal, the shortage-list status, and 503A patient-specific rules all govern compounded copies of these approved drugs. This is the lane the current GLP-1 news sits in.
• Lane 2 — compoundable peptides (503A / Category 1). The licensed compounding channel: substances a pharmacy may compound for a patient. The twelve peptides pulled from Category 2 are candidates for this lane, not residents of it — six are recommended, none is confirmed, and the FDA has not finalized anything.
• Lane 3 — research-use-only peptides. The “for laboratory research only” market of compounds sold by vendors. This lane is not part of either FDA action above. Neither the 503B GLP-1 exclusion nor the Category 2 peptide removals authorize, ban, or reclassify anything sold as a research chemical.

That last point is the one most easily blurred, so we state it plainly. Prof. Peptide indexes research-use peptides — Lane 3. The 503A and 503B actions described here govern the licensed and approved channels — compounded and FDA-approved drugs. They do not govern the research-chemical market, and nothing in these specific actions changes the status of the compounds this site catalogs. A vendor that folds a 503B proposal or a Category 2 removal into a “peptides are being legalized” pitch is crossing lanes that the FDA has kept separate.

What this is, and isn’t

This is policy reporting. A bulk-list proposal, a Category 2 removal, or an advisory-committee vote is a regulatory-process event — not a safety, efficacy, or approval determination, and not a dosing or usage recommendation. Nothing here should be read as a statement that any compound named is safe, effective, or approved for human use. We will update this article as the FDA acts on either lane.

Sources

• FDA Proposes to Exclude Semaglutide, Tirzepatide, and Liraglutide on 503B Bulks List (FDA press announcement, Apr 30, 2026) — primary, for the proposed 503B exclusion and the “no clinical need” finding.
• List of Bulk Drug Substances for Which There Is a Clinical Need Under Section 503B…, 91 Fed. Reg. 23431 (May 1, 2026) — primary docket, for the Federal Register notice.
• …Extension of Comment Period, FR 2026-12937 (Jun 26, 2026) — primary docket, for the July 30, 2026 comment deadline.
• Pharmacy Compounding Advisory Committee; Notice of Meeting, Docket FDA-2025-N-6895 (Apr 16, 2026) — primary docket, for the Category 2 removals and PCAC schedule.
• Tiny Chains, Big Changes? What FDA’s Latest Actions Mean for Peptide Compounding (National Law Review) — secondary legal analysis, for “removal from Category 2 does not authorize compounding” and the Category 1 status.
• Heeding RFK Jr.’s call, FDA reclassifies 12 unapproved peptides (Fierce Pharma) — secondary, attributed, for HHS Secretary Kennedy’s “about 14” framing and the twelve-peptide removal.