FDA Tightens GLP-1 Compounding Rules While Scheduling First Formal Review of BPC-157, TB-500 and Five Other Peptides

Overview

Two parallel FDA actions published in the final week of April 2026 are reshaping the regulatory landscape for peptide procurement professionals in the United Kingdom and beyond. On one side, the agency is moving to close the door permanently on large-scale compounding of three approved GLP-1 receptor agonists. On the other, it has opened a structured public process that could, after several years of rulemaking, permit licensed compounding of widely researched peptides such as BPC-157 and TB-500. Understanding both actions — and their limits — is essential for procurement teams assessing supply risk and research-use sourcing.

Action 1: FDA Proposes to Exclude Semaglutide, Tirzepatide and Liraglutide from the 503B Bulks List

On 30 April 2026, the FDA announced that it is proposing to exclude semaglutide, tirzepatide and liraglutide from the 503B Bulks List, finding no clinical need for outsourcing facilities to compound these drugs from bulk drug substances.

The 503B Bulks List identifies bulk drug substances that outsourcing facilities may use in compounding under section 503B of the Federal Food, Drug, and Cosmetic Act. In most cases, outsourcing facilities cannot compound drugs using bulk drug substances unless the substance appears on the 503B Bulks List, or the compounded drug is on the FDA's drug shortage list at the time of compounding, distribution, and dispensing.

The FDA resolved the tirzepatide shortage in December 2024 and the semaglutide shortage in February 2025, establishing phased enforcement deadlines for compounders to wind down operations. The Outsourcing Facilities Association filed federal lawsuits challenging both determinations, but courts denied preliminary injunctions in each case, and the enforcement deadlines held.

If finalised, the rule would prohibit 503B outsourcing facilities from compounding these agents from bulk substances under any circumstances, regardless of future market conditions. With neither condition met for these three agents, a formal exclusion would foreclose any future pathway for bulk compounding, even in the event of a new shortage designation. A public comment period is now open through 29 June 2026 via the federal docket.

"When FDA-approved drugs are available, outsourcing facilities cannot lawfully compound using bulk drug substances unless there is a clear clinical need," FDA Commissioner Marty Makary said in the agency's announcement.

Safety background informing the proposal

As of early 2025, the FDA had received more than 455 adverse event reports linked to compounded semaglutide and more than 320 reports associated with compounded tirzepatide, many involving dosing errors from patients self-administering incorrect doses from multidose vials — some of which required hospitalisation. Mass compounding of GLP-1 medications has also been linked to recalls involving thousands of contaminated or improperly dosed vials.

What this means for 503A pharmacies

Importantly, this proposal does not directly alter the legal framework for 503A compounding pharmacies. Section 503A pharmacies operate under a separate statutory provision and compound drugs pursuant to individual patient-specific prescriptions under state board of pharmacy oversight. They do not rely on the 503B Bulks List to authorise their compounding activities, and the proposed exclusion has no independent legal effect on their operations. However, the removal of semaglutide and tirzepatide from the FDA's drug shortage list in 2025 already eliminated the primary legal basis that had permitted 503A pharmacies to compound drugs that are "essentially a copy" of the commercially available branded products. Absent a shortage listing, 503A pharmacies are prohibited from regularly or in inordinate amounts compounding drugs that are essentially copies of commercially available products.

IQVIA reported that more than 80% of compounded semaglutide and tirzepatide prescriptions included supplemental ingredients such as B vitamins or levocarnitine, a formulation approach some compounders have pursued to differentiate from branded products. The FDA has taken measures to constrain certain activities of 503A compounders by sending warning letters to pharmacies and telemedicine practices, and clarifying conditions under which it will consider 503A-compounded medications to be "essentially a copy" of approved medications — including certain drug combinations such as GLP-1s with Vitamin B12.

Action 2: PCAC Meeting Confirmed for 23–24 July 2026 — Seven Peptides Under Formal Evaluation

On 16 April 2026, the FDA announced it will convene the Pharmacy Compounding Advisory Committee (PCAC) on 23 and 24 July 2026 to discuss permitting compounding pharmacies to prepare certain peptides used for ulcerative colitis, wound healing, obesity, insomnia, opioid withdrawal, inflammatory conditions, and osteoporosis, among other conditions.

The confirmed agenda, published in the Federal Register (FR Doc. 2026-07361), covers seven substances across two days:

On 23 July 2026, the Committee will discuss BPC-157 (free base/acetate), KPV (free base/acetate), TB-500 (free base/acetate), and MOTS-C (free base/acetate) for potential inclusion on the 503A Bulks List. On 24 July 2026, the Committee will discuss Emideltide (delta sleep-inducing peptide/DSIP), Semax, and Epitalon.

The FDA also announced the PCAC will convene again before the end of February 2027 to review five additional peptides for the 503A Bulks List, including GHK-Cu, Melanotan II, Cathelicidin (LL-37), Dihexa acetate and Mechano Growth Factor, Pegylated (PEG-MGF).

Background: why these substances are before the committee now

On 27 February 2026, HHS Secretary Robert F. Kennedy Jr. publicly addressed FDA action on a group of peptide substances that had been on the FDA's Category 2 restricted compounding list. The companies that originally nominated those peptides for that list have since withdrawn their nominations, and the peptides came off Category 2 effective 23 April 2026.

Category 2 designates bulk drug substances the FDA has determined raise significant safety concerns, restricting their use in compounding under Section 503A. Removal — in this case because nominators voluntarily withdrew their submissions — means the substance is no longer under that active safety-concern designation.

Why the July meeting is not the finish line

The July 2026 meeting is likely a necessary procedural step, not the finish line. Under the FDA's typical process, changes to the 503A Bulk Drug Substances List are routed through the PCAC; without such a review, any modification would likely face a legal challenge. PCAC's recommendation is non-binding, and formal rulemaking is what comes next.

Even if the PCAC recommends adding these peptides to the Category 1 list, and even if the FDA agrees, notice-and-comment rulemaking is still required — a process that, under standard timelines, can take more than a year. Given that the bulks list final rulemaking has not yet occurred under Section 503A for most substances, the process could take a very long time. For industry participants planning product or service launches around peptide compounding, that timeline is important to internalise.

Public comment and participation deadlines

The public docket (FDA-2025-N-6895) is open for written comments at Regulations.gov. Any comments submitted by 9 July 2026 will be formally provided to the PCAC members ahead of the meeting. Individuals wishing to make oral presentations at the meeting must notify the FDA contact person by 30 June 2026.

What Research-Procurement Professionals Should Note

GLP-1 research-grade supply remains largely unaffected by the 503B proposal. The Research Use Only channel for tirzepatide operates under separate regulations and is unaffected by the compounding restrictions; research laboratories continue to source it for laboratory and in-vitro work.

Peptide quality vigilance remains warranted. Peptide products from grey-market sources may contain endotoxins, truncated sequences, solvent residues, heavy metals, microbial contamination, and degradation by-products. Because no GMP requirements apply to the grey-market category, quality may be suspect. Reports indicate that some suppliers may issue certificates of analysis in the absence of actual product testing.

Timeline for regulatory clarity on BPC-157, TB-500 and related compounds remains extended. Even a favourable PCAC outcome in July 2026 will not deliver compounding eligibility immediately; formal rulemaking is still required, and the FDA has been silent on whether any of the twelve peptides removed from Category 2 will be reviewed under the separate 503B framework. The FDA has not indicated that these twelve peptides will be reviewed for, or otherwise moved to, the Agency's separate 503B Category 1 list.

Key Takeaways

• The FDA's 30 April 2026 proposal to exclude semaglutide, tirzepatide and liraglutide from the 503B Bulks List, if finalised, would permanently close the large-scale compounding route for these GLP-1s regardless of future shortage conditions. The comment period closes 29 June 2026.
• Seven peptides — BPC-157, TB-500, KPV, MOTS-C, Semax, Epitalon and Emideltide (DSIP) — are confirmed for formal PCAC review on 23–24 July 2026. This is a procedural milestone, not an authorisation to compound.
• Five further peptides, including GHK-Cu and PEG-MGF, are scheduled for a second PCAC session before February 2027.
• Notice-and-comment rulemaking following any favourable PCAC recommendation is expected to take in excess of one year under standard FDA timelines.
• Research-use supply chains for these peptides operate under distinct regulatory provisions and are not directly affected by compounding classification changes.