The June 29 Deadline: What the FDA's 503B Comment Period Means and What Comes Next
On April 30, 2026, the FDA published a proposed rule in the Federal Register that would formally exclude semaglutide, tirzepatide, and liraglutide from the 503B Bulks List. The public comment period closes June 29, 2026. If finalized, 503B outsourcing facilities will be permanently prohibited from compounding these drugs from bulk substances — under any circumstances, including future shortages.1
What the Proposal Actually Says
The 503B Bulks List identifies which bulk drug substances outsourcing facilities may use for compounding under Section 503B of the FD&C Act. To be included on the list, a substance must demonstrate a clinical need for compounding beyond what's commercially available.2
The FDA's position is that this clinical need no longer exists for GLP-1 active ingredients because:
- The semaglutide and tirzepatide shortages that drove compounding demand have been resolved
- Multiple FDA-approved formulations are now commercially available (injectable and oral for semaglutide; injectable for tirzepatide; oral orforglipron for the GLP-1 class)
- Safety signals from compounded products (455+ adverse events for semaglutide, 320+ for tirzepatide) indicate patient risk
The proposal would exclude these drugs permanently — meaning even if a new shortage occurs, 503B facilities would not be able to resume compounding without a new rulemaking process.5
What About 503A Pharmacies?
503A pharmacies operate under a different statutory framework. They compound individual prescriptions for specific patients under state pharmacy board oversight. The proposed 503B exclusion has no independent legal effect on 503A operations.2
However, this does not mean 503A pharmacies can freely compound GLP-1s. With the shortage resolved, 503A pharmacies are already prohibited from regularly compounding drugs that are "essentially a copy" of commercially available products. The practical space for legal 503A compounding of semaglutide and tirzepatide is narrowing even without the 503B rule.2
What Happens After June 29
| Phase | Expected Timeline | What Happens |
|---|---|---|
| Comment period closes | June 29, 2026 | FDA reviews all submitted comments |
| FDA deliberation | July–December 2026 (estimated) | Agency considers comments, drafts final rule |
| Final rule published | Late 2026 or 2027 (estimated) | Rule becomes effective upon publication or with short delay |
| Enforcement | Ongoing | 503B facilities must cease GLP-1 compounding |
For patients currently using compounded GLP-1 medications: the regulatory direction is clear, but the transition will not happen overnight. The comment period, final rule, and inevitable legal challenges create a window — but planning a transition to brand-name alternatives now, rather than waiting for enforcement, is the more prudent course.
SOURCES
- FDA. Proposed exclusion of semaglutide, tirzepatide, and liraglutide from the 503B Bulks List. Federal Register. April 30, 2026.
- Orrick Herrington. FDA Moves to Shut the Door on Large-Scale Compounding of GLP-1 Drugs. May 2026.
- Drug Topics. FDA Proposes to Exclude GLP-1s From 503B Bulk List. May 2026.
- Alliance for Pharmacy Compounding. Statement on FDA proposed rule. May 2026.
- Pharmacy Times. FDA Moves to Permanently Close the Door on Compounded GLP-1s. May 2026.