The 503B Compounding Exclusion: What the FDA Comment Period Closure Means

The June 29, 2026 closure of the public comment period on FDA's proposed 503B compounding guidance received 45,000+ submissions. What the guidance proposes, the major comment arguments, and what comes next.

On June 29, 2026, the FDA closed the public comment period on its proposed guidance that would formalize the exclusion of semaglutide and tirzepatide from 503B compounding eligibility. The comment period received over 45,000 submissions — one of the largest comment responses for any FDA pharmaceutical guidance in recent history. Here's what the proposal contains, what comments argued, and what happens next.

The Regulatory Background

Under Section 503B of the Federal Food, Drug, and Cosmetic Act, outsourcing facilities (503B compounders) may produce large-scale batches of compounded drugs without individual prescriptions, but they are prohibited from compounding drugs that are "essentially a copy" of an FDA-approved drug unless that drug is on the FDA's drug shortage list. Semaglutide and tirzepatide were added to the shortage list in 2022 (semaglutide) and 2023 (tirzepatide), and this shortage status was the legal basis for widespread compounding.

FDA formally removed tirzepatide from the shortage list in October 2024 and semaglutide in February 2025, triggering the transition period that concluded with the current guidance proposal.

What the Proposed Guidance Does

The guidance, if finalized as proposed, would:

1. Formally prohibit 503B outsourcing facilities from producing semaglutide or tirzepatide formulations without a demonstrable clinical difference from the approved product
2. Create a pathway for compounders to petition for patient-specific exemptions documenting individual clinical need
3. Require 503A compounders (smaller pharmacies filling individual prescriptions) to follow existing state pharmacy board rules, with FDA reserving the right to act on egregious cases

The Comment Arguments

In support of finalization: Novo Nordisk, Eli Lilly, branded pharmacy benefit managers, and some patient safety organizations argued the shortage has ended, the essential copy prohibition should apply, and that unregulated compounding creates quality and safety risks.

Against finalization: Compounding pharmacies (IACP), telehealth platforms, patient advocacy groups citing access and cost, and a substantial volume of individual patient comments argued that branded product cost (still $1,000+/month out-of-pocket for many patients) creates effective access disparities that the shortage removal guidance fails to address.

What Comes Next

FDA will review the comments and issue either a final guidance or a revised proposal. The timeline for final guidance is not publicly specified — FDA guidance documents do not have mandatory timelines. Legal challenges from compounding industry groups are considered likely if guidance is finalized as proposed; litigation on the shortage determination itself is already pending in federal courts.