If finalised, outsourcing facilities would lose a pathway for compounding these molecules at scale.
FDA has proposed excluding semaglutide, tirzepatide and liraglutide from the 503B bulk drug substances list. Outsourcing facilities compound from bulk substances under that list; exclusion would remove a pathway for producing these molecules at scale outside patient-specific prescriptions.
This is a proposal rather than a final rule, and coverage frequently conflates the two. Patient-specific compounding under section 503A is a separate pathway and is not what this proposal addresses.
The practical exposure is for programmes sourcing from 503B outsourcing facilities. If you have chosen a programme partly because it names a 503B partner, ask what its plan is if the exclusion is finalised — a good answer exists, and a programme that has not thought about it is telling you something.
We will update this item when a final rule appears. Treat any summary of compounding rules, including ours, as needing verification against current FDA communications before you rely on it.
Sources
- FDA proposed exclusion of semaglutide, tirzepatide and liraglutide from the 503B bulks list
- FDA human drug compounding programme — source
Dated 2026-06-01. If this item is out of date or wrong, tell us through contact and the change is logged in corrections.
Primary sources
Clinical, dosing and regulatory statements on this page rest on the documents below. Links go to the publisher, not to a summary of it. Prices are not sourced here — they carry a verification date instead, and the reason is set out in the source ledger.
- ZEPBOUND (tirzepatide) full prescribing information — DailyMed, US National Library of Medicine. Dose ladder, contraindications, warnings, storage.
- FDA’s concerns with unapproved GLP-1 drugs used for weight loss — US Food and Drug Administration. Compounded GLP-1 risks, API import alert, cold-chain complaints.
- FD&C Act provisions that apply to human drug compounding — US Food and Drug Administration. Why a compounded preparation is lawful without being FDA-approved.
- Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1) — N Engl J Med 2022;387:205-216. Registration NCT04184622. The weight-reduction and adverse-event figures used across this site.
- The full source ledger — every primary source, what it supports, the date we read it, and the claims we deliberately do not source.