Category 1, Category 2 and the 503A Bulks List, Explained

It is FDA's official list of bulk drug substances that a state-licensed pharmacy or physician may use to compound a drug under section 503A, added through formal notice-and-comment rulemaking. FDA's first final rule under this process, in February 2019, placed six substances on the list and explicitly declined to place four others.

Category 1 substances were nominated with enough supporting information for FDA to evaluate them, may be eligible for the Bulks List, and do not appear on any other list. Under FDA's interim policy, the agency does not intend to take enforcement action against compounding with a Category 1 substance when other conditions in the policy are met. That is enforcement discretion, not a Bulks List listing.

Category 2 substances were also nominated with sufficient information to evaluate, but FDA identified significant safety risks in that review. FDA states it would consider enforcement action against a compounder using one. Several substances marketed as peptides, including BPC-157, sit in a related table for substances nominated but withdrawn. FDA's safety-risk language is kept in place there.

No. FDA's significant-safety-risks page has a separate table of substances that were nominated into Category 2 and then withdrawn by the people who nominated them. Withdrawal removes an entry from that table. It does not grant approval, establish safety or efficacy, or add the substance to the 503A Bulks List. A substance can leave Category 2 and still be ineligible for lawful compounding.

Under section 503A(b)(1)(A)(i), a bulk drug substance is eligible only on one of three paths. It complies with an applicable United States Pharmacopeia or National Formulary monograph, it is a component of an FDA-approved drug, or it appears on the 503A Bulks List. Category 1 or Category 2 status, or removal from either, does not satisfy any of those three paths.

Yes, in two places, and neither is a standalone spreadsheet. The rule that first populated the list is a downloadable PDF final rule on federalregister.gov. The current codified text sits in the Code of Federal Regulations at 21 CFR 216.23, also downloadable as a PDF from govinfo.gov. It covers the six substances plus the four FDA declined to add. There is no separate 'master list' document. The regulation text is the list.

No blanket ban exists as of this writing, and tirzepatide is not a 503A Bulks List question at all, because it is the active ingredient in FDA-approved drugs. It already satisfies one of the three eligibility paths above. What can restrict compounding it is separate: the statutory 'essentially a copy' restriction. For 503B outsourcing facilities compounding from bulk substance, it also matters whether tirzepatide is on FDA's drug shortage list or on the 503B bulks list. It has been off the shortage list since FDA declared the shortage resolved on 19 December 2024. FDA proposed excluding it from the 503B bulks list on 30 April 2026.

Only licensed 503A pharmacies and 503B outsourcing facilities operating within FDA's rules may compound and dispense it. Nobody else may legally sell a compounded drug. Section 503A restricts producing 'essentially a copy' of an approved drug outside a valid patient-specific prescription. Section 503B ties bulk-substance compounding of a copy to the drug's presence on FDA's shortage list. FDA declared the tirzepatide injection shortage resolved on 19 December 2024, so that shortage basis no longer applies.

There is no published end date, but the shortage-era opening has already closed. FDA declared the tirzepatide shortage resolved on 19 December 2024, and its transition period for compounders ended in early 2025. What remains is narrower: 503A pharmacies filling patient-specific prescriptions for products that are not essentially copies of the approved drug. FDA proposed on 30 April 2026 to exclude tirzepatide from the 503B bulks list, and I found no final decision as of this writing. Check FDA's own announcements rather than a seller's claim.

It is FDA's list of bulk drug substances that outsourcing facilities may use when compounding under section 503B, separate from the 503A Bulks List for pharmacies. An outsourcing facility generally cannot compound from a bulk substance unless it is on that list or the finished drug is on FDA's shortage list at the time. On 30 April 2026, FDA proposed excluding semaglutide, tirzepatide and liraglutide from it.