# Category 1 vs Category 2 bulk substances explained > What FDA's interim Category 1, 2 and 3 lists for nominated compounding ingredients mean, which peptides are on them, and what withdrawn means. - Canonical URL: https://livingpluspeptides.com/regulation/category-1-vs-category-2-bulk-substances/ - Last updated: October 25, 2026 - Publisher: Living+ Category 1 and Category 2 are FDA's interim labels for bulk ingredients that people nominated for compounding while FDA reviews them. Category 1 substances may be used under FDA's interim policy if its conditions are met. Category 2 substances raise significant safety risks, so that policy does not apply and FDA may take enforcement action [1, 4]. ## Why the categories exist Under section 503A, a compounder may use a bulk drug substance only if it meets a USP or National Formulary monograph, is a component of an FDA-approved drug, or appears on FDA's 503A bulks list [5]. That list is set by regulation. It names six substances today [6]. FDA asked for nominations for the list in 2015. It is reviewing them with help from the Pharmacy Compounding Advisory Committee (PCAC) [1]. FDA made the interim policy to avoid disrupting patient care while that review goes on [1]. Outsourcing facilities under section 503B have a separate bulks list and a matching set of interim categories [4]. Our page on [503A vs 503B pharmacies](/regulation/503a-vs-503b-pharmacies/) explains the two paths [1, 4]. ## The three categories - Category 1: the substance was nominated with enough information for FDA to evaluate it and may be eligible for the list. FDA does not intend to take action against a compounder using it, provided the conditions in FDA's guidance are met [1]. - Category 2: the substance was nominated with enough information, but FDA has identified significant safety risks. FDA does not extend the Category 1 policy to it and would consider action under its general enforcement policies [1]. - Category 3: the substance was nominated without enough information for FDA to evaluate it. It can be nominated again with better support, but it is not covered by the Category 1 policy [1]. None of the three categories is an approval. A Category 1 substance is still under evaluation, and FDA can remove it from Category 1, for example based on new safety information [1]. ## No new substances are being sorted FDA revised the policy so that it does not intend to place substances nominated on or after January 7, 2025, into these categories [1, 4]. Substances already in Category 1 can stay under the interim policy until FDA decides whether to add them to the bulks list [1]. ## Which peptides are where in 2026 FDA's 503A category list was updated May 14, 2026 [2]. On it: - Category 2 holds six substances. Two of them have pages on this site: ibutamoren mesylate ([MK-677](/peptides/mk-677/)) and [kisspeptin-10](/peptides/kisspeptin/) [2]. - Category 3 includes GHRP-2 and GHRP-6 ([GHRP-2 and GHRP-6](/peptides/ghrp-2-ghrp-6/)) [2]. - [GHK-Cu](/peptides/ghk-cu/) for non-injectable routes will be added back to Category 1 after a nominator clarified on May 5, 2026 that it withdrew only the injectable route. FDA plans to consult the PCAC on GHK-Cu before the end of February 2027 [2]. The 503B category list, updated March 21, 2025, places GHRP-2 (for injectable and nasal routes), GHRP-6, ibutamoren mesylate and [ipamorelin](/peptides/ipamorelin/) acetate in 503B Category 2 [3]. ## What "nominated but withdrawn" means FDA keeps a second list of substances that were in Category 2 until the people who nominated them withdrew the nominations [7]. As of April 22, 2026, it includes [BPC-157](/peptides/bpc-157/), [TB-500](/peptides/tb-500-thymosin-beta-4/), [MOTS-c](/peptides/mots-c/), [KPV](/peptides/kpv/), [Semax](/peptides/semax/), [Epitalon](/peptides/epitalon/) and several other peptides [7]. Withdrawal does not move a substance into Category 1. It leaves the substance outside all three categories, while FDA's safety summary for it stays posted [1, 7]. Some of these peptides later went to the PCAC. The July 23 and 24, 2026 meeting discussed BPC-157, KPV, TB-500, MOTS-c, DSIP, Semax and Epitalon for possible inclusion on the 503A bulks list [8]. Advisory committees make non-binding recommendations to FDA [8]. ## What FDA says about peptide risks FDA's safety page gives a reason for each substance. For many peptides, including BPC-157 and kisspeptin-10, FDA says compounded versions may pose a risk of immunogenicity for certain routes and may have problems with peptide-related impurities. It adds that it lacks enough information to know whether the drug would cause harm in humans [7]. For GHRP-2, FDA notes reports of serious adverse events, though causality has not been established [7]. ## Categories versus the final list The categories are a temporary enforcement policy. The binding answer is the 503A bulks list in 21 CFR 216.23, which FDA changes only through notice-and-comment rulemaking [1, 6]. On the 503B side, FDA adds or excludes substances through Federal Register notices in docket FDA-2018-N-3240 [9, 10]. Check the [FDA Peptide Status Tracker](/regulation/tracker/) for each peptide's current status [2, 7]. ## Frequently asked questions ### What does Category 2 mean for compounding? FDA has identified significant safety risks for a Category 2 substance. FDA does not extend its Category 1 interim policy to it and would consider enforcement action against a compounder using it [1]. ### Does Category 1 mean a substance is approved? No. Category 1 means the substance is still under evaluation. FDA does not intend to take action while its guidance conditions are met, and it can remove a substance from Category 1 [1]. ### Is BPC-157 in Category 1 or Category 2? Neither. FDA lists BPC-157 as previously in Category 2 with the nominations withdrawn, and it was discussed at the July 23, 2026 PCAC meeting [7, 8]. ### Which peptides are in 503A Category 2 now? On FDA's list updated May 14, 2026, 503A Category 2 includes ibutamoren mesylate and kisspeptin-10 [2]. ### Can new substances still be added to the categories? No new ones. FDA does not intend to place substances nominated on or after January 7, 2025, into the categories [1]. ### What is Category 3? Category 3 holds substances nominated without enough information for FDA to evaluate them. They can be nominated again with more support [1]. ## Sources 1. [FDA: Bulk Drug Substances Used in Compounding Under Section 503A (current as of May 14, 2026)](https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act) 2. [FDA: Bulk Drug Substances Nominated for Use in Compounding Under Section 503A, category list (updated May 14, 2026)](https://www.fda.gov/media/94155/download) 3. [FDA: Bulk Drug Substances Nominated for Use in Compounding Under Section 503B, category list (updated March 21, 2025)](https://www.fda.gov/media/94164/download) 4. [FDA: Bulk Drug Substances Used in Compounding Under Section 503B](https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503b-fdc-act) 5. [21 U.S.C. 353a (FD&C Act section 503A), U.S. Code 2024 edition (govinfo)](https://www.govinfo.gov/content/pkg/USCODE-2024-title21/html/USCODE-2024-title21-chap9-subchapV-partA-sec353a.htm) 6. [eCFR: 21 CFR 216.23, the 503A bulks list](https://www.ecfr.gov/current/title-21/chapter-I/subchapter-C/part-216/subpart-B/section-216.23) 7. [FDA: Certain bulk drug substances for use in compounding that may present significant safety risks (current as of April 22, 2026)](https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks) 8. [FDA: July 23-24, 2026 Pharmacy Compounding Advisory Committee meeting](https://www.fda.gov/advisory-committees/advisory-committee-calendar/july-23-24-2026-meeting-pharmacy-compounding-advisory-committee-07232026) 9. [Regulations.gov: Docket FDA-2018-N-3240, 503B clinical need list](https://www.regulations.gov/docket/FDA-2018-N-3240) 10. [Federal Register: 503B clinical need list notice (May 1, 2026)](https://www.federalregister.gov/documents/2026/05/01/2026-08552/list-of-bulk-drug-substances-for-which-there-is-a-clinical-need-under-section-503b-of-the-federal) Educational information, not medical advice. This site sells nothing.