Category 1 vs Category 2 bulk substances explained

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 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) and kisspeptin-10 ^[2].
Category 3 includes GHRP-2 and GHRP-6 (GHRP-2 and GHRP-6) ^[2].
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 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, TB-500, MOTS-c, KPV, Semax, 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 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].