Evidence review

Category 3: Nominated, Not Reviewed

What does Category 3 of the FDA 503A bulks list actually mean?

The answer

It means the nomination was too thin to evaluate: not that the substance is unsafe, which is Category 2, and not that a pharmacy may compound it, which is Category 1. Seven substances in this index sit there and the category has moved none of them.

Molecules
GHRP-2, GHRP-6, Mechano growth factor, ARA-290, Secretin, Thymulin, L-carnosine
US status
No lawful route (6) · FDA-approved (1)
Sources
8
Reviewed
September 2026
Where this index's molecules sit on the 503A list

Counts of the substances this index tracks, not of the categories, which hold many substances that are not peptides.

By Diane Walker · Reference Editor

The three categories

The FDA's interim list of bulk drug substances nominated for compounding under section 503A sorts nominations into three files, and the document names them plainly: Category 1 for substances under evaluation, Category 2 for substances that raise significant safety risks, and Category 3 for substances nominated without adequate support [1].

Two of those three are widely understood. Category 1 is a permission during review — a pharmacy may compound with the substance while the agency's work continues. Category 2 is a prohibition with a stated reason, and the agency publishes the reason substance by substance [7]. Category 3 is the one that gets reported as whichever of the other two suits the reporter, and it is neither.

Category 3 records a fact about a document, not about a molecule. A party nominated the substance; the submission that accompanied the nomination did not contain enough for the agency to evaluate; the nomination was filed accordingly. Nothing in that sequence is a finding about safety, and nothing in it is an authorization.

What sits there

Seven of the substances this index tracks are in Category 3 on the list FDA published May 14, 2026: GHRP-2 [1], GHRP-6 [2], mechano growth factor [3], ARA-290 [4], secretin [5], thymulin [6], and L-carnosine [8]. The figure is a count of this index's own rows and not a total of the category, which contains a great many substances that are not peptides; no source this index has verified states a peptide subtotal, so none is printed here.

Six of the seven have no lawful United States route of any kind. The seventh is secretin, which is the instructive case: an approved diagnostic product has existed since 2004, and the bulk substance was separately nominated and separately found inadequately supported [5]. An approval and a nomination are different records, filed by different parties, and one does not carry the other.

The evidentiary range inside the category is the second surprise. ARA-290 has five indexed records that administer the peptide to patients in completed trials [4]. Thymulin has none that administer it at all [6]. L-carnosine has the largest randomized literature of any unapproved substance in this index [8]. All three are filed identically, because the category is not measuring any of that.

Why the misreading is commercially useful

A substance in Category 3 is on an FDA list. That sentence is true, and it is the whole of what a seller needs. It permits a page to say the compound is "under FDA review" or "nominated to the FDA bulks list" without stating anything false, while a reader takes from it that a decision is pending and favorable.

The correction is short. Being named in Category 3 is the record of a failed submission, not of a pending review. Nothing about the placement suggests the agency is working toward a listing, and for several of these substances the nomination is the only interaction with the agency that has ever occurred.

The two GHRP substances make the point sharpest, because they are simultaneously in Category 2 of the separate section 503B policy governing outsourcing facilities, added September 29, 2023, where FDA does state safety concerns about them [7]. A reader given only the 503A line has been told the half of the record that sounds like progress.

What would have to change

A Category 3 substance reaches a lawful compounding route by the same path as anything else: a nomination adequate to evaluate, a review, an advisory committee, and a final rule. None of the seven has begun that path. None was among the seven peptides the advisory committee reviewed in July 2026, so none carries a vote, a recommendation, or a pending rulemaking [1].

Until then the position is the one the nomination tracker prints and the research-only page explains: material offered for these substances is sold outside pharmacy licensure and outside the quality obligations that attach to a drug. The category on the FDA list changes none of that, which is precisely why it is worth knowing what the category is.

Elsewhere in this index

Monographs

Topics

Reference tables

Sources

Every source below is inherited from a monograph in this index, verified September 2026; this review introduces none of its own. The pointer beside each entry names the monograph and the reference number it came from.

  1. US Food and Drug Administration. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act, updated May 14, 2026. Fetched and read in full 2026-09-01: GHRP-2 appears in Category 3 and in neither Category 1 nor Category 2. Source See the ghrp-2 monograph, reference 7.
  2. US Food and Drug Administration. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act, updated May 14, 2026. Fetched and read in full 2026-09-01: GHRP-6 appears in Category 3 and in neither Category 1 nor Category 2. Source See the ghrp-6 monograph, reference 7.
  3. US Food and Drug Administration. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act, updated May 14, 2026. Fetched and read in full 2026-09-01: Mechano growth factor (MGF) appears in Category 3; the pegylated form appears in no category. Source See the mgf monograph, reference 6.
  4. PubMed, National Library of Medicine. Census run 2026-09-01 across five name variants — "ARA-290" OR "ARA 290" OR "cibinetide" OR "helix B surface peptide" OR "pyroglutamate helix B surface peptide" — returning 99 indexed records, 40 carrying the Humans MeSH term, 5 under "clinical trial"[Publication Type] and 4 under "randomized controlled trial"[Publication Type]. All 5 trial-type records were retrieved through esummary and read individually; every one administers the peptide to human participants. In the same run the control term aspirin returned 8,906 records under the clinical-trial filter and 6,115 under the randomized filter; the invalid tag clinicaltrial[pt] returned 0 for that same control term; and esummary on the invalid record identifier 99999999 errored. Source See the ara-290 monograph, reference 1.
  5. US Food and Drug Administration. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act, updated May 14, 2026. Fetched and read in full 2026-09-02: the entry "Secretin, human 99%" appears in Category 3 and in neither Category 1 nor Category 2. Source See the secretin monograph, reference 16.
  6. PubMed, National Library of Medicine. Census run 2026-09-02 across two name variants — "thymulin" OR "serum thymic factor" — returning 498 indexed records, 226 carrying the Humans MeSH term, 8 under "clinical trial"[Publication Type] and 5 under "randomized controlled trial"[Publication Type]. All 8 trial-type records were retrieved through esummary and read individually; seven measure endogenous thymulin as a marker of zinc status and one administers a synthetic analogue. In the same run the control term aspirin returned 8,906 records under the clinical-trial filter and 6,115 under the randomized filter; the invalid tag clinicaltrial[pt] returned 0 for that same control term; and esummary on the invalid record identifier 99999999 errored. Source See the thymulin monograph, reference 1.
  7. US Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks, content current as of April 22, 2026. Read 2026-09-01: the Category 2 table lists Growth hormone releasing peptide-2 (GHRP-2) for injectable and nasal routes of administration under the 503B policy, date added September 29, 2023. Source See the ghrp-2 monograph, reference 8.
  8. PubMed, National Library of Medicine. Census run 2026-09-02 across three name variants — "carnosine" OR "L-carnosine" OR "beta-alanyl-L-histidine" — returning 3,602 indexed records, 1,384 carrying the Humans MeSH term, 196 under "clinical trial"[Publication Type] and 158 under "randomized controlled trial"[Publication Type]. Reported as a magnitude; the 25 most relevant randomized records were retrieved through esummary and read. In the same run the control term aspirin returned 8,906 records under the clinical-trial filter and 6,115 under the randomized filter; the invalid tag clinicaltrial[pt] returned 0 for that same control term; and esummary on the invalid record identifier 99999999 errored. Source See the l-carnosine monograph, reference 1.