FDA 503A Category System

The FDA 503A Category System is the framework the FDA uses to evaluate and classify bulk drug substances that may be used in compounding by pharmacies operating under Section 503A of the Federal Food, Drug, and Cosmetic Act (FD&C Act).

Background: Section 503A

Section 503A of the FD&C Act provides exemptions from certain FDA requirements for pharmacies that compound drugs for individual patients based on valid prescriptions. To qualify for these exemptions, pharmacies must meet specific conditions, including only using bulk drug substances that appear on an FDA-approved list or that meet certain criteria.

The single most important distinction on this page

There are two different things people routinely conflate:

1. The 503A bulks list — the actual list, established by rulemaking, of bulk drug substances a 503A pharmacy may lawfully compound with. Getting onto it requires notice-and-comment rulemaking.
2. The interim categories (1, 2, 3) — a triage of nominated substances that FDA published while it works through the backlog. These are not the bulks list. A substance can sit in Category 1 for years and never be listed.

Neither a category placement nor an advisory-committee recommendation is an approval. The chain is: nominated → categorised → reviewed by the Pharmacy Compounding Advisory Committee (PCAC) → FDA decision → proposed rule → comment period → final rule → on the 503A bulks list. Nothing before the final rule makes a substance compoundable.

The Three Interim Categories

Category 1 — “Under Evaluation” (enforcement discretion, not authorization)

Category 1 is titled “Under Evaluation.” For substances in it, FDA’s stated posture is that it “does not intend to take action … provided that the conditions described in the guidance are met.”

That is enforcement discretion while an evaluation is pending — a statement about how FDA intends to exercise its resources. It is not approval, it is not the same as being on the 503A bulks list, and it can end when the evaluation concludes. Writing “Category 1 = can be compounded” is the most common error in peptide content, and it is wrong.

Where Category 1 does apply, the ordinary 503A conditions still apply on top of it: a valid patient-specific prescription, a state-licensed pharmacy meeting all other 503A requirements, and no compounding of a copy of a commercially available FDA-approved drug.

Peptide-relevant Category 1 entries (per the FDA interim list updated May 14, 2026):

• GHK-Cu — except for injectable routes of administration. The route qualifier is load-bearing. GHK-Cu was removed from Category 1 on April 22, 2026; on May 5, 2026 a nominator clarified it had withdrawn only the injectable route, and FDA re-added the non-injectable forms. Injectable GHK-Cu is in no category.
• Nicotinamide Adenine Dinucleotide (NAD) — see NAD+
• Vasoactive Intestinal Peptide — see VIP

Category 2 — Significant safety risks (exactly six substances)

Category 2 holds substances FDA has evaluated and determined raise significant safety risks. FDA’s posture is that it intends to take action against compounding with them.

The current Category 2 list contains exactly six substances (per the FDA interim list updated May 14, 2026):

1. Cesium Chloride
2. Domperidone
3. Germanium Sesquioxide
4. Ibutamoren Mesylate — see MK-677
5. Kisspeptin-10 — see Kisspeptin
6. Quinacrine Hydrochloride (for intrauterine administration)

That is the whole list. Any page — including earlier versions of this one — stating that BPC-157, TB-500, CJC-1295, Ipamorelin, AOD-9604, GHRP-2, GHRP-6 or Melanotan II is “currently Category 2” is out of date. BPC-157 and TB-500 left Category 2 in April 2026; CJC-1295, Ipamorelin, AOD-9604 and Melanotan II appear in no category at all; GHRP-2 and GHRP-6 are Category 3.

Leaving Category 2 is not permission to compound. A substance that is in no category is not on the 503A bulks list either, so there is still no lawful compounding route for it. See FDA-Category-2-Designations-2023-2024 for the history.

Category 3 — Nominated without adequate support

Category 3 holds substances that were nominated for the 503A bulks list without adequate supporting information for FDA to evaluate them. Category 3 is not a holding pattern that implies eventual acceptance and it is not permission:

• The substance is not on the 503A bulks list, so there is no lawful compounding route
• FDA may request additional data from nominators
• Pharmacies compounding with these substances are doing so outside the 503A exemption

Peptide-relevant Category 3 entries include GHRP-2 and GHRP-6. The list also carries plain “Mechano growth factor (MGF)”; whether that is the same nomination as PEG-MGF is unverified.

Substances in no category at all

A large number of well-known peptides appear nowhere in FDA’s nominated-substances document — including BPC-157, TB-500, Epithalon, Semax, CJC-1295, Ipamorelin, AOD-9604, Sermorelin, Melanotan II, LL-37 and Dihexa. This confirms that the PCAC bulks-list track and the interim Category 1/2/3 list are separate processes. Absence from the category lists means no lawful compounding route, not an open door.

PCAC, July 23-24, 2026 — recommendation ≠ listing ≠ approval

On July 23-24, 2026 the Pharmacy Compounding Advisory Committee met under docket FDA-2025-N-6895 and voted on seven peptides. It recommended six of them for the 503A bulks list — BPC-157, KPV, TB-500, MOTS-c, Epitalon and Semax — and rejected Emideltide (DSIP).

The committee voted against FDA’s own scientific reviewers. All seven FDA briefing documents close with the same conclusion: “a balancing of the criteria weighs against [substance] being placed on that list.”

What this does and does not mean:

• The vote is advisory and non-binding. FDA has not adopted it.
• None of these six is on the 503A bulks list. None is FDA-approved. Compounding them is not currently permitted.
• Any actual change in legal status would arrive as a proposed rule in the Federal Register, with its own comment period, followed by a final rule.
• It is an open question whether FDA will move these substances onto the interim Category 1 list (which would confer enforcement discretion) ahead of rulemaking. It has not done so as of this writing.

The safest and most accurate framing for any page touching these compounds: an FDA advisory committee recommended inclusion; FDA has not adopted it; these substances are not on the 503A bulks list and compounding them is not permitted.

The Evaluation Process

The FDA evaluates nominated bulk drug substances using several criteria:

1. Safety: Is the substance safe for use in compounding? Are there known adverse effects?
2. Physicochemical characterization: Is the substance well-characterized? Can it be reliably identified and tested?
3. History of use: Has the substance been used historically in compounding? What is the clinical evidence base?
4. Evidence of efficacy: Is there adequate evidence that the substance is effective for its intended use?
5. Availability of alternatives: Are there FDA-approved alternatives available?

The Pharmacy Compounding Advisory Committee (PCAC) reviews nominated substances and makes recommendations to the FDA.

503A vs 503B

It is important to distinguish between the two compounding exemptions:

The 503B outsourcing-facility bulks list is a separate list with its own criteria. A substance’s presence in a 503A interim category says nothing about whether a 503B facility may use it. Category 2 designations primarily affect 503A pharmacies, but they also signal FDA concerns that carry over to 503B.

The Kennedy reclassification and what actually happened

In February 2026, HHS Secretary Robert F. Kennedy Jr. announced intent to reclassify 14+ peptides from Category 2 back to Category 1. See FDA-Reclassification-Announcement-Feb-2026 for details.

As of July 2026:

• Roughly a dozen peptides — including BPC-157, TB-500, Semax, Epitalon, MOTS-c, Melanotan II, GHK-Cu, KPV, DSIP, Dihexa and Selank — were removed from Category 2 in April 2026. They were not moved to Category 1. Most are now in no category at all.
• Removal from Category 2 is not authorization to compound. It removes a prohibition-flavoured designation; it does not add the substance to the 503A bulks list.
• Seven of these went to PCAC on July 23-24, 2026 (see above). Six were recommended. None has been listed.
• FDA’s enforcement posture is unchanged. Warning letters to peptide vendors and telehealth compounders have continued throughout 2025-2026 — see FDA-Warning-Letters-April-2026 and FDA-crackdown-on-peptide-vendors-2025-2026.
• Compounding pharmacies should not resume peptide compounding until a final rule places the substance on the 503A bulks list.

Related Notes

• FDA-Category-2-Designations-2023-2024 — initial wave of peptide restrictions
• FDA-Reclassification-Announcement-Feb-2026 — Kennedy’s proposed reversal
• FDA-Warning-Letters-April-2026 — continued enforcement under current rules
• Semaglutide-Compounding-Shortage-Resolution — related compounding regulatory issue