How the FDA categorizes peptides for 503A compounding

The sorting hat for compounded peptides — and the rules behind which one a peptide ends up in.

TL;DR

• The FDA sorts compounding-eligible bulk substances into Category 1 (compoundable) and Category 2 (not eligible for 503A compounding).
• Category assignment is recommended by the Pharmacy Compounding Advisory Committee (PCAC) and finalized by the FDA.
• In 2023, the FDA moved several popular research peptides — BPC-157, TB-500, KPV, DSIP, epitalon, Selank, Semax, melanotan-2 — to Category 2.

What it is

The Category 1 / Category 2 framework is how the FDA sorts bulk substances proposed for compounding under Section 503A of the Federal Food, Drug, and Cosmetic Act. The 503A bulks list is the public registry of which substances may be compounded by state-licensed 503A pharmacies. Category 1 substances are eligible while review continues or after a positive recommendation. Category 2 substances are flagged as posing significant safety risks or as having insufficient evidence to support a clinical need (FDA, 503A bulks).

How it works

Think of PCAC as a building permit office. Anyone may nominate a substance for the 503A list. The committee reviews the physicochemical profile, the historical use, the available safety data, and any safety signals. It then makes a non-binding recommendation. The FDA reviews the recommendation and publishes its decision in the Federal Register. A substance does not become “approved.” It becomes eligible — or not eligible — to be compounded.

Who asks about it

People come to this topic after their clinician explains that a peptide they read about online is “Category 2” and not currently available at the local 503A pharmacy. Many are surprised the FDA does not “approve” or “ban” peptides per se. The actual mechanism is narrower: it decides whether each substance is eligible to be compounded into patient-specific medications.

What the research says

The framework was clarified in the Drug Quality and Security Act (DQSA) of 2013 and has been applied to dozens of substances since. PCAC meetings publish meeting minutes and decision rationales. Category 2 decisions for peptides like BPC-157 and TB-500 cited insufficient human safety data — not evidence of harm. A February 2026 HHS announcement proposed returning several Category 2 peptides to Category 1, pending formal Federal Register notice (Federal Register, 2019 503B list as reference).

What to know before considering it

Category status changes. A peptide that is Category 2 today may move to Category 1 after a Federal Register update. A peptide that is Category 1 today may move the other way if new safety signals emerge. Any access to a compounded peptide requires a licensed clinician and a state-licensed 503A pharmacy. Cross-border or “research-use-only” peptides do not pass through this framework at all.

The Halftime POV

The category system is not a verdict on a peptide’s value. It is a regulatory status that can change with new data. Patients are best served by clinicians who know the current status, the current evidence, and the difference between the two.

Related reading:

• The ‘banned overnight’ myth: what actually happened to peptides in 2023
• Why BPC-157 animal studies don’t automatically translate to humans
• How 503A pharmacies compound peptides from API to vial

FAQ

Q: How does the FDA categorize peptides for compounding? A: The FDA’s Pharmacy Compounding Advisory Committee (PCAC) reviews each bulk substance and recommends it for Category 1 (eligible for compounding under 503A) or Category 2 (significant safety risk or not eligible). The FDA then publishes the official list.

Q: What is the difference between Category 1 and Category 2? A: Category 1 substances may be compounded under 503A while review is ongoing or after a positive recommendation. Category 2 substances are flagged for significant safety risk or insufficient evidence and are not eligible for 503A compounding.

Q: Which peptides became Category 2 in 2023? A: The FDA reclassified BPC-157, TB-500, KPV, DSIP, epitalon, Selank, Semax, melanotan-2, and several others to Category 2. The decision was based on insufficient human safety data, not on evidence of harm.

Q: Is Category 2 status permanent? A: No. A February 2026 HHS announcement proposed returning several peptides to Category 1 pending formal FDA Federal Register notice. The PCAC review process is ongoing.

Disclaimer

As of 2026-05-25, several peptides discussed in this article — including BPC-157, TB-500, KPV, DSIP, epitalon, Selank, Semax, and melanotan-2 — are classified by the FDA as Category 2, which means they are not currently available from 503A compounding pharmacies. A February 2026 HHS announcement proposed returning these peptides to Category 1 pending formal FDA Federal Register notice. This article is educational and is not medical advice. Halftime Health only prescribes through licensed clinicians in states where our partner physicians are credentialed.

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Sources

• FDA, “Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act”
• Federal Register, List of Bulk Drug Substances for Compounding (2019, reference)