The FDA's framework for regulating bulk drug substances used in compounding has become one of the most consequential policy mechanisms affecting peptide access in the United States. Under this system, peptides and other compounds are sorted into two distinct categories — Category 1 and Category 2 — each carrying dramatically different implications for compounding pharmacies, prescribers, and patients seeking these therapies.
With 2026 bringing renewed scrutiny and proposed reclassifications for more than a dozen peptides, understanding these categories has never been more important for anyone involved in peptide research or therapeutic access.
What Are FDA Bulk Drug Substance Categories?
The FDA's bulk drug substance categorization system was established under the Drug Quality and Security Act (DQSA) of 2013. This framework determines which substances 503A (traditional) and 503B (outsourcing facility) compounding pharmacies may legally use to prepare compounded medications.
Category 1 substances are those that the FDA has evaluated and determined can be used in compounding, subject to applicable conditions. A Category 1 designation means compounding pharmacies may source and compound with the substance, provided they meet all other regulatory requirements under sections 503A or 503B of the Federal Food, Drug, and Cosmetic Act.
Category 2 substances are those the FDA has evaluated and determined present significant safety or quality concerns, or for which there is insufficient data to support use in compounding. A Category 2 designation effectively prohibits compounding pharmacies from using the substance, though the FDA's enforcement posture can vary.
Current Category 1 and Category 2 Peptide Lists
The following table summarizes the current FDA categorization of key peptides as of early 2026. Note that some substances remain under active review, and classifications can change following public comment periods and FDA rulemaking.
| Peptide | Current Category | Compounding Permitted? | Notes |
|---|---|---|---|
| BPC-157 (Body Protection Compound) | Category 2 | No | Ruled Cat 2 in late 2024; insufficient safety data |
| TB-500 (Thymosin Beta-4) | Category 2 | No | Classified alongside BPC-157 |
| Thymosin Alpha-1 | Category 2 | No | Previously compounded widely; under review |
| AOD-9604 | Category 2 | No | Anti-obesity fragment; limited clinical data |
| Semaglutide | Category 1 (conditional) | During shortage only | Compounding tied to FDA shortage declarations |
| Tirzepatide | Category 1 (conditional) | During shortage only | Similar status to semaglutide |
| GHK-Cu | Category 1 | Yes | Classified as cosmetic ingredient in some contexts |
| PT-141 (Bremelanotide) | Category 2 | No | FDA-approved version (Vyleesi) exists |
| CJC-1295 | Category 2 | No | Growth hormone secretagogue; safety concerns cited |
| Ipamorelin | Category 2 | No | Often combined with CJC-1295 |
| Sermorelin | Category 1 | Yes | Previously FDA-approved (Geref); well-characterized |
| Gonadorelin | Category 1 | Yes | Established safety profile |
| DSIP (Delta Sleep-Inducing Peptide) | Category 2 | No | Limited human safety data |
| Selank | Category 2 | No | Nootropic peptide; insufficient US clinical data |
The 2026 Reclassification Proposal
In early 2026, the FDA announced it was reviewing the status of approximately 14 peptides currently designated as Category 2 substances. This review was prompted in part by mounting pressure from compounding pharmacy trade groups, patient advocacy organizations, and members of Congress who argued that the original classifications were overly restrictive and based on incomplete analysis.
The proposed reclassifications center on peptides for which new safety data, published research, or international regulatory precedent may support moving them to Category 1. Substances under review reportedly include thymosin alpha-1, AOD-9604, CJC-1295, and ipamorelin, among others. The FDA opened a public comment period that is expected to close in mid-2026, with final determinations anticipated by late 2026 or early 2027.
Industry analysts have noted that the reclassification process is closely linked to the broader political debate over compounding pharmacy rights. Several proposed bills in Congress — including the Pharmacy Compounding Access Act — would require the FDA to apply a more transparent and science-based framework when evaluating bulk drug substances.
What This Means for Compounding Pharmacies
For 503A and 503B compounding pharmacies, the distinction between Category 1 and Category 2 is existential. A Category 2 designation means a pharmacy cannot legally compound with that substance. Pharmacies that continue to use Category 2 substances risk FDA enforcement actions, including warning letters, injunctions, and product seizures.
Pharmacies that previously compounded popular peptides like BPC-157 and TB-500 were forced to discontinue those products following the late 2024 Category 2 rulings. Many shifted their focus to Category 1 substances like sermorelin and gonadorelin, while others have explored legal challenges to the FDA's categorization decisions.
What This Means for Patients and Researchers
For patients who had been receiving compounded peptide therapies, Category 2 designations have significantly limited access. Without a commercially available FDA-approved version, a Category 2 peptide is effectively unavailable through legitimate pharmacy channels in the United States.
Researchers working with these peptides in laboratory settings are generally not affected by the compounding restrictions, as the FDA's bulk drug substance categories apply specifically to pharmacy compounding for human use. However, the regulatory environment has created confusion around the availability of research-grade peptides as well.
How the FDA Makes Category Decisions
The FDA evaluates substances for categorization based on several factors outlined in its guidance documents:
- Safety profile: Published clinical and preclinical data on adverse effects
- Physical and chemical characterization: Whether the substance can be reliably identified and tested for purity
- History of use: Track record in compounding, including adverse event reports
- Available literature: Peer-reviewed studies supporting or raising concerns about the substance
- Public comments: Input received during the notice-and-comment rulemaking process
Critics of the current system argue that the FDA has applied these criteria inconsistently, and that some peptides were placed in Category 2 based on the absence of data rather than the presence of demonstrated harm.
FAQ: FDA Peptide Categories
Can my doctor still prescribe a Category 2 peptide?
Category 2 designations apply to compounding pharmacies, not to FDA-approved drugs. If a peptide has an FDA-approved version (such as bremelanotide/Vyleesi), a doctor can prescribe the approved product. However, a compounding pharmacy cannot make a compounded version of a Category 2 substance.
How long does the reclassification process take?
FDA rulemaking typically takes 12-24 months from the opening of a public comment period to a final rule. The 2026 reclassification review is expected to produce final determinations by late 2026 or early 2027, though delays are common in regulatory proceedings.
Can compounding pharmacies challenge a Category 2 designation?
Yes. Compounding pharmacies and trade organizations can submit petitions, provide new safety data during public comment periods, and pursue legal challenges in federal court. Several pharmacy associations have active litigation challenging specific Category 2 designations.
Does Category 2 mean a peptide is dangerous?
Not necessarily. Category 2 indicates that the FDA has determined there is insufficient evidence to support safe use in compounding, or that safety concerns exist. It does not equate to a finding that the substance is inherently dangerous. Many Category 2 peptides have extensive preclinical research and are used in clinical settings internationally.
Sources and References
- FDA — Bulk Drug Substances Used in Compounding
- Federal Register — FDA Bulk Drug Substance Notices
- FDA — Drug Quality and Security Act (DQSA)
- Congress.gov — Drug Quality and Security Act, H.R. 3204
- Sidley Austin LLP — FDA Compounding and Bulk Drug Substance Analysis
This article is for educational and informational purposes only and does not constitute legal or medical advice. Regulatory classifications are subject to change. Consult a qualified attorney or healthcare professional for guidance specific to your situation.