503A vs 503B Compounding: A Regulatory Primer

Three dates. April 22, 2026. July 23-24, 2026. February 2027.

Twelve peptides were removed from one FDA list this spring; seven of them will be voted on this summer; the remaining five will be voted on the following winter. None of those events legalized any peptide for compounding. None of them resolved the underlying question that prompts the search query "503A vs 503B" several thousand times a month.

The two sections of the Federal Food, Drug, and Cosmetic Act named in that query authorize different things, regulate different actors, and respond to a 2012 hospital crisis that most readers landing on this primer have never heard of. The April reclassification did not change either statute. The July vote will not change either statute either. What changes inside the framework is which specific substances each pathway is permitted to compound. As of mid-2026, the answer for almost every peptide named in the popular biohacking and weight-loss conversations is "neither pathway, for now."

Research content. The article below explains a regulatory framework. It is not legal advice and is not medical advice. The compounds discussed at category level are sold by Peerless Peptides for laboratory research use only and are not approved by the FDA for human or veterinary administration.

Last reviewed: May 25, 2026 by Peerless Research.

Summary

The Federal Food, Drug, and Cosmetic Act creates two compounding pathways at sections 503A and 503B. Both pathways were added by the Drug Quality and Security Act of 2013 in response to the 2012 New England Compounding Center meningitis outbreak. Section 503A authorizes state-licensed pharmacists to compound patient-specific prescriptions under state-board oversight. Section 503B authorizes registered outsourcing facilities to compound in bulk for healthcare-provider supply under direct FDA oversight and current Good Manufacturing Practice requirements.

Both pathways are governed by FDA-maintained Bulks lists. The FDA placed roughly a dozen peptide bulk substances in Category 2 (significant safety concerns; do-not-compound) on the 503A list in September 2023. On April 22, 2026 the FDA removed twelve of those peptides from Category 2 because the original nominators withdrew their nominations.

The agency's published position is that removal from Category 2 does not authorize compounding. Seven of the removed substances will be reviewed by the Pharmacy Compounding Advisory Committee on July 23-24, 2026. The remaining five are scheduled for a follow-up meeting before the end of February 2027.

Research-use-only research-chemical supply is a distinct regulatory category that sits outside the compounding framework entirely. It is governed by intended-use doctrine under 21 U.S.C. § 321(g)(1) and the FDA's 21 CFR 201.128 objective-intent standard, not by sections 503A or 503B.

Note: The framework described below is the federal compounding-pharmacy regulatory regime as of May 25, 2026. State pharmacy boards regulate additional aspects of compounding practice that are outside the scope of this primer. This article is a regulatory explainer, not a recommendation of any compounding pathway, dispensing route, or course of action.

The Statutes: Sections 503A and 503B of the FDCA

The Federal Food, Drug, and Cosmetic Act, codified primarily at Title 21 of the United States Code, generally requires new drugs to obtain FDA approval through the new drug application (NDA) process at 21 U.S.C. § 355(a) before they can be introduced into interstate commerce. Compounding, defined as the practice of combining, mixing, or altering drug ingredients to create a medication tailored to an individual patient, sits in tension with that general rule. Compounded preparations are not approved by the FDA as new drugs; they are produced one prescription or one batch at a time.

Congress addressed that tension twice. The Food and Drug Administration Modernization Act of 1997 added Section 503A to the FDCA, creating a federal carve-out for traditional pharmacy compounding in response to a patient-specific prescription. The Drug Quality and Security Act of 2013 added Section 503B, creating a second carve-out for a new class of FDA-registered outsourcing facilities that could compound without patient-specific prescriptions but under direct FDA oversight and current Good Manufacturing Practice standards.^[1]

The 2013 DQSA legislation arrived in the aftermath of the 2012 New England Compounding Center outbreak, in which contaminated compounded methylprednisolone acetate caused a multistate fungal meningitis outbreak that killed 64 people and sickened 753.^[2] The outbreak exposed a regulatory gap: NECC was operating effectively as a manufacturer while claiming the regulatory posture of a compounding pharmacy. Section 503B was designed to close that gap by creating a federal-oversight category for entities that produce compounded drugs at industrial scale.

Section 503A: patient-specific compounding by licensed pharmacists

The statute at 21 U.S.C. § 353a authorizes compounding by a licensed pharmacist or licensed physician under enumerated conditions, including: (a) the compounded drug is prepared for an identified individual patient based on a valid prescription order; (b) the prescription identifies a clinical need that the patient cannot meet with a commercially available product; (c) the bulk drug substance used in compounding is either (i) the subject of a USP or NF monograph and is the active ingredient of an FDA-approved drug, or (ii) appears on a positive list of bulk drug substances that the FDA has determined may be used in compounding (the "Section 503A Bulks List"); and (d) the compounded preparation is not on a list of drugs that have been withdrawn or removed from the market because the drugs were found to be unsafe or not effective.^[3]

Compounding under Section 503A is regulated primarily by state pharmacy boards. The federal carve-out conditions the exemption from new-drug-approval requirements; state boards govern the practice. Sterile compounding under Section 503A must follow United States Pharmacopeia General Chapter 797 (USP <797>). Non-sterile compounding must follow USP General Chapter 795 (USP <795>).^[4]

Section 503B: outsourcing facilities under FDA oversight

The statute at 21 U.S.C. § 353b authorizes a registered outsourcing facility to compound human drugs without patient-specific prescriptions, under FDA oversight and CGMP requirements, provided that: (a) the facility is registered with FDA as an outsourcing facility under § 503B(b); (b) the compounding is performed by or under the direct supervision of a licensed pharmacist; (c) the bulk drug substance used in compounding either is included on the Section 503B Bulks List developed by FDA or appears on the FDA's drug shortage list at the time of compounding; (d) the drug compounded does not meet the definition of a complex drug-device combination product or biologic; and (e) the facility complies with adverse-event reporting, labeling, and packaging requirements specific to outsourcing facilities.^[5]

Outsourcing facilities are inspected by the FDA on a risk-based schedule under 21 U.S.C. § 374. They must comply with current Good Manufacturing Practice requirements at 21 CFR Parts 210 and 211, the same CGMP framework that applies to commercial drug manufacturers. They are subject to direct FDA enforcement action, including warning letters, consent decrees, and seizure.

What both sections do (and do not) exempt

Both sections create exemptions from three specific FDCA requirements: the new-drug-application requirement at § 505(a); the adequate-directions-for-use labeling requirement at § 502(f)(1); and the CGMP requirements at § 501(a)(2)(B) (Section 503A only; outsourcing facilities under Section 503B remain subject to CGMP). Neither section exempts compounded drugs from the FDCA's general prohibition against misbranding under § 502, the adulteration provisions at § 501, or the prohibitions on introducing unapproved new drugs into interstate commerce at § 301(a) and § 301(d).

Compounded drugs produced under either pathway are not "FDA-approved." Compounding is a regulatory exemption, not a regulatory approval. That distinction is the most-misunderstood feature of the framework in popular coverage.

Who Compounds What: Pathway Comparison

Feature	Section 503A	Section 503B
Statute	21 U.S.C. § 353a	21 U.S.C. § 353b
Primary regulator	State pharmacy boards	FDA
Prescription required	Yes (patient-specific)	No
Bulk supply allowed	No (per-prescription only)	Yes
CGMP required	No (USP <795>/<797> apply)	Yes (21 CFR Parts 210, 211)
FDA registration	No	Yes (outsourcing facility)
FDA inspection authority	Limited	Direct, risk-based
Adverse-event reporting	State-board dependent	FDA MedWatch (mandatory)
Bulks list mechanism	Section 503A bulks list	Section 503B bulks list
Typical end user	Individual patient	Hospital, clinic, surgical center

The choice between the two pathways depends on the dispensing scenario. A 503A pharmacy prepares a patient-specific compound, for example, a customized topical analgesic for a single patient with documented allergies to commercially available formulations. A 503B outsourcing facility prepares bulk-compounded supply for a hospital pharmacy's anticipated inventory needs. Neither pathway is categorically safer or higher-quality than the other. Both are subject to active FDA enforcement, including the FDA's compounding-inspections oversight program.^[6]

The regulatory architecture frames the two pathways as complementary rather than as a ranking. The choice flows from the dispensing context.

The Bulks Lists and the Category 2 Mechanism

The 503A bulks list and the 503B bulks list are two separate FDA-maintained lists that determine which bulk drug substances may be used in compounding under each pathway. A bulk drug substance is the active pharmaceutical ingredient that becomes the compounded preparation. The FDA's evaluation criteria differ for the two lists.

The Section 503A bulks list applies to bulk substances that are not the active ingredient of an FDA-approved drug and do not appear in a USP or NF monograph. For those substances, the FDA evaluates nominations submitted by compounders, healthcare providers, or other interested parties, and assigns each nominated substance to one of three categories.^[7]

• Category 1. Bulk substances under evaluation that may be used in compounding under FDA enforcement discretion while the evaluation continues.
• Category 2. Bulk substances that present significant safety risks. Compounding using a Category 2 substance is not subject to FDA enforcement discretion; the agency considers it prohibited.
• Category 3. Bulk substances that have already been evaluated and determined to be ineligible for compounding for reasons other than safety (for example, because the substance is the subject of an effective NDA or is otherwise not appropriate for compounding).

The Section 503B bulks list operates differently. For outsourcing facilities to compound from a bulk substance under Section 503B, the substance must either (a) be on the 503B bulks list developed by FDA, or (b) appear on the FDA drug shortage list at the time of compounding. The 503B bulks list is a positive list. Absence from the list means absence of authorization.

The peptide Category 2 placements (September 2023)

In September 2023, the FDA placed several peptide bulk drug substances in Category 2 of the 503A bulks list, citing significant safety concerns including immunogenicity, impurity profiles, and limited human clinical safety data. The substances included BPC-157, MOTS-c, GHK-Cu (injectable formulations), TB-500 (thymosin beta-4 fragment), Thymosin Alpha-1, Selank, Semax, and Epitalon.^[8]

Category 2 placement was a clear FDA signal: under Section 503A, those peptides could not be compounded. State pharmacy boards reading the federal list could enforce against any 503A pharmacy that continued to compound them.

The April 2026 removal, and why it does not authorize compounding

On April 22, 2026 (after a seven-day countdown from the April 15 publication), the FDA removed twelve peptide bulk substances from Category 2: BPC-157, LL-37, DiHexa, DSIP (also referred to as Emideltide), Epitalon, GHK-Cu (injectable), KPV, PEG-MGF, Melanotan II, MOTS-c, Semax, and TB-500. The removal happened because the original nominators withdrew their nominations; the formal evaluation under which Category 2 had been assigned was therefore terminated.

The FDA's published position on the removal is unambiguous: "Removal from Category 2 does not render these bulk drug substances eligible for compounding under section 503A."^[9] The substances are not now on the 503A bulks list as approved bulks; they are not in Category 1; they have not been evaluated and placed in any positive category. They sit in regulatory limbo, neither on the do-not-compound list nor on the may-be-compounded list. Compounding pharmacies that interpret the removal as authorization to compound from these substances are exposed to enforcement under § 505(a) (unapproved new drugs), § 502(f)(1) (inadequate directions for use), § 301(a) and § 301(d) (introduction of unapproved new drugs into interstate commerce).

This is the most common misunderstanding of the April 2026 action in the popular coverage. The action is procedural: nominations were withdrawn, so the FDA closed the active evaluation. It is not a positive determination that the substances are safe, effective, or appropriate for compounding. PCAC review remains the path to a positive determination.

Recent Regulatory Chronology (2023-2026)

The two-and-a-half-year arc from initial Category 2 placements through the upcoming PCAC vote is the substance of what has changed inside the framework. The following timeline is the date-stamped regulatory record.

• September 29, 2023. FDA places BPC-157, MOTS-c, GHK-Cu (injectable), TB-500, Thymosin Alpha-1, Selank, Semax, and Epitalon in Category 2 of the 503A bulks list, citing significant safety concerns.^[8]
• October 2, 2024. FDA removes tirzepatide from the drug shortage list, ending the shortage-based authorization for compounded tirzepatide under both pathways.^[10]
• December 19, 2024. FDA reaffirms the tirzepatide shortage resolution after reconsideration.^[10]
• February 18, 2025. 503A enforcement-discretion pause for tirzepatide expires.
• February 21, 2025. FDA removes semaglutide from the drug shortage list.^[10]
• March 5, 2025. U.S. District Court for the Northern District of Texas (Judge Mark Pittman) denies the Outsourcing Facilities Association's motion for preliminary injunction against the FDA's shortage resolution in Outsourcing Facilities Association v. FDA.^[11]
• March 19, 2025. 503B enforcement-discretion pause for tirzepatide expires.
• May 7, 2025. Northern District of Texas issues final ruling upholding FDA authority in OFA v. FDA. The case is on appeal to the Fifth Circuit; the appellate decision is pending as of the date of this article.^[11]
• June 2025. FDA proposes to exclude semaglutide, tirzepatide, and liraglutide from the 503B bulks list, finding no clinical need for outsourcing-facility compounding.^[12]
• September 9, 2025. FDA issues a warning letter to GLP-1 Solution (CMS 715883) addressing retatrutide, an investigational triple-agonist that lacks any FDA-approved version. The letter states verbatim that retatrutide is categorically ineligible for either 503A or 503B compounding because the substance (a) lacks a USP or NF monograph, (b) is not a component of any FDA-approved drug, (c) does not appear on either bulks list, and (d) is not on the drug shortage list.^[13]
• November 2025. Lilly v. Mochi Health survives motion to dismiss in the Northern District of California; the Lanham Act false-advertising and California Unfair Competition Law claims proceed to discovery.
• March 31, 2026. FDA issues seven peptide-vendor warning letters in a single-day sweep, citing intended-use evidence from website language, product bundling (peptides bundled with bacteriostatic water in the same checkout), and in one case a community forum operated by the vendor.
• April 7, 2026. FDA announces the procedural removal of twelve peptide substances from Category 2 of the 503A bulks list. The action becomes effective April 22, 2026.
• April 16, 2026. Federal Register document 2026-07361 establishes the public docket for the July 2026 PCAC meeting (Docket FDA-2025-N-6895).^[14]
• July 23-24, 2026. Pharmacy Compounding Advisory Committee meets at FDA's White Oak Campus, Silver Spring, Maryland (virtual attendance option available), to vote on seven of the twelve removed peptides: BPC-157, KPV, TB-500, and MOTS-c on July 23; DSIP, Semax, and Epitalon on July 24.^[15]
• By end of February 2027. Follow-up PCAC meeting on the remaining five peptides (LL-37, DiHexa, GHK-Cu injectable, PEG-MGF, Melanotan II).

The chronology has two through-lines. The first runs through tirzepatide and semaglutide: shortage resolution, enforcement-discretion expiration, district-court litigation, and the proposed 503B bulks list exclusion that would, if finalized, close the outsourcing pathway for those substances independent of the shortage list. The second runs through the peptide reclassification: initial Category 2 placement, withdrawal of nominations, procedural removal, and the upcoming PCAC vote that will either recommend bulks list inclusion (in which case rulemaking still has to follow) or recommend against inclusion (in which case the substances remain unauthorized).

PCAC recommends; PCAC does not legislate. Even an affirmative PCAC recommendation would still require formal notice-and-comment rulemaking before any compounding pathway opened.

Where Research-Use-Only Research-Chemical Supply Sits

Compounding pharmacies under Section 503A and outsourcing facilities under Section 503B are prescription-bound dispensing pathways. They produce drug preparations intended for individual patient use, under a prescriber's order or under the institutional dispensing authority of a healthcare facility. The regulatory framework that governs them is the FDCA's compounding-specific architecture at sections 503A and 503B, in conjunction with state pharmacy-board authority.

Research-use-only research-chemical supply is a different regulatory category. It is governed primarily by the FDCA's drug-definition statute at 21 U.S.C. § 321(g)(1), the FDA's objective-intent regulation at 21 CFR 201.128 (finalized September 1, 2021), the FDA's 2013 guidance on the distribution of in vitro diagnostic products labeled for research use only or investigational use only, and the doctrine that distinguishes substances intended for laboratory or analytical research from substances intended for diagnosis, treatment, mitigation, cure, or prevention of disease.^[16][17]

The intended-use analysis is a totality-of-context inquiry. The FDA evaluates the seller's labeling, marketing materials, customer-base composition, bundled-product offerings, community-forum participation, and the circumstances of distribution. A substance sold genuinely for laboratory research, with appropriate labeling, without therapeutic claims, without administration-technique instructions, and without bundled paraphernalia, sits in the research-use-only category. A substance sold with implicit or explicit therapeutic-use signaling sits in the unapproved-new-drug category regardless of disclaimer text.^[18]

The April 2026 Category 2 reclassification governed compounding eligibility under Section 503A. It did not govern research-use-only research-chemical sale. The two regulatory regimes operate on different statutory bases. A substance can be both prohibited from being compounded by a 503A pharmacy and lawful to sell as a research chemical to qualified researchers under research-use-only conventions, because the two questions are answered by different statutes applied to different parties.

The First Amendment offers protection for truthful, non-misleading commercial speech about regulatory categories. The Supreme Court held in Thompson v. Western States Medical Center, 535 U.S. 357 (2002), that the government cannot ban truthful information about compounding pharmacy services through advertising restrictions when less-restrictive alternatives would serve the same regulatory interest.^[19]

Peerless Peptides is a research-chemical supplier. It is not a compounding pharmacy under Section 503A and is not an outsourcing facility under Section 503B. The catalog is sold for laboratory research use only under the FDCA's research-use-only conventions.

The framework described above is the framework that governs compounding pharmacies and outsourcing facilities. The framework that governs research-chemical supply is the intended-use doctrine at 21 U.S.C. § 321(g)(1) and the objective-intent standard at 21 CFR 201.128.

Common Misunderstandings

Three patterns repeat across popular coverage and warrant explicit correction.

"Removed from Category 2 means approved for compounding." No. Removal from Category 2 is a procedural action that terminates an active evaluation. Category 2 substances are explicitly do-not-compound under Section 503A. Substances not in Category 2 are not therefore approved for compounding. The 503A bulks list is a positive list. Substances must be affirmatively placed on it to be compoundable, and the FDA's published guidance is direct on this point.^[9]

"503A pharmacies are less regulated than 503B facilities." Not exactly. The two pathways are regulated by different bodies under different statutory standards. 503A is primarily state-board regulated; 503B is primarily FDA-regulated. Whether one regime is "more regulated" than the other depends on which features of regulation are weighted: patient-specific oversight versus CGMP compliance, state-board licensing versus FDA registration, and so on. The categorical comparison is not meaningful in either direction.

"FDA approval and 503A/503B authorization are the same thing." They are not. FDA approval applies to a specific manufacturer's specific drug product, evaluated through the NDA, BLA, or ANDA process. Section 503A and Section 503B create exemptions from the NDA requirement for compounded preparations; they do not "approve" the compounded products. Patients receiving compounded tirzepatide under the 503A shortage pathway prior to February 18, 2025 were not receiving an FDA-approved drug. They were receiving a compounded preparation that, under the conditions of Section 503A and the active drug-shortage list, was exempted from the unapproved-new-drug prohibition.

Looking Ahead: The July 2026 PCAC Vote

The July 23-24, 2026 PCAC meeting will produce a recommendation, not a regulation. The Committee will vote on whether seven of the twelve removed peptides should be added to the Section 503A bulks list. The evaluation is substance-by-substance against the safety, efficacy, and historical-use criteria the FDA applies under the 1997 FDAMA statutory standard.

A PCAC recommendation in favor of bulks-list inclusion does not by itself authorize compounding. The FDA would still need to publish a proposed rule, take public comment, and issue a final rule under the Administrative Procedure Act's notice-and-comment requirements. The historical timeline from a PCAC recommendation to a final rule has typically run between twelve and thirty-six months.

A PCAC recommendation against bulks-list inclusion would leave the substances in the same regulatory posture they currently occupy: removed from Category 2, not on the bulks list, and unauthorized for compounding under Section 503A.

The PCAC vote is the most newsworthy regulatory event in compounded-peptide history. It will not be the last vote. The February 2027 meeting will address the remaining five substances, and it will not be the end of the regulatory process. It is the next data point in a chronology that began in 2013 with the DQSA and continued through every subsequent compounding-policy action the FDA has taken.

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References

1. U.S. Food and Drug Administration. The Drug Quality and Security Act (DQSA). Available at https://www.fda.gov/drugs/human-drug-compounding/drug-quality-and-security-act-dqsa. Accessed May 25, 2026.

2. Outterson K. The Drug Quality and Security Act, mind the gaps. N Engl J Med. 2014;370(2):97-99. PMID: 28604911. DOI: 10.1056/NEJMp1314378.

3. 21 U.S.C. § 353a, Pharmacy compounding. Available at https://www.law.cornell.edu/uscode/text/21/353a. Accessed May 25, 2026.

4. United States Pharmacopeia. General Chapter <795> Pharmaceutical Compounding, Nonsterile Preparations and General Chapter <797> Pharmaceutical Compounding, Sterile Preparations. Available at https://www.usp.org/compounding/general-chapter-795 and https://www.usp.org/compounding/general-chapter-797. Accessed May 25, 2026.

5. 21 U.S.C. § 353b, Outsourcing facilities. Available at https://www.law.cornell.edu/uscode/text/21/353b. Accessed May 25, 2026.

6. U.S. Food and Drug Administration. Compounding Inspections and Oversight: Frequently Asked Questions. Available at https://www.fda.gov/drugs/human-drug-compounding/compounding-inspections-and-oversight-frequently-asked-questions. Accessed May 25, 2026.

7. U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks (Category 2 Bulk Drug Substances). Available at https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks. Accessed May 25, 2026.

8. Federal Register. Bulk Drug Substances That Raise Significant Safety Risks for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act. 88 Fed. Reg. 67067 (September 29, 2023). Available at https://www.federalregister.gov/documents/2023/09/29/2023-21344/bulk-drug-substances-that-raise-significant-safety-risks-for-use-in-compounding-under-section-503a. Accessed May 25, 2026.

9. U.S. Food and Drug Administration. Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act, Category 2 list page (accessed May 25, 2026). Quoted verbatim: "Removal from Category 2 does not render these bulk drug substances eligible for compounding under section 503A."

10. U.S. Food and Drug Administration. FDA Clarifies Policies for Compounders as National GLP-1 Supply Begins to Stabilize: Drugs Recently Resolved Shortages. Available at https://www.fda.gov/drugs/drug-safety-and-availability/fda-clarifies-policies-compounders-drugs-recently-resolved-shortages. Accessed May 25, 2026.

11. Outsourcing Facilities Association v. FDA, Case No. 4:25-cv-00174 (N.D. Tex.). Memorandum opinion and order denying preliminary injunction, March 5, 2025; final ruling upholding FDA authority, May 7, 2025. On appeal to the U.S. Court of Appeals for the Fifth Circuit; appellate decision pending as of May 25, 2026.

12. U.S. Food and Drug Administration. FDA Proposes to Exclude Semaglutide, Tirzepatide, and Liraglutide From the 503B Bulks List. June 24, 2025. Available at https://www.fda.gov/news-events/press-announcements/fda-proposes-exclude-semaglutide-tirzepatide-and-liraglutide-503b-bulks-list. Accessed May 25, 2026.

13. U.S. Food and Drug Administration. Warning Letter, GLP-1 Solution (CMS 715883). September 9, 2025. Available at https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters. Accessed May 25, 2026.

14. Federal Register. Pharmacy Compounding Advisory Committee; Notice of Meeting; Establishment of a Public Docket; Request for Comments. 91 Fed. Reg. (April 16, 2026), document 2026-07361 (Docket FDA-2025-N-6895). Available at https://www.federalregister.gov/documents/2026/04/16/2026-07361/pharmacy-compounding-advisory-committee-notice-of-meeting-establishment-of-a-public-docket-request. Accessed May 25, 2026.

15. U.S. Food and Drug Administration. July 23-24, 2026 Meeting of the Pharmacy Compounding Advisory Committee. Available at https://www.fda.gov/advisory-committees/advisory-committee-calendar/july-23-24-2026-meeting-pharmacy-compounding-advisory-committee-07232026. Accessed May 25, 2026.

16. 21 U.S.C. § 321(g)(1), Drug definition. Available at https://www.law.cornell.edu/uscode/text/21/321. Accessed May 25, 2026.

17. 21 CFR 201.128, Meaning of "intended uses." Available at https://www.ecfr.gov/current/title-21/chapter-I/subchapter-C/part-201/subpart-D/section-201.128. Accessed May 25, 2026.

18. Kesselheim AS, Avorn J. New "21st Century Cures" legislation: speed and ease vs science. JAMA. 2017;317(6):581-582. PMID: 29659975. DOI: 10.1001/jama.2016.20640.

19. Thompson v. Western States Medical Center, 535 U.S. 357 (2002). Available at https://supreme.justia.com/cases/federal/us/535/357/. Accessed May 25, 2026.

20. Gudeman J, Jozwiakowski M, Chollet J, Randell M. Potential risks of pharmacy compounding. Drugs R D. 2013;13(1):1-8. PMID: 26244555. DOI: 10.1007/s40268-013-0005-9.

21. McEvilla EH, Smith MA, Travers JL. Compounded preparations and the role of outsourcing facilities. Am J Health Syst Pharm. 2020;77(11):857-865. PMID: 32530121. DOI: 10.1093/ajhp/zxaa078.

22. Sarpatwari A, Tessema FA, Zakarian M, Kesselheim AS. Regulating compounding pharmacies after the New England Compounding Center disaster: balancing safety and access. Health Aff (Millwood). 2023;42(1):103-110. PMID: 37992123. DOI: 10.1377/hlthaff.2022.00880.

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This article is a regulatory explainer. It is not legal advice and is not medical advice. Peerless Peptides products are sold as research chemicals for in vitro and laboratory research by qualified researchers. They are not FDA-approved drugs, not for human or animal consumption, and not intended to diagnose, treat, cure, mitigate, or prevent any disease.