The U.S. peptide market has expanded rapidly in recent years, fueled by growing interest in regenerative medicine, weight management, and wellness therapies. Alongside drugs approved by the U.S. Food & Drug Administration (FDA), lawfully compounded peptides prepared under Sections 503A and 503B of the Federal Food, Drug, and Cosmetic Act (FD&C Act) have become a regular part of clinical practice.
The surge in demand for compounded GLP-1 receptor agonists in recent years, mainly semaglutide and tirzepatide, was initially driven by FDA officially declaring a national shortage of these two popular peptides. Over time, consumer demand for compounded products has also come to reflect a growing need for lower-cost alternatives to expensive branded products. In addition, clinics, prescribers, and patients now regularly look to compounding as a way to obtain personalized formulations they could not otherwise available through branded drugs.
Beyond GLP-1 weight loss medications, the market has also experienced a surge in demand for other peptide drug products. What was once a niche subculture in performance-enhancement and early biohacking communities has now gained mainstream traction through a mix of health-optimization culture, savvy marketing, celebrity promotion, and the promise of greater performance, longevity, and untapped health benefits.
From anecdotal accounts of improved fitness, higher libido, faster recovery, greater weight loss and muscle gain, or even improved cognitive performance, to endorsements by athletes, influencers, or even licensed professionals, the names of little-known peptides have now entered the vocabulary of many American households: GLP-1’s, BPC-157 (the, so called, “Wolverine compound”), Tesofensine (“Teso”), the Russian drug Selank, Sermorelin, Tesamorelin, CJC-1295, and many others.
A quick online search reveals hundreds, if not thousands, of peptide marketers and sellers: telehealth startups, compounding pharmacies, med spas, wellness websites, and also a range of unregulated vendors, many offering a wide array of products. But between FDA-approved drugs, compounded products, and peptides that are outright prohibited for human use, how does a compounder, prescriber, or a consumer know what’s legal, what’s safe for human consumption, or what is prohibited by law?
As is usual in our field, let us begin with the standard disclaimers: this article is neither medical nor legal advice. (As attorneys, we are bound to say this at least once in an article like this.) This is also not an endorsement or condemnation of peptide products, compounded products, or branded drugs. What we offer here is a guided overview through a regulatory maze—and, frankly, what many would characterize as a “wild west” that is the U.S. peptide market today.
We will start with the basics: what peptides are, how FDA regulates them, and where peptides fit in the regulatory landscape today. We will also briefly explore the FDA drug approval process and the basics of pharmaceutical compounding, while discussing key legal nuances and shedding light on the patchwork of federal enforcement, state-level requirements, and current market practices. Our goal is to provide you with a glimpse of what we know best—science and FDA regulatory law.
How FDA Regulates Peptide Drugs
Peptides are the building blocks of proteins. They are short chains of amino acids that occur naturally in the human body and in nature, and play key roles in various biological functions, including hormone signaling, immune response, tissue repair, and metabolism. Peptides can be isolated, chemically modified, or synthesized by various chemical and biotechnological methods for application in medicine, pharmacy, and research.
The FDA regulates drugs and biologics, medical devices, dietary supplements, food, cosmetics and tobacco. Under federal law, drugs are articles intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease, or intended to affect the structure or any function of the human body.[i] This broad definition encompasses prescription medications, over-the-counter drugs, and even products that may not have gone through any FDA approval process. This includes peptides, which can be regulated as either drugs or biologics depending primarily on the length of their alpha-amino acid sequence, with shorter peptides being regulated as drugs.[ii]
While drug products must generally navigate one of two primary approval pathways before they can be lawfully sold in the U.S.—the New Drug Application (NDA) for branded drugs and the Abbreviate New Drug Application (ANDA) for generics—any substance that is introduced into interstate commerce with therapeutic intent or with the intent to affect the structure or any function of the human body will also be regulated as a drug. If, for example, a drug product is marketed that has not gone through one of these approval pathways, the FDA can determine that it is adulterated, misbranded or merely an unapproved new drug, subject to its enforcement authority. The same applies to biological products, which require FDA approval to be lawfully marketed, subject to the requirements of the Public Health Service Act and associated regulations.
The placement of adulterated, misbranded, or unapproved drugs into interstate commerce is prohibited by federal law and can result in both civil and criminal enforcement actions. Under 21 USC §331, for example, introducing, delivering, or receiving adulterated or misbranded drugs in interstate commerce, as well as manufacturing such drugs within U.S. territories are explicitly prohibited. Among other things, Federal law defines a drug as “adulterated” if it is contaminated, does not conform to standards of strength, quality, or purity, or fails to meet performance standards.[iii] Additionally, a drug is considered “misbranded” if its labeling is false or misleading, lacks adequate directions for use, or fails to meet specific labeling requirements.[iv] These laws aim to ensure the safety, efficacy, and proper labeling of drugs and devices, thereby protecting public health and maintaining regulatory compliance.
Whether a substance is considered a drug for the purposes of FDA enforcement hinges on the intent of those legally responsible for introducing the product into interstate commerce. A product is classified as a drug if it is used or intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease, or if it is intended to affect the structure or function of the body of humans or animals.[v]
FDA and courts take a broad view when interpreting intended use regulation,[vi] and can determine such intent through various forms of evidence. FDA may, for example, determine that a “research use only” (RUO) peptide is, in fact, an unapproved drug if it is marketed in connection with medical claims, if it is introduced into commerce with the intent that it be directed for human or animal use, or if evidence shows that consumers or medical practitioners are using it for therapeutic purposes or to affect the structure or any function of the human body. Such a determination may result in potentially serious legal consequences that include enforcement actionor criminal prosecution.
So where does pharmaceutical compounding fit within this regulatory framework?
Under 21 USC, §353A,[vii] compounded drugs are exempt from the FD&C Act “new drug” approval requirement if they are compounded by a licensed pharmacist or physician using bulk drug substances that comply with United States Pharmacopoeia standards, are components of an FDA-approved drug, or appear on FDA’s 503A Bulk’s list.[viii] Compounded drugs must also not appear on a list of drugs withdrawn for safety or efficacy reasons, may not be compounded in “inordinate amounts,” or be “essentially copies” of commercially available drugs.[ix]
A compounded drug is considered “essentially a copy” if it is identical or nearly identical to an approved drug,[x] unless the compounded drug appears on FDA’s drug shortage list at the time of compounding, distribution, or dispensing. [xi] Alternatively, if the compounded drug includes a bulk drug substance that is a component of an approved drug, it must produce a clinical difference for an individual patient as determined by the prescribing practitioner to be lawfully compounded.
FDA guidance indicates that a compounded product may be considered “essentially a copy” of a commercially available drug product if:
- The compounded product has the same active pharmaceutical ingredient (API),
- The API has the same, similar or an easily substitutable dosage strength, and
- Thee commercially available drug product can be used by the same route of administration as prescribed for the compounded drug.[xii]
A compounded drug meeting all these criteria is considered “essentially a copy” unless the prescribing practitioner determines that there is a change, made for an identified individual patient, that produces a significant clinical difference for that patient compared to the commercially available drug.[xiii]
Pharmacies compounding formulations that use the same API as branded peptide drugs like, for example, semaglutide (Ozempic®, Wegovy®), tirzepatide (Mounjaro®, Zepbound®), tesamorelin (Egrifta®), or bremelanotide (Vyleesi®) should ensure regulatory and non-infringement compliance due to their potential exposure to both regulatory and civil liability. That is because, in addition to possible violations of the FD&C Act (compounded products that are “essentially copies” of a commercially available drug may be deemed an unapproved new drug by FDA), there is also the risk of civil liability from brand-name drug manufacturers. This has been exemplified through several dozen of lawsuits and demand letters issued by pharmaceutical drugmakers Novo Nordisk and Eli Lilly against pharmacies, telehealth platforms, weight-loss clinics, and medical spas, alleging various violations related to the marketing or sale of compounded versions of their respective semaglutide and tirzepatide products.
It is important to note that certain U.S. states have imposed even more restrictive standards than federal law when it comes to compounding what could be considered “essentially copies” of commercially available drug products. In California, for example, regulation adopted by the State’s Board of Pharmacy in June 2025 imposes an affirmative duty on the pharmacist to verify and document that any compounded preparation differing from a commercially available drug is clinically justified for the identified patient.[xiv] The regulations also more broadly define “essentially a copy” to encompass formulations that would otherwise not be considered “essentially copies” under federal law.[xv] State laws and regulations like this should prompt pharmacies operating or doing business in those states to revise formularies and update their protocols accordingly.
Bulk Drug Substances
Compounded drugs, as mentioned above, are exempt from federal “new drug” approval requirements if they are compounded by a licensed pharmacist or physician using bulk drug substances that comply with United States Pharmacopoeia standards, are components of FDA-approved drugs, or appear on FDA’s 503A bulk’s list.
As originally promulgated by regulation, the 503A bulk list is narrow. FDA is currently in the process of updating the list to consider the inclusion of new substances, including certain peptides. In the meantime, the Agency has issued an interim guidance allowing state-licensed pharmacies and physicians to compound certain bulk drug substances listed in Category 1 of its interim list.[xvi] This is permitted subject to FDA’s enforcement discretion and only if specific conditions are met.[xvii] These include:
- Registration of the manufacturer under Section 510 of the FD&C Act;
- A valid certificate of analysis for the bulk substance; and
- Full compliance with all other requirements of Section 503A.[xviii]
Category 1 bulk drug substances are those that have been nominated for inclusion on FDA’s bulks list with sufficient supporting information and without significant safety risks identified. Peptides such as Sermorelin Acetate, and coenzymes like beta-Nicotinamide Adenine Dinucleotide (NAD+) and glutathione are included in this category. In contrast, despite their widespread availability on the open market, many peptides popular in biohacking and longevity circles—for example, BPC-157, Thymosin Beta-4, or CJC-1295—cannot, at present, be lawfully compounded for human use. This is because they do not meet the statutory criteria for compounding, fall outside FDA’s discretionary policy exemption, or have been identified by FDA as presenting significant safety risks for human use.
To make matters more confusing for compounders, prescribers, and consumers, FDA’s determinations regarding which peptides appear in Category 1 not only depend on the substance itself but also on its route of administration. What this means in practice is that a peptide prohibited for use as an injectable could, for example, be permitted for use as a topical formulation. Additionally, less common routes of administration for compounded products, such as intranasal or transdermal, may not be explicitly addressed in guidance or regulation and could require more nuanced regulatory considerations.
Enforcement
Whether offered through regulated channels or otherwise, widespread availability of a numerous peptide drug products has created significant confusion among consumers, professionals, and marketplace participants who seek to access or offer lawful, safe, and effective products. Despite serious potential penalties—including criminal penalties—for the introduction of adulterated, misbranded, or unapproved drugs into interstate commerce, in violation of the FD&C Act, enforcement at the federal level remains sparse. This has contributed to the proliferation of non-compliant as well as unregulated activity in the peptide space. At the state level, enforcement activity against pharmacists, compounders, clinics, or medical professionals continues to increase, particularly by boards of pharmacy and medicine.
While the Department of Justice (DOJ) has, to date, initiated very few enforcement actions against peptide marketers involved in practices potentially violative of the FD&C Act, DOJ recently announced the creation of an Enforcement & Affirmative Litigation Branch within its civil division.[xix] This new branch will include an Enforcement Section drawing on extensive experience prosecuting landmark cases under statutes such as the Controlled Substances Act, the FD&C Act, the Consumer Product Safety Act, and the Federal Trade Commission Act.[xx] Whether this development will translate into an increase in enforcement activity in the peptide space remains to be seen.
As scientific and clinical innovation continues to advance, and as peptides see broader use among U.S. consumers, confusion regarding compliance with the complex web of federal and state regulations is source of great confusion in the marketplace. Consumers, compounders and prescribing clinicians may be eager to access or offer cutting-edge therapies, but the highly regulated world of therapeutic drugs, as regulated by the FDA, is not the place to “move fast and break things.” Ensuring precise regulatory compliance—rather than following the pack—not only promotes patient safety and safeguards against enforcement action, but also ensures you won’t need a peptide to sleep soundly while running your business.
Edgar J. Asebey, a partner in Frier Levitt’s Life Science Group, is a life sciences regulatory and transactional attorney with over 20 years of experience advising pharmaceutical, biotechnology, biologics, medical device, food, and dietary supplement companies on FDA compliance and related regulatory matters, including licensing, transactions, and venture finance. Edgar represents clients before the U.S. Food and Drug Administration (FDA), the United States Department of Agriculture (USDA), U.S. Customs and Border Protection (CBP), the U.S. Federal Trade Commission (FTC), the U.S. Environmental Protection Agency (EPA), the National Institute for Occupational Safety & Health (NIOSH), and the Drug Enforcement Agency (DEA). His work includes providing compliance and enforcement defense services before these agencies. He assists companies with FDA registration, clearance, and pre-market approval, and advises on compliance throughout the development, manufacturing, marketing, and sale of FDA-regulated products.
Guilherme Ferrari Faviero, Esq., MS, MPH, is a senior associate in Frier Levitt’s Life Science Group. His practice focuses on FDA regulatory law and compliance, as well as transactional work in the food and drug, biotechnology, cannabis, hemp, and psychedelics sectors. A scientifically trained attorney with graduate degrees in biomedical sciences and public health, he offers a unique perspective to clients in highly regulated industries.
[i] 21 U.S.C. § 321(g).
[ii] 21 CFR § 600.3.
[iii] 21 U.S.C. § 351.
[iv] 21 U.S.C. § 352.
[v] 21 U.S.C. § 321(ff).
[vi] 21 C.F.R. §801.4; See also Regulations Regarding “Intended Uses,” Federal Register, volume 86, number 145.
[vii] Note that our article does not address compounding under §503B.
[viii] 21 U.SC. § 353a(b)(1)(A)(i)(I)-(III).
[ix] See 21 U.S.C §§ 353b, 216.24, 353a.
[x] 21 U.S.C. § 353b(d)(2).
[xi] 21 USCS § 356e.
[xii] Compounded Drug Products That Are Essentially Copies of a Commercially Available Drug Product Under Section 503A of the Federal Food, Drug, and Cosmetic Act, FDA (Jan. 2018), Guidance for Industry, at 5-6.
[xiii] Id at 6.
[xiv] 16 C.C.R. § 1731.1(e).
[xv] 16 C.C.R. § 1735(d).
[xvi] Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the FDCA (Updated September 27, 2024) (Last accessed on October 30, 2025): Access at: https://www.fda.gov/media/94155/download.
[xvii] Interim Policy on Compounding Using Bulk Drug Substances Under Section 503A of the FDCA at 12-13 (January 2025).
[xviii] Id.
[xix] U.S. Dep’t of Justice, Press Release, The Department of Justice Creates New Civil Division Enforcement & Affirmative Litigation Branch, (Sept. 25, 2025), https://www.justice.gov/opa/pr/department-justice-creates-new-civil-division-enforcement-affirmative-litigation-branch.
[xx] Id.
