By Guilherme Ferrari Faviero, Esq, MS, MPH, Edgar J. Asebey, Esq.
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?
This article is neither medical nor legal advice. It is also not an endorsement or condemnation of peptide products, compounded products, or branded drugs. This is a guided overview through a complex regulatory landscape.
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. 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.
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 Abbreviated 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 a drug product is marketed that has not gone through one of these approval pathways, FDA can determine that it is adulterated, misbranded or merely an unapproved new drug, subject to its enforcement authority.
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.
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. FDA and courts take a broad view when interpreting intended use regulation, and can determine such intent through various forms of evidence. FDA may 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.
So Where Does Pharmaceutical Compounding Fit?
Under 21 USC §353A, 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 bulks list. 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.
A compounded drug is considered “essentially a copy” if it is identical or nearly identical to an approved drug, unless the compounded drug appears on FDA’s drug shortage list at the time of compounding, distribution, or dispensing. 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 a compounded product may be considered “essentially a copy” if:
- The compounded product has the same active pharmaceutical ingredient (API)
- The API has the same, similar, or an easily substitutable dosage strength
- The commercially available drug product can be used by the same route of administration as prescribed for the compounded drug
Pharmacies compounding formulations that use the same API as branded peptide drugs like 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.
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.
Bulk Drug Substances
Compounded drugs 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 bulks list.
FDA is currently in the process of updating the list to consider the inclusion of new substances, including certain peptides. In the meantime, FDA 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, subject to enforcement discretion and only if specific conditions are met.
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 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.
Enforcement
Despite serious potential penalties—including criminal penalties—for the introduction of adulterated, misbranded, or unapproved drugs into interstate commerce, 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.
DOJ recently announced the creation of an Enforcement & Affirmative Litigation Branch within its civil division. This new branch will include an Enforcement Section drawing on experience prosecuting cases under statutes such as the Controlled Substances Act, the FD&C Act, the Consumer Product Safety Act, and the Federal Trade Commission Act.
As scientific and clinical innovation continues to advance, and as peptides see broader use among U.S. consumers, the highly regulated world of therapeutic drugs 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 helps you run your business with confidence.
