Compounding & the law
Pharmacy compounding is older than the modern FDA, and it's governed by a specific federal framework that matters a lot for peptide therapy. Here's how it actually works.
What compounding is
Compounding is the practice of a licensed pharmacist preparing a customized medication for a specific patient based on a specific prescription. It predates industrial drug manufacturing — before mass-produced brand-name drugs existed, nearly all medications were compounded.
Today, compounding fills gaps that commercial pharmaceuticals can't: patient-specific dose strengths, combination formulations, preservative-free preparations for allergic patients, liquid versions of drugs only commercially available as tablets, and so on. It's a legal, regulated pharmacy practice that has existed for as long as modern pharmacy has.
Critically: compounded medications are not FDA-approved drugs. That's a regulatory distinction, not a quality statement. Compounded preparations are legally prepared by licensed pharmacies and are subject to pharmacy quality standards, but they don't go through the multi-year FDA approval process that brand-name drugs do.
503A and 503B — the two frameworks
The 2013 Drug Quality and Security Act created the modern structure. It split compounding pharmacies into two categories with different rules.
Traditional compounding
Licensed pharmacies or physician offices preparing patient-specific prescriptions. Each preparation requires an active, named prescription. Regulated primarily by state boards of pharmacy, with FDA oversight on bulk drug substances.
This is traditional pharmacy compounding — small-scale, custom-prepared for individual patients. Most compounded semaglutide, tirzepatide, and NAD+ prescribed via telehealth comes from 503A pharmacies.
Outsourcing facilities
Larger-scale compounding facilities registered directly with the FDA. Subject to Current Good Manufacturing Practice (cGMP) requirements similar to commercial pharmaceutical manufacturing. Can prepare compounded drugs for office use without patient-specific prescriptions.
503B facilities look more like pharmaceutical manufacturers than traditional pharmacies — higher throughput, more rigorous quality controls, direct FDA oversight.
Brand-name vs. compounded
A brand-name drug (Ozempic, Wegovy, Mounjaro, Zepbound) is a specific formulation that the manufacturer submitted to the FDA for approval. The FDA reviewed safety, efficacy, manufacturing, and labeling; once approved, the drug can be marketed for specific indications and manufactured at commercial scale.
A compounded version uses the same active ingredient (for example, semaglutide) but is prepared by a pharmacy under the 503A or 503B framework rather than by the brand manufacturer. The compounded version is not FDA-approved, is not legally marketed as a commercial product, and is prepared in response to specific prescriptions.
Both can be effective. They're regulated differently, priced differently, and come with different risk profiles around quality control. That's the honest answer about what the distinction is and isn't.
FDA bulk drug substance categories
The FDA classifies bulk drug substances used in compounding into three categories. Knowing which category a peptide is in tells you whether it can legally be compounded today.
Compoundable
Substances that can currently be compounded by licensed pharmacies. Most active ingredients in prescription medications fall here. This is the default state.
Under FDA review
Substances the FDA is actively evaluating for safety or efficacy concerns in compounding. Cannot be legally compounded by U.S. pharmacies while under review. BPC-157, TB-500, Thymosin Alpha-1, Selank, and Semax are currently here.
Not appropriate
Substances the FDA has determined are not appropriate for compounding — typically because of safety concerns that outweigh any clinical value. Cannot be legally compounded.
Drug shortages change the picture
The FDA maintains a public list of drugs officially in shortage. When a brand-name drug is on that list, the regulatory picture for compounding shifts meaningfully: compounding pharmacies gain explicit permission to prepare patient-specific versions of the shortage drug at scale.
This is the regulatory mechanism that has allowed compounding pharmacies to serve millions of patients who couldn't access brand-name Ozempic or Wegovy during sustained manufacturer shortages. It's not a loophole — it's the exact use case Congress designed 503A to address.
Shortage status is dynamic. When the FDA declares a drug resolved and removes it from the shortage list, compounding pharmacies lose the explicit permission and have to wind down production of that specific compound. This has been a source of uncertainty for GLP-1 compounding specifically; your clinician and pharmacy monitor shortage-list status closely.
Recent regulatory history
The last few years have seen unusually active regulation of peptide compounding.
September 2023: The FDA added BPC-157 to the Category 2 list, alongside several other research peptides. Legal compounding of those substances stopped in the U.S. Some gray-market vendors continued to sell “research chemical” versions, but these are unregulated and fall outside the pharmacy compounding framework entirely.
February 27, 2026: The U.S. Department of Health and Human Services, under Secretary Robert F. Kennedy Jr., announced an intent to reclassify certain peptides to make them available again through compounding. As of this writing, that announcement has not been formally published in the Federal Register and has no legal effect until it is. Implementation timing is unknown.
The PepScribe Peptide Library tracks each Category 2 peptide's legal status on its research page.
What this means for patients
If you're considering peptide therapy through PepScribe or any other provider, a few things are worth understanding.
Compounded is not equivalent to unregulated. Licensed 503A and 503B compounding is a federally regulated pharmacy practice. That's different from the purely black-market “research chemical” ecosystem, which is not regulated at all and where product identity and purity can't be verified.
Regulatory status can change. A peptide's legal compoundability is a snapshot of current FDA policy, not a fixed state. Category 2 substances can be moved to Category 1 (re-enabling compounding) or to Category 3 (blocking it permanently). Shortage-list entries can come and go. Services like PepScribe build this dynamism into how we operate — we only sell what's legally compoundable right now.
Educational content is legal even when the compound isn't. Our Tier 2 research pages cover compounds like BPC-157 and TB-500 because the research is interesting and patient-relevant. But we won't sell what we can't legally prescribe. The distinction is intentional.
Keep reading
What are peptides?
The biology primer — amino acids, peptides vs. proteins, and why peptides have become a major therapeutic category.
The Peptide Library
See each peptide's current regulatory status. Available now, pending reclassification, and the research behind each.