Most peptides sold online as "research" products (BPC-157, GLP-1 analogues, growth-hormone secretagogues) are drugs, not dietary ingredients, and we will not quote them as supplements. Small peptides with a history of supplement use, such as glutathione and carnosine, can be evaluated for a film and fit the dose targets. For any peptide, the film questions are pH, water, heat during casting, and whether an absorption claim is being made that no supplement strip can support.
| Ingredient | Molecular weight | US regulatory position | Film note |
|---|---|---|---|
| Glutathione (tripeptide) | 307.3 g/mol | Marketed as a dietary ingredient for years; fits the statutory categories | 100–250 mg fits our targets; thiol taste and oxidation need work |
| Carnosine (dipeptide) | 226.2 g/mol | Marketed as a dietary ingredient | Fits at low hundreds of mg |
| Collagen peptides (hydrolysate) | Mixture | Dietary ingredient (protein hydrolysate) | Servings are measured in grams; a strip cannot carry a meaningful serving |
| BPC-157 | 1,419.5 g/mol, 15 residues | Not a dietary ingredient; unapproved drug. Removed from FDA's 503A Category 2 list in April 2026 but not placed in Category 1 | Not quoted |
| Semaglutide | 4,114 g/mol, 31 residues | Approved drug, excluded from the supplement definition; FDA warning letters to "research" sellers, December 2024 | Not quoted |
| Ipamorelin, GHRP-2, GHRP-6, kisspeptin-10 | Varies | FDA 503A Category 2 (significant safety risk), added September 2023 | Not quoted |
Sort by law first, then by chemistry
A dietary ingredient is a vitamin, mineral, herb or botanical, amino acid, a dietary substance used to supplement the diet, or a concentrate, metabolite, constituent or extract of those (21 U.S.C. 321(ff)(1)). An article approved as a new drug, or under public clinical investigation, is excluded unless it was sold as a supplement or food first. Semaglutide and tirzepatide fail outright. BPC-157 and the growth-hormone secretagogues were never dietary ingredients and sat on FDA's compounding safety-risk list from September 2023.
FDA's December 10, 2024 warning letters to online peptide sellers made "for research only" irrelevant; the websites themselves showed intended human use. We follow the same line and do not quote prescription-pathway peptides as supplement projects.
Which peptides can be dietary ingredients
Small peptides with a supplement history fit: glutathione, carnosine, collagen hydrolysates. Any peptide not marketed in the United States before October 15, 1994 is a new dietary ingredient and needs a 75-day premarket notification unless it was already in the food supply in the same form.
Molecular weight and dose are the physics
Oral peptide bioavailability is low even with pharmaceutical help. Oral semaglutide tablets, co-formulated with an absorption enhancer, reach about 0.4–1 percent absolute bioavailability. Desmopressin as a sublingual lyophilisate is labelled at 0.25 percent. A 2026 study of a GLP-1 analogue in a pullulan-based buccal film moved about 2–4.5 percent across porcine mucosa in three hours, and only with a bile-salt enhancer.
For a supplement strip the conclusion is blunt: at 1,400–4,100 g/mol, absorption from a plain dissolving film is negligible and cannot be claimed. At 200–300 g/mol, peptides behave like ordinary ingredients dosed by the milligram, where our ~250 mg single-active target applies.
Stability in a cast film
Films are cast from a water-based mass and dried with heat, which is where peptides degrade. Exenatide data show the pattern: at pH 4.5 and 37 °C it lost 11.4 percent in 28 days; at pH 7.5–8.5 the parent peak fell to 20–31 percent through deamidation and aggregation. Our rules: fix film pH for the peptide, keep water activity low with a foil sachet, assay at release, and start accelerated stability on the pilot lot before a date prints. The 24-month shelf life is a target the data must earn.
Testing and packaging
Release for a peptide strip covers identity, assay, peptide-related impurities where a method exists, disintegration, moisture and microbial limits, run through ILS Lab and reported in the Lot Release Packet. The film's own moisture uptake sets the sachet seal specification.
Worked example: two requests, one week
Request one: a "BPC-157 sublingual strip, 500 mcg." Declined at intake. It is not a dietary ingredient, and an absorption claim at 1,419 g/mol would be unsupportable; formulation changes neither fact.
Request two: a 150 mg glutathione strip. Inside the 250 mg target. Open questions for the 3–5 day feasibility review: thiol taste, film pH, oxidation during drying, and whether the brand accepts "dissolves in the mouth" with no absorption language. If yes, it moves to formulation.
Bring a qualification-ready brief
Provide the exact ingredient, supplier, certificate of analysis, basis for dietary-ingredient status, target amount per strip, serving plan, market, draft claims, packaging, quantity, timing and the regulatory contact who signs off. For payment and underwriting questions in this category, PeptideRails publishes a separate resource; it has no bearing on feasibility or regulatory status. We confirm scope before any pilot path is discussed.
Common questions
No. The label does not change the ingredient's status, and FDA's 2024 warning letters classed such products as drugs intended for human use. We decline these at intake.
Marginally, and only in pharmaceutical designs with permeation enhancers and pharmacokinetic studies behind them. A supplement strip has neither and cannot claim it.
Small ones with a supplement history and milligram doses: glutathione and carnosine are the common examples. Collagen fails on serving size, not legality.
Primary sources
- FDA — New Dietary Ingredients in Dietary Supplements: Background for Industry (dietary ingredient definition, drug exclusion, 75-day notification)
- FDA — Certain Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks (503A Category 2)
- FDA — Concerns with Unapproved GLP-1 Drugs Used for Weight Loss
- FDA — Warning letter, Prime Vitality Inc. dba Prime Peptides, December 10, 2024
- FDA — Information on Select Dietary Supplement Ingredients and Other Substances
- FDA — Rybelsus (semaglutide) tablets prescribing information (absolute bioavailability)
- emc — DDAVP Melt oral lyophilisate SmPC (sublingual bioavailability 0.25%)
- Carbohydrate Polymers (2026) — A pullulan-based bilayer film for buccal delivery of a GLP-1 peptide analogue
- Pharmaceutics (2021) — The Effects of pH and Excipients on Exenatide Stability in Solution
- PubChem — BPC-157 (CID 9941957)
- PubChem — Semaglutide (CID 56843331)
Formula feasibility, packaging, testing, claims, timing, and final quantities depend on the exact product. Use this guide to prepare better questions, then confirm the production plan for your project.