Gray-market peptides, retatrutide, and the difference between a drug and a vial

Two products can share a name and have almost nothing else in common. One is a molecule moving through FDA trials, with verified manufacturing and dose-finding studies. The other is a vial of powder sold online under the same name, made by an unknown facility. Most of the confusion in the current peptide market comes from treating those two things as one.

Where the compounds came from

The common gray-market peptides have different histories, and few of them match the story usually told about them.

BPC-157 came out of an academic lab, not a drug company. Predrag Sikiric's group at the University of Zagreb described it in 1993 as a fragment of a protein found in human gastric juice [1]. A 2026 investigation co-published by STAT and Undark reported that the group has never published key details of the discovery, including the sequence of the parent protein, which makes the original isolation work impossible for others to reproduce [2]. A Croatian company, Pliva, ran small ulcerative colitis trials of the peptide in the 2000s; the results appeared only as conference abstracts and were never published in full [2, 3].

TB-500 is a short synthetic fragment of thymosin beta-4 (the acetylated residues 17 to 23, the actin-binding region) [4]. A small biotech, RegeneRx, ran Phase 2 trials of the full-length protein for pressure ulcers, venous stasis ulcers and dry eye [5, 6]. Those trials tested the whole protein, not the seven-amino-acid fragment sold as TB-500.

CJC-1295 is the one that did go through a company program. ConjuChem, a small Canadian biotech, published Phase 1 data in 2006: in healthy adults a single injection raised growth hormone 2- to 10-fold for six days or more and IGF-1 1.5- to 3-fold for 9 to 11 days [7]. A Phase 2 trial in HIV-related visceral obesity was stopped in July 2006 after a participant died at a site in Argentina [8]. The Phase 2 results were never published.

None of this is evidence that a compound works, and none of it is evidence that it does not. It is evidence that the work was not finished.

What the approved pipeline shows

Retatrutide is the clearest current example of the difference. It is Eli Lilly's drug acting on GLP-1, GIP and glucagon receptors. In the Phase 2 trial published in 2023, 338 adults with obesity or overweight were randomized to weekly retatrutide or placebo for 48 weeks; the 12 mg group lost a mean 24.2 percent of body weight against 2.1 percent on placebo [9]. In 2026 Lilly reported Phase 3 results: in TRIUMPH-1, 2,339 participants were randomized to 4, 9 or 12 mg or placebo, and weight fell 28.3 percent at 80 weeks on 12 mg against 2.2 percent on placebo [10]. Those Phase 3 numbers are sponsor-reported topline results presented at the American Diabetes Association meeting in June 2026; the full peer-reviewed papers had not appeared as of this writing. Lilly said in its second-quarter 2026 report that it plans to file for approval in the first quarter of 2027 [11].

So, as of November 2026, retatrutide is not approved. It cannot be prescribed, and no licensed pharmacy dispenses it.

Product sold today under that name therefore comes from research chemical suppliers, many overseas, outside any inspection regime. Independent testing of this market has found what one would expect. In a 2024 study, researchers bought semaglutide from six online sellers that did not require a prescription; the vials were labeled 99 percent pure, measured purity was 7.7 to 14.4 percent, and every sample contained endotoxin [12]. A 2026 preprint analyzed 6,285 lab reports on 14 peptides from 203 manufacturers, submitted to a public testing platform between December 2024 and April 2026, and found that 41.6 percent failed on dose accuracy, purity or identity even against the looser standard applied to compounded drugs [13]. That preprint has not been peer reviewed, and its samples came from a voluntary testing program, not random purchases, so the true failure rate across the market could be higher or lower. Seller-issued certificates of analysis are produced by the sellers.

The evidence problem underneath

Even a genuine vial would leave the central problem untouched. For most of these compounds, human efficacy data do not exist. A 2025 systematic review of BPC-157 in HSS Journal found 36 studies published between 1993 and 2024: 35 were animal studies and one was an uncontrolled human chart review. The authors wrote that there are no clinical safety data in humans [14]. No randomized, placebo-controlled trial of BPC-157 has been published in full.

Growth hormone secretagogues have more human data, but of a narrow kind. The CJC-1295 trial measured hormone levels over 28 to 49 days and nothing else [7]. The one published Phase 2 outcome trial of ipamorelin, in 114 patients recovering from bowel surgery, found no difference from placebo in time to tolerating a meal [15]. Raising growth hormone or IGF-1 is a lab result; healing tissue, building muscle or extending health is an outcome, and the outcome trials have not been done.

The FDA's position has moved in both directions. In September 2023 the agency placed BPC-157, CJC-1295, ipamorelin and other peptides in Category 2 of its interim list for 503A compounding, citing immunogenicity risk, peptide-related impurities and limited human safety data; Category 2 means compounding pharmacies may not use them [16]. CJC-1295 and ipamorelin were later removed from Category 2 after their nominators withdrew, and in December 2024 the Pharmacy Compounding Advisory Committee voted against adding any form of CJC-1295 to the compounding list [17]. In April 2026 the FDA removed twelve peptides, including BPC-157 and TB-500, from Category 2, again because nominations were withdrawn, and sent them to the committee for review [18]. On July 23, 2026 the committee voted 8 to 6 to recommend adding BPC-157 and TB-500 to the 503A list, against the recommendation of FDA's own reviewers, who had concluded the evaluation criteria weighed against both [19, 20]. The vote is advisory. As of November 2026 the FDA has not added either peptide to the list, and until it does, no compounding pharmacy may legally prepare them. Supply remains with unregulated sellers.

Interpretation

Three questions separate a medication from an experiment: has it been tested in humans, at this dose, for this condition; who manufactured this batch and what independent testing verifies its contents; and what outcome, measured how, would count as it working. Approved drugs answer all three. The gray market, at present, answers none of them reliably. Retatrutide may well become an approved drug in 2027 or 2028. A vial bought today has no connection to that trial program beyond the name on the label.

Sources

1. Sikiric P, Petek M, Rucman R, et al. A new gastric juice peptide, BPC: an overview of the stomach-stress-organoprotection hypothesis and beneficial effects of BPC. Journal of Physiology (Paris), 1993;87(5):313-327.
2. Talpos S. BPC-157 peptide: a secretive Croatian researcher's 50-year quest. STAT, co-published with Undark, June 1, 2026. https://www.statnews.com/2026/06/01/bpc-157-researcher-predrag-sikiric-addesses-skeptics-questions/
3. Croatian researchers thrust into limelight as their 1990s peptide discovery goes mainstream in the US. Chemistry World, 2026. https://www.chemistryworld.com/news/croatian-researchers-thrust-into-limelight-as-their-1990s-peptide-discovery-goes-mainstream-in-the-us/4023660.article
4. TB-500 (thymosin beta-4 fragment 17-23, Ac-LKKTETQ), CAS 885340-08-9. Chemical supplier entry, EvitaChem. https://evitachem.com/product/evt-242849
5. RegeneRx reports Phase II pressure ulcer trial results. Fierce Biotech. https://www.fiercebiotech.com/biotech/regenerx-reports-phase-ii-pressure-ulcer-trial-results
6. RegeneRx reports Phase II venous stasis trial results. Fierce Biotech, 2009. https://www.fiercebiotech.com/biotech/regenerx-reports-phase-ii-venous-stasis-trial-results
7. Teichman SL, Neale A, Lawrence B, Gagnon C, Castaigne JP, Frohman LA. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. Journal of Clinical Endocrinology and Metabolism, 2006;91(3):799-805. PMID 16352683.
8. Lipodystrophy study halted after patient death. aidsmap, July 2006. https://www.aidsmap.com/news/jul-2006/lipodystrophy-study-halted-after-patient-death (trial registration NCT00267527).
9. Jastreboff AM, Kaplan LM, Frias JP, et al. Triple-hormone-receptor agonist retatrutide for obesity: a Phase 2 trial. New England Journal of Medicine, 2023;389(6):514-526. https://doi.org/10.1056/NEJMoa2301972
10. TRIUMPH-1: retatrutide substantially lowers weight, BMI in patients with obesity or overweight (ADA Scientific Sessions, June 6, 2026). HCPLive, 2026. https://hcplive.com/view/triumph-1-retatrutide-substantially-lowers-weight-bmi-in-patients-with-obesity-or-overweight
11. Eli Lilly and Company. Second-quarter 2026 financial results (Form 8-K), August 5, 2026. https://www.sec.gov/Archives/edgar/data/0000059478/000005947826000077/q226lillysalesandearningsp.htm
12. Ashraf AR, et al. Safety and risk assessment of no-prescription online semaglutide purchases. Journal of Medical Internet Research, 2024;26:e65440. https://jmir.org/article/export/ris/jmir_v26i1e65440
13. Mendias CL, Awan T. Evaluation of research grade peptides marketed directly to consumers reveals extensive variability in purity and measured abundance. Preprints.org, April 2026 (not peer reviewed). https://doi.org/10.20944/preprints202604.1748.v1
14. Vasireddi N, et al. Emerging use of BPC-157 in orthopaedic sports medicine: a systematic review. HSS Journal, 2025. PMID 40756949. https://pmc.ncbi.nlm.nih.gov/articles/PMC12313605/
15. Beck DE, Sweeney WB, McCarter MD; Ipamorelin 201 Study Group. Prospective, randomized, controlled, proof-of-concept study of the ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. International Journal of Colorectal Disease, 2014;29(12):1527-1534. https://doi.org/10.1007/s00384-014-2030-8
16. FDA. Certain bulk drug substances for use in compounding that may present significant safety risks (interim 503A bulks list, Category 2). https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
17. FDA. Pharmacy Compounding Advisory Committee, December 4, 2024: briefing document on CJC-1295 and summary minutes (approved February 21, 2025). https://www.fda.gov/media/183945/download and https://fda.gov/media/185642/download
18. Mondaq. FDA signals potentially evolving stance toward compounding of certain peptides (Category 2 removals announced April 15, 2026). https://www.mondaq.com/unitedstates/healthcare/1785274/fda-signals-potentially-evolving-stance-toward-compounding-of-certain-peptides
19. FDA. Briefing document, Pharmacy Compounding Advisory Committee meeting July 23-24, 2026 (BPC-157, KPV, TB-500, MOTS-c). https://www.fda.gov/media/193343/download
20. FDA panel backs 6 peptides for compounding. American Journal of Managed Care, July 2026. https://www.ajmc.com/view/fda-panel-backs-6-peptides-for-compounding