What is inside
“KLOW” is a marketing name, not a scientific or regulatory one. Sellers of research peptides use it for a vial containing four separate lab-made peptides: KPV, BPC-157, TB-500 and GHK-Cu. In practice it is the three-peptide GLOW blend with KPV added. None of the four is an approved medicine anywhere.
There is no official recipe. The amount of each peptide, the ratios between them, and which chemical form of each is used vary by seller and are not standardised. No pharmacopoeia or regulator defines what “KLOW” contains, so the label is the only description of what is inside. Each ingredient has its own page on this site, and the next four sections summarise them.
The product is a physical mixture of four unrelated synthetic peptides: KPV (Lys-Pro-Val, C16H30N4O4, 342.4 g/mol), BPC-157 (linear pentadecapeptide, C62H98N16O22, 1419.5 g/mol), TB-500 (Ac-LKKTETQ, the N-acetylated 17–23 fragment of thymosin β4, C38H68N10O14, 889.0 g/mol) and GHK-Cu (the 1:1 copper(II) complex of glycyl-L-histidyl-L-lysine, about 401.9 g/mol). Per-vial amounts and ratios are set by each seller and are not standardised, and the TB-500 name is used loosely: FDA identifies it as the LKKTETQ fragment, but a 2026 rat study describes TB-500 as synthetic thymosin β4.
A four-peptide mixture multiplies the formulation unknowns. Whether copper from GHK-Cu redistributes to the other peptides, promotes oxidation, or alters stability in powder or solution has not been reported, and no compatibility, degradation or impurity data for the mixture were found. No reference standard exists, so identity, purity and content would have to be verified separately for each peptide. Human pharmacokinetics are unpublished for all four components individually, and KPV has no human exposure data of any kind.
Ingredient: KPV
KPV is three amino acids, lysine, proline and valine: the tail end of the natural hormone alpha-MSH, which darkens skin and also damps inflammation. In 1989 researchers in Texas reported that this short tail on its own reduced chemically induced ear swelling in mice.
Since then it has been studied mainly in mice with chemically inflamed bowels, where KPV added to drinking water or given in other ways reduced signs of inflammation, and in cells in a dish. It has never been tested in a human clinical trial. When the FDA reviewed it in 2023, it said it could find no human exposure data by any route, so its effects and side effects in people are unknown.
KPV (L-lysyl-L-prolyl-L-valine, CAS 67727-97-3) corresponds to residues 11–13 of α-MSH. Its anti-inflammatory effect in mouse colitis appears to be at least partly independent of the MC1 receptor (Kannengiesser et al., 2008). Proposed mechanisms include inhibition of NF-κB and MAP-kinase signalling with reduced pro-inflammatory cytokine secretion, and uptake into intestinal epithelial and immune cells through the di/tripeptide transporter PepT1 (SLC15A1), which is induced in the colon during inflammatory bowel disease (Dalmasso et al., 2008). PepT1 dependence was shown in cell lines, not in PepT1-deficient animals.
Animal data: KPV at 100 µM in drinking water reduced DSS- and TNBS-induced colitis in mice, with lower colonic myeloperoxidase activity and pro-inflammatory cytokine expression (Dalmasso et al., 2008). Kannengiesser et al. (2008) reported faster weight regain and less inflammatory infiltrate with KPV in DSS colitis and in CD45RBhi transfer colitis. Human data: none. No trial is registered on ClinicalTrials.gov, no pharmacokinetic study exists, and adverse effects in humans are unknown rather than absent.
Ingredient: BPC-157
BPC-157 is a chain of 15 amino acids described in 1993 by researchers at the University of Zagreb in Croatia as a fragment of a protein reported in stomach juice. Nearly all the evidence comes from rats and mice, where it has been reported to speed the healing of tendons, muscles and ligaments and to protect the stomach lining. Most of those studies come from the same group, with little independent replication.
In people, no controlled trial has been published in full; the FDA’s 2026 review found only a 2005 conference summary of a small placebo-controlled enema study in ulcerative colitis, which it judged inadequate. A small oral safety study from 2015 never reported results, and a trial registered in Arkansas in 2026 had not started recruiting when this was written; a second 2026 registry entry comes from a sponsor that also posted a self-described fictional record. Its effects and side effects in humans are not known.
No receptor for BPC-157 has been identified. Preclinical work proposes VEGFR2 up-regulation with activation of the VEGFR2–Akt–eNOS pathway, modulation of nitric-oxide signalling, and increased growth-hormone-receptor and EGR-1 expression in fibroblasts (Seiwerth et al., 2018); none of these has been tested in humans. Typical rodent regimens were 10 µg/kg or 10 ng/kg intraperitoneally or in drinking water.
The only controlled human data are a 2005 meeting abstract (Ruenzi et al.) of an 80 mg daily enema versus placebo for two weeks in 53 people with ulcerative colitis, judged inadequate by FDA in 2026. Registered studies are NCT02637284 (Phase 1, oral, 2015, no results), NCT07437547 (Phase 2, subcutaneous once daily for 14 days in hamstring strain, listed as recruiting since 2026; same sponsor as the self-described fictional TB-500 record described below, so not counted as a confirmed trial) and NCT07803250 (Phase 1, subcutaneous daily for 90 days after rotator-cuff repair, not yet recruiting). No pharmacokinetic data exist after oral or subcutaneous dosing. FDA’s 2023 Category 2 assessment cited immunogenicity risk, peptide-related impurities and a lack of human safety information; the 2026 advisory committee reviewed it for ulcerative colitis. Full detail is on the BPC-157 page.
Ingredient: TB-500
TB-500 is a lab-made copy of seven amino acids from thymosin β4, a natural protein found in almost every cell, where it holds actin, the building block of the cell’s internal skeleton.
TB-500 is not thymosin β4 itself. The human trials often quoted for TB-500 used the full 43-amino-acid protein, mostly as eye drops for dry eye and for a nerve-damage condition of the cornea, and their results were mixed. No genuine human study of the seven-amino-acid fragment was found: the one 2026 registry entry naming TB-500 describes itself as a fictional example record. Its effects and side effects in people are unknown.
TB-500 (Ac-LKKTETQ) reproduces the LKKTET actin-binding motif (residues 17–22) of thymosin β4. Full-length Tβ4 is reported in preclinical models to promote keratinocyte and endothelial migration, angiogenesis and cardiomyocyte survival and to reduce inflammatory cytokine release (Goldstein et al., 2005); whether the isolated fragment does the same is unsettled.
Full-length Tβ4 as RGN-259 eye drops missed its primary endpoints in ARISE-2 (n=601) and ARISE-3 (n=700) in dry eye; SEER-1 (n=18) in neurotrophic keratopathy reported complete healing in 6 of 10 versus 1 of 8 on placebo at day 29 (p=0.0656). For the fragment, no genuine trial was found: the only ClinicalTrials.gov record naming it, NCT07487363 (posted March 2026), states in its summary that it is “a fictional study” and an example record, and it gives no doses. FDA stated in 2023 that it had not identified any human exposure data for the fragment, and no pharmacokinetic data have been published.
Ingredient: GHK-Cu
GHK-Cu is a three-amino-acid peptide carrying a copper atom, found naturally in human blood, saliva and urine, with blood levels that fall with age. Loren Pickart identified it in 1973. It has been an ingredient in skin creams and hair products for decades at low concentrations, where it is regulated as a cosmetic.
Small, mostly company-run studies reported improved appearance of aged skin with creams and better wound closure with gels, and lab studies link it to collagen production. No controlled human study of GHK-Cu injections exists, and there are no published data on how much copper an injection delivers into the body. A trial of a gel on small skin wounds was registered in China in 2026 and has not reported; its sponsor also posted the fictional TB-500 registry entry mentioned above.
GHK (glycyl-L-histidyl-L-lysine, C14H24N6O4, 340.4 g/mol) binds copper(II) through the glycine α-amino nitrogen, the histidine imidazole and a deprotonated amide nitrogen, with high affinity (log K about 16). Plasma GHK is about 200 ng/mL in young adults and roughly 80 ng/mL by age 60 (Pickart’s figures), and it is thought to be released by proteolysis of extracellular-matrix proteins at injury sites.
In vitro, GHK-Cu increases fibroblast synthesis of collagen, elastin, decorin and glycosaminoglycans, modulates matrix metalloproteinases and their inhibitors, and attracts immune and endothelial cells; in rodent and porcine wound models, topical application increased granulation tissue and angiogenesis (reviewed by Pickart and Margolina, 2018). Human evidence is limited to small, mostly unregistered topical studies. NCT07437586, a Phase 2 split-wound entry for 0.1% w/w gel once daily for 14 days, was posted by Hudson Biotech, the sponsor of the self-described fictional TB-500 record NCT07487363, and is not counted as a confirmed trial. Pharmacokinetics after injection are unpublished.
Why researchers might study these together
The reasoning offered for this mix is a hypothesis stitched together from separate animal and lab research. KPV has been linked to calming inflammation, BPC-157 to the growth of new blood vessels, thymosin β4 (the parent protein of TB-500) to cells moving into a wound, and GHK-Cu to making collagen. The suggestion is that four peptides touching different stages of repair might add up.
No study in animals or people has tested all four together, or KPV with any of the other three. The only controlled experiment on any part of the mix is a 2026 rat study of BPC-157 with TB-500, which found the pair did no better than either alone. No clinical trial has tested the combination.
The hypothesis extends the GLOW rationale by adding an agent aimed at the inflammatory phase of repair. KPV’s proposed NF-κB inhibition and PepT1-mediated uptake come from mouse colitis and cell studies; BPC-157’s VEGFR2–Akt–eNOS and nitric-oxide effects, thymosin β4’s actin-linked cell migration, and GHK-Cu’s fibroblast collagen synthesis and MMP modulation each come from separate preclinical literatures. None of these mechanisms has been confirmed in humans.
Two caveats follow from that literature. KPV’s best-characterised uptake route, PepT1, is an intestinal transporter up-regulated in inflamed colon, so its relevance to an injected mixture is unknown. And whether early anti-inflammatory signalling complements or counteracts the pro-angiogenic and pro-migratory effects proposed for the other three has never been examined.
PubMed searches found no preclinical or clinical study of KPV combined with BPC-157, TB-500 or GHK-Cu, and none of all four together. The only controlled study of any subset is Biçer et al. (2026), in which intraperitoneal BPC-157 plus TB-500 in rats after Achilles tendon repair did not outperform either peptide alone. No trial registered on ClinicalTrials.gov has tested the combination.
Regulatory picture
Approval: none of the four peptides is an approved drug anywhere, and no regulator has evaluated the combination. FDA decisions apply to each peptide separately.
Compounding: in September 2023 the FDA placed KPV, BPC-157, TB-500 and injectable GHK-Cu, each on its own review, in Category 2, the group it said raises significant safety risks, so pharmacies compounding with them could face FDA action. By April 2026 all four were listed as withdrawn from that category by their nominators. In July 2026 an FDA advisory committee voted narrowly in favour of KPV, BPC-157 and TB-500; GHK-Cu was not on the agenda, and blends were not discussed. The FDA says it intends to put GHK-Cu before the same committee by the end of February 2027. No final FDA decision had been published when this was written.
Sport: the World Anti-Doping Agency prohibits TB-500 and BPC-157 at all times, so any product containing them is prohibited too.
Approval: none. No IND-stage programme for the combination, or for any of its components, could be verified.
Compounding: under section 503A(b)(1)(A)(i) of the FD&C Act, each bulk drug substance in a compounded product must independently comply with a USP or NF monograph, be a component of an FDA-approved drug, or appear on the 503A bulks list (21 CFR 216.23). A blend has no status of its own; it inherits the status of each ingredient, and none of the four is on the bulks list or a component of an approved drug. All four entered Category 2 of the interim policy on 2023-09-29 (GHK-Cu for injectable routes) and are listed as withdrawn by the nominators on FDA’s page updated 2026-04-22. On 2026-07-23 the Pharmacy Compounding Advisory Committee voted narrowly in favour of KPV, BPC-157 and TB-500 as separate substances; GHK-Cu was not reviewed; FDA’s 503A categories list updated 2026-05-14 returned non-injectable GHK-Cu to Category 1 and states that FDA intends to consult the committee on GHK-Cu before the end of February 2027, so a favourable final rule on the other three would still leave one component unresolved. This article records compounding status as unknown, the status all four currently share.
Anti-doping: the 2026 WADA Prohibited List names TB-500 under S2.3 and BPC-157 as an example under S0, non-approved substances.
