What is inside
“KLOW” is a sales name. It is not a scientific or official name. Sellers use it for a vial that holds four lab-made peptides (short chains of amino acids): 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. Each seller decides how much of each peptide goes in. Sellers also decide the ratios and which chemical form to use. None of this is standardised. No official drug standard or regulator says what “KLOW” must contain. So the label is the only description of what is inside. Each ingredient has its own page on this site. The next four sections sum them up.
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 Human pharmacokinetics are unpublished for all four components individually, and KPV has no human exposure data of any kind.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 made of three amino acids: lysine, proline and valine. It is the tail end of a natural hormone called alpha-MSH. That hormone darkens skin and also calms inflammation (swelling and irritation). In 1989, researchers in Texas reported that this short tail alone reduced ear swelling in mice. The swelling had been caused by a chemical.
Since then, KPV has mostly been studied in mice and in cells in a dish. In mice with chemically inflamed bowels, KPV in drinking water or given in other ways reduced signs of inflammation. It has never been tested in a human clinical trial. The FDA reviewed it in 2023. It said it could find no data on people taking KPV 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. Researchers at the University of Zagreb in Croatia described it in 1993. They said it was a piece of a protein reported in stomach juice. Almost all the evidence comes from rats and mice. In those animals, it was reported to help tendons, muscles and ligaments heal faster. It was also reported to protect the stomach lining. Most of these studies come from the same research group. Few other groups have repeated them.
No controlled human trial has been published in full. The FDA reviewed it in 2026. It found only a short 2005 conference summary of a small study. That study gave an enema in ulcerative colitis (a bowel disease) and compared it with a dummy treatment (placebo). The FDA said this was not good enough. A small safety study of BPC-157 taken by mouth dates from 2015. It never reported results. A trial was registered in Arkansas in 2026. It had not started signing up people when this was written. A second 2026 registry entry comes from a sponsor that also posted a record it called fictional. The effects and side effects of BPC-157 in people 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 a protein called thymosin β4. This natural protein is found in almost every cell. There it holds on to actin, a building block of the cell’s inner frame.
TB-500 is not the same as thymosin β4. The human trials often quoted for TB-500 used the whole protein, which has 43 amino acids. Most of those trials used eye drops. They tested dry eye and a nerve-damage condition of the cornea (the clear front of the eye). The results were mixed. No genuine human study of the seven-amino-acid piece was found. The one 2026 registry entry that names TB-500 calls itself a fictional example. 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 that carries a copper atom. It is found naturally in human blood, saliva and urine. Blood levels drop with age. Loren Pickart identified it in 1973. For decades it has been used in small amounts in skin creams and hair products. In those products it is regulated as a cosmetic.
Small studies, mostly run by companies, reported that creams made aged skin look better. They also reported that gels helped wounds close. Lab studies link it to making collagen, a protein in skin. No controlled human study of GHK-Cu injections exists. No one has published how much copper an injection puts into the body. A trial of a gel on small skin wounds was registered in China in 2026. It has not reported results. 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 reason given for this mix is only an idea (a hypothesis). It is pieced together from separate animal and lab studies. KPV has been linked to calming inflammation. BPC-157 has been linked to growing new blood vessels. Thymosin β4 (the parent protein of TB-500) has been linked to cells moving into a wound. GHK-Cu has been linked to making collagen. The idea is that four peptides that act on different steps of healing might add up.
No study in animals or people has tested all four together. None has tested KPV with any of the other three. Only one controlled experiment has tested any part of the mix. It was a 2026 rat study of BPC-157 with TB-500. The pair worked no better than either one 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. No regulator has reviewed the combination. FDA decisions apply to each peptide on its own.
Compounding (pharmacies mixing their own drugs): in September 2023, the FDA reviewed KPV, BPC-157, TB-500 and injected GHK-Cu one by one. It put each in Category 2. That is the group the FDA said carries significant safety risks. Pharmacies that mixed drugs with them could face FDA action. By April 2026, all four were listed as withdrawn from that group by the people who had put them forward. In July 2026, an FDA advisory committee voted narrowly in favour of KPV, BPC-157 and TB-500. GHK-Cu was not on the list for that meeting. Blends were not discussed. The FDA says it plans to bring GHK-Cu before the same committee by the end of February 2027. No final FDA decision had been published when this was written. In October 2026 the US health department (HHS) published a draft policy easing enforcement for single-ingredient KPV, BPC-157 and TB-500 products under set conditions. It does not cover GHK-Cu or any blend, and it is not FDA approval.
Sport: the World Anti-Doping Agency bans TB-500 and BPC-157 at all times. So any product that contains them is banned 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. HHS’s draft enforcement-discretion policy of 2026-10-30 covers single-active-ingredient KPV, BPC-157 and TB-500 (among six peptides), not GHK-Cu and not blends. 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.
