KLOW is not a single substance but a mixture (blend) of four peptides in one pen or vial: GHK-Cu, BPC-157, TB-500 and KPV. A KLOW pen or KLOW vial from Clean Peptides contains 80 mg in total: 50 mg of GHK-Cu and 10 mg each of BPC-157, TB-500 and KPV. The name KLOW is a trade name, not a scientific term. For research purposes, the main consequence of a blend is that analysis is more complex than for a single peptide.
What is in KLOW
| Component | Amount per pen or vial (% of total) | What it is | PubChem | WADA 2026 |
|---|---|---|---|---|
| GHK-Cu | 50 mg (62.5%) | tripeptide glycyl-histidyl-lysine with copper | CID 139035031 | not named |
| BPC-157 | 10 mg (12.5%) | 15-amino-acid peptide | CID 9941957 | class S0 |
| TB-500 | 10 mg (12.5%) | synthetic peptide derived from thymosin β4 | CID 62707662 | class S2 |
| KPV | 10 mg (12.5%) | tripeptide lysyl-prolyl-valine | CID 125672 | not named |
| Total | 80 mg (100%) | four peptides in one pen or vial | – | – |
This composition applies to both the KLOW pen 80 mg and the KLOW vial 80 mg. The pen contains the blend in solution; the vial contains it as a lyophilised powder. A related blend called GLOW contains the same substances without KPV.
Why a blend? The practical advantage is that you get four substances in one pack and, with the vial, only need to reconstitute once. The drawback is that you cannot choose the ratio yourself, and observations in an experiment cannot be attributed to any single substance. Researchers who want to study the substances separately use the individual peptides.
The four components in brief
GHK-Cu is the tripeptide GHK (glycyl-L-histidyl-L-lysine) bound to a copper ion. GHK occurs naturally in the human body. Research focuses mainly on cell and tissue models and on cosmetic applications [1]. Read more in What is GHK-Cu?
BPC-157 (body protection compound-157) is a synthetic 15-amino-acid peptide with the sequence Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val. A 2025 systematic review identified 36 studies, 35 of which were preclinical. BPC-157 has not been approved by the FDA [2]. Read more in What is BPC-157?
TB-500 is a synthetic peptide derived from thymosin β4, a protein that occurs naturally in the body. Products sold under this name are not always the same. A Belgian doping control laboratory found the acetylated fragment Ac-LKKTETQ, amino acids 17 to 23 of thymosin β4, in a TB-500 product [3]; PubChem also lists TB-500 as that fragment. Clean Peptides supplies TB-500, including the TB-500 in KLOW, as the common research variant sold on the market under that name; the specifications are on the product pages for KLOW and for TB-500 10 mg. Read more in What is TB-500?
KPV is the tripeptide lysyl-prolyl-valine (Lys-Pro-Val), the last three amino acids of the hormone α-MSH. Cell and mouse models have been used to study how KPV enters cells via the transporter PepT1 and how it influences inflammatory signalling [4].
These are descriptions of the substances and of the directions research has taken. They say nothing about what a combination does: we are not aware of any studies of the four substances together in this ratio.
What a blend means for the analysis
With a single peptide, you look for one clear main peak on an HPLC chromatogram. With KLOW, there should be at least four main peaks, one for each component, plus the small impurity peaks of each individual peptide. A chromatogram of a blend is therefore always busier.
There are also a few pitfalls:
- Peak area is not quantity. A UV detector does not respond equally to every peptide, so the ratio of the peak areas is not the same as the ratio in milligrams. To determine how much of each component is present, you need a reference standard and a calibration curve for each substance.
- Purity per component or overall. ‘99%’ can refer to one component, to each component separately or to the sum of all main peaks. A good certificate of analysis makes clear which calculation was used.
- Identity per component. With mass spectrometry (MS), each main peak should be matched to the correct mass. Only then do you know which peak belongs to which substance.
- Pen or vial. In the pen, the four substances are combined in a single solution, so an analysis of the pen concerns that solution, not the powders used to prepare it.
- Batch. Every vial and pen has a batch number on its label. Record it with every experiment.
How to read HPLC and MS data is explained in detail in How to read a certificate of analysis (COA). Other points to look out for, such as endotoxins and heavy metals, are covered in Purity, endotoxins and heavy metals.
Regulation and WADA status
KLOW is not a medicine, and none of the four components has been authorised as a medicine by the European Medicines Agency (EMA) or the US FDA. Clean Peptides sells KLOW exclusively as research material (research use only).
Two of the four components are on WADA’s 2026 Prohibited List. BPC-157 is explicitly named in class S0 (non-approved substances). Thymosin β4 and its derivatives, with TB-500 cited as an example, fall under class S2 [5]. Substances in both classes are prohibited for athletes at all times. GHK-Cu and KPV are not named.
Products and further reading
Products
KLOW is available as a KLOW pen 80 mg (solution) and as KLOW 80 mg in a vial (lyophilised powder). The components are also available individually: GHK-Cu 100 mg, BPC-157 10 mg and TB-500 10 mg.
Further reading
- What is GHK-Cu? The copper peptide in research and cosmetics
- What is BPC-157? The state of the research
- What is TB-500, and how does it relate to thymosin beta-4?
- Purity, endotoxins and heavy metals in peptides
Sources
- Pickart L, Margolina A. Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data. International Journal of Molecular Sciences 2018;19(7):1987. doi:10.3390/ijms19071987
- Vasireddi N, Hahamyan H, Salata MJ, et al. Emerging Use of BPC-157 in Orthopaedic Sports Medicine: A Systematic Review. HSS Journal 2025;21(4):485–495. doi:10.1177/15563316251355551
- Esposito S, Deventer K, Goeman J, et al. Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potential. Drug Testing and Analysis 2012;4(9):733–738. doi:10.1002/dta.1402
- Dalmasso G, Charrier-Hisamuddin L, Nguyen HT, et al. PepT1-mediated tripeptide KPV uptake reduces intestinal inflammation. Gastroenterology 2008;134(1):166–178. doi:10.1053/j.gastro.2007.10.026
- World Anti-Doping Agency. Prohibited List 2026, classes S0 and S2 (accessed 30 September 2026)
For laboratory research only. Clean Peptides products are not intended for use in humans or animals. This article provides general information and is not medical advice.
