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KLOW vs GLOW: Differences, FDA Status and Price

· Education

KLOW and GLOW are vendor names for two research peptide blends, each sold as a single vial of freeze-dried powder. GLOW combines three peptides: GHK-Cu, BPC-157 and TB-500. KLOW holds the same three plus a fourth, KPV. That one compound is the whole difference between them.

Neither name is a chemical or regulatory term. Each blend is a mixture with no CAS number of its own, and no controlled human trial has tested either combination.

What is in each vial

Most vendors sell each blend at one standard composition:

Both are built on the same base, BPC-157 and TB-500, which vendors also sell as a pair under the name Wolverine. GHK-Cu makes up most of the mass in both vials, about 71% of a 70mg GLOW and 62.5% of an 80mg KLOW.

Both blends also share one ambiguity. "TB-500" can mean full-length thymosin beta-4, a 43-amino-acid protein, or TB-500 Frag 17-23, a seven-residue piece of it. The two are different molecules with different CAS numbers, and a blend listing that names its component only as "TB-500" does not say which. The certificate of analysis is the check, and how to read a peptide COA covers what it shows.

What KPV adds

KPV is the tripeptide lysine-proline-valine, the last three amino acids (residues 11 to 13) of alpha-melanocyte-stimulating hormone (alpha-MSH). It lacks the four-residue core that alpha-MSH needs to bind its melanocortin receptors, and its reported activity does not appear to run through them. Cell and rodent studies instead describe KPV entering intestinal and immune cells through PepT1, a transporter that normally absorbs small peptides from digested protein, and suppressing NF-kB, a signaling pathway that drives the production of inflammatory cytokines.

The most cited work is a 2008 paper in Gastroenterology by Dalmasso and colleagues in Didier Merlin's group, then at Emory University, which reported that KPV taken up through PepT1 reduced inflammation in two mouse models of colitis. The briefing document the U.S. Food and Drug Administration (FDA) prepared for its July 2026 advisory committee meeting says its search identified no clinical studies of KPV in humans. KPV's page covers the mechanism and the literature in more detail.

That puts KPV on a different research track from the other three, which are studied mostly in tissue-repair models:

The four share no sequence, origin or mechanism, so combining them in one vial is a market convention rather than a pharmacological one. Each compound's page covers its own clinical record.

Where FDA stands

FDA has not reviewed either blend as a blend, because nominations to the list of substances compounding pharmacies may use are made one substance at a time. Each component has its own record, and KPV's is the one that separates the two blends.

Full-length thymosin beta-4 was not the substance at any of these steps. The committee's votes are advisory, and the 503A list changes only through notice-and-comment rulemaking. Our writeup of the July vote, our post on the HHS policy and our preview of the February meeting cover each step.

Names on vendor listings

KLOW is GLOW with its G swapped for the K of KPV. Two products sold under the same name match only when the milligrams of each component match, so the split printed on the listing is what to compare.

What they cost

As of November 4, 2026, 44 of the 47 vendors in our index list KLOW and 42 list GLOW. Median price for a single vial at the standard composition, one price per vendor:

Of the 39 vendors that sell both blends at these sizes, 38 charge more for KLOW. At the median vendor, KLOW costs $20 more than GLOW, and the gap runs from $5 to $49.99 among the vendors that charge more. At 31 of the 32 vendors that also sell a 10mg KPV vial, the step from GLOW to KLOW costs less than that vial, a median of 42% of its price.

The comparison is per vial because a blend's price per milligram averages compounds with very different prices, and both vials are mostly GHK-Cu, the least expensive of the four per milligram. One vendor each sells GLOW at 50mg and 90mg, and those vials are left out, as are multi-vial kits and capsule, spray, dropper and pen listings. Definitions are on the methodology page, and blends vs separate vials compares each blend with the same compounds bought as single vials.

Sources

Prices are as of November 4, 2026, computed from the PeptideScouter index. Sources checked November 4, 2026.

PeptideScouter indexes vendor prices for research chemicals sold for laboratory use only, not for human consumption. Nothing here is medical, legal, or investment advice. We earn affiliate commissions on some outbound vendor links - see our disclosure.