GHK-Cu

What GHK-Cu is

GHK is a naturally occurring tripeptide — glycine-histidine-lysine — first isolated from human plasma in the 1970s. It has a strong affinity for copper(II), and the complex it forms is written GHK-Cu. Plasma levels of GHK decline with age, which is the observation that launched most of the interest in it.

It is one of the few peptides in this reference with a substantial, mainstream commercial life: GHK-Cu is a long-established cosmetic ingredient found in serums and creams sold openly worldwide, where it is regulated as a cosmetic rather than a medicine. The lyophilised vial form sold for research is a different product category with none of that regulatory oversight.

How it is supplied and stored

The most important practical fact about GHK-Cu vials is their size. Where BPC-157 and TB-500 arrive as 2–10 mg, GHK-Cu is routinely supplied as 50 mg, 100 mg or even 200 mg per vial. Apps and calculators that silently cap vial mass at 50 mg — a real limitation users complain about in competing trackers — simply cannot represent a 100 mg vial.

• The dry powder is blue-tinted; reconstituted solution is a clear, distinctly blue liquid. This is the copper complex and is expected.
• Colour intensity depends on concentration, so a darker solution means a more concentrated one — it is not a purity indicator.
• Copper complexes are sensitive to light; suppliers generally specify storage protected from light, refrigerated once reconstituted.
• Because the vials are large, they are often in use far longer than a 5 mg vial, which makes recording the reconstitution date more important, not less.

Units and why the maths shifts

The conversion chain is identical to any other peptide, but the numbers land in a different range. Reconstituting a 100 mg vial with 5 mL of bacteriostatic water yields 20 mg/mL — that is 20,000 mcg per mL, or 200 mcg per single U-100 syringe unit. A calculator built around 5 mg vials will produce awkward decimals here even when it is arithmetically correct.

GHK-Cu entries are therefore usually recorded in milligrams. Use the unit converter if you need to move between mg, mcg and mL for a given concentration, and keep one unit for the whole cycle.

Research context and status

GHK-Cu has an unusually broad literature for a peptide of this kind, spanning skin biology, wound-healing models and gene-expression studies. Much of it is in vitro or in animal models; the strongest human evidence relates to topical cosmetic use, where controlled studies of skin appearance have been published, and where the product is regulated as a cosmetic.

Injectable GHK-Cu has no approved human indication. Copper is also a mineral with a genuine upper intake limit and known toxicity at excess, which distinguishes GHK-Cu from peptides that carry no metal — a fact worth raising with a clinician rather than working out from a forum.

What to record

• Vial mass in mg — and use an app that accepts three-digit vial sizes without complaint.
• Water volume, reconstitution date and the vial's appearance at the time.
• Whether the entry is topical or from a vial. These are separate compounds in a log, not two forms of one.
• Any note about colour change over time, which is the kind of observation you cannot reconstruct from memory.

PepCycle places no ceiling on vial mass, so a 200 mg GHK-Cu vial is entered exactly as it appears on the label, and remaining contents count down correctly across a long cycle.