Two things about a GHK-Cu vial break the habits built on every other peptide. The powder is blue, not white. And the vial is large — where a research peptide typically ships at 2, 5 or 10 mg, the copper tripeptide is commonly sold at 50, 100 or 200 mg. Neither changes the method; both change the numbers, and one changes what counts as a passed inspection. This is general information about mechanics and arithmetic, not medical advice.

What is in a GHK-Cu vial

GHK is a tripeptide — glycine, L-histidine, L-lysine, 340.38 g/mol. Loren Pickart isolated it from human plasma albumin in 1973; it occurs naturally in plasma, saliva and urine. GHK-Cu is that tripeptide holding a single copper(II) ion, which takes the mass to roughly 404 g/mol. The copper is chelated, not merely mixed in: the histidine imidazole nitrogen, the terminal amine and a deprotonated backbone nitrogen hold it in a tight square-planar arrangement, so the complex behaves as one molecule rather than as a peptide plus a metal salt.

That copper is where the colour comes from. A bound copper(II) ion absorbs in the red-orange part of the spectrum, with a maximum near 590 nm, so what reaches your eye is the complement — royal blue, or blue-teal in dilute solution. The compound is sold as a research chemical and is not an approved medicine; it also appears widely as an ingredient in topical cosmetic formulations, which is why the same name turns up on two very different kinds of label. What it is claimed to do is outside the scope of this page.

How to reconstitute GHK-Cu, step by step

The mechanics are the ordinary ones, with two adjustments for the copper and the vial size.

Turning fifty milligrams into units

Once it is liquid the rest is division. The milligrams on the label divided by the millilitres of water gives the concentration, and a unit on a U-100 barrel is 0.01 ml — always, regardless of what is dissolved in it.

mg in vial ÷ ml of water = mg/ml  ·  ÷ 100 = mg per unit  ·  × 1,000 = mcg per unit

As an example, purely to run the maths: a 50 mg vial with 5 ml of bacteriostatic water sits at 10 mg/ml, so one mark holds 0.1 mg — 100 mcg. The same vial with 2 ml lands at 25 mg/ml, and one mark is then 0.25 mg. A 100 mg vial with 5 ml gives 20 mg/ml, or 0.2 mg per mark. Set that beside a 5 mg vial mixed with 2 ml, where a mark is worth 25 mcg: the same syringe, the same line, ten times the content.

Because the vials are large, GHK-Cu amounts are usually written in milligrams rather than micrograms — and a barrel is marked in neither. Convert once, write the result on the vial, and you remove the step where a factor of a thousand travels the wrong way.

The amount to administer comes from a qualified clinician; this arithmetic only translates it into a position on the barrel. If you would rather not redo the division at every new vial, that conversion is what the Vialog calculator runs.

Blue is the inspection rule

Every other reconstitution guide ends the mixing step with clear and colourless. Here that verdict is inverted, and applying the usual rule out of habit is the mistake. A correctly dissolved GHK-Cu solution is blue, and the intensity tracks the concentration: a 25 mg/ml mix is visibly deeper than a 10 mg/ml one from the same vial. Colour is a rough qualitative signal that the copper is still held by the peptide, not an assay — but a solution gone pale or colourless is saying something has changed about the complex, and that is a stop. Clear, in this one case, is not a pass.

Storage and the 28-day clock

Lyophilized powder is the stable form, which is why vials ship dry: sealed, cold, dark and away from moisture, it keeps far longer than anything in solution. Once mixed, refrigerate at 2 to 8 °C, in the body of the fridge rather than the door where the temperature swings, protected from light, and do not freeze it. The in-use window is then set by the water rather than by the peptide. Bacteriostatic water for injection is labelled for use within 28 days of the first puncture, and that clock starts when the stopper is pierced, not when the vial runs low. With a 50 mg vial that matters more than usual: at ordinary amounts the water expires long before the powder is finished. Write the date on the vial.

This is general educational information about reconstitution mechanics and unit arithmetic. It is not medical advice and not a dosing recommendation. What to administer, and whether to administer anything at all, is a decision for a qualified healthcare professional.

Frequently asked

How much bacteriostatic water goes into a 50 mg GHK-Cu vial?

There is no fixed answer, because the volume is a choice about readability rather than a property of the vial. Adding 5 ml gives 10 mg/ml, so one mark on a U-100 barrel is 0.1 mg; adding 2 ml gives 25 mg/ml and 0.25 mg per mark. The right volume is the one that puts the amount your clinician specified on a whole line you can read.

Why is GHK-Cu blue, and should it be clear?

The blue is the bound copper(II) ion, which absorbs red-orange light with a maximum near 590 nm and reflects the complement. A properly mixed solution is blue and free of particles, not colourless. A mix that looks pale or has lost its colour is a reason to stop rather than to draw from it.

Can sterile water be used instead of bacteriostatic water?

It dissolves the powder identically, but it carries no preservative, so the vial has no protection against contamination once entered. Bacteriostatic water contains 0.9% benzyl alcohol for that purpose and is what makes a multi-entry vial workable. Sterile water is generally treated as single-use, which sits badly with a 50 mg vial.

Does GHK-Cu need to be protected from light?

Copper complexes are light-sensitive, so the reconstituted vial is kept in the dark — an amber vial, the original carton, or the back of the fridge shelf rather than the door. Light exposure is one of the things that shows up as a faded colour, the visual signal that the complex has changed.

Why does a GHK-Cu vial give such large numbers per unit?

Because a unit is a volume, not an amount. One mark on a U-100 barrel is 0.01 ml whatever is in it, so the milligrams it holds are set by the vial's mass divided by the water added. A 50 mg vial is ten times the mass of a 5 mg one, so at the same water volume every mark is worth ten times as much.

Keep reading: How to reconstitute a peptide · How much bacteriostatic water to add.