GHK-Cu Reconstitution Concentration and Dose Planner

Published 2026-08-20 · Lyophile Editorial

How much bacteriostatic water do you add to a 50 mg GHK-Cu vial?

Add 2 mL of bacteriostatic water to a 50 mg GHK-Cu vial for a 25 mg/mL stock concentration. That gives you 25,000 mcg/mL, or 250 mcg per 1-unit mark on a U-100 insulin syringe. If you need more injection volume for comfort, 4 mL yields 12.5 mg/mL (125 mcg per unit). The math is linear: divide 50,000 mcg by your chosen diluent volume in mL to get mcg/mL, then divide by 100 to get mcg per U-100 unit. Per USP <797>, use sterile water for injection with 0.9% benzyl alcohol as a preservative when preparing multi-dose vials for research use.

GHK-Cu reconstitution calculator: 50 mg vial

The calculator below works for any peptide mass, but the numbers are pre-set for a 50 mg GHK-Cu vial because that's the most common research size on the market. Enter your diluent volume and desired dose to see the full syringe math.

Inputs:

• Peptide mass: 50 mg (fixed for this calculator)
• Diluent volume: 1–5 mL (your choice)
• Desired dose: 0.5–10 mg per application (your choice)

The formula:

1. Convert peptide mass to mcg: 50 mg × 1000 = 50,000 mcg
2. Find concentration: 50,000 mcg ÷ diluent mL = mcg/mL
3. Find mcg per U-100 unit: concentration ÷ 100 = mcg/unit
4. Find units per dose: desired dose (mcg) ÷ mcg/unit = units on the syringe

Worked example — 2 mL diluent, 2 mg dose:

| Step | Calculation | Result | |------|------------|--------| | 1 | 50 mg × 1000 | 50,000 mcg | | 2 | 50,000 ÷ 2 mL | 25,000 mcg/mL | | 3 | 25,000 ÷ 100 | 250 mcg/unit | | 4 | 2,000 mcg ÷ 250 | 8 units |

Eight units on a U-100 syringe. That's 0.08 mL. Small enough that you barely feel the pin, but large enough to measure accurately — 8 units is well above the 2-unit minimum where syringe graduations get ambiguous.

Worked example — 4 mL diluent, 2 mg dose:

| Step | Calculation | Result | |------|------------|--------| | 1 | 50 mg × 1000 | 50,000 mcg | | 2 | 50,000 ÷ 4 mL | 12,500 mcg/mL | | 3 | 12,500 ÷ 100 | 125 mcg/unit | | 4 | 2,000 mcg ÷ 125 | 16 units |

Sixteen units, or 0.16 mL. The trade-off is clear: more diluent means more syringe volume per dose, which means a slightly longer injection, but it also means less concentrated peptide in solution — relevant if you're concerned about peptide stability at high concentration over multiple days of use.

Topical vs subcutaneous: does the dilution math change?

Yes — and this is where most reconstitution guides go wrong. For subcutaneous injection, you're calculating per-syringe doses. For topical application, you're calculating per-mL-of-solution concentration, and the volume math is entirely different because you're not measuring with a syringe at all.

Subcutaneous (SC): You draw a precise volume with a U-100 insulin syringe. The math above applies directly. Your dose is controlled by units on the syringe, and the concentration determines how many units you draw.

Topical: You're applying a solution to skin, typically with a dropper, spray, or measured pipette. The dose per application depends on how much liquid actually stays on the skin — which is highly variable. A 0.1 mL drop spread over a 2 cm² area delivers far less peptide through the stratum corneum than the same drop injected subcutaneously, because skin penetration is the rate-limiting step, not the concentration in the vial.

The practical difference: for topical use, you don't need a U-100 syringe at all. You need a 1 mL graduated pipette or a dropper with a known drop volume. A standard dropper delivers roughly 0.05 mL per drop — but that varies by orifice size, viscosity, and temperature, so calibrate your own dropper before relying on it for dosing.

Common failure mode: researchers reconstitute for SC, then apply the same concentration topically, assuming the dose is equivalent. It isn't. Topical peptide delivery through intact skin is typically a small fraction of the applied dose — published work on copper peptides suggests penetration is limited without penetration enhancers or iontophoresis. If you're switching routes, reconstitute for the route, not the vial.

| Parameter | Subcutaneous | Topical | |-----------|-------------|---------| | Measurement tool | U-100 insulin syringe | Dropper, pipette, or spray | | Dose control | Precise (units on syringe) | Approximate (drop volume varies) | | Typical volume per application | 0.05–0.3 mL | 0.1–1.0 mL | | Concentration relevance | Determines syringe units | Determines mcg per drop | | Key variable | Syringe accuracy | Skin penetration rate |

What concentration should I use for GHK-Cu?

For subcutaneous research use, 25 mg/mL (2 mL diluent on a 50 mg vial) is the most common starting point in published animal studies, though concentrations from 10–50 mg/mL appear in the literature. For topical research, concentrations of 1–10 mg/mL are more typical, since higher concentrations don't necessarily translate to proportionally higher skin penetration — the stratum corneum saturates.

The practical constraint is solubility. GHK-Cu (copper tripeptide-1) is freely soluble in water at these concentrations — 50 mg in 1 mL (50 mg/mL) dissolves without issue if you give it a minute and roll the vial gently. Don't shake; copper peptides are sensitive to oxidation, and vigorous agitation introduces air bubbles that can accelerate degradation. Roll the vial between your palms until the lyophilized cake dissolves.

Stability note: GHK-Cu in solution is most stable at refrigerated temperatures (2–8°C) and neutral to slightly acidic pH. The 0.9% benzyl alcohol in bacteriostatic water keeps the solution preserved against bacterial growth but does not protect the peptide from oxidation — keep the vial sealed, minimize air exposure, and use within 28 days per USP <797> guidelines for multi-dose vials. If you see discoloration — the solution turning a darker blue-green than the characteristic copper-blue of fresh GHK-Cu — that's oxidation, and the peptide should be considered degraded.

How do I measure GHK-Cu doses on a U-100 insulin syringe?

A U-100 insulin syringe is marked in "units" from 0 to 100, where 100 units = 1 mL. Each 1-unit line equals 0.01 mL. This is the standard research syringe because it's precise, inexpensive, and the markings are fine enough for sub-0.1 mL doses.

Reading the syringe:

• 1 unit = 0.01 mL
• 5 units = 0.05 mL
• 10 units = 0.1 mL
• 25 units = 0.25 mL
• 50 units = 0.5 mL

Converting your dose to units:

1. Know your concentration (mcg/mL) from the reconstitution math above
2. Divide by 100 to get mcg per unit
3. Divide your desired dose (mcg) by mcg per unit

Example — 25 mg/mL concentration, 1 mg dose:

• 25,000 mcg/mL ÷ 100 = 250 mcg/unit
• 1,000 mcg ÷ 250 = 4 units

Four units. That's 0.04 mL — a very small volume. On most U-100 syringes, 4 units is the fourth tick mark past the needle hub. At this volume, dead space in the needle hub becomes significant — a standard insulin syringe has 2-4 units of dead space, so you may be under-dosing by up to 50% if you don't account for it. Use a low dead-space syringe (LDS) if you're working with sub-10-unit volumes, or increase your diluent volume so your dose falls in the 10–30 unit range where dead space matters less.

Syringe selection tips:

• 0.3 mL (30-unit) syringes: best for doses under 15 units — finer graduations, less dead space
• 0.5 mL (50-unit) syringes: good all-around for research doses
• 1 mL (100-unit) syringes: only for larger volumes; graduations are coarser

Where to source bacteriostatic water

Bacteriostatic water is 0.9% benzyl alcohol in water for injection, USP grade. It's widely available without a prescription in the US. Common sources:

• BAC Water Depot — USP-grade bacteriostatic water, multi-dose vials
• Cascade Biologics — sterile filtration, single-use ampoules
• MedSupply Partners — bulk packaging for research facilities

Where to source research peptides

GHK-Cu is available from a range of suppliers; quality varies significantly by vendor. Look for per-lot HPLC/MS COA and third-party testing:

• Alpha Amino USA — per-lot HPLC/MS COA, US-shipped
• PurePeptide Research — mass spec verification on every batch
• LabGrade Peptides — independent third-party assay results published per lot

For research use only — not clinical guidance. Always verify purity and identity with your own analytical methods before use in any experimental protocol.