GHK-Cu dosage research and oral bioavailability

Published concentrations

The collagen-culture study used GHK-Cu at 10^-12 to 10^-9 M. Stimulation began between 10^-12 and 10^-11 M and peaked near 10^-9 M. M expresses concentration in the culture medium.

Reviewed topical cosmetic and clinical formulations ranged from approximately 0.05% to 2%. Those percentages describe creams, serums or gels. They carry no direct instruction about the amount reaching a person’s bloodstream.

The hair trial tested a 5-aminolevulinic acid plus GHK mixture at 50 mg/mL and 100 mg/mL. The measured hair-count changes apply to that combination. Quoting either concentration as a pure GHK-Cu dose would change what the study tested.

I prefer leaving those units visibly different. Converting them into a single neat regimen would conceal differences in material, delivery and experimental purpose.

GHK-Cu oral bioavailability

The available record provides no validated human oral bioavailability for GHK-Cu: the fraction of a swallowed amount reaching the circulation has not been established. The broader literature includes rodent oral research, alongside other animal routes, but it supplies no sound human oral dose.

Human evidence is concentrated in small topical dermatology studies and the combination hair trial. Injectable, oral and other systemic uses lack validated human pharmacokinetic data, including peak blood concentration and tissue distribution. No FDA- or EMA-approved therapeutic use exists for GHK-Cu.

For the dosage question, missing human exposure data are decisive. A biological effect in a different species or a different compartment cannot fill in a missing human exposure measurement.

Half-life and the rat plasma study

The closest pharmacokinetic paper in this collection is a rat study measuring GHK and its metabolite. After intravenous administration, free GHK was rapidly metabolized to histidyl-lysine, the shorter peptide HK. It examined the copper-free peptide in rats.

Secondary literature cites a systemic half-life on the order of 1–2 hours, but no rigorous human GHK-Cu half-life has been published. I would leave the human entry blank rather than give that estimate the authority of a measured result. The copper-bound form also needs its own human data.

Copper retained in skin

The human skin penetration experiment found 97 ± 6.6 µg/cm² of copper retained as a dermal depot over 48 hours in its ex-vivo setup. This was human skin outside the body. Skin retention and blood clearance are different measurements.

The delivery review describes fatty modification, lipid carriers and other experimental ways of addressing the skin barrier. Their purpose is to alter local delivery. Their results cannot establish the safety of injecting or swallowing the compound.

The skin studies cover those formulation questions in more detail. The reported-effects page sets the longer cosmetic history beside the unresolved systemic safety questions.