# GHK-Cu Dosage Research: Concentrations, Routes, Stability, and Safety

> GHK-Cu dosage research context: fibroblast collagen synthesis at 10^-12 to 10^-9 M, topical formulations of 0.05% to 2%, intranasal 15 mg/kg in mice. Routes, stability, side effects, and safety, cited — no human dosing advice.

What was administered, to which species, by which route — and where the human pharmacokinetic record simply does not exist. A research-context catalogue, not a dosing guide.

## GHK-Cu dosage in the research context

GHK-Cu dosage in the research record spans nine orders of magnitude of concentration and a half-dozen routes, because the molecule has been studied in cell culture, in rodents, and in topical human formulations — never as a standardized systemic human protocol. This page catalogues what was administered in studies. It is not a dosing guide, and no human dosing recommendation appears here.

In human fibroblast cultures, collagen synthesis onset occurs between 10^-12 and 10^-11 M and peaks near 10^-9 M [1]. Topical cosmetic and clinical formulations run roughly 0.05% to 2% (w/w) in creams, serums, and gels [3]. Rodent systemic studies used intraperitoneal doses spanning micrograms-per-gram to milligrams-per-kilogram depending on the model. The neuroprotection mouse studies delivered GHK intranasally at 15 mg/kg, daily or three times weekly [8][13]. The human hair-loss RCT applied a 5-ALA + GHK topical complex at 50-100 mg/mL [4]. These are study parameters, not instructions.

## Half-life, routes, and stability

No rigorous human pharmacokinetic half-life has been published for GHK-Cu. The free tripeptide (340.38 Da) is rapidly cleared by plasma peptidases; a rat HPLC study documented rapid metabolism of GHK to the dipeptide histidyl-lysine after intravenous dosing [16]. Secondary literature cites a short systemic elimination half-life on the order of 1-2 hours, with the copper-chelated complex more stable than free GHK. Topical application forms a dermal copper depot — about 97 ug/cm^2 retained over 48 hours — giving prolonged local availability [5].

Stability is chemistry, not marketing. The GHK-Cu complex has a very high copper stability constant (log K approximately 16.4), which limits pro-oxidant free-copper release, and it is most stable near pH 5-6.5 at a 1:1 copper-to-peptide ratio [7]. The blue-violet color of a reconstituted solution is the expected Cu(II) absorption and indicates an intact complex; brown or green shifts indicate oxidation or precipitation. Strong reducing agents and low-pH actives break the complex — a formulation fact catalogued plainly below.

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A dried herbarium of the GHK-Cu copper-tripeptide literature, pressed plate by plate and traced to its paper — the place where the materia is catalogued and studied, never a clinic, a counter, or anything dispensed.