# GHK-Cu Research Dosing Context: Concentrations, Routes, and Half-Life > GHK-Cu research-dosing context: the concentrations, routes, and stability conditions used in published studies — research framing only, with the human pharmacokinetics gap cited. What was administered to which models at which concentrations and by which routes — a study log, with the human pharmacokinetics gap marked in plain hand. ## How GHK-Cu has been dosed in studies GHK-Cu research-dosing figures span cell culture, topical formulation, and rodent systemic work — and none of them is a human regimen. In human fibroblast cultures, collagen synthesis responded across 10^-12 to 10^-9 M, with onset at 10^-12 to 10^-11 M and a peak near 10^-9 M [1]. Topical cosmetic and clinical formulations sit at roughly 0.05% to 2% (w/w) in creams, serums, and gels [3]. The human hair-loss RCT used a 5-ALA + GHK complex at 50-100 mg/mL topically [4]. The span between those numbers is the first thing to notice. The in vitro collagen response is picomolar-to-nanomolar — vanishingly small concentrations — while the topical and hair-trial figures are formulation percentages and milligrams-per-milliliter applied to a surface, not a circulating dose. They are not convertible into one another, and neither converts into a systemic human dose [16]. Everything on this page is research-context framing: what was administered to which model by which route. It is not a recommendation, and the validated systemic human numbers that a dosing recommendation would require do not exist. ## Rodent systemic dosing in the literature Rodent systemic studies used intraperitoneal, intranasal, and oral routes at model-specific doses. Reported examples include alternate-day intraperitoneal dosing in a mouse pulmonary-emphysema model, 20 mg/kg oral gavage daily in a mouse DSS-colitis model, and 15 mg/kg intranasal dosing in aging and cognition mouse work [16]. These are species-and-model-specific experimental doses. The gap between these and any human protocol is the point: rodent studies used copper loads below the roughly 35 mg/kg ion-toxicity threshold, but no validated human pharmacokinetic data exist to translate any of it into a human dose. The site's position is to report the research doses and decline to convert them. ## GHK-Cu half-life and clearance research 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 HK after IV dosing, and secondary literature cites a short systemic elimination half-life on the order of 1-2 hours, with the copper chelate more stable than free GHK [16]. Topical application instead forms a dermal copper depot — about 97 ug/cm^2 retained over 48 hours — giving prolonged local availability without relying on systemic circulation [5]. ## Routes studied and topical delivery GHK-Cu has been studied topically (creams, serums, liposomes, nano-lipid carriers, ionic-liquid microemulsions, wound dressings and hydrogels, nanofibers), intraperitoneally and intranasally in rodents, by oral gavage in rodent colitis, and intravenously or subcutaneously in rodent pharmacokinetic studies [16]. Topical is the route with the human safety record. Delivery is the limiting factor. Free GHK is highly hydrophilic (clogP -2.24), which restricts passive stratum-corneum penetration; palmitoylation (Pal-GHK, clogP ~1.14), liposomal encapsulation, ionic-liquid microemulsions, and microneedle pretreatment improve it, with a 2025 review reporting about 134 nmol of GHK permeating with microneedling versus none through intact skin [16]. The research-dose context here is delivery science, summarized for general readers. ## Stability and the blue-violet color check The GHK-Cu complex has a very high copper stability constant (log K ~16.4), far higher than free GHK, and 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) d-orbital absorption and indicates an intact complex; brown or green shifts indicate oxidation or precipitation [6]. Strong reducing agents — ascorbic acid below about pH 3.5 — reduce Cu(II) and break the complex, and AHAs, BHAs, and low-pH actives can destabilize it or compete for copper [16]. The color check is the simplest at-a-glance integrity signal the literature offers. --- The GHK-Cu copper-peptide literature cut out and taped to one wall — each verified figure circled by hand, each inflated one struck through, and every missing stretch of human data marked in the margin, with no clinic pinned to this board and nothing here for sale.