# GHK-Cu Research-Dose Context, Routes, and Stability > GHK-Cu research-dose context: in-vitro picomolar-to-nanomolar ranges, rodent IP and intranasal doses, topical formulation percentages, half-life, and complex stability. Cited. What was administered, to which species, by which route — reported as study parameters, never as a human recommendation. Plus half-life and the copper-complex stability rules. ## GHK-Cu doses are reported here as study parameters GHK-Cu has no approved human dose by any route, so this page reports the doses that appear in the published studies as study parameters — the concentration, species, and route a given experiment used — and nothing here is a protocol. The in-vitro work that defines the mechanism used picomolar-to-nanomolar concentrations: fibroblast collagen synthesis began between 10^-12 and 10^-11 M and peaked near 10^-9 M [1]. Read against that, the systemic rodent doses and topical formulation percentages below are simply the conditions under which the literature was generated. ## Concentrations and doses by model In vitro, fibroblast collagen synthesis onsets at 10^-12 to 10^-11 M and maximizes near 10^-9 M [1], and GHK-modified hydrogels were non-cytotoxic from 1 to 500 ng/mL on human mesenchymal stem cells [13]. In topical cosmetic and clinical formulations, GHK-Cu typically appears at roughly 0.05% to 2% (w/w) in creams, serums, and gels [3]. Rodent systemic studies span a wide range by route: intraperitoneal dosing in mouse pulmonary and fibrosis models used microgram-per-gram to milligram-per-kilogram amounts, intranasal cognition studies used about 15 mg/kg, and oral gavage colitis work used 20 mg/kg [6]. The controlled human hair trial applied the ALAVAX 5-ALA + GHK complex topically at 50-100 mg/mL [9]. These are model-specific experimental doses; the species, route, and formulation are inseparable from the number. ## Half-life and clearance No rigorous human pharmacokinetic half-life has been published for GHK-Cu [6]. The free tripeptide (340.38 Da) is rapidly cleared by plasma peptidases — a rat 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-chelated complex more stable than free GHK. Topically, the picture inverts toward persistence: a human skin-penetration study measured a permeability coefficient of 2.43 x 10^-4 cm/h, with about 97 ug/cm^2 of copper retained as a dermal depot over 48 hours [5]. The depot is what gives topical application prolonged local availability even though the systemic peptide is short-lived. ## Routes studied The route list is broad and tells you where the molecule has actually been tested. Topical delivery dominates — creams, serums, liposomes, nano-lipid carriers, ionic-liquid microemulsions, wound dressings and hydrogels, and nanofiber systems [10][15]. Systemic and CNS rodent work used intraperitoneal injection (pulmonary, fibrosis, behavioral models), intranasal administration (cognition), and oral gavage (colitis) [6][16]. Intravenous and subcutaneous routes appear in rodent pharmacokinetic studies, and intradermal or microneedle delivery appears in hair work. The human evidence sits almost entirely on the topical end of that list. ## Stability: reading the complex by its color The GHK-Cu complex has a very high copper stability constant (log K ~16.4), far higher than free GHK, which limits pro-oxidant free-copper release [6]. It is most stable near pH 5-6.5 at a 1:1 copper-to-peptide ratio. The blue-violet color of a reconstituted solution is the expected copper(II) d-orbital absorption and indicates an intact complex; a shift toward brown or green indicates oxidation or precipitation [6]. Strong reducing agents — ascorbic acid below about pH 3.5 — reduce copper(II) and break the complex, and AHAs, BHAs, and other low-pH actives can destabilize it or compete for the copper. Free GHK is highly hydrophilic (clogP -2.24), which limits passive stratum-corneum penetration; palmitoylation, liposomal encapsulation, ionic-liquid microemulsions, and microneedle pretreatment are the studied workarounds [10]. ## Human clinical data is topical and limited Human evidence for GHK-Cu is predominantly topical and dermatologic: small placebo-controlled facial cream and serum trials (n roughly 20-71) reporting improved skin density, firmness, fine lines, and wrinkle depth, plus the 6-month, 45-patient ALAVAX hair trial [9]. There are no completed Phase 2/3 trials for systemic or injectable GHK-Cu; a topical wound-healing trial (CuHeal) has been registered. Injectable and systemic dosing protocols circulated in community contexts have no peer-reviewed human pharmacokinetic basis [6], which is why this page reports research-model parameters and stops there. --- A critical broadsheet of the GHK-Cu copper-tripeptide record — what the literature confirms set in black, what it cannot yet promise stamped in the margin, with no clinic behind the masthead and nothing here to dispense.