# GHK-Cu Dosage in Research: Concentrations, Routes and Half-Life > GHK-Cu dosage as it appears in the research record — picomolar fibroblast concentrations, topical cosmetic ranges, rodent routes, and why no validated human half-life exists. Research context only. The concentrations, routes and durations used in published studies — described as study parameters, never as a usage recommendation. ## How GHK-Cu dosage is reported in studies GHK-Cu dosage in the literature spans an enormous range, because the same molecule has been studied in cell culture, on skin, and inside rodents by half a dozen routes. The numbers below are study parameters — what was administered to which model at which concentration by which route — not instructions. There is no human dosing recommendation anywhere on this site, and none can be derived from this record. The lowest active concentrations are extraordinary. In human fibroblast culture, collagen synthesis began between 10^-12 and 10^-11 M and peaked near 10^-9 M [1]. Topical cosmetic and clinical formulations sit far higher, at roughly 0.05% to 2% by weight in creams, serums and gels [3]. The human hair-loss trial used a 5-ALA + GHK complex at 50 to 100 mg/mL applied to the scalp [4]. ## Routes studied and the concentrations used The routes form a long list because GHK-Cu has been a formulation problem as much as a pharmacology one. Published work covers topical (cream, serum, liposome, nano-lipid carrier, ionic-liquid microemulsion, wound dressing, hydrogel and nanofiber), intraperitoneal in rodent systemic studies, intranasal in rodent cognitive studies, oral gavage in rodent colitis, intravenous and subcutaneous in pharmacokinetic studies, and intradermal delivery in hair studies [6][3]. Representative rodent concentrations from the record include mouse pulmonary emphysema at 0.2, 2 and 20 micrograms per gram per day on alternate days by intraperitoneal injection, mouse silicosis at 2 and 20 mg/kg, mouse DSS-colitis at 20 mg/kg by oral gavage, and aging and Alzheimer-model cognition work at 15 mg/kg intranasally [7]. Rat behavioral studies ranged from roughly 0.5 micrograms/kg to 0.5 mg/kg intraperitoneally [10]. These are model-specific doses, reported here so the literature is legible, not as a bridge to human use. ### Copper peptide vs retinol in the published comparisons In one comparative review, topical GHK-Cu increased collagen production in 70% of treated women, versus 40% for retinoic acid and 50% for vitamin C [3]. That is a single comparative dataset on a procollagen endpoint, so it indicates GHK-Cu performed favorably on that measure rather than establishing a definitive head-to-head superiority [3]. ## The half-life question No rigorous human pharmacokinetic half-life has been published for GHK-Cu — this is one of the clearest river crossings on the trail. 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, with detection limits of 50 ng/mL for GHK and 15 ng/mL for HK [9]. Secondary literature cites a short systemic elimination half-life on the order of 1 to 2 hours, with the copper-chelated complex more stable than free GHK [3]. Topical application tells a different story. Copper applied as the GHK-Cu tripeptide penetrated dermatomed human skin with a permeability coefficient of 2.43 x 10^-4 cm/h; over 48 hours, 136.2 micrograms/cm^2 of copper permeated and 97 micrograms/cm^2 was retained as a dermal depot [5]. That depot gives prolonged local availability and is the basis for topical formulation strategy [5]. ### What is the GHK-Cu research dosage context? GHK-Cu dosage in research is reported by model and route: picomolar-to-nanomolar in fibroblast culture, roughly 0.05% to 2% topically, single-digit-to-double-digit mg/kg in rodent systemic studies, and 50 to 100 mg/mL of a 5-ALA + GHK complex in the human hair trial [1][3][4][7]. None of these is a human dosing recommendation; injectable or systemic protocols circulated in community contexts have no peer-reviewed human pharmacokinetic basis [3]. ## Stability and what destabilizes the complex The complex is stable, but conditionally. Strong reducing agents break it: ascorbic acid below about pH 3.5 reduces the Cu(II) and destroys the complex, and AHAs, BHAs and other low-pH actives can compete for the copper [3]. Free GHK is highly hydrophilic, with a clogP of -2.24, which limits passive stratum-corneum penetration — the reason palmitoylation, liposomal encapsulation, ionic-liquid microemulsions and microneedle pretreatment all appear in the delivery literature [14]. The complex itself is robust where it counts. Its copper stability constant of log K around 16.4 is far higher than free GHK, and it is most stable near pH 5 to 6.5 at a 1:1 copper-to-peptide ratio; the blue-violet color of a reconstituted solution is the expected Cu(II) absorption and indicates an intact complex, while brown or green shifts indicate oxidation or precipitation [6]. That high stability constant is also a safety feature, because it limits how much loose, pro-oxidant copper the complex can shed [6]. There is no completed Phase 2 or 3 trial for systemic or injectable GHK-Cu; a topical wound-healing trial, CuHeal (NCT07437586), has been registered [3]. The human clinical evidence that does exist is dermatologic — small placebo-controlled facial trials and one 6-month hair-count study — and the [GHK-Cu safety and regulatory status](/faq) page treats that boundary directly. Injectable or systemic dosing protocols circulated in community contexts have no peer-reviewed human pharmacokinetic basis, which is why this page describes only what was administered in studies and stops there [3]. --- An expedition map of the GHK-Cu copper-peptide literature — each study set down as a waypoint and each missing stretch of human data marked as a river to ford, guiding no patient and dispensing nothing.