DOSAGE / 05
GHK-Cu Dosage in Research Models
The concentrations and routes used in published studies, the stability constant that keeps the complex intact, and the pharmacokinetic line the literature has not yet filled in — read as figures, not instructions.
Concentrations used across the research models
GHK-Cu dosage in research models spans many orders of magnitude, because the studies span cell culture, topical formulation and rodent systemic work. This page posts what was administered to which model at which concentration by which route. It is a record of the literature, not a protocol — there is no validated human dose for GHK-Cu by any systemic route, and none should be inferred from these figures [6].
In human fibroblast cultures, collagen synthesis rose between 10⁻¹² and 10⁻¹¹ M and peaked near 10⁻⁹ M — a picomolar-to-nanomolar window [1]. Topical cosmetic and clinical formulations run roughly 0.05% to 2% (w/w) in creams, serums and gels [3][14]. Rodent systemic studies used intraperitoneal dosing for pulmonary and behavioral endpoints, and intranasal dosing for cognitive endpoints; rat behavioral work covered roughly 0.5 µg/kg to 0.5 mg/kg IP [9][10]. The human hair-loss RCT applied a 5-ALA + GHK complex topically at 50-100 mg/mL [4]. These are model-specific exposures; they do not convert into a human regimen.
The two highest-confidence dose figures are the fibroblast dose-response [1] and the ALAVAX topical concentration [4]. The rest are mechanistic or species-specific and carry the corresponding caveats.
Routes studied and the dermal depot
GHK-Cu has been studied across an unusually wide range of routes: topical (cream, serum, liposome, nano-lipid carrier, ionic-liquid microemulsion, hydrogel, nanofiber), intraperitoneal (rodent systemic studies), intranasal (rodent cognitive studies), oral gavage (rodent colitis), and intravenous or subcutaneous (rodent pharmacokinetic work) [6]. Topical is the route with human evidence; the systemic routes are rodent-only.
Topical application forms a measurable dermal copper depot — about 97 ± 6.6 µg/cm² retained over 48 hours [5]. That depot is the basis for prolonged local availability and the reason topical formulation strategy focuses on penetration enhancement rather than dose escalation [5][14]. The neuroprotection studies used intranasal delivery precisely because it is CNS-accessible, since direct blood-brain-barrier passage of a systemic dose is uncharacterized [15].
Half-life and the missing pharmacokinetic line
No rigorous human pharmacokinetic half-life has been published for GHK-Cu. The free tripeptide (340.38 Da) is rapidly cleared by plasma peptidases, 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 [6]. Topical application sidesteps the plasma-clearance question by forming the dermal depot described above [5].
This is the amber line on the dosage statement, and it is worth printing in full: there is no validated human Cmax, half-life, bioavailability or tissue-distribution figure for injectable or systemic GHK-Cu, and community dosing protocols circulated outside the literature have no peer-reviewed basis [6]. A digest can report what rodent and topical studies measured; it cannot supply the human pharmacokinetic data that does not yet exist.
Stability: the figure that signals an intact complex
The GHK-Cu complex carries a very high copper stability constant — log K approximately 16.4 — far higher than free GHK, which limits pro-oxidant free-copper release [6]. The complex 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 Cu(II) d-orbital absorption and indicates an intact complex; brown or green shifts indicate oxidation or precipitation [6].
The destabilizers are well-characterized. Strong reducing agents — ascorbic acid below about pH 3.5 — reduce Cu(II) and break the complex, and AHAs, BHAs and other low-pH actives can destabilize it or compete for copper [6][14]. Native GHK is highly hydrophilic (clogP −2.24), which limits passive stratum-corneum penetration and is why palmitoylation, liposomal encapsulation, ionic-liquid microemulsions and microneedle pretreatment are studied as delivery enhancements [13][14].