# GHK-Cu Dosage in Research: Concentrations, Routes and Half-Life > GHK-Cu dosage in the research context: in-vitro 10^-9 M, topical 0.05-2% w/w, rodent routes, the ALAVAX 50-100 mg/mL trial, and the absent human half-life — all study-framed and cited. The concentrations, routes and durations that studies actually used — in cell culture, in rodents, and in the controlled human topical trials. Study parameters, not usage guidance. ## Research concentrations and routes, by study GHK-Cu dosage in the literature is not a single number — it is a set of study parameters that differ by model and route, and this site reports them as such, never as a usage recommendation. In cell culture, collagen synthesis in human fibroblasts began between 10^-12 and 10^-11 M and peaked near 10^-9 M [1]. Topical cosmetic and clinical formulations run roughly 0.05% to 2% (w/w) in creams, serums and gels [3]. The controlled human hair trial used a 5-ALA plus GHK complex at 50 and 100 mg/mL applied to the scalp [4]. Rodent systemic studies used a wide dose range by route: intraperitoneal dosing in mouse pulmonary, fibrosis and silicosis models from micrograms per gram up to 2-20 mg/kg, oral gavage at 20 mg/kg in colitis, intranasal at 15 mg/kg in cognition studies, and low microgram-to-milligram-per-kilogram intraperitoneal doses in rat behavioral work [14][15]. The hair microemulsion study used 2% GHK-Cu topically [12]. Every one of these is a study parameter in a named species and model — the table on this page lists them with their citations, and none of them is a human dose. ## The human-tested parameters, separated from the rest Of all the numbers above, only a small set comes from controlled human studies, and the ledger keeps that distinction sharp. The human dermatology evidence used topical creams and serums in the 0.05% to 2% (w/w) range across small placebo-controlled facial trials, with reported improvements in skin density, firmness, fine lines and wrinkle depth [3]. The one controlled human hair study used a combination product — a 5-aminolevulinic-acid plus GHK complex (ALAVAX) at 50 and 100 mg/mL applied to the scalp over six months, with the 50 mg/mL arm producing the larger hair-count gain of 71.5 versus 9.6 for placebo [4]. Two cautions belong on that human line. First, the strongest hair result came from a combination formulation, not pure GHK-Cu, so it speaks to the complex-in-context rather than the peptide alone [4]. Second, there are no completed Phase 2 or 3 trials for systemic or injectable GHK-Cu of any kind; a topical wound-healing trial has been registered, but the systemic dosing protocols that circulate in community settings have no peer-reviewed human pharmacokinetic basis [3]. The honest dosage picture is thus narrow on the human side: topical concentrations with small-trial support, and a single combination hair trial — everything else in the dose table is a cell-culture or rodent parameter. ## Half-life and pharmacokinetics: what is and is not known ### What is known about GHK-Cu half-life? 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 [10]. Secondary literature cites a short systemic elimination half-life on the order of one to two hours, with the copper-chelated complex more stable than free GHK [3]. The more informative pharmacokinetic fact for a topical compound is the dermal depot. The penetration study found that after 48 hours about 97 ug/cm^2 of copper was retained in skin as a depot [5], giving prolonged local availability that a plasma half-life would not capture. So the honest pharmacokinetic summary is two-sided: rapid systemic clearance of the free peptide [10], and a persistent local reservoir after topical application [5]. There is no validated human half-life, Cmax or bioavailability for injectable or systemic use [3]. ### Why does the form change the pharmacokinetics? The copper-chelated complex is more stable than the free peptide. Free GHK's very stability problem — rapid peptidase conversion to the dipeptide HK in plasma [10] — is partly mitigated by copper coordination, which holds the molecule in a defined geometry with a high stability constant (log K around 16.4) [3]. This is why secondary literature distinguishes a short systemic half-life for free GHK from greater stability for GHK-Cu, and why the topical dermal depot matters more than any single plasma figure: in skin, the retained copper reservoir is doing the work, not a circulating concentration [3][5]. ## Stability and the form question Dose discussions for GHK-Cu are incomplete without the stability chemistry, because the active form can be destroyed before it ever reaches tissue. The complex has a very high copper stability constant (log K around 16.4), far higher than free GHK, which limits release of pro-oxidant free copper, and it is most stable near pH 5 to 6.5 at a 1:1 copper-to-peptide ratio [3]. Strong reducing agents — ascorbic acid below about pH 3.5 — reduce the Cu(II) and break the complex, as can AHAs, BHAs and other low-pH actives [3]. The form a study used also changes what a 'dose' means. Many papers use the free GHK peptide and report systemic or gene-level effects, while the copper complex is required for most matrix-remodeling activity [3][6]. A milligram of free GHK and a milligram of GHK-Cu are not interchangeable in the evidence, which is why this ledger records the form alongside the dose for every entry. The blue-violet color of a reconstituted GHK-Cu solution is itself a readout — the expected Cu(II) absorption — and a shift to brown or green indicates oxidation or precipitation [3]. The practical consequence is that a stated concentration tells you little on its own. The same 0.05% to 2% (w/w) range can describe a stable, correctly buffered topical formulation or a destabilized one, depending on pH, the copper-to-peptide ratio and what else is in the vehicle [3]. This is the recurring theme of the GHK-Cu dose record: the number on the label is necessary but not sufficient, because the form, the pH and the delivery vehicle determine whether the dose that was weighed is the dose that reaches tissue [3][5]. Every concentration on this page should be read with that caveat attached. --- A compliance-grade ledger of the GHK-Cu copper-tripeptide literature — every collagen study, skin trial and regulatory status posted as a line item and reconciled to its source, with no clinic behind the statement and nothing here for sale.