So it also looks like it can work orally if encapsulated in liposomes.
"It is possible that administration of GHK-Cu could be used as a preventive and regenerative therapy for senescent or damaged brain tissue. Using GHK-Cu has an advantage over using just GHK, since it alleviates copper deficiency without the risk of oxidative damage. Even though it is yet not clear whether or not the GHK-Cu peptide can pass the blood-brain barrier, there is a high possibility that it will do so, since GHK-Cu has a very high uptake into human skin, easily passing through the lipids of the epidermal barrier [66, 67]. The peptide could be administered intravenously or orally when encapsulated into liposomes. Strong systemic wound healing was induced in pigs at about 1.1 mg GHK-Cu per kilogram body weight which would correspond to about 75 mgs in humans. This is about 300-fold below GHK-Cu's toxic action (lowering of blood pressure). Much lower dosages may also be effective since GHK-Cu's actions on cells generally occur at a 1 nanomolar concentration [68].
The multifaceted nature of age-associated cognitive decline calls for complex approaches that address all key factors involved in the development of neurodegenerative disorders such as oxidative stress, neuroinflammation, disrupted bioavailability of copper, impaired circulation, and altered gene expression.
The human tripeptide GHK has a long history of safe use in wound healing and skin care; it is naturally occurring, nontoxic, and is active at a very low nanomolar concentration. It readily forms complexes with copper, regulating its metabolism and improving its bioavailability. It possesses antioxidant, anti-inflammatory, and regenerative properties, improves circulation, supports stem cell functions, and promotes nerve outgrown and synthesis of neurotrophic factors. Recent studies demonstrated its ability to regulate a large number of human genes. At 1 micromolar it was able to suppress 70% of genes overexpressed in metastatic colon cancer. It upregulates p63 and integrins in epidermal stem cells, increases collagen, glycosaminoglycans, and decorin expression. Our studies with the Broad Institute's Connectivity Map revealed its ability to regulate a large number of human genes including those that are involved in nervous system physiology, development, and maintenance.
Even though it is not always possible to distinguish between activity of GHK peptide and its copper complex GHK-Cu, we strongly believe that for the future therapeutical applications GHK-Cu should be used. Numerous studies demonstrating pleiotropic health promoting and antiage activity of the GHK-Cu peptide together with recent studies revealing gene regulating activity of GHK suggest that this compound may belong to a class of epigenetic modifiers capable of exhibiting broad protective and restorative actions, reducing harmful epigenetic changes caused by environmental perturbagens. The GHK-Cu peptide should be considered a promising neuroprotective agent capable of preventing the development of common age-associated neurodegenerative disorders."
it is not like a deep intramuscular injection