adenosine + ghk-cu Peptide for Skin & Hair Copper peptide GHK-Cu · Ascend Bio Labs

It can also dull pain

Critical take (university): McGill Office for Science and Society, The Human Lab Rats Injecting Themselves with Peptides McGill OSS

A dull needle (common with thinner gauges that bend easily) drags through tissue instead of cutting cleanly

Internal recovery, muscle repair, GI research applications where the skin/copper-peptide angle isn't part of the research design

Intramuscular injections deliver a concentrated dose directly into the blood flow and provide the highest bioavailability of active ingredients and an immediate start of action

The biological rationale is interesting but unproven