Topical GHK Cu: Skin Benefits, Best Forms, and Where to Buy A lot of people asked how I use GHK Cu (copper peptide) with a pen device, so here's a quick tutorial showing exactly how I do it. In this video I show how Copper Peptide (GHK Cu): Clinical Uses, Stability & Compounding Tips GHK Cu Peptide Therapy: The Definitive Clinical Guide to Gene Modulation, Protocols, and Efficacy