doi: 10.1111/j.1753-4887.2008.00031.x
A 2021 analytical study developed and validated an LC-MS/MS method to measure 5-amino-1-methylquinolinium in rat plasma and urine

According to a 2018 review, GHK-Cu as a cosmetic ingredient has demonstrated the ability to:3 Tighten loose skin Reverse age-related skin thinning Repair the skins protective barrier proteins Improve skin firmness and elasticity Reduce the appearance of fine lines and wrinkles Smooth rough skin Stimulate wound healing Lessen the appearance of photodamage (sun damage), hyperpigmentation, skin spots, lesions, and more Reduce inflammation and damage from free radicals Increase hair growth and thickness Additionally, in research from 2015, the authors noted that GHK-Cu may be able to stimulate collagen, regulate the skin remodeling process, attract immune cells to the site of an injury, and restore replicative vitality to fibroblasts (a cell that helps form connective tissue) in patients whove undergone radiation therapy for cancer.2 6 GHK-Cu isnt limited to topical/cosmetic forms, however

Many patients notice a boost in energy and overall well-being within a few hours of receiving their B12 shot, while others may take a few days to feel the full benefits
Discuss with your healthcare provider the best ways to manage your B12 levels, which may include dietary supplements or fortified foods like breakfast cereals
Oral administration is more convenient for daily dosing and avoids additional injection sites beyond the weekly tirzepatide shot