US$ 24.23
zinc thymulin ghk-cu Zn-Thymulin/GHK-Cu - 30mL Peptides for Hair Growth: promising,
Description
Some studies suggest that administering the peptide on an empty stomach particularly in the morning before breakfast may enhance its fat-burning effects
[DOI] [PubMed] [Google Scholar] 301.Limbocker R., Mannini B., Ruggeri F.S., Cascella R., Xu C.K., Perni M., Chia S., Chen S.W., Habchi J., Bigi A., et al

Not sure why you mention bum pain though, as I have mine in my arm

Whats BPC-157
