GHRP-6 (Growth Hormone Releasing Peptide-6) is a single, non-glycosylated polypeptide synthetic met-enkephalin analogue. GHRP-6 is one of several synthetic met-enkephalin analogues that include unnatural D-amino acids and were developed for their growth hormone-releasing activity. GHRP-6 (Growth Hormone Releasing Hexapeptide) is a hexapeptide of 6 amino acids: L-Histidine, D-Tryptophan, L-Alanine, L-Tryptophan, D-Phenylalanine and L-Lysine. An “L” before the amino acid signifies that it is the endogenous form the amino acid, while a “D” before the amino acid signifies that the amino acid is an analog of the naturally occurring “L” form. GHRP-6 and GHRP-2 (Growth Hormone Releasing Peptide 2) are similar, however GHRP-2 was developed from GHRP-6.