Ipamorelin: The 1998 Study That Defined a Selective GH Secretagogue

Growth hormone secretagogues (GHSs) are compounds that stimulate the release of growth hormone (GH) from the pituitary. Early GHSs also affected other hormones, which complicated their use as research tools.

The original paper

In 1998 Raun and colleagues published Ipamorelin, the first selective growth hormone secretagogue in the European Journal of Endocrinology. They described ipamorelin, a synthetic pentapeptide, and characterised its GH-releasing activity in vitro and in animal models.

What "selective" meant

The central finding was selectivity. In the authors' experiments, ipamorelin released GH without the marked increases in ACTH and cortisol that had been seen with some earlier secretagogues at comparable GH-releasing doses. This profile made it a useful tool for studying GH release in experimental systems.

Chemical features

Ipamorelin contains non-proteinogenic building blocks, including aminoisobutyric acid and D-amino acids, and an amidated C-terminus. Such features are common in designed peptides and are often introduced to improve resistance to enzymatic degradation.

Analytical considerations

• The presence of D-amino acids makes stereochemical purity a relevant quality attribute.
• The small size of the molecule means mass-spectrometric identity confirmation is straightforward.

Ipamorelin supplied by ICU RESEARCH is for laboratory research use only.