Ipamorelin: What the Research Says About a Selective Ghrelin-Receptor Agonist

Ipamorelin is a short synthetic pentapeptide. It binds the growth-hormone secretagogue receptor, GHS-R1a, which is the receptor the hormone ghrelin uses. Compounds like this are called growth-hormone secretagogues because they signal the pituitary to release growth hormone. What sets ipamorelin apart in the papers is how selective it is. This is an educational summary of the research and does not describe any human or veterinary use.

Why it was called the first selective secretagogue

The paper that introduced ipamorelin reported that, in the models tested, it raised growth hormone without the cortisol and prolactin increases that came with older secretagogues (Raun et al., Eur J Endocrinol, 1998). [1] That selectivity is the reason it is cited so often.

Acting like ghrelin

Since it binds GHS-R1a, ipamorelin is treated as a ghrelin mimetic. Researchers have asked whether GH-releasing peptides work through ghrelin-receptor pathways (Ahnfelt-Rønne, Nowak & Olsen, Endocrine, 2001). [2] That puts it next to a wider body of work on appetite and gut motility, which run through the same receptor.

Bone and tissue studies

Some animal studies went past GH release and looked at downstream effects, for example in bone research models (Andersen et al., Growth Horm IGF Res, 2001). [3] These are controlled preclinical results.

Note: Most of the ipamorelin evidence is preclinical, though the compound did reach Phase 2 human trials. Research-grade material is for laboratory Research Use Only and is not for human or veterinary use.

FAQ

What does "selective" mean for a secretagogue?

In the original research, ipamorelin triggered growth-hormone release without the rise in cortisol and prolactin seen with earlier secretagogues. Compared with those compounds, its effect was more targeted.

References

1. Raun et al. — Ipamorelin, the first selective GH secretagogue (Eur J Endocrinol, 1998)
2. Ahnfelt-Rønne et al. — GH-releasing peptides as ghrelin secretagogues (Endocrine, 2001)
3. Andersen et al. — Ipamorelin in bone research (Growth Horm IGF Res, 2001)