At a glance
Type
Pentapeptide · GH secretagogue
Molecular weight
711.86 g/mol
Studied for
Selective GH releaseRecoveryBody compositionSleep & GH rhythm
Ipamorelin is a synthetic pentapeptide and one of the most selective growth hormone secretagogues ever developed. First described by Raun and colleagues in 1998, it mimics ghrelin at the growth hormone secretagogue receptor (GHS-R1a) in the pituitary, prompting the gland to release the body’s own growth hormone (GH) in a natural, pulse-like pattern rather than supplying GH directly.
How ipamorelin works
Ipamorelin binds the ghrelin/GHS-R1a receptor on the pituitary and triggers a discrete pulse of growth hormone. Because it acts on the pituitary rather than replacing GH, release stays closer to the body’s own rhythm. Downstream, that GH pulse can raise insulin-like growth factor-1 (IGF-1) — the mediator behind many of GH’s effects on tissue.
What set ipamorelin apart at its discovery was selectivity. Earlier growth-hormone-releasing peptides such as GHRP-2 and GHRP-6 also raised ACTH and cortisol. In the original research, ipamorelin released GH with comparable potency but did not meaningfully raise ACTH or cortisol above the levels seen with GHRH — making it the first GH secretagogue with a clean, GHRH-like selectivity profile.
What the research shows
- Selective GH release (Raun et al., 1998). The founding study established ipamorelin as the first selective GH secretagogue, releasing GH without the cortisol and prolactin rise seen with older GHRPs.
- Longitudinal bone growth (animal studies). In young rats, ipamorelin increased longitudinal bone growth and bone mineral content through greater bone volume — consistent with GH/IGF-1 signalling on the growing skeleton.
- Bone formation under steroid stress (animal studies). In adult rats given dexamethasone, ipamorelin counteracted part of the steroid’s effect and supported bone formation — a model used to study GH-based approaches to steroid-induced bone loss.
- IGF-1 and body composition. A consistent theme across GH-secretagogue research is a rise in serum IGF-1 alongside shifts in body-composition markers, reflecting GH’s role in how the body builds and uses tissue.
A candid note on the evidence: much of the strongest data still comes from animal models and early studies, and large human trials remain limited. That is exactly why peptide selection and use should be directed by your physician.
Molecular specification
| Type | Pentapeptide · GH secretagogue (GHS-R1a / ghrelin-receptor agonist) |
| Sequence | Aib-His-D-2-Nal-D-Phe-Lys-NH2 |
| Molecular formula | C38H49N9O5 |
| Molecular weight | 711.86 g/mol |
| CAS number | 170851-70-4 |
Quality and sourcing
Every batch of Azzurri Wellness ipamorelin is compounded through a Registered 503B outsourcing facility under GMP-compliant processes, HPLC-tested for purity and potency, and third-party lab verified. Shipped cold-pack when needed to protect stability.
References
- Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552–561. PubMed
- Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. Growth Horm IGF Res. 1999. PubMed
- The growth hormone secretagogue ipamorelin counteracts glucocorticoid-induced decrease in bone formation in adult rats. PubMed
- Ishida J, et al. Growth hormone secretagogues: history, mechanism of action, and clinical development. JCSM Rapid Communications. 2020. Wiley
Compiled by the Azzurri Wellness Research Team and checked against the cited literature. Educational only — not medical advice.
