Source: Raun K. et al., European Journal of Endocrinology, 1998, Ipamorelin: The First Selective Growth Hormone Secretagogue
Study Objective
To determine the pharmacological profile of Ipamorelin – the first selective Growth Hormone Secretagogue (GHS) – and to evaluate its ability to stimulate growth hormone (GH) secretion without affecting other pituitary hormones such as ACTH, cortisol, and prolactin.
Ipamorelin is a synthetic pentapeptide developed as a selective GHS-R1a receptor agonist, designed to provide more specific and safer GH stimulation compared to older GHRP peptides (such as GHRP-2 and GHRP-6), which often cause non-specific hormonal responses.
Study Design
Type: preclinical and clinical experimental studies
Models: animal models (rats, pigs) and healthy volunteers
Interventions: administration of Ipamorelin in various doses
Comparative agents: GHRP-6 and GHRP-2
-
Measured parameters:
Serum growth hormone (GH) levels
Levels of ACTH, cortisol, prolactin, and other hormones
Duration and intensity of the hormonal response
Key Results
Selectivity of action
Ipamorelin caused a dose-dependent and selective increase in GH, without changes in ACTH, cortisol, and prolactin levels.
Its profile differed from that of GHRP-6 and GHRP-2, which also activate other hormonal pathways.
Pharmacodynamics
A rapid peak of GH was observed approximately 10 minutes after administration, with a short duration of action (30–60 minutes).
The effect was reproducible and stable with consecutive administrations, without signs of desensitization.
Comparative efficacy
Ipamorelin showed similar efficacy to GHRP-6 in terms of GH release, but with significantly better selectivity and safety.
Safety
No adverse effects on the adrenal axis or other endocrine systems were observed.
Good tolerability in animal and human models.
Conclusions
Ipamorelin is the first selective GHS-R1a agonist that stimulates only growth hormone without affecting other pituitary hormones.
It shows a dose-dependent, predictable, and safe hormonal response.
Suitable for studies on GH regulation, anabolic processes, and models of GH deficiency.
Limitations
The main data are from early preclinical and phase I studies.
Long-term clinical results are not available.
Practical Significance
Ipamorelin is a promising selective GH secretagogue with an excellent safety profile.
Suitable for research applications in endocrinology and metabolic sciences.
Advantage over classical GHRP peptides due to the lack of effect on ACTH and cortisol.
