Ipamorelin: The First Growth Hormone Peptide That Only Boosts GH Without Other Hormones
Ipamorelin was identified as the first truly selective GH secretagogue — it potently releases growth hormone without increasing cortisol, prolactin, or other hormones like older GHRP compounds do.
Quick Facts
What This Study Found
Ipamorelin released GH with potency similar to GHRP-6 but did not increase ACTH, cortisol, prolactin, or FSH even at doses 200-fold higher than effective GH-releasing doses, making it the first truly selective GH secretagogue.
Key Numbers
How They Did This
Clinical pharmacology study describing ipamorelin's development from a chemistry program. Tested in vitro and in vivo including human subjects. GH, cortisol, ACTH, prolactin, and other hormones measured after various doses.
Why This Research Matters
Older GH-releasing peptides boosted cortisol and prolactin along with GH, limiting their therapeutic use. Ipamorelin's selectivity means it could stimulate growth hormone without these unwanted hormonal side effects.
The Bigger Picture
The quest for a clean GH-releasing agent has been a major goal in endocrinology. Ipamorelin's selectivity represented a breakthrough, showing it was possible to separate GH release from other hormonal effects. This principle has influenced all subsequent GH secretagogue development.
What This Study Doesn't Tell Us
Clinical data available at time of publication was limited. Long-term safety and efficacy studies were not yet completed. Selectivity in healthy volunteers may differ from patient populations.
Questions This Raises
- ?What structural features give ipamorelin its selectivity?
- ?Does ipamorelin maintain selectivity during long-term use?
- ?Can ipamorelin treat GH deficiency states without the side effects of other secretagogues?
Trust & Context
- Key Stat:
- 200x dose with no cortisol rise Even at 200 times the effective GH-releasing dose, ipamorelin did not increase cortisol, ACTH, or prolactin — unprecedented selectivity
- Evidence Grade:
- Strong evidence from comprehensive pharmacological characterization including human clinical data showing selectivity across a wide dose range.
- Study Age:
- Published in 1998. Ipamorelin has since become one of the most studied and commonly referenced GH secretagogues in the field.
- Original Title:
- Ipamorelin, the first selective growth hormone secretagogue.
- Published In:
- European journal of endocrinology, 139(5), 552-61 (1998)
- Authors:
- Raun, K(3), Hansen, B S(4), Johansen, N L(3), Thøgersen, H, Madsen, K, Ankersen, M, Andersen, P H
- Database ID:
- RPEP-00485
Evidence Hierarchy
Frequently Asked Questions
Why is selectivity important for a GH peptide?
Older GH-releasing peptides like GHRP-6 also raised stress hormones (cortisol) and prolactin. This limits their use because these side effects can cause problems. Ipamorelin only raises GH, making it theoretically safer and cleaner.
How does ipamorelin compare to GHRP-6?
Both release similar amounts of growth hormone, but ipamorelin does it without affecting cortisol, ACTH, or prolactin. This selectivity makes ipamorelin potentially more suitable for therapeutic use with fewer side effects.
Read More on RethinkPeptides
Cite This Study
https://rethinkpeptides.com/research/RPEP-00485APA
Raun, K; Hansen, B S; Johansen, N L; Thøgersen, H; Madsen, K; Ankersen, M; Andersen, P H. (1998). Ipamorelin, the first selective growth hormone secretagogue.. European journal of endocrinology, 139(5), 552-61.
MLA
Raun, K, et al. "Ipamorelin, the first selective growth hormone secretagogue.." European journal of endocrinology, 1998.
RethinkPeptides
RethinkPeptides Research Database. "Ipamorelin, the first selective growth hormone secretagogue." RPEP-00485. Retrieved from https://rethinkpeptides.com/research/raun-1998-ipamorelin-the-first-selective
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.