Does ipamorelin raise cortisol?
No — ipamorelin was characterised in the original Raun research as the first selective growth hormone secretagogue with minimal effect on cortisol, prolactin, or ACTH at the doses studied. The selectivity for GH release is the central pharmacological distinction from earlier-generation GH secretagogues that elevated multiple pituitary hormones.
What the research literature says
The Raun characterisation paper established ipamorelin as the first growth hormone secretagogue with high selectivity for GH release relative to other pituitary hormones (PMID 9849822). Selectivity was characterised in vitro and in vivo, with the compound showing high potency at the growth hormone secretagogue receptor (GHSR-1a, the ghrelin receptor) but minimal activation of pathways driving cortisol, prolactin, or ACTH release.
This selectivity was a development-program target — the Novo Nordisk research aimed to deliver a GH secretagogue without the prolactin and ACTH elevations seen with earlier compounds in the class (notably GHRP-6 and GHRP-2). The Hansen development series characterised hybrid structures designed off the ipamorelin scaffold with the goal of further refining the selectivity profile (PMID 9733495, PMID 11459660).
The pharmacokinetic profile (PMID 9879640) supports the selectivity finding indirectly — the short ~2-hour half-life produces a discrete GH-release pulse per dose without sustained-elevation pharmacology that might recruit cortisol-release pathways at high steady-state ligand concentrations.
Why this matters in research context
The cortisol-selectivity profile is the central reason research protocols favour ipamorelin over earlier-generation GH secretagogues. Protocols studying isolated GH-axis effects need clean selectivity to avoid confounding from cortisol or prolactin elevations. The Raun selectivity finding has held up across subsequent research and is the basis for the compound’s standard inclusion in GH-axis combination protocols (typically paired with a GHRH analogue for dual-receptor engagement).
Related compounds
- Ipamorelin 10mg — the compound covered by this answer
- CJC-1295 + Ipamorelin Blend — single-vial combination engaging both ghrelin and GHRH receptors
Related research questions
- What is the half-life of ipamorelin?
- Can CJC-1295 be stacked with ipamorelin?
- Does tesamorelin raise IGF-1?
References
- Raun K et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol 1998;139(5):552-561. [PMID 9849822]
- Ankersen M et al. A new series of highly potent growth hormone-releasing peptides derived from ipamorelin. J Med Chem 1998;41(19):3699-3704. [PMID 9733495]
- Hansen TK et al. Highly potent growth hormone secretagogues: hybrids of NN703 and ipamorelin. Bioorg Med Chem Lett 2001;11(14):1915-1918. [PMID 11459660]
- Johansen PB et al. Pharmacokinetic evaluation of ipamorelin and other peptidyl growth hormone secretagogues with emphasis on nasal absorption. Xenobiotica 1998;28(11):1083-1095. [PMID 9879640]
Research-questions pages describe research-context use of peptide-research terminology. They do not constitute medical, veterinary, or clinical advice. Ipamorelin is sold strictly as a research-grade reagent for laboratory and bench research applications.