Preclinical Research & Case Studies

Mechanism: A synthetic pentapeptide agonist at the ghrelin / growth-hormone-secretagogue receptor (GHS-R1a). Notable within its class for selectivity — stimulating GH release with minimal cortisol or prolactin effect.

• Raun et al. (1998), European Journal of Endocrinology (139:552–561): The foundational study: ipamorelin produced robust GH release in rats comparable to GHRP-6, but with significantly lower cortisol and ACTH responses — establishing its selective profile.
  Model: Rat GH-release model | Source →
• Johansen et al. (1999), Growth Hormone & IGF Research: Chronic ipamorelin administration increased longitudinal bone growth and body-weight gain in rats, supporting sustained GH-axis engagement.
  Model: Rat model (chronic administration) | Source →
• Selectivity within the GHRP class (subsequent reviews): Across the secretagogue literature, ipamorelin is repeatedly distinguished from earlier GHRPs (GHRP-2, GHRP-6, hexarelin) by releasing GH without the off-target cortisol and prolactin elevation those compounds produce.
  Model: Rodent GH-axis comparison studies | Source →

Research stage: Selectivity and GH-axis effects are well documented preclinically in rodents.