What it is
Ipamorelin is a synthetic pentapeptide GHS developed by NovoNordisk in the 1990s. Acts at the GHSR-1a receptor — the same receptor targeted by ghrelin.
Evidence snapshot
Category: Growth Hormone. Status: Preclinical. See the references section below for the underlying primary sources.
Mechanism
Activation of GHSR-1a on pituitary somatotrophs triggers GH release. Unlike earlier GHS molecules, ipamorelin produces GH release without significant increases in cortisol, ACTH, or prolactin.
Key research findings
In rodent and pig models, ipamorelin increases GH pulse amplitude without changing pulse frequency, produces dose-dependent GH release with defined duration, avoids acute tachyphylaxis.
Limits of the evidence
No large peer-reviewed human RCTs. The Phase 2 program was halted before meaningful efficacy data was generated. Off-label human use in biohacking contexts is widespread.