Ipamorelin

Research-Grade

Ipamorelin is a pentapeptide GHRP developed by Novo Nordisk in the late 1990s as a growth-hormone secretagogue with improved receptor selectivity. It binds the growth-hormone secretagogue receptor (GHSR-1a, also known as the ghrelin receptor) on anterior pituitary somatotrophs, triggering pulsatile GH release. Its distinguishing feature among GHRPs is selectivity: unlike GHRP-2 (which raises prolactin) or GHRP-6 (which raises cortisol and induces hunger via ghrelin crosstalk), Ipamorelin's GH effect is relatively isolated from other hypothalamic-pituitary-adrenal axis perturbations in head-to-head pharmacodynamic studies. Ipamorelin is almost never used alone in modern off-label protocols. Instead, it is paired with a GHRH analog (Sermorelin, CJC-1295 no-DAC, or Tesamorelin) because GHRH + GHRP combinations produce synergistic GH pulses — larger than either alone — by activating two distinct receptor classes on the same target cell. Clinical development in humans did not advance to late-stage trials; the molecule remains a research peptide in most jurisdictions despite decades of pharmacodynamic characterization.