
Ipamorelin binds the ghrelin receptor (GHS-R) in the pituitary, triggering a pulsatile release of the body's own growth hormone. Its defining feature relative to earlier ghrelin-mimetic peptides is selectivity — in preclinical models it stimulates GH release with comparatively little effect on cortisol, prolactin, or appetite, the off-target effects that limited older secretagogues.