Growth Hormone Releasing Peptide · Selective GH Secretagogue
A selective pentapeptide growth hormone secretagogue that stimulates GH release through the ghrelin receptor pathway without significantly elevating cortisol, prolactin or ACTH — making it one of the cleanest GH-releasing compounds in research.
Ipamorelin is a synthetic pentapeptide (5 amino acids) that acts as a selective agonist of the ghrelin receptor (GHS-R1a), stimulating growth hormone release from the pituitary. It was developed as a cleaner alternative to earlier GHRPs like GHRP-2 and GHRP-6 which caused significant elevations in cortisol and prolactin alongside GH.
The key differentiator of Ipamorelin over other GHRPs is its selectivity. Research has consistently shown that at therapeutic doses, Ipamorelin produces robust GH release without meaningful elevation of cortisol, ACTH or prolactin — the side effects that made earlier GHRPs problematic. This selectivity makes it significantly more suitable for extended use in anti-aging and body composition research contexts.
Ipamorelin mimics ghrelin by binding to GHS-R1a receptors on pituitary cells and in the hypothalamus, triggering GH pulse release. The mechanism is distinct from and complementary to GHRH receptor stimulation (CJC-1295's mechanism) — when both pathways are stimulated simultaneously, the resulting GH pulse is significantly larger than either compound produces alone. This is the pharmacological basis for the CJC-1295 + Ipamorelin stack.
Studies have shown Ipamorelin produces dose-dependent GH release. The GH pulse typically peaks 15–30 minutes after administration and returns to baseline within 2–3 hours, preserving the natural pulsatile pattern. Administered at bedtime, it amplifies the largest natural GH pulse which occurs during slow-wave sleep — making timing critical for maximising benefit.
Animal studies and limited human data suggest Ipamorelin administration leads to increased lean body mass and reduced adiposity over extended periods, consistent with the known effects of elevated GH and IGF-1 on body composition. Recovery time from exercise and injury has also been noted to improve in research subjects.