Also known as: NNC 26-0161
Ipamorelin is a selective pentapeptide growth hormone releasing peptide (GHRP) that stimulates pituitary GH release with minimal impact on cortisol, prolactin, or ACTH levels. Its receptor selectivity and clean side-effect profile make it the most widely studied GHRP for anti-aging and recovery applications.
Ipamorelin was developed by Novo Nordisk in the late 1990s as a highly selective ghrelin receptor (GHS-R1a) agonist. Its key differentiator from other GHRPs (GHRP-2, GHRP-6, Hexarelin) is selectivity: it robustly stimulates GH release without the corresponding cortisol, prolactin, or ACTH spikes seen with older GHRPs, which can suppress immune function, promote fat storage, and cause hormonal dysregulation.
Ipamorelin is commonly combined with CJC-1295, a GHRH analog, creating a synergistic dual-pathway approach — Ipamorelin triggers the amplitude of GH pulses while CJC-1295 increases pulse frequency. This combination mimics youthful GH secretory patterns more closely than either peptide alone.
Ipamorelin binds to the growth hormone secretagogue receptor 1a (GHS-R1a) on pituitary somatotrophs, triggering intracellular calcium influx and GH granule exocytosis. Unlike GHRP-6 and GHRP-2, Ipamorelin does not significantly activate GHS-R subtypes associated with cortisol or prolactin release.
GH release from Ipamorelin is pulsatile rather than tonic, mimicking the natural ultradian rhythm of GH secretion. Pulsatile release is important for preserving GH receptor sensitivity and avoiding the receptor downregulation that occurs with continuous GH administration.
Ipamorelin is the most selective GHRP available — it releases GH without significant co-stimulation of cortisol, prolactin, or ACTH, which is the primary limitation of older GHRPs like GHRP-6. Its 5-amino-acid pentapeptide structure confers excellent bioavailability and tolerability. Side effects are minimal: mild transient water retention and flushing at higher doses. No desensitisation observed at standard doses in research. Always source from reputable suppliers with mass spec or HPLC certificate.
Ipamorelin cycles are typically 8–12 weeks when used for body composition or recovery goals, followed by an off-cycle to allow pituitary sensitivity to reset. When stacked with CJC-1295 (no DAC), the same cycling principle applies to both peptides simultaneously. IGF-1 levels can be monitored mid-cycle as a proxy for GH axis activity.
Ask anything about Ipamorelin — mechanisms, dosing protocols, interactions, or research comparisons.
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