Ipamorelin is a selective growth hormone secretagogue peptide and one of the most widely used GHRP compounds in GH axis research. This profile covers its mechanism, receptor selectivity, and how it fits into growth hormone research protocols.
What is Ipamorelin?
Ipamorelin is a synthetic pentapeptide designed to selectively stimulate growth hormone release via the ghrelin receptor (GHS-R1a). It was developed as a cleaner alternative to earlier growth hormone-releasing peptides (GHRPs) like GHRP-2 and GHRP-6, with improved selectivity for the GH axis and reduced activity at off-target receptors.
Mechanism of action
Ipamorelin acts as a selective agonist at the ghrelin receptor (GHS-R1a), which is the same receptor activated by the endogenous hunger hormone ghrelin. Activation of this receptor in the pituitary and hypothalamus stimulates growth hormone release. What distinguishes Ipamorelin from earlier GHRPs is its high selectivity — it produces GH release without the significant cortisol, prolactin or ACTH release seen with less selective peptides like GHRP-6. This selectivity makes it particularly useful in research designs where isolated GH axis effects are required.
Comparison with other GHRPs
The GHRP family includes GHRP-2, GHRP-6, Hexarelin and Ipamorelin. Of these, Ipamorelin is generally considered the most selective for GH release. GHRP-6 is well-studied but produces significant ghrelin-mediated appetite stimulation and cortisol release. GHRP-2 is more potent but also less selective. Ipamorelin's selectivity profile makes it the preferred compound for research where off-target hormonal effects would confound results.
CJC-1295 and Ipamorelin in combined protocols
Ipamorelin is commonly studied in combination with CJC-1295 (No DAC), a GHRH analogue that acts through a complementary pathway. CJC-1295 stimulates GH release via the GHRH receptor, while Ipamorelin acts via the ghrelin receptor — the two mechanisms are additive in preclinical models. This combination is one of the most studied GH axis research protocols, and Pepreta offers a pre-combined CJC-1295 + Ipamorelin blend for researchers running stacked protocols.
Purity requirements
GH axis research requires well-characterised compounds to produce reproducible results. Peptide impurities can activate or antagonise the same receptors as the target compound and introduce noise into GH secretion assays. Every Ipamorelin batch Pepreta supplies is characterised by RP-HPLC to ≥99% purity, ESI-MS identity confirmation and LAL endotoxin screening, with a batch Certificate of Analysis available.
Sourcing Ipamorelin for research
Pepreta supplies Ipamorelin as HPLC-verified lyophilised powder in 10mg vials, dispatched from Sydney and Melbourne. For reconstitution guidance see our reconstitution guide. Supplied for laboratory and research use only — not for human or animal consumption.