What is Ipamorelin?
The sequence recorded in the molecular reference is notable for how little of it is standard. Aib is alpha aminoisobutyric acid, a non-proteinogenic residue that constrains backbone conformation; D-2-Nal is a D configured naphthylalanine; D-Phe is the mirror image of the usual phenylalanine; and the chain terminates in a carboxamide rather than a free acid. Each feature exists to resist proteolysis, which is why so small a molecule survives in biological media at all.
In the published literature ipamorelin is an agonist at the growth hormone secretagogue receptor, the same receptor engaged by ghrelin. Its interest as a tool compound comes from selectivity. In rodent and pituitary cell studies it stimulates growth hormone release without the marked increases in corticotropin and prolactin reported for earlier secretagogues in the same class (Raun, 1998), which makes it useful for isolating growth hormone axis effects from broader pituitary activation.
What is not settled is the structural basis of that selectivity, whether the described signalling bias holds across cell backgrounds and species, and how receptor desensitization develops under sustained exposure in vitro.
Reconstitution & handling
Sterile or bacteriostatic water is added slowly down the inner wall of the vial and swirled gently until clear, which happens quickly at this size. Lysine and histidine make the peptide basic and readily soluble in neutral water, and no co-solvent is needed. Concentration is a simple division, so 2 mL added to a 5 mg vial yields 2.5 mg per millilitre.
Storage & stability
Sealed lyophilized vials are stored at -20 °C, protected from light and moisture, and warmed to room temperature before the stopper is pierced. Reconstituted solution is refrigerated at 2 to 8 °C, divided into single use aliquots, and protected from repeated freezing and thawing. The sequence contains no methionine or cysteine, so oxidation is a minor concern, and the non-standard residues resist enzymatic breakdown; the practical limits in solution are microbial growth in unpreserved water and adsorption losses when dilute.
How it's tested
Lots are analysed by reversed phase HPLC at 214 and 220 nm, and the naphthylalanine gives a strong aromatic signal at higher wavelengths as well. Main peak area is reported at 99 percent or greater. Mass spectrometry confirms identity against the theoretical mass of 711.85 from C38H49N9O5, and is paired with chromatography because a D to L epimer shares the same mass and can only be resolved by separation.