Comparing Ipamorelin and GHRP-6

by | Feb 16, 2022 | Research


Growth hormone-releasing peptides GHRPs are synthetic, non-natural peptides. They are capable of potent stimulatory effects on the induction and secretion of Growth hormones in animal test subjects. However, they have no structural resemblance with Growth Hormone-Releasing Hormones and mediate their action by binding with specific cognate receptors present in animals at the pituitary or hypothalamic level. The GH-releasing function of GHRPs is significantly observable and dose-dependent when administered through intravenous subcutaneous intranasal and oral administration.
Some biomolecules that affect the Growth Hormone Releasing Peptides include glucose, free fatty acids, glucocorticoids, and somatostatin.



Ipamorelin is one of the most sought-after and versatile synthetic peptides. Composed of only five amino acids, it is a potent growth hormone secretagogue receptor (GHS-R) agonist controlling aging and obesity. Animal studies have revealed its diverse beneficial roles, such as promoting gut function, lean body mass, muscle growth, and bone health without affecting hair growth and sexual drive.
Ipamorelin is gentle compared to other peptides like Sermorelin or GHRP-6, as it affects only the growth hormone axis. Hence it helps study the isolated effects of growth hormone secretagogue agonists.


How does Ipamorelin work?

The binding of Ipamorelin peptide activates the ghrelin (growth hormone secretagogue) receptor. The ghrelin receptor (a.k.a. GHS-R) in the brain, liver, heart, and skin muscle regulates energy and body weight. It is highly exclusive for growth hormone release from the pituitary gland. Having a half-life of just 2 hours is ideal for various biological studies.
Both Ipamorelin and GHRP-6 belong to the class of third-generation GHRP. They are among the first synthetic peptides studied extensively in animal models. Ipamorelin and GHRP-6 are similar in their functions. Both peptides release GH at similar rates. At the same time, they do not show the side effects that GHRP-6 exhibits. However, there is a moderate difference in how the two peptides mediate their action. GHRP-6 also causes a release and an increase in cortisol and prolactin levels, whereas Ipamorelin only selectively releases GH.


Growth Hormone-Releasing Peptide-6

Growth hormone-releasing peptide-6 is a first-line synthetic hexapeptide and a met-enkephalin derivative. It comprises a chain of 6 unnatural D amino acids with the sequence (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2). Additionally, the peptide also contains two methyl groups as modifications. It happens to be the first hexapeptide studied in animal model studies, and researchers identified it more than a decade ago.


Mechanism of action

GHRP-6 recognizes and binds to specific receptors present at the pituitary or hypothalamic glands. Studies have shown that GHRP-6 receptors are abundant in different peripheral tissues such as the heart, adrenal, ovary, testis, lung, and skeletal muscle.
Studies in animal test models show that GHRP-6 stimulates Ghrelin. Ghrelin, in turn, increases the production of growth hormone (GH) by acting at the level of the pituitary or hypothalamus through a specific receptor which is different from that of the endogenous Growth Hormone-Releasing Hormone (GHRH).
The four essential organs of the test subjects that demonstrate the role of GHRP-6 include the pituitary gland, central nervous system, liver, and stomach.
Studies in animal test subjects have highlighted that GHRP-6 and Ipamorelin stimulate Ghrelin, “the hunger hormone,” by associating with its ghrelin receptor. This association triggers a cascade of events by inducing increased growth hormone production (GH) by acting at the level of the pituitary or hypothalamus through a specific receptor different from that of the endogenous Growth Hormone-Releasing Hormone GHRH. Researchers achieved the effects of GHRP-6 on GH release by calibrating various doses and administration routes.
Іn comparison with GHRP-6, Iраmоrеlіn induces more selective асtіvаtіоn of GHRH as it doesn’t have any effect on cortisol or prolactin. It gets mеtаbоlіzеd ѕlоwеr thаn GHRP-6, hence remains in the body for a longer duration of time, making іt mоrе ѕtаblе аnd is thеrеbу еffесtіvе fоr lоngеr period.


Comparing and contrasting the effects of Ipamorelin and GHRP-6

Ipamorelin and GHRP-6 have similar effects on animal test subjects but exhibit significant structural differences. They both act on the pituitary gland to release growth hormones. We will list the differences in the table below.

Effect on hunger Increases hunger markedly Doesn’t promote hunger
Effect on growth hormone release More Less
Effect on prolactin and cortisol release Less control None observed
Potency Same Same
Half-life Shorter half-life Longer half-life



The two peptides have more remarkable similarities than differences. At the same time, their unique differences make both of them highly relevant in a specific milieu. Researchers can utilize a vast source of information about the effects of these peptides obtained from prior clinical trials.

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