Sermorelin vs Ipamorelin: Structure and Route of Administration
Sermorelin is made up of the first 29 amino acids from the much larger, naturally occurring GHRH peptide. It is the smallest fraction of GHRH than retains all of the properties of the parent molecule. Weighing in at 3357.9 g/mol, Sermorelin is a relatively large, heavy peptide that must be injected sub-cutaneous to be absorbed. It is not orally bioavailable. As a result of its large size, Sermorelin has a more significant three-dimensional structure than Ipamorelin and is thus is a little less stable in terms of storage half-life.
Source: PubChem
Ipamorelin is substantially smaller than Sermorelin at just 5 amino acids and 711.868 g/mol. It is a derivative of GHRP-1, which is itself a derivative of met-enkephalin. Though the most common route of administration for Ipamorelin is via sub-cutaneous injection, the peptide is also orally active and can even be absorbed though the nasal mucosa.
Source: PubChem
Ipamorelin vs Sermorelin: Lean Body Mass
Both Sermorelin and Ipamorelin favor the development of lean body mass over fat mass, but Sermorelin is the more potent of the two. This arises from the fact that Sermorelin is both a growth stimulator and a fat burner while Ipamorelin is a more general growth stimulator. That is not to say that Ipamorelin isn’t effective, it is, but ipamorelin isn’t as strictly favorable of lean body mass deposition as Sermorelin. This difference arises from the fact that Ipamorelin is a ghrelin analogue and ghrelin favors food intake in general. Its growth hormone boosting properties shift the overall balance away from fat deposition and toward lean body mass deposition, but the Ipamorelin peptide is best thought of as a general weight boosting peptide while Sermorelin is best thought of as a more exclusive booster of lean body mass. In fact, Sermorelin is often referred to as a lipolytic or fat-burning peptide.
Both peptides stimulate the development of bone and other connective tissue, but Ipamorelin appears to have the advantage in this realm. In fact, ipamorelin is so effective in boosting bone density and mineralization that it has been investigated as a potential treatment for corticosteroid-induced bone loss as well as osteoporosis[7], [8].
When it comes to muscle growth, Sermorelin is probably the big winner, though this can be debated endlessly. Sermorelin not only boosts muscle hypertrophy and hyperplasia, it reduces fat mass and thus causes a shift in body chemistry toward lean body weight. In other words, Sermorelin will always favor the production of lean body mass even if diet is not perfectly geared toward muscle development. Ipamorelin, on the other hand, is more of a mixed bag. It will always cause muscle growth, but ipamorelin may channel some of those calories into fat deposition as well.
