Twenty-nine residues, and not one more
Natural GHRH is forty-four amino acids. Sermorelin is the first twenty-nine, which turned out to be the minimum length retaining full activity at the receptor. Everything past residue twenty-nine is, functionally, optional.
Establishing that was useful work. It defined the active core that every subsequent GHRH analogue, tesamorelin included, has been built on.
Defining a minimum is not only an academic result either. A shorter chain costs less to synthesise, purifies more cleanly and is simpler to confirm by analysis, so showing that fifteen residues could be dropped without losing receptor activity changed what was practical as well as what was known.
The half-life problem
Sermorelin keeps the natural sequence, and with it the natural vulnerability: DPP-4 clears it within minutes. Its half-life is measured in single-digit minutes, which makes any sustained protocol awkward.
Tesamorelin solves exactly this by adding a modification at the N-terminus that blocks the cleavage site. Same active core, protected. That is the difference between the two compounds in one sentence.
Rapid clearance also shapes what can be measured. Work on a compound that disappears this fast tends to look at acute responses rather than sustained ones, and the endpoints chosen reflect that. Reading such a paper as though it described a long exposure is one of the commoner ways to misread this corner of the literature.
| Length | 29 amino acids |
| Relationship | GHRH fragment 1–29 |
| Significance | Shortest fully active GHRH sequence |
| Half-life | Minutes, cleared by DPP-4 |
| Protected version | Tesamorelin |
| Stocked here | No, reference page |
| Closest product | Tesamorelin peptide pen |
| Category | Research use only |
A materials table. Effects are discussed in the text, not here.
We do not supply sermorelin
The protected version is in the catalogue and has a completed clinical programme behind it. Selling the unprotected version alongside it would mostly mean selling a shorter duration to people who did not know the difference.
If GHRH is the mechanism you want, tesamorelin is the page to read. If you want the ghrelin route as well, the combination pen covers both.
The plain reply to what is sermorelin, then: the opening twenty-nine residues of a natural releasing hormone, kept exactly as they occur, with every bit of the fragility that implies. The hexarelin page describes the other early route to the same endpoint, reaching the pituitary through the ghrelin receptor instead.
What an unprotected sequence asks of the paperwork
A peptide that an enzyme clears quickly in circulation is not automatically fragile in a vial, and the two questions get run together constantly. Stability in storage is a matter of temperature, light, moisture and repeated handling; it is settled by what degradation actually does to a sample rather than by anything in the pharmacokinetics.
What does follow from a short natural sequence is that identity confirmation carries more weight. Small peptides are easy to synthesise and just as easy to synthesise wrongly, and a truncated or scrambled batch does not announce itself in the vial. The certificate of analysis is where the sequence and the purity are stated for the lot actually in front of you.
For the record itself, the indexed literature on PubMed holds the endocrine and diagnostic work, while the registry entries on ClinicalTrials.gov show where it has been formally studied. Both are better starting points than a summary written by anyone with something to sell.
Sermorelin in the catalogue
Nothing is released below 99% purity, and the paperwork follows the lot.
Where Sermorelin fits in
Three pages that answer what this one leaves open.
About Sermorelin
Common questions, answered without marketing.