What Tesamorelin is
Tesamorelin, development code TH9507, is a stabilised analogue of growth-hormone-releasing hormone — specifically of GHRH(1–44). Its defining structural feature is a trans-3-hexenoyl group attached at the N-terminus. Native GHRH is cleaved rapidly at the N-terminal end by dipeptidyl peptidase-4; the added acyl group obstructs that cleavage, extending the molecule’s usable window considerably. It is a clean example of a recurring theme in peptide design: identify the enzyme that destroys the native molecule, then block its access point.
- TesamorelinStabilised GHRH analogue
- GHRH receptorResistant to DPP-4 cleavage
- GH → hepatic IGF-1Downstream axis activation
- Visceral adipose endpointsAs measured in clinical trials
Mechanism as described in published research. Nothing here describes an effect in a person — these compounds are supplied for laboratory research use only.
GHRH-receptor signalling
Tesamorelin is an agonist at the GHRH receptor on pituitary somatotrophs, acting through the same pathway as endogenous GHRH. This places it in a different mechanistic class from the ghrelin-receptor secretagogues such as ipamorelin, which reach the GH axis by a separate receptor entirely.
That distinction is why the two classes are so often studied together: because they converge on the same output through different receptors, combining them is a way of probing whether the axis responds additively or whether one pathway is rate-limiting. The comparison with the shorter GHRH fragments — sermorelin, which is GHRH(1–29), and modified GRF(1–29) — isolates what the additional residues and the stabilising group contribute.
What the literature covers
Published work includes:
- GHRH-receptor pharmacology — binding, potency and duration relative to native GHRH and its shorter fragments.
- Visceral adipose tissue models — the metabolic context in which tesamorelin is most heavily published.
- Enzymatic stability — DPP-4 resistance conferred by N-terminal acylation, as a design principle applicable to other peptides.
- Axis-level study design — GHRH-receptor versus ghrelin-receptor stimulus, alone and in combination.
See also the complete guide to research peptides for how the growth-hormone secretagogue classes relate.
Identity and verification
Tesamorelin has the molecular formula C221H366N72O67S and a molecular weight of 5136 g/mol (CAS 218949-48-5). Identifiers matter more here than in most categories: research compounds are sold under trade names, development codes and abbreviations that do not always refer to the same molecule, and a formula is unambiguous where a name is not.
The lot we currently hold measured 99.78% for the 10 mg (lot 261807) and 99.83% for the 20 mg (lot 261807), tested by Freedom Diagnostics. The certificate is published in full, including the raw chromatogram and mass spectrum — so the number can be read off the underlying trace rather than taken on trust.
We use two laboratories because purity and identity are different questions. Vanguard Laboratory is ISO/IEC 17025:2017 accredited (A2LA #6377.01.01) and reports chromatographic purity and net quantity with a stated measurement uncertainty. Freedom Diagnostics reports HPLC-UV purity together with LC-MS identity confirmation — the test that catches a substituted compound rather than merely an impure one. A sample can be 99% pure and still be the wrong molecule. How we test →
Handling, reconstitution and storage
Tesamorelin ships lyophilized — freeze-dried to a solid and sealed under vacuum — which is what makes it stable in transit rather than a solution racing a clock. Reconstitute with bacteriostatic water, added slowly down the inside wall of the vial rather than directly onto the powder, then swirled gently. Do not shake: mechanical shear is one of the few things that reliably degrades a peptide in the lab.
Final concentration is a function of the volume added, not of the compound, so the same vial can be prepared at very different concentrations. The reconstitution calculator works out the volume for a target concentration and the reconstitution guide covers the procedure. Store lyophilized vials at −20 °C (−4 °F) protected from light; refrigerate once in solution, and see the storage and stability guide for how long reconstituted material holds.
Common questions
What is the difference between tesamorelin and sermorelin?
Sermorelin is GHRH(1–29), the shortest fragment retaining activity. Tesamorelin is based on GHRH(1–44) with a trans-3-hexenoyl group at the N-terminus that blocks DPP-4 cleavage, giving it a considerably longer usable window. Both act at the same receptor.
How does tesamorelin differ from ipamorelin?
Different receptors. Tesamorelin is a GHRH-receptor agonist; ipamorelin is a selective ghrelin-receptor agonist. They converge on the same axis through separate pathways, which is why research designs often examine them together.
What does TH9507 refer to?
TH9507 is the development code for tesamorelin. The two names refer to the same molecule.
Why does the N-terminal modification matter?
Native GHRH is rapidly cleaved at its N-terminus by dipeptidyl peptidase-4. The trans-3-hexenoyl group obstructs that cleavage, which is what extends the molecule's stability — a general design principle in peptide chemistry rather than a quirk of this compound.
Where to get it
Buy research-grade Tesamorelin — independently tested, certificate published, shipped from Miami with cold-chain packaging. Current pricing for every size is on the price list, and we ship worldwide.
Research use only
Everything referenced here is supplied strictly for laboratory research. These compounds are not drugs, foods, cosmetics or medical devices, are not for human or veterinary use, and are not approved for diagnostic or therapeutic application. Mechanisms are described as studied in preclinical and laboratory research; nothing above describes dosing, treatment or clinical outcome.
