Tesamorelin is a synthetic 44-amino-acid analogue of growth hormone-releasing hormone, modified at the N-terminus with a trans-3-hexenoyl group. Molecular formula C221H366N72O67S, molecular weight 5135.86 g/mol.
That single acyl modification is the reason the molecule exists. Native GHRH(1-44) is cleaved rapidly by dipeptidyl peptidase-4 at the N-terminal end; attaching the hexenoyl group blocks the cleavage site and extends the working half-life substantially, without altering the receptor-binding portion of the sequence.
Research context
Tesamorelin is studied as a GHRH receptor agonist. The distinction that matters is between this approach and administering growth hormone directly: a GHRH analogue stimulates endogenous release from the pituitary, which preserves the pulsatile secretion pattern and the feedback regulation that direct growth hormone administration bypasses.
For researchers modelling physiological signalling rather than achieving elevated hormone levels, that difference is often the reason for choosing a secretagogue over the hormone itself. Published work examines pituitary GH release, downstream hepatic IGF-1 production, and visceral adipose tissue endpoints.
For a fuller treatment of the sequence, published models and technical data, see the tesamorelin research guide.
Specification
CAS number 218949-48-5. Supplied as a white lyophilized powder, soluble in sterile or bacteriostatic water. This batch assayed at 99.12% purity, verified by HPLC and LC-MS at ILS Lab. Available in 5mg and 10mg presentations.
Handling
Reconstitute with bacteriostatic or sterile water, introducing the diluent against the vial wall and swirling gently rather than shaking. At 44 residues this is a substantial peptide and more conformationally sensitive than short sequences — avoid foaming.
Store lyophilized at −20°C protected from light; refrigerate at 2–8°C once reconstituted.
Ships with a batch-specific Certificate of Analysis. Cross-check the batch ID printed on your vial against the CoA before use — see the guide to reading a CoA if you are unfamiliar with the format.
Frequently asked questions about tesamorelin
What is the difference between tesamorelin and HGH?
Where in the pathway they act. HGH is the hormone itself, administered directly. Tesamorelin acts one step upstream at the GHRH receptor, stimulating the pituitary to release its own growth hormone. The practical consequence is that tesamorelin preserves pulsatile secretion and negative feedback regulation, whereas direct administration overrides both.
Why choose a secretagogue over the hormone?
When the research question concerns physiological signalling rather than defined exposure. Endogenous GH release is pulsatile, and that pattern is itself biologically meaningful — receptor desensitisation and downstream signalling both respond to pulse frequency, not just total amount. A secretagogue keeps that structure intact. For work requiring a known, controlled quantity of hormone, direct administration is the appropriate tool.
What does the hexenoyl modification do?
It blocks degradation. Native GHRH(1-44) is cleaved rapidly by dipeptidyl peptidase-4 at the N-terminal end — the same enzyme that degrades native incretins, which is why tirzepatide and semaglutide carry Aib residues at the equivalent position. Attaching a trans-3-hexenoyl group to the N-terminus blocks the cleavage site while leaving the receptor-binding portion unchanged.
How should tesamorelin be handled?
Bacteriostatic or sterile water for reconstitution. At 44 residues this is a substantial peptide, more conformationally sensitive than the short sequences in this catalogue — introduce diluent slowly against the vial wall, swirl gently, and avoid foaming. Store lyophilized at −20°C protected from light; refrigerate at 2–8°C once reconstituted.
Research use only. Not for human or veterinary use, not for use in diagnostic procedures, and not evaluated by the U.S. Food and Drug Administration.
