Tesamorelin: A Research Primer

Tesamorelin is a synthetic analog of human growth-hormone-releasing hormone, built on the full 44-residue GHRH(1-44) sequence with a small chemical group attached to one end. It carries CAS number 218949-48-5 and the molecular formula C221H366N72O67S, and it appears in metabolic and endocrine research.

What tesamorelin is

Tesamorelin is a modified peptide, not a naturally occurring one. Chemists take the sequence of native GHRH(1-44), the hypothalamic peptide hormone, and cap its N-terminal end with a trans-3-hexenoyl group. Everything downstream of that cap is the ordinary GHRH chain. The cap is the whole reason the word "stabilized" gets attached to the name: the added group changes how the molecule behaves toward the peptidases that would otherwise act on the unmodified hormone, which is a property of the chemistry and not a statement about use.

So when a listing calls tesamorelin a stabilized GHRH analog, read that as a structural description. It is native GHRH(1-44) plus one N-terminal modification. That places it in the GHRH-analog family, and it is fully synthetic, assembled residue by residue rather than extracted from any tissue.

The chemistry

The identity data is the part that does not vary between suppliers, so it is what to check first.

• CAS number: 218949-48-5
• Molecular formula: C221H366N72O67S
• Molecular weight: approximately 5135.9 g/mol
• Amino-acid sequence: YADAIFTNSYRKVLGQLSARKLLQDIMSRQQGESNQERGARARL (GHRH residues 1 to 44), with a trans-3-hexenoyl group on the N-terminal tyrosine
• Class: growth-hormone-releasing-hormone (GHRH) analog
• Also known as: TH9507

The single sulfur atom in that formula comes from the lone methionine, residue 27 in the chain, which is worth knowing if you are sanity-checking a mass figure. The compound is usually handled as the acetate salt, so a report that lists an acetate content is describing the counterion rather than an impurity. When you cross-check identity against a certificate, match the CAS number before anything else. A name can be transcribed a dozen ways and a formula can pick up a typo, but the registry number is unambiguous.

Where it appears in the research literature

Tesamorelin shows up in metabolic and endocrine research, in the corner of endocrinology concerned with the growth-hormone axis. That is the field it sits in.

I am not going to paraphrase what any of those papers found. If you want the studies themselves rather than a secondhand gloss, the CAS number and the sequence above are the search terms that pull them up cleanly, and "tesamorelin" together with "GHRH" will find the rest. Naming the subject area is a statement about what researchers have looked at, not about any outcome.

How it is supplied and handled

Tesamorelin is supplied as a lyophilized solid, meaning freeze-dried. Peptides travel this way because a dry solid holds together far better in transit than anything in solution, and a chain of this length is no exception.

Store it cold, at around -20C, and keep the vial sealed and out of the light until you are working with it. Moisture and repeated temperature swings are the variables worth controlling for a peptide this size. As with most freeze-dried peptides, expect a bulking agent in the vial so there is something physical to see and weigh, and a proper report accounts for that filler in the stated mass. None of this is preparation guidance. It is how you keep a reagent intact on a shelf.

How each lot is tested

Kits third-party tests each lot it stocks, sending samples to an independent third-party laboratory. Purity is measured by HPLC read at 220 nm, the standard wavelength for the peptide bond, and identity is confirmed by mass spectrometry, which checks that the molecule matches the label rather than only measuring how clean the sample is. Those two numbers, one for how much target peptide is present and one for whether it is the right peptide, are what a certificate of analysis exists to report.

If you have not read one of these documents before, there is a walkthrough on [how to read a peptide COA](/research/how-to-read-a-peptide-coa) that goes through real reports line by line, plus a broader [checklist for buying research peptides in Canada](/research/buying-research-peptides-canada). Current stock status and any published report live on the [tesamorelin product page](/products/tesamorelin). Kits Peptides ships tracked from Vancouver, BC across Canada.

*All products are supplied as laboratory reagents for research use only. Not for human or veterinary use.*