Tesamorelin: what it is, what it is for and what FDA says

What tesamorelin is

Tesamorelin (development code TH9507) keeps the full 44-amino-acid sequence of human GHRH, the hypothalamic hormone that tells the pituitary to release growth hormone. Its one chemical difference is a trans-3-hexenoyl group added to the tyrosine at the start of the chain.

That change makes it resistant to the enzyme that inactivates native GHRH (dipeptidyl peptidase-4). In in vitro studies published in 2007, tesamorelin broke down more slowly than the native hormone in rat, dog and human plasma.

It should not be confused with sermorelin or CJC-1295: those are other GHRH analogs with different structures.

What tesamorelin is used for

As a medicine, tesamorelin has one FDA-approved indication: reducing excess abdominal (visceral) fat in adults with HIV who have lipodystrophy. FDA approved it on November 10, 2010 as Egrifta (now Egrifta SV and Egrifta WR), from Theratechnologies.

It is not approved as a weight-loss medicine, for abdominal fat in people without that condition, or for performance. Social media claims about "tesamorelin for fat loss" do not rest on an approval for those uses.

In the laboratory, tesamorelin is used to study the GHRH, growth hormone and IGF-1 axis, and as a standard in analytical chemistry: anti-doping laboratories have published methods to detect it in plasma and urine.

Chemical identity

• Formula: C221H366N72O67S (PubChem CID 16137828).
• Molecular mass: about 5136 g/mol (the FDA label gives 5135.9 Da).
• CAS: 218949-48-5 for the free peptide; the acetate salt has its own record.
• Sequence: 44 residues, with a methionine at position 27 and an amidated end.

With more than 40 amino acids, FDA technically treats it as a protein, even though it is made by chemical synthesis.

What to check on a tesamorelin COA

• Identity by mass spectrometry, with a mass close to 5136 Da. That test also separates it from unmodified GHRH(1-44), which is about 96 Da lighter.
• Oxidation: a signal 16 Da heavier means methionine 27 has oxidized.
• Purity by HPLC, ideally with the chromatogram.
• Peptide, acetate and water content, which explain the gap between the powder weight and the actual tesamorelin.

The guide how to read a COA explains each of these lines.

Laboratory storage

Store the vial as its COA and label state. Methionine 27 is the residue most likely to oxidize, so the vial should spend as little time open as possible. If it is kept cold, let it reach room temperature before opening so no moisture condenses on the powder.

Egrifta’s storage instructions belong to a formulated medicine and cannot be applied as they are to research powder.

Where to get tesamorelin in Puerto Rico

As a medicine, Egrifta is only available on prescription. As research material, CaribePeptides tesamorelin is sold in lyophilized vials, with price per vial and live stock on its page, and ships from Puerto Rico with tracking. We give no doses or instructions for use in people: it is for research only.