Where to Buy Tesamorelin in 2026: Sizes, Purity Reports & Verification

Tesamorelin is the largest peptide in the GHRH-analogue category at 44 residues, and the one with the most distinctive chemical signature: a trans-3-hexenoyl group capping the N-terminal tyrosine. That single modification is what separates it from the unmodified 44-residue sequence on a mass spectrum, and it is the first thing to check on any listing. This guide covers the chemistry, how Pepta Labs lists tesamorelin, how to read the analytical report, storage, and its US regulatory record.

What Is Tesamorelin?

Tesamorelin is a synthetic linear 44-residue peptide amide. The amino-acid sequence is unchanged from the parent human GRF (growth hormone-releasing factor) 1-44 sequence, all residues are L-amino acids, and the C-terminus is a primary amide. The modification that defines the molecule sits at the N-terminus: a trans-3-hexenoyl group, a six-carbon unsaturated acyl chain (C6H9O), joined to the alpha-amine of Tyr1 as an amide. It adds 96.13 Da relative to the unmodified 44-residue amide and is part of the structure registered under CAS 218949-48-5. The single sulfur atom in the formula is the methionine at position 27. For how CAS numbers and salt forms interact on listings, see the CAS number and molecular weight reference.

How Pepta Labs Lists Tesamorelin

Pepta Labs lists tesamorelin at 10 mg per vial from $66.58 as a lyophilized powder in a sealed glass vial, in the GHRH analogues category. The product page shows the reported purity by reversed-phase HPLC (RP-HPLC) for the production run we sourced; identity is confirmed by mass spectrometry on the same report, and the salt form (acetate or trifluoroacetate) is stated there. The full analytical report (COA) is available by email request to support@peptalabs.com before purchase.

The report is produced by an independent laboratory commissioned through a cooperative purchasing group, so the client field may name the group or the source rather than Pepta Labs, and supplier-identifying fields are redacted before the report is shared. Pepta Labs does not test in-house, and vials do not carry lot numbers. The report covers RP-HPLC purity and MS identity only. See the Testing and Documentation page for the full policy.

How to Verify a Tesamorelin Listing

What an HPLC/MS report shows

The RP-HPLC section gives purity as the main-peak area as a percentage of total peak area, along with the column, gradient, detection wavelength and retention time. A 44-residue peptide with a hydrophobic acyl cap elutes later than sermorelin under the same gradient, which is one internal consistency check. The MS section gives the observed mass. At about 5.1 kDa, tesamorelin appears in an electrospray spectrum as a series of multiply charged ions ([M+4H]4+ through [M+7H]7+ are typical), which the software deconvolutes to a single neutral mass.

Comparing observed mass to theoretical mass

Compare the deconvoluted mass to the theoretical value. The average molecular weight is 5135.86 Da; PubChem's computed monoisotopic mass is 5132.72 Da. For a peptide of this size the isotope envelope is broad and most instruments report the average mass, so agreement within about 1-2 Da of 5135.86 Da is the normal expectation. Two mismatches have specific meanings: an observed mass near 5039.7 Da (M-96) is the unmodified 44-residue amide without the hexenoyl cap, and a mass near 5151.9 Da (M+16) indicates oxidation of Met27 to the sulfoxide.

What the report does not show

The report does not give net peptide content. A 10 mg fill of lyophilized salt includes counter-ion and residual water, and the trifluoroacetate form in particular carries a meaningful mass fraction of TFA across a 44-residue chain with several basic side chains; the TFA vs acetate guide covers the arithmetic. Sterility, endotoxin, residual solvents and chiral purity are not covered unless listed as separate tests. The COA verification guide and the HPLC vs mass spectrometry guide go through each section of a report.

Production-run report vs lot-specific COA

A lot-specific COA is tied to a lot number printed on the vial. A production-run report, which is what Pepta Labs provides, describes the sourced batch and is not tied to a number on the vial. Ask which a vendor is offering, and confirm that the name, formula (C221H366N72O67S) and molecular weight on the document match tesamorelin rather than sermorelin or an uncapped GRF(1-44) sequence.

Storage and Shipping

• Tesamorelin ships as a lyophilized powder at ambient temperature; no cold chain is required for the dry solid in transit.
• Refrigerate sealed vials at 2-8 C on arrival; use -20 C for long-term storage.
• Keep the vial sealed, dry and protected from light. The hexenoyl group carries a carbon-carbon double bond and Met27 a thioether, both of which are oxidation-sensitive over long exposure to air, so leave the seal intact until the vial is needed.
• Free US shipping; most orders ship the next business day. The peptide storage guide covers handling of sealed vials in more detail.

US Regulatory Status

Tesamorelin is the ingredient of an approved US product. Drugs@FDA records Egrifta (tesamorelin acetate), application number 022505, held by Theratechnologies, originally approved on 10 November 2010 and currently listed with a marketing status of Prescription. As of the date this guide was prepared, tesamorelin is not named on the FDA's page listing bulk drug substances placed in Category 2 under the interim compounding policies. The framework that applies to research-use peptides generally, including the Category 2 list and the intended-use distinction, is summarised at Peptide Legal Status 2026 and FDA Category 2 Peptides 2026.

Frequently Asked Questions

What is the trans-3-hexenoyl group in tesamorelin?

It is a six-carbon unsaturated acyl group (C6H9O) joined to the N-terminal alpha-amine of Tyr1 as an amide. It adds 96.13 Da relative to the unmodified 44-residue peptide amide and is part of the structure identified by CAS 218949-48-5.

Which CAS number applies to tesamorelin?

CAS 218949-48-5 identifies the free tesamorelin peptide; CAS 804475-66-9 identifies tesamorelin acetate. Either can legitimately appear on a listing, and the analytical report states which form is supplied.

Does the 10 mg on the label equal 10 mg of peptide?

No. The label gives the gross fill of lyophilized powder, which includes counter-ion and residual water. Net peptide content is lower and is not reported on a standard HPLC/MS report; see the net peptide content guide.

Can I see the report before ordering?

Yes. Email support@peptalabs.com and the current production-run report for tesamorelin will be sent, with supplier-identifying fields redacted.