By BioLabs Research · Last reviewed: October 8, 2026
What Is Tesamorelin? Chemical Identity, Sequence and Its Two Regulatory Identities
Research use only. This article covers chemical identity, analytical documentation and regulatory status. It gives no guidance on human or veterinary use, and it makes no claims about effects.
Tesamorelin has one sequence and two regulatory identities. In the United States, a licensed prescription product contains it. The same name also appears on research-use-only (RUO) reagent listings sold for in-vitro and analytical work. Those are different products under different rules. The molecule they share is defined by its sequence, its N-terminal modification, its mass and its salt form, which is why identity documentation matters more for tesamorelin than for most catalog peptides.
US search interest reflects the confusion. In Google Trends (US, pulled 2 October 2026), the average for "tesamorelin" over the last eight weeks was 67.2, against 26.0 in the first eight weeks of the 12-month window. Interest peaked the week of 17 May 2026. Autocomplete suggestions such as "is tesamorelin a peptide", "tesamorelin fda approved" and "tesamorelin cas number" show people asking what the compound is. This article answers that question with verifiable data.
What tesamorelin is, chemically
Tesamorelin is a synthetic analogue of human growth hormone-releasing factor (GRF, also called GHRH). The FDA prescribing information describes it as the 44-amino-acid sequence of human GRF with a hexenoyl moiety (a C6 chain with a double bond at position 3) attached to the N-terminal tyrosine. PubChem specifies the double-bond geometry as E (trans), giving the common description trans-3-hexenoyl-GHRH(1-44)-NH2. The development code was TH9507.
Sequence
The peptide portion matches residues 32–75 of the human somatoliberin precursor (UniProt P01286), with a C-terminal amide:
(trans-3-hexenoyl)-Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met-Ser-Arg-Gln-Gln-Gly-Glu-Ser-Asn-Gln-Glu-Arg-Gly-Ala-Arg-Ala-Arg-Leu-NH2One-letter: (hexenoyl)-YADAIFTNSYRKVLGQLSARKLLQDIMSRQQGESNQERGARARL-NH2
As a cross-check, we calculated the formula from this sequence: 44 residues, plus the hexenoyl group, plus the C-terminal amide. It reproduces the formula published by PubChem and the FDA label exactly.
Formula, mass and registry numbers
| Field | Tesamorelin (free base) | Source |
|---|---|---|
| Molecular formula | C221H366N72O67S | PubChem CID 16137828; FDA label |
| Molecular weight (average) | 5135.9 Da (free base equivalent) | FDA label (PubChem: 5136 g/mol) |
| Monoisotopic mass | 5132.7166 Da | PubChem (computed) |
| CAS number | 218949-48-5 | FDA GSRS; DrugBank DB08869 |
| FDA UNII | MQG94M5EEO | FDA GSRS |
| Tesamorelin acetate CAS | 901758-09-6 (UNII LGW5H38VE3) | FDA GSRS; DrugBank salt record |
Some supplier catalogs list a third number, 804475-66-9. We couldn't match it to an FDA GSRS record, so we don't use it.
The single sulfur atom comes from the methionine at position 27 (Met27). That matters analytically: methionine is prone to oxidation, which adds 16 Da.
The acetate salt form
The licensed product contains tesamorelin as an acetate salt. The FDA label gives the formula as C221H366N72O67S · x C2H4O2 (x ≈ 7) and quotes the molecular weight "as free base equivalent". A vial of salt-form peptide therefore isn't 100% peptide by weight: acetate counter-ions and residual water account for part of the mass. Research-grade synthetic peptides may come as acetate or trifluoroacetate (TFA) salts, depending on the purification route. The counter-ion should be stated on the lot documentation, not assumed. For why this matters for concentration work, see HPLC area percent vs net peptide content.
The two regulatory identities
1. An FDA-licensed prescription product
The FDA approved EGRIFTA (tesamorelin acetate) for Theratechnologies Inc. under application 022505 on 10 November 2010 (Drugs@FDA). Because tesamorelin has 44 amino acids, it meets the FDA definition of a "protein" (an alpha amino acid polymer of more than 40 amino acids; 21 CFR 600.3(h)(6)). On 23 March 2020 its approved NDA was therefore deemed a biologics license application (BLA 022505), along with the other biological products that transitioned that day. The FDA Purple Book lists the original 1 mg presentation as discontinued, EGRIFTA SV (2 mg) as marketed, and EGRIFTA WR (11.6 mg) as marketed. EGRIFTA WR was approved through a supplemental BLA on 25 March 2025.
The label sets out an approved indication and conditions of use. Those are a matter for prescribers and the label itself (linked under Sources), and are outside the scope of a research-reagent article. We mention the product here only as a regulatory fact.
2. A research-use-only reagent
The second identity is the one BioLabs supplies: tesamorelin as a lyophilized laboratory reagent for in-vitro and analytical research. An RUO reagent isn't the licensed drug, isn't made or released to that drug's specifications, and isn't a substitute for it. It carries no prescribing information, no NDC and no sterility claim unless one is documented. It is sold for laboratory use only. Our tesamorelin catalog listing is a reagent listing on those terms.
Where compounding fits (and doesn't)
People searching about tesamorelin often ask about compounding, especially after the 2026 FDA news on peptides. Under section 503A, the FDA says compounders may use only bulk drug substances that do one of the following:
- comply with a USP or NF monograph, if one exists;
- are components of FDA-approved drug products, if no monograph exists; or
- appear on the 503A bulks list.
Bulk substances must also come from an FDA-registered establishment, with a valid certificate of analysis. The FDA's Category 1/2/3 system is an interim policy for nominated substances that don't otherwise qualify.
Tesamorelin is a component of an FDA-licensed product, which places it under the second pathway rather than the category system. As of the FDA nominations list updated 14 May 2026, it doesn't appear in any category [VERIFY against the current FDA document]. The April 2026 Category 2 changes and the July 23–24, 2026 Pharmacy Compounding Advisory Committee meeting concerned other peptides, such as BPC-157 and TB-500. None of this changes what an RUO reagent is. A research reagent isn't a compounding ingredient, and higher search interest doesn't change any product's regulatory status.
Why identity documentation matters for research buyers
A 5.1 kDa peptide with a modified N-terminus offers several ways for the wrong molecule to carry the right name. Four documents rule them out.
Mass spectrometry: the identity test
Electrospray MS of a peptide this size shows a series of multiply charged ions. As a reference, we calculated the average-mass [M+zH]z+ values from 5135.9 Da:
| Charge state | Calculated m/z (average mass) |
|---|---|
| 4+ | 1284.98 |
| 5+ | 1028.19 |
| 6+ | 856.99 |
| 7+ | 734.71 |
Acceptance criteria belong to the laboratory's method; these values are arithmetic, not a specification. Mass differences worth knowing:
- Missing hexenoyl cap: unmodified GHRH(1-44)-NH2 is about 96 Da lighter (calculated). A COA showing that mass isn't tesamorelin.
- Free acid instead of amide: about 1 Da heavier. At ~5 kDa this needs high-resolution data or a method that resolves it.
- Met27 oxidation: +16 Da, a common degradation product.
HPLC: purity, not identity
Reversed-phase HPLC reports the main peak as a percentage of the total peak area at a stated wavelength. It shows how much of the UV-absorbing material is one species. It doesn't show which species, and it isn't the same as peptide content per milligram. See Peptide purity and COA explained and Lot docs, not a purity percentage.
Sequence and modification statement
The COA should state the full modified sequence: the hexenoyl group, the 44 residues and the C-terminal amide. "GHRH analogue" alone isn't an identity.
Counter-ion and net peptide content
Acetate and TFA salts weigh differently per mole of peptide, so the counter-ion and net peptide content should be on the lot paperwork whenever the work is quantitative. Blends add another layer: a tesamorelin/ipamorelin blend needs an observed mass for each component.
How to tell the research reagent and the drug product apart
| Licensed drug product (EGRIFTA SV / WR) | RUO research reagent | |
|---|---|---|
| Regulatory basis | FDA BLA 022505; prescription only | Not an FDA-approved drug; laboratory use only |
| Identifiers | Brand name, NDC on carton | Catalog number, lot number |
| Formulation | Finished dosage form with excipients listed on the label | Lyophilized peptide salt; contents per lot COA |
| Documentation | FDA prescribing information | Lot COA (HPLC, MS), SDS |
| Sterility | Labeled sterile | Not sterile unless documented |
| Where it's supplied | Pharmacies, on prescription | Laboratory reagent suppliers |
If a listing uses the brand name, implies equivalence to the licensed product, or gives use instructions, it isn't a legitimate RUO listing.
Checklist before accepting a tesamorelin lot
- The COA lot number matches the vial (how to read a COA)
- The full modified sequence is stated (hexenoyl, 44 residues, C-terminal amide)
- The observed mass is consistent with C221H366N72O67S (~5135.9 Da average)
- HPLC method, wavelength and chromatogram are included
- The counter-ion (acetate or TFA) and net peptide content are stated for quantitative work
- The CAS number matches the form supplied (218949-48-5 free base; 901758-09-6 acetate)
Frequently asked questions
Is tesamorelin a peptide?
Yes. Tesamorelin is a 44-amino-acid synthetic peptide with an N-terminal trans-3-hexenoyl group and a C-terminal amide. Under the FDA's definition (more than 40 amino acids), it also counts as a "protein" for licensing purposes, which is why its application became a BLA in 2020.
What is tesamorelin's CAS number?
The FDA's substance registry (GSRS) lists 218949-48-5 for tesamorelin and 901758-09-6 for tesamorelin acetate. Check which form your documentation refers to.
What is the molecular weight of tesamorelin?
5135.9 Da as the free base (FDA label). The monoisotopic mass is 5132.7166 Da (PubChem). Salt forms weigh more per mole of peptide because of the counter-ions.
Is tesamorelin FDA approved?
A tesamorelin product (EGRIFTA, now EGRIFTA SV and EGRIFTA WR) has been FDA-approved since 2010 and is now licensed under BLA 022505. RUO tesamorelin reagents aren't that product and aren't FDA-approved drugs.
Is research-grade tesamorelin the same as the prescription product?
It's the same peptide sequence, but not the same product. The licensed product is a finished, sterile, labeled dosage form made to an approved specification. An RUO reagent is a laboratory chemical documented by its lot COA.
Related reading
- Tesamorelin / Ipamorelin: two CAS numbers on one vial
- One vial, two CAS numbers
- Tesamorelin vs ipamorelin
- HPLC area percent vs net peptide content
- Tesamorelin · Tesamorelin / Ipamorelin · COA library · Our RUO standard
Research use only. BioLabs Research supplies tesamorelin as a laboratory research reagent for in-vitro and analytical use by qualified researchers. It isn't EGRIFTA, EGRIFTA SV or EGRIFTA WR. It isn't a medicine, food, supplement or cosmetic, and it isn't for human or veterinary use, self-administration or diagnostic use. Nothing in this article describes effects or a protocol for administration. See our Zero-Tolerance policy.
Sources
- U.S. FDA / DailyMed, EGRIFTA SV (tesamorelin) for injection, prescribing information (revised 03/2024), section 11 Description. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=3d783378-b02d-4f19-99dd-0fc91a042224
- U.S. FDA / DailyMed, EGRIFTA WR (tesamorelin) for injection, prescribing information (revised 03/2025). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=839334d3-8c1d-4c26-9036-2ab524a6ea75 · FDA label PDF: https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/022505s020lbl.pdf
- PubChem, Tesamorelin, CID 16137828 (formula, computed masses, IUPAC name). https://pubchem.ncbi.nlm.nih.gov/compound/16137828
- FDA Global Substance Registration System (GSRS): Tesamorelin, UNII MQG94M5EEO; Tesamorelin acetate, UNII LGW5H38VE3. https://gsrs.ncats.nih.gov/ginas/app/beta/substances/MQG94M5EEO · https://gsrs.ncats.nih.gov/ginas/app/beta/substances/LGW5H38VE3
- DrugBank, Tesamorelin (DB08869) and Tesamorelin acetate (DBSALT001835). https://go.drugbank.com/drugs/DB08869
- UniProt P01286, Somatoliberin (GHRH), human. https://www.uniprot.org/uniprotkb/P01286
- Drugs@FDA / openFDA, application 022505 (original approval 10 Nov 2010). https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=022505
- FDA, Revised Final List of Approved NDAs for Biological Products That Were Deemed to be BLAs on March 23, 2020. https://www.fda.gov/media/119229/download
- FDA Purple Book, BLA 022505 product details. https://purplebooksearch.fda.gov/index.cfm?blaNo=022505&event=productdetails
- 21 CFR 600.3(h)(6), definition of "protein" (eCFR). https://www.ecfr.gov/current/title-21/chapter-I/subchapter-F/part-600/subpart-A/section-600.3
- Theratechnologies, press release, 25 March 2025: FDA approval of the sBLA for EGRIFTA WR. https://www.globenewswire.com/news-release/2025/03/25/3049233/0/en/
- FDA, Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act. https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act
- FDA, Bulk Drug Substances Nominated for Use in Compounding Under Section 503A (categories list). https://www.fda.gov/media/94155/download
- Google Trends, "tesamorelin", United States, past 12 months, pulled 2 Oct 2026 (BioLabs internal data file
iot_12m_tesamorelin.csv).