Tesamorelin

1 Identity

Synthetic acylated 44-residue peptide amide — not a plain peptide. 'Stabilized' in trade descriptions means precisely the N-terminal acylation, and because the word conceals it, the acyl group has historically never reached a specification. The backbone is the full human growth-hormone-releasing factor 1-44 sequence, all L, with no non-proteinogenic residue; the C-terminus is a primary amide; the alpha-amino group of the N-terminal tyrosine carries a trans-3-hexenoyl group whose double-bond position and geometry are both part of the identity. One methionine at position 27; no cysteine, no disulfide. Eight basic side chains (six arginines, two lysines), so acetate stoichiometry is measured rather than assumed. CAS 218949-48-5 (free base) and 901758-09-6 (acetate). Do not confuse with sermorelin, GRF(1-29)-NH2.

Sequence

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-NH2. One-letter with the cap: [trans-3-hexenoyl]-YADAIFTNSYRKVLGQLSARKLLQDIMSRQQGESNQERGARARL-NH2. Forty-four residues, all L, no D-residue and no non-proteinogenic residue in the backbone. The acyl group is a C6 chain with a defined double-bond position (3) and defined geometry (trans/E); cis-3-hexenoyl and 2-hexenoyl are exactly isobaric with it and are separable only chromatographically, so a document that never names the isomer has not tested for it. Met27 is the oxidation-labile residue. Two tyrosines, at positions 1 and 10, which is why the deletion-peptide mass ceiling on this chain IS 163.18 Da.

Molecular formula

C221H366N72O67S (free base); the supplied article is the acetate, written C221H366N72O67S with x C2H4O2, x approximately 7.

Average mass

5135.856 Da for the free base, C221H366N72O67S, on IUPAC 2021 abridged conventional atomic weights. The EGRIFTA WR prescribing information (2025) states 5,135.9 Da as the free-base equivalent and a research-supplier catalog publishes 5135.78 for the same formula; the three agree to within 0.08 Da. With x approximately 7 acetate equivalents the salt is roughly 5556.2 Da gross, so a content figure that does not declare free base or salt is out by about 7.6 percent.

Monoisotopic mass

5132.71664 Da (free base), to be used with a deconvoluted charge envelope rather than a single-ion match.

Salt / variant note

Free base C221H366N72O67S 5135.856 / 5132.71664, CAS 218949-48-5. Acetate salt, the supplied article, CAS 901758-09-6, at +60.05 Da per acetate equivalent; with x approximately 7 the gross is about 5556.2 and with eight basic side chains the acetate count is a measurement, not an assumption. Des-hexenoyl tesamorelin is simply hGRF(1-44)-NH2, C215H358N72O66S at 5039.727 / 5036.65913, 96.13 Da light — the single most likely manufacturing shortfall, and a molecule with its own commercial identity as somatorelin, so it is both an impurity and a substitution. The C-terminal free acid instead of the amide is C221H365N71O68S at 5136.840 / 5133.70066, only 0.98 Da heavy and invisible to any instrument reporting '5136'. Methionine-27 sulfoxide is C221H366N72O68S at 5151.855 / 5148.71156, +16.00. The cis-3-hexenoyl geometric isomer and the 2-hexenoyl positional isomer are exactly isobaric with parent at 5135.856 and are separable only chromatographically — the one class of defect on this record that no mass measurement at any resolving power will find. Free hexenoic acid C6H10O2 at 114.144 / 114.06808 is the corresponding process residue. The cheap adjacent article in this channel is sermorelin, GRF(1-29)-NH2, C149H246N44O42S at 3357.933 / 3355.81870 — 1,777.92 Da lighter, a 29-mer synthesis instead of a 44-mer, and the substitution most likely to be attempted. Deletion peptides span 57.05 Da (Gly) to 163.18 Da (Tyr), and here the tyrosine ceiling IS correct, because this sequence contains tyrosine at positions 1 and 10.

2 Class & testing panel

Form

Single article

Testing panel

P2 — panel definition

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

The only compound in its category with a genuine multi-trial human evidence base, and the label itself sets the limits on what that base supports. Pivotal Phase 3, n=412, 26 weeks, in HIV-associated lipodystrophy: Falutz et al., N Engl J Med 2007;357:2359-2370, PMID 18057338, DOI 10.1056/NEJMoa072375. Pooled analysis of two Phase 3 trials, n=806 (543 tesamorelin, 263 placebo), 26 weeks plus a 26-week safety extension: Falutz et al., J Clin Endocrinol Metab 2010;95:4291-4304, PMID 20554713, DOI 10.1210/jc.2010-0490. Randomized trials on hepatic fat in HIV-associated NAFLD: Stanley et al., JAMA 2014, n=50, PMID 25038357; Stanley et al., Lancet HIV 2019, PMID 31611038; Fourman et al., JCI Insight 2020, mechanistic sub-study, PMID 32701508. Efficacy maintained on integrase inhibitors: Russo et al., AIDS 2024, n=38, PMID 38905488. A 2026 meta-analysis of five RCTs is in the citation index with its null findings recorded in the same typeface as its positive ones. Regulatory: approved 10 November 2010 under NDA 022505; EGRIFTA WR approved 25 March 2025. The label's own limitations of use are carried verbatim on the citation page — long-term cardiovascular safety has not been established, it is not indicated for weight-loss management, and there are no data supporting improved antiretroviral compliance. Absences stated as absences: no adequately powered RCT in non-HIV general obesity; no cardiovascular outcome trial; longest controlled human exposure in the published record is 52 weeks, in a diseased population; no human data in healthy adults. A small number of investigator-initiated magnetic-resonance-spectroscopy and cognition studies of growth-hormone-releasing-hormone administration exist and are frequently mis-stated in the retail peptide market in direction as well as in strength; the citation index records the direction of each reported analyte explicitly for that reason.

4 Storage & specification

Storage

The acetate salt is held lyophilized at -20 degrees C plus or minus 5 degrees C, desiccated and protected from light, in amber glass with the headspace displaced with nitrogen and re-blanketed after subdivision. The N-terminal hexenoyl amide is the hydrolysis-sensitive point in solution and the methionine is the oxidation-sensitive point in both the solid and the reconstituted state; light and oxygen controls are written against that reason rather than as house habit. Eight basic side chains make the acetate salt strongly hygroscopic, so the container is equilibrated to room temperature inside a desiccator before opening. An acylated 44-mer adsorbs to glass at low concentration and aggregates on freeze-thaw, so container-closure qualification includes a measured recovery check and reconstituted material is single-use.

Shelf life

Provisional 24 months at -20 degrees C plus or minus 5 degrees C, the interval that applies to an acylated 44-mer acetate of this type, pending study data, with three attributes trended by name — total oxidized species, des-hexenoyl content, and high-molecular-weight species by SE-HPLC — because those are the three chemically predictable failure routes on this structure rather than a generic list.