Tesamorelin is a synthetic peptide derived from growth hormone-releasing hormone (GHRH), a hormone produced in the hypothalamus. It has the same 44-amino-acid sequence as human GHRH, with one small additional chemical group at the start of the chain [1][4]. In the United States, tesamorelin has been approved as a prescription medicine since 2010 under the brand name Egrifta, for one narrowly defined indication [1]. In the European Union, it has no marketing authorisation: the application was withdrawn in 2012 [2].
What a GHRH analogue is
GHRH (also known as GRF, growth hormone-releasing factor) is a peptide produced in the hypothalamus. It acts on the somatotroph cells of the pituitary gland, stimulating them to produce growth hormone and release it in pulses (pulsatile release). Growth hormone, in turn, acts largely via IGF-1 (insulin-like growth factor 1), which is produced mainly in the liver [1]. Tesamorelin therefore acts at the start of this chain, not on growth hormone itself.
An analogue is a molecule that closely resembles the natural hormone in structure and binds to the same receptor, but has been chemically modified. According to the US prescribing information, tesamorelin binds to the human GHRH receptor in vitro and activates it with a potency similar to that of the body’s own hormone [1].
Why modify it? Natural GHRH is rapidly broken down by the enzyme dipeptidyl peptidase-IV (DPP-IV). In the developer’s preclinical studies, tesamorelin (then known as TH9507) resisted this enzyme and was degraded more slowly than the natural peptide in rat, dog and human plasma [4].
Tesamorelin is not the only GHRH analogue. WADA lists sermorelin, CJC-1293 and CJC-1295 in the same group [3].
Structure and identity
| Feature | Tesamorelin |
|---|---|
| Substance class | synthetic GHRH analogue (peptide) |
| Length | 44 amino acids, the sequence of human GHRH |
| Modification | trans-3-hexenoyl group (C6 chain with one double bond) on the tyrosine at position 1 |
| Molecular formula | C221H366N72O67S (PubChem CID 16137828) |
| Development code | TH9507 (Theratechnologies, Canada) |
| Salt form in the medicine | acetate |
The structural data come from the US prescribing information, the preclinical publication and PubChem [1][4][5]. The sulphur atom in the formula comes from the single methionine in the chain.
Regulatory status: US, EU and WADA
United States. The FDA approved tesamorelin in 2010 as Egrifta (NDA 022505). The approval covers one specific indication in adults with HIV-associated lipodystrophy [1]. Outside that indication, it is not an approved product in the US.
European Union. The company Ferrer Internacional applied to the European Medicines Agency (EMA) for a marketing authorisation but withdrew the application in June 2012. At the time of withdrawal, the EMA’s scientific committee (CHMP) was of the view that the data submitted did not demonstrate a positive benefit–risk balance [2]. Tesamorelin is therefore not an authorised medicine in the EU.
Sport. On WADA’s 2026 Prohibited List, tesamorelin falls under class S2 (peptide hormones, growth factors, related substances and mimetics), in the group ‘GHRH and its analogues’, where it is explicitly named [3]. Substances in class S2 are prohibited for athletes at all times.
Clean Peptides tesamorelin is research material (research use only). It is not the same as the approved medicine and is not intended for use in humans or animals.
What research has been done on tesamorelin
- Preclinical. Pharmacological and toxicological studies in rats, dogs and pigs, covering, among other things, plasma stability, growth hormone and IGF-1 release, and safety during long-term exposure [4].
- Clinical. Two multicentre, randomised, double-blind, placebo-controlled studies formed the basis of the US approval [1]. ClinicalTrials.gov also lists more than twenty studies of tesamorelin addressing other research questions, often run by university hospitals.
We deliberately do not discuss the outcomes of these studies here. Approval for one indication says nothing about other applications, nor about products that were not manufactured to pharmaceutical standards.
Quality and analysis
With 44 amino acids, tesamorelin is a relatively long peptide. During chemical synthesis, which adds one amino acid at a time, chains can form in which a single amino acid is missing. The longer the chain, the more steps there are at which this can happen.
- Identity. Mass spectrometry (MS) checks whether the measured mass matches the complete structure, including the hexenoyl group. A difference equal to the mass of one amino acid points to an incomplete chain.
- Purity. HPLC shows what proportion of the signal belongs to the main peak; see How to read a certificate of analysis (COA).
- Oxidation. The methionine in the chain can oxidise. This produces a separate peak with a mass 16 daltons higher.
- Storage. As lyophilised powder: dry, cool and dark; see How to store peptides.
Every vial has a batch number on its label. Record it with every experiment.
Products and further reading
Products
Tesamorelin 10 mg is supplied as lyophilised powder in a vial. Another GHRH analogue, CJC-1295, is included in the combination ipamorelin 5 mg + CJC-1295 (no DAC) 5 mg. Solvent for lab use: bacteriostatic water 3 ml or 10 ml.
Further reading
- What is MOTS-c? A mitochondrial peptide in research
- Retatrutide vs semaglutide and tirzepatide: the differences
- Purity, endotoxins and heavy metals in peptides
- Research use only (RUO): what does it mean?
- What is ipamorelin? A GH secretagogue in research
Sources
- U.S. Food and Drug Administration. Egrifta (tesamorelin), Prescribing Information, NDA 022505 (revised 2019). accessdata.fda.gov (accessed 30 September 2026)
- European Medicines Agency. Ferrer Internacional, S.A. withdraws its marketing authorisation application for Egrifta (tesamorelin), 26 June 2012. ema.europa.eu
- World Anti-Doping Agency. Prohibited List 2026, class S2 (accessed 30 September 2026)
- Ferdinandi ES, Brazeau P, High K, et al. Non-clinical pharmacology and safety evaluation of TH9507, a human growth hormone-releasing factor analogue. Basic & Clinical Pharmacology & Toxicology 2007;100(1):49–58. doi:10.1111/j.1742-7843.2007.00008.x
- PubChem. Tesamorelin, CID 16137828 (accessed 30 September 2026)
For laboratory research only. Clean Peptides products are not intended for use in humans or animals. This article provides general information and is not medical advice.
