What is Tesamorelin?

Compound Spotlight

Tesamorelin is the full 44-amino-acid sequence of human growth hormone-releasing hormone with one small chemical addition at the front end. That single change is enough to keep the molecule from being switched off within minutes, and it carried tesamorelin through phase 3 trials to an FDA approval, which almost nothing else in the growth hormone secretagogue category can claim.

Why native GHRH needed fixing

Growth hormone-releasing hormone is the hypothalamic signal that tells pituitary somatotroph cells to make and release growth hormone. As a research tool and drug candidate, the natural peptide has a practical problem: DPP-4 in plasma cleaves it at the N-terminus, removing the first two residues and leaving an inactive fragment.

Tesamorelin, developed by Theratechnologies under the code TH9507, addresses this with a minimal edit. A six-carbon trans-3-hexenoyl chain is attached to tyrosine at position 1, and the rest of the 44-residue human sequence is left unchanged. In the developer’s non-clinical work, the modified peptide resisted DPP-4 inactivation, degraded more slowly in rat, dog and human plasma, and produced marked increases in growth hormone and IGF-1 in pigs, rats and dogs. The FDA label describes the same structure.

Mechanism: amplifying the pituitary’s own output

According to the prescribing information, tesamorelin binds and stimulates human GHRH receptors in vitro with potency similar to the endogenous hormone. The receptor drives synthesis and pulsatile release of growth hormone, which in turn raises IGF-1 and IGFBP-3. The label also reports no clinically significant changes in TSH, LH, ACTH or prolactin in the clinical trials, which fits a compound acting through the GHRH receptor rather than the ghrelin receptor.

Because the signal passes through the pituitary, the response remains subject to the normal feedback that limits growth hormone secretion. Our overview of growth hormone secretagogues covers why that pulsatile, feedback-limited pattern is the main argument for secretagogues over exogenous growth hormone.

The trials behind the approval

Tesamorelin was developed against a specific problem: many patients on antiretroviral therapy for HIV accumulate visceral adipose tissue, the fat stored around the abdominal organs.

The first phase 3 trial, published in the New England Journal of Medicine in 2007, randomized 412 patients with HIV and abdominal fat accumulation to tesamorelin or placebo for 26 weeks. Visceral fat measured by CT fell 15.2% in the tesamorelin group and rose 5.0% with placebo. Triglycerides and the total-to-HDL cholesterol ratio also improved, and IGF-1 rose 81%. More patients in the tesamorelin group withdrew because of adverse events.

A pooled analysis of two phase 3 trials covering 806 patients reported a 15.4% treatment effect on visceral fat at 26 weeks, while abdominal subcutaneous fat did not change significantly. In patients who continued for a further 26 weeks, the visceral fat reduction was maintained at week 52. That pattern, visceral fat down and subcutaneous fat largely unchanged, is the most distinctive finding in the tesamorelin literature.

The FDA approved tesamorelin in November 2010. The current label states the indication as the reduction of excess abdominal fat in HIV-infected adult patients with lipodystrophy, and lists limitations: long-term cardiovascular safety has not been established, and it is not indicated for weight loss management because it has a weight-neutral effect.

Research beyond the approved indication

Liver fat. A 50-patient randomized trial at Massachusetts General Hospital (JAMA, 2014) found that six months of tesamorelin reduced both visceral fat and liver fat in people with HIV, with a net effect of -2.9% in hepatic lipid-to-water percentage. Fasting glucose was higher with tesamorelin at two weeks but not at six months. A follow-up multicentre trial in 61 people with HIV and non-alcoholic fatty liver disease (Lancet HIV, 2019) reported a 37% relative reduction in hepatic fat fraction over 12 months versus placebo. The authors called for longer studies of liver histology.

Cognition. A 20-week placebo-controlled trial in 152 adults aged 55 to 87, some with mild cognitive impairment, used tesamorelin as a stabilized GHRH and reported a favorable effect on a cognitive composite, driven mainly by executive function. Adverse events were reported by 68% of the treated group and 36% of the placebo group.

ARC also lists a TESA+IPA Blend, which combines tesamorelin with ipamorelin, a ghrelin-receptor agonist. The published trials above studied tesamorelin alone.

What the evidence supports

Tesamorelin has an unusually strong evidence base for this category: randomized, placebo-controlled human trials with hundreds of participants, CT-measured endpoints and a regulatory review. What that evidence shows is narrow: visceral fat in adults with HIV and treatment-associated abdominal fat accumulation.

The liver fat and cognition trials are randomized and human but small, and none has led to an approved use. The honest summary is a well-characterized GHRH analog with one regulator-reviewed finding and several open questions.

Frequently asked questions

Is tesamorelin the same as GHRH?

It has the same 44-amino-acid sequence as human GHRH, plus a trans-3-hexenoyl group on the first tyrosine. That addition protects it from DPP-4 cleavage, which is what inactivates the native hormone so quickly.

What exactly is it approved for?

The FDA label indication is the reduction of excess abdominal fat in HIV-infected adult patients with lipodystrophy. The label states it is not indicated for weight loss management.

How do I know what is actually in the vial?

Every lot we sell has a published Certificate of Analysis from an independent, third-party lab confirming identity and purity. Lot numbers on the vial should match the COA you are referencing.

References

• Ferdinandi ES, et al. Non-clinical pharmacology and safety evaluation of TH9507, a human growth hormone-releasing factor analogue. Basic Clin Pharmacol Toxicol. 2007;100(1):49–58.
• Falutz J, et al. Metabolic effects of a growth hormone-releasing factor in patients with HIV. N Engl J Med. 2007;357(23):2359–2370.
• Falutz J, et al. Effects of tesamorelin (TH9507), a growth hormone-releasing factor analog, in human immunodeficiency virus-infected patients with excess abdominal fat: a pooled analysis of two multicenter, double-blind placebo-controlled phase 3 trials with safety extension data. J Clin Endocrinol Metab. 2010;95(9):4291–4304.
• Stanley TL, et al. Effect of tesamorelin on visceral fat and liver fat in HIV-infected patients with abdominal fat accumulation. JAMA. 2014;312(4):380–389.
• Stanley TL, et al. Effects of tesamorelin on non-alcoholic fatty liver disease in HIV: a randomised, double-blind, multicentre trial. Lancet HIV. 2019;6(12):e821–e830.
• Baker LD, et al. Effects of growth hormone-releasing hormone on cognitive function in adults with mild cognitive impairment and healthy older adults. Arch Neurol. 2012;69(11):1420–1429.
• EGRIFTA SV (tesamorelin for injection) prescribing information. U.S. Food and Drug Administration label, Sections 1, 11 and 12.

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For laboratory and research use only. Not for human consumption. Tesamorelin is FDA approved, as Egrifta, only for the reduction of excess abdominal fat in HIV-infected adult patients with lipodystrophy; the research-grade compound sold here is not that drug product and is not approved for any use. This article summarizes published research for informational purposes and is not medical advice, nor a recommendation or protocol for use.

Related research compounds

Arc Peptides supplies these compounds, each third-party tested for purity and identity with a lot-specific Certificate of Analysis:

• TESA+IPA Blend
• Tesamorelin

For laboratory research use only. Not for human consumption.