Tesamorelin vs Sermorelin: Two GHRH Analogues with Opposite Regulatory Histories

Q: What is the difference between tesamorelin and sermorelin?

Length and one acyl group. Sermorelin is the first 29 amino acids of human growth hormone-releasing hormone as a C-terminal amide, unmodified. Tesamorelin is the full 44-residue sequence carrying a (3E)-3-hexenoyl group on its N-terminal tyrosine, which shields the 2-3 amino acid bond from dipeptidyl peptidase-4 — the enzyme that clears native GHRH within minutes . Their first 29 residues are identical.

Q: Do they act at the same receptor?

Yes. Both act at the pituitary growth hormone-releasing hormone receptor, a class B1 G protein-coupled receptor cloned from human anterior pituitary in 1993 that signals through Gs and cyclic AMP . Neither is described as having altered receptor selectivity relative to the other; the difference between them is enzymatic stability.

Q: Is tesamorelin's modification the same as albumin binding?

No. The hexenoyl group is short and its function is steric protection of a cleavage site. The acylated incretin analogues elsewhere in this library carry a fatty diacid that binds serum albumin reversibly, and CJC-1295 DAC carries a maleimidopropionamide that bonds covalently to albumin cysteine 34 . Those strategies produce plasma half-lives measured in days; tesamorelin's does not.

Q: Have the two been compared in a trial?

No. There is no head-to-head study, and the two clinical literatures do not intersect at any point. Sermorelin's trials were conducted largely in children with growth disorders in the late 1980s and 1990s ; tesamorelin's registrational programme was conducted in adults with HIV infection and abdominal fat accumulation from the mid-2000s .

Q: What did the randomised withdrawal phase of the tesamorelin programme show?

That the change did not persist after administration stopped. In a twelve-month trial of 404 participants, those on tesamorelin were re-randomised at six months to continue or switch to placebo with blinding maintained. Those continuing reached a reduction in visceral adipose tissue of approximately 18 per cent; in those switched to placebo, the six-month change was rapidly lost . It is the most informative result in the programme.

Q: Does sermorelin's short plasma half-life mean a short response?

Not for this class. In healthy men, growth hormone concentrations remained elevated for approximately three hours after intravenous injection despite rapid elimination of the peptide itself; nasal bioavailability was measured at 3 to 5 per cent . The dissociation between residence time and duration of response is the central pharmacological observation for sermorelin.

Q: Do the tesamorelin trial results apply outside HIV?

Nothing in the published programme addresses that. Every trial cited here enrolled a population defined by HIV infection and antiretroviral therapy, used imaging measures as primary endpoints rather than clinical outcomes, and ran between 26 weeks and 12 months . The approval is likewise specific to that indication.

Tesamorelin and sermorelin act at the same receptor. One is a stabilised 44-residue analogue approved in the United States; the other is GHRH(1-29).

By Elegance Peptides Editorial TeamUpdated September 22, 2026

These two compounds act at the same receptor and derive from the same hormone, and the differences between them are almost entirely about chemistry and about regulators. One is the natural sequence, shortened to its minimum active fragment and left otherwise untouched. The other is the full-length sequence with a single acyl group added at the N-terminus to defeat the enzyme that destroys it.

That one acyl group is the difference between a compound with a current United States approval and one whose approval lapsed when its product left the market.

What they are

Property	Tesamorelin	Sermorelin
Development code	TH9507	Not established
Compound type	Synthetic modified peptide	Synthetic peptide (hormone fragment)
Peptide family	Glucagon / secretin peptide superfamily (growth hormone-releasing hormone analogues)	Glucagon / secretin peptide superfamily (growth hormone-releasing hormone)
Primary target	Growth hormone-releasing hormone receptor (GHRHR)	Growth hormone-releasing hormone receptor (GHRHR)
Secondary targets	Not established	Not established
Receptor family	Class B1 (secretin-like) G protein-coupled receptors	Class B1 (secretin-like) G protein-coupled receptors
Agonist / antagonist	Agonist at the GHRH receptor	Agonist at the GHRH receptor
Highest research phase	Phase 3 completed; regulatory approval granted in one indication; investigator-initiated randomised trials continuing	Reached regulatory approval as a pharmaceutical product; that product is no longer marketed
Regulatory status (United States)	Approved as a pharmaceutical product in one indication. Tesamorelin for injection is approved by the U.S. Food and Drug Administration and marketed as Egrifta for the reduction of excess abdominal fat in adults with HIV infection and lipodystrophy. That approval attaches to a specific manufactured pharmaceutical product, its labelling and that single indication. It does not extend to any other indication, to any other product, or to research-grade material supplied for laboratory use.	Formerly approved, no longer marketed. Sermorelin acetate was approved in the United States and sold as Geref; the product was subsequently withdrawn from commercial sale and there is no currently marketed sermorelin product in the United States. That approval attached to a specific pharmaceutical product and its labelled indications and says nothing about research-grade material.
Human trials published	Yes	Yes

Every value in this table is read from the two compounds’ own library entries when the site is built, so it cannot disagree with them. Nothing here ranks one compound against the other.

Sermorelin is the first 29 amino acids of human growth hormone-releasing hormone, synthesised as a C-terminal amide: YADAIFTNSYRKVLGQLSARKLLQDIMSR. CAS registry number 86168-78-7, molecular weight 3,357.9 g/mol. It is the shortest fragment of the parent hormone with full biological activity. It was approved in the United States and sold as Geref; that product was withdrawn from commercial sale, and there is no currently marketed sermorelin product in the country.

Tesamorelin is a synthetic 44-residue analogue of human growth hormone-releasing hormone — the full-length sequence — carrying a (3E)-3-hexenoyl group on its N-terminal tyrosine. CAS registry number 218949-48-5, molecular weight 5,135.9 g/mol. Tesamorelin for injection is approved by the U.S. Food and Drug Administration and marketed as Egrifta, in a single HIV-related indication.

Their first 29 residues are identical. Tesamorelin continues for a further fifteen residues, completing the natural sequence, and carries the acyl modification that sermorelin does not.

Receptor and mechanistic differences

At the receptor, there is no difference reported. Both act at the pituitary growth hormone-releasing hormone receptor, a class B1 G protein-coupled receptor cloned and expressed from human anterior pituitary in 1993, signalling through Gs and cyclic AMP ^[3]. Neither is described in the literature as having altered receptor selectivity relative to the other. Both raise growth hormone and, through it, insulin-like growth factor 1.

The difference is enzymatic stability, and it is one bond. Native GHRH is cleared within minutes by dipeptidyl peptidase-4, which cleaves the molecule between residues 2 and 3 — a route characterised in plasma in 1989 alongside trypsin-like degradation ^[2]. Sermorelin carries no protection against that cleavage: it is the native sequence, shortened. Tesamorelin carries the (3E)-3-hexenoyl group on its N-terminal tyrosine, which shields the 2-3 amino acid bond from the enzyme.

Note what that is not. It is not an albumin-binding modification. The acylated incretin analogues elsewhere in this library carry a fatty diacid that binds serum albumin reversibly to extend residence time into days, and CJC-1295 DAC carries a maleimidopropionamide that bonds covalently to albumin cysteine 34. Tesamorelin's hexenoyl group is short and its function is steric protection of a cleavage site, not plasma-protein binding. The two strategies solve overlapping problems by different means and produce very different half-lives.

A consequence worth stating precisely. Sermorelin's peptide is eliminated rapidly after intravenous administration, yet growth hormone concentrations in healthy men remained elevated for approximately three hours ^[4]. So a short plasma half-life does not, for this class, imply a correspondingly short response. That dissociation is why the case for stabilising the molecule rests on practicality rather than on the response being otherwise unobtainable.

Receptor: Both — pituitary GHRH receptor, class B1, Gs-coupled ^[3].
Sequence: Sermorelin, GHRH(1-29) as a C-terminal amide. Tesamorelin, the full 44-residue sequence.
Modification: Sermorelin, none. Tesamorelin, a (3E)-3-hexenoyl group on the N-terminal tyrosine protecting the 2-3 bond from dipeptidyl peptidase-4 ^[2].
Molecular weight: 3,357.9 g/mol against 5,135.9 g/mol.
Regulatory position: Sermorelin, formerly approved in the United States; product no longer marketed. Tesamorelin, currently approved as a specific product in one HIV-related indication.
Published clinical era: Sermorelin, largely late 1980s to 1990s, largely paediatric. Tesamorelin, 2005 onward, in adults with HIV ^{[10, 11]}.

What the research compares

No trial has compared tesamorelin with sermorelin. There is no head-to-head study, and the two clinical literatures do not intersect at any point — not in population, not in endpoint, not in decade. Sermorelin's trials were conducted largely in children with growth disorders in the late 1980s and 1990s; tesamorelin's registrational programme was conducted in adults with HIV infection and abdominal fat accumulation from the mid-2000s.

What the literature does establish is the mechanistic continuity between them, and it does so indirectly. The plasma-degradation work that identified dipeptidyl peptidase-4 as the route by which GHRH is cleared is common to both compounds' rationale ^[2], and the analytical and anti-doping literature treats the GHRH analogues as one detection problem, reviewing the synthetic analogues of this hormone together ^[16].

There is also a structural asymmetry in how each compound's evidence should be read, beyond the absence of a head-to-head. Tesamorelin's record is a registrational programme: prespecified primary endpoints, placebo controls, a randomised withdrawal phase, hundreds of participants, and results published in journals that report the designs in full. Sermorelin's is a scattered set of smaller investigator and sponsor studies from an earlier era, many of them in children, and its approval rested on a dossier rather than on the published literature alone.

What the human research shows for each

Human clinical research

Results from pharmaceutical clinical trials describe the investigational material and populations used in those studies and should not be interpreted as establishing the effects of research-grade materials offered for laboratory use.

Tesamorelin — a registrational programme in one population

Amount-ranging. A placebo-controlled study of a growth hormone releasing factor in HIV-infected patients with abdominal fat accumulation established the range carried into phase 3 ^[10].

Phase 3. 412 participants with HIV infection and abdominal fat accumulation, 86 per cent men, randomised to 2 mg daily subcutaneously or placebo for 26 weeks. Visceral adipose tissue fell 15.2 per cent in the treated group and rose 5.0 per cent on placebo. Triglycerides fell by 50 mg/dL and rose by 9 mg/dL; the total-to-HDL cholesterol ratio fell 0.31 and rose 0.21 (p < 0.001 for all three). IGF-1 rose 81.0 per cent against a 5.0 per cent fall on placebo. No significant differences were observed in glycaemic measures ^{[11, 18]}.

Phase 3 with randomised withdrawal. 404 participants over twelve months in two sequential phases; those initially on tesamorelin were re-randomised at six months to continue or switch to placebo, with blinding maintained. Over the first six months, visceral adipose tissue fell 10.9 per cent (−21 cm²) against 0.6 per cent (−1 cm²) on placebo (p < 0.0001), with no change in limb or abdominal subcutaneous adipose tissue. In those continuing for twelve months the reduction reached approximately 18 per cent; in those switched to placebo, the six-month change was rapidly lost ^[12].

That withdrawal result is the most informative part of the entire programme and the most sobering: the effect did not persist once administration stopped.

Hepatic endpoints. A single-centre randomised trial in 50 participants reported a treatment effect on visceral adipose tissue of −42 cm² (95% CI −71 to −14; p = 0.005) and a net treatment effect on liver fat of −2.9 per cent (p = 0.003), with fasting glucose higher in the treated group at two weeks but not significantly different at six months ^{[14, 19]}. A twelve-month randomised trial in 61 people with HIV and a hepatic fat fraction of 5 per cent or more reported an absolute effect of −4.1 per cent (95% CI −7.6 to −0.7; p = 0.018) and a relative reduction of 37 per cent, with 35 per cent of the treated group against 4 per cent of placebo below a 5 per cent hepatic fat fraction at twelve months ^{[15, 20]}.

Later work. Efficacy and safety in people with HIV on integrase inhibitor regimens has been examined more recently ^[17], and the compound's use in HIV-associated lipodystrophy has been reviewed ^[13].

Limitations. Every one of these trials is in a population defined by HIV infection and antiretroviral therapy, with imaging measures as primary endpoints rather than clinical outcomes, over 26 weeks to 12 months. The authors of the 50-participant trial describe it as preliminary and state that further work is needed to determine clinical importance. Nothing in this programme was conducted outside that population.

Sermorelin — an earlier and more scattered record

Pharmacokinetics and response. In healthy men, growth hormone concentrations remained elevated for approximately three hours after intravenous injection despite rapid elimination of the peptide; nasal bioavailability was measured at 3 to 5 per cent ^[4].

Growth hormone deficiency and growth disorders. Treatment of growth hormone deficiency with growth hormone-releasing hormone was reported in 1987 ^[1]. Growth response to GHRH(1-29)NH₂ was compared with growth hormone itself ^[5], sustained increases in growth velocity were reported in children with idiopathic short stature ^[6], and radiation-induced growth hormone deficiency was treated with GHRH in a separate study ^[7]. A review consolidated its use in diagnosis and treatment of children with idiopathic growth hormone deficiency ^[8].

Limitations. Small studies, largely in children, from the late 1980s and 1990s, belonging to a pharmaceutical product that is no longer marketed. The former approval covered diagnostic use and treatment of idiopathic growth hormone deficiency in children with growth failure.

The two records are not comparable, and not because of quality

Neither literature is weak on its own terms. They simply answer different questions in different populations. A 26-week change in visceral adipose tissue in adults with HIV and a multi-year change in growth velocity in children with growth failure are not two measurements of the same thing, and no arithmetic relates them. The receptor is shared; nothing else about the two evidence bases is.

What the in vitro and degradation research shows

In vitro research

The relevant molecular work predates both compounds and explains both.

The human anterior pituitary GHRH receptor was cloned and expressed in 1993, defining the class B1 G protein-coupled receptor that both compounds act at ^[3]. Plasma-stability work in 1989 identified dipeptidyl peptidase-4 and trypsin-like enzymatic degradation as the routes by which native human GHRH is cleared within minutes ^[2] — the finding that every stabilised analogue in this family, tesamorelin included, was built in response to.

The analytical literature treats the whole family together, because distinguishing these analogues in biological samples is a single technical problem: advances in detecting synthetic GHRH analogues cover sermorelin, tesamorelin and the CJC-1295 forms in one review ^[16].

No in vitro study has characterised tesamorelin and sermorelin against each other at the receptor. Their shared target means such a study would be possible in principle, unlike several other pairs in this library; it has simply not been published.

Research status of each

Tesamorelin for injection is approved by the U.S. Food and Drug Administration and marketed as Egrifta for the reduction of excess abdominal adipose tissue in adults with HIV infection and lipodystrophy. That approval attaches to a specific manufactured pharmaceutical product, its labelling and that single indication. It does not extend to any other indication, to any other product, or to research-grade material supplied for laboratory use. Investigator-initiated randomised trials continue ^{[15, 17]}.

Sermorelin acetate was approved in the United States and sold as Geref; the product was withdrawn from commercial sale and no sermorelin product is currently marketed in the country. That former approval attached to a specific product and its labelled indications.

The contrast between "currently approved in one narrow indication" and "formerly approved, product withdrawn" is the sharpest difference between these two compounds — and it is a fact about products and marketing authorisations, not a statement about the molecules.

Frequently Asked Questions

What is the difference between tesamorelin and sermorelin?

Length and one acyl group. Sermorelin is the first 29 amino acids of human growth hormone-releasing hormone as a C-terminal amide, unmodified. Tesamorelin is the full 44-residue sequence carrying a (3E)-3-hexenoyl group on its N-terminal tyrosine, which shields the 2-3 amino acid bond from dipeptidyl peptidase-4 — the enzyme that clears native GHRH within minutes ^[2]. Their first 29 residues are identical.

Do they act at the same receptor?

Yes. Both act at the pituitary growth hormone-releasing hormone receptor, a class B1 G protein-coupled receptor cloned from human anterior pituitary in 1993 that signals through Gs and cyclic AMP ^[3]. Neither is described as having altered receptor selectivity relative to the other; the difference between them is enzymatic stability.

Is tesamorelin's modification the same as albumin binding?

No. The hexenoyl group is short and its function is steric protection of a cleavage site. The acylated incretin analogues elsewhere in this library carry a fatty diacid that binds serum albumin reversibly, and CJC-1295 DAC carries a maleimidopropionamide that bonds covalently to albumin cysteine 34 ^[9]. Those strategies produce plasma half-lives measured in days; tesamorelin's does not.

Have the two been compared in a trial?

No. There is no head-to-head study, and the two clinical literatures do not intersect at any point. Sermorelin's trials were conducted largely in children with growth disorders in the late 1980s and 1990s ^{[1, 5, 6]}; tesamorelin's registrational programme was conducted in adults with HIV infection and abdominal fat accumulation from the mid-2000s ^{[11, 12]}.

Which of the two is approved in the United States?

Tesamorelin for injection is approved by the U.S. Food and Drug Administration and marketed as Egrifta for the reduction of excess abdominal adipose tissue in adults with HIV infection and lipodystrophy. That approval attaches to a specific manufactured product, its labelling and that single indication. Sermorelin acetate was formerly approved and sold as Geref; the product was withdrawn from commercial sale and no sermorelin product is currently marketed in the country.

What did the randomised withdrawal phase of the tesamorelin programme show?

That the change did not persist after administration stopped. In a twelve-month trial of 404 participants, those on tesamorelin were re-randomised at six months to continue or switch to placebo with blinding maintained. Those continuing reached a reduction in visceral adipose tissue of approximately 18 per cent; in those switched to placebo, the six-month change was rapidly lost ^[12]. It is the most informative result in the programme.

Does sermorelin's short plasma half-life mean a short response?

Not for this class. In healthy men, growth hormone concentrations remained elevated for approximately three hours after intravenous injection despite rapid elimination of the peptide itself; nasal bioavailability was measured at 3 to 5 per cent ^[4]. The dissociation between residence time and duration of response is the central pharmacological observation for sermorelin.

Do the tesamorelin trial results apply outside HIV?

Nothing in the published programme addresses that. Every trial cited here enrolled a population defined by HIV infection and antiretroviral therapy, used imaging measures as primary endpoints rather than clinical outcomes, and ran between 26 weeks and 12 months ^{[11, 12, 14, 15]}. The approval is likewise specific to that indication.

References

Treatment of growth-hormone deficiency with growth-hormone-releasing hormone Lancet; 1987. PMID 2879138 doi:10.1016/s0140-6736(87)90699-4
Dipeptidylpeptidase IV and trypsin-like enzymatic degradation of human growth hormone-releasing hormone in plasma The Journal of Clinical Investigation; 1989. PMID 2565342 doi:10.1172/JCI114049
Molecular cloning and expression of a human anterior pituitary receptor for growth hormone-releasing hormone Molecular Endocrinology; 1993. PMID 7680413 doi:10.1210/mend.7.1.7680413
Pharmacokinetics of growth hormone-releasing hormone(1-29)-NH2 and stimulation of growth hormone secretion in healthy subjects after intravenous or intranasal administration Acta Paediatrica Supplement; 1993. PMID 8329825 doi:10.1111/j.1651-2227.1993.tb12827.x
Growth response to growth hormone-releasing hormone(1-29)-NH2 compared with growth hormone Acta Paediatrica Supplement; 1993. PMID 8329826 doi:10.1111/j.1651-2227.1993.tb12828.x
Treatment with GHRH(1-29)NH2 in children with idiopathic short stature induces a sustained increase in growth velocity Clinical Endocrinology; 1994. PMID 7955460 doi:10.1111/j.1365-2265.1994.tb02580.x
Treatment of radiation-induced growth hormone deficiency with growth hormone-releasing hormone Clinical Endocrinology; 1997. PMID 9231053 doi:10.1046/j.1365-2265.1997.1790998.x
Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency BioDrugs; 1999. PMID 18031173
Human growth hormone-releasing factor (hGRF)1-29-albumin bioconjugates activate the GRF receptor on the anterior pituitary in rats: identification of CJC-1295 as a long-lasting GRF analog Endocrinology; 2005. PMID 15817669 doi:10.1210/en.2004-1286
A placebo-controlled, dose-ranging study of a growth hormone releasing factor in HIV-infected patients with abdominal fat accumulation AIDS; 2005. PMID 16052083 doi:10.1097/01.aids.0000180099.35146.30
Metabolic effects of a growth hormone-releasing factor in patients with HIV The New England Journal of Medicine; 2007. PMID 18057338 doi:10.1056/NEJMoa072375
Effects of tesamorelin, a growth hormone-releasing factor, in HIV-infected patients with abdominal fat accumulation: a randomized placebo-controlled trial with a safety extension Journal of Acquired Immune Deficiency Syndromes; 2010. PMID 20101189 doi:10.1097/QAI.0b013e3181cbdaff
Tesamorelin: a review of its use in the management of HIV-associated lipodystrophy Drugs; 2011. PMID 21668043
Effect of tesamorelin on visceral fat and liver fat in HIV-infected patients with abdominal fat accumulation: a randomized clinical trial JAMA; 2014. PMID 25038357 doi:10.1001/jama.2014.8334
Effects of tesamorelin on non-alcoholic fatty liver disease in HIV: a randomised, double-blind, multicentre trial The Lancet HIV; 2019. PMID 31611038 doi:10.1016/S2352-3018(19)30338-8
Advances in the detection of growth hormone releasing hormone synthetic analogs Drug Testing and Analysis; 2021. PMID 34665524 doi:10.1002/dta.3183
Efficacy and safety of tesamorelin in people with HIV on integrase inhibitors AIDS; 2024. PMID 38905488 doi:10.1097/QAD.0000000000003965
TH9507 in Patients With HIV-Associated Lipodystrophy. NCT00123253
Effects of Growth Hormone Releasing Hormone in HIV. NCT01263717
Tesamorelin Effects on Liver Fat and Histology in HIV. NCT02196831

Every identifier above is resolved against PubMed, Crossref or ClinicalTrials.gov at build time, and the title returned by the register is compared with the title stored here. A page does not publish if a reference fails to resolve.

Research-Use Information

For in vitro research use only. This material is a laboratory reagent. It is not a drug, food, dietary supplement, or cosmetic and is not for human or veterinary use, including ingestion, injection, or any other administration. No information on this page describes or implies any effect in humans or animals. Sold only to researchers under our Terms of Sale.