Sermorelin vs Tesamorelin vs Ipamorelin: Two Receptors, Three Peptides

Sermorelin and tesamorelin are GHRH analogues that act on the GHRH receptor; ipamorelin is not — it is a ghrelin-receptor (GHS-R1a) agonist that reaches the pituitary through a different receptor [R1][R2][R3]. All three are peptides, but they differ in length, structure, clinical history and regulatory status. This article compares them point by point, with a source for each claim.

The Short Answer

Two Receptors, Not One

The pituitary has two separate receptors that these peptides use. The GHRH receptor is a G protein-coupled receptor, cloned in 1992, found mainly in the anterior pituitary, and it signals through cAMP [R9]. The growth hormone secretagogue receptor (GHS-R1a) is a different G protein-coupled receptor, cloned in 1996 [R10]; its natural ligand, ghrelin, was identified in the stomach in 1999 [R11].

Sermorelin and tesamorelin bind the first. Ipamorelin binds the second. In primary rat pituitary cells, antagonist profiling showed that ipamorelin acts through the GHRP (ghrelin) receptor, like GHRP-6, and not through the GHRH pathway [R3]. This is why “sermorelin vs ipamorelin” is not a comparison of two versions of one thing; it is a comparison of two mechanisms.

Sermorelin vs Tesamorelin

Both are GHRH analogues; tesamorelin is longer and capped, while sermorelin is the bare 1–29 fragment.

• Length. Sermorelin is residues 1–29 of human GHRH [R1]. Tesamorelin keeps all 44 [R4].
• Modification. Tesamorelin adds a hexenoyl group (a six-carbon chain with a double bond at position 3) to the N-terminal tyrosine [R4]. Sermorelin has no added group.
• Half-life. Tesamorelin’s label reports a mean elimination half-life of 11 minutes in healthy subjects [R4]. By comparison, CJC-1295 with DAC, an albumin-binding analogue, had an estimated half-life of 5.8–8.1 days in healthy adults [R12].
• Clinical history. Sermorelin was approved as a pituitary diagnostic in 1990 and for children with idiopathic growth hormone deficiency in 1997; both products were later discontinued [R6]. Tesamorelin was approved in 2010 [R7].

Tesamorelin trial evidence. In a 26-week randomized, double-blind trial of 412 HIV-infected adults with excess abdominal fat, visceral adipose tissue fell 15.2% with tesamorelin and rose 5.0% with placebo, and IGF-I rose 81.0% in the tesamorelin group [R13]. A pooled analysis of two phase 3 trials reported similar findings and maintenance through 52 weeks in patients who continued treatment [R14]. Its label limits the indication to that population, states it is not indicated for weight-loss management, and notes that long-term cardiovascular safety has not been established [R4].

Sermorelin vs Ipamorelin

Sermorelin mimics GHRH; ipamorelin mimics ghrelin. They share a downstream hormone but not a receptor.

• Structure. Sermorelin is a 29-residue chain of natural L-amino acids [R1]. Ipamorelin is a five-residue peptide containing non-natural residues: Aib (2-aminoisobutyric acid), D-2-naphthylalanine and D-phenylalanine [R5].
• Selectivity. In the 1998 discovery paper, ipamorelin released growth hormone in rat pituitary cells with potency similar to GHRP-6. In swine it did not significantly raise ACTH or cortisol, unlike GHRP-6 and GHRP-2, and it did not affect FSH, LH, prolactin or TSH [R3].
• Clinical history. Sermorelin reached approval [R6]. Ipamorelin reached a phase 2 trial for postoperative ileus after bowel resection: in 114 analyzed patients, median time to first tolerated meal was 25.3 hours with ipamorelin versus 32.6 hours with placebo, a difference that was not statistically significant (p = 0.15) [R15]. It has never been approved.

Tesamorelin vs Ipamorelin

Tesamorelin is a 44-residue approved GHRH analogue; ipamorelin is a five-residue, never-approved ghrelin-receptor agonist. Tesamorelin is about seven times heavier (5135.78 vs 711.85 g/mol) [R2][R5]. Their clinical programs targeted unrelated conditions: HIV-associated abdominal fat for tesamorelin [R13], postoperative ileus for ipamorelin [R15]. Research blends that pair tesamorelin with ipamorelin combine the two receptor pathways; we found no published randomized trial of such a combination.

Where CJC-1295 Fits

CJC-1295 is a third kind of GHRH analogue. It is GRF(1–29) with four substitutions (D-Ala2, Gln8, Ala15, Leu27). The version with DAC adds a lysine carrying a maleimide linker that binds serum albumin; the No-DAC version, also called Mod GRF 1–29, does not [R16]. The published human study used the DAC version [R12]. Sequora’s CJC-1295 No DAC + Ipamorelin blend pairs a GHRH analogue with a ghrelin-receptor agonist in one vial. For the DAC vs No-DAC difference in detail, see What are GHRH analogues?

Limits of the Evidence

• Head-to-head human studies comparing sermorelin, tesamorelin and ipamorelin do not exist in the published literature we reviewed.
• Tesamorelin’s trial data come from one population, HIV-infected adults with lipodystrophy [R13][R14].
• Ipamorelin’s largest trial missed its primary endpoint [R15].
• A review of growth hormone secretagogues found few long-term, rigorously controlled studies [R17].

Regulatory Status

Tesamorelin is an approved drug for reducing excess abdominal fat in HIV-infected adults with lipodystrophy [R4]. Sermorelin’s approved products were discontinued and approval withdrawn effective June 18, 2009; in 2013 FDA found this was not for safety or effectiveness reasons [R6]. Ipamorelin was never approved: an FDA advisory committee voted 0–12 (one abstention) against adding it to the 503A compounding list on October 29, 2024, citing a lack of safety and efficacy information, and ipamorelin acetate is in Category 2 for 503B outsourcing facilities [R8][R18]. Research-labeled versions of all three are research chemicals, not approved drug products. See RUO peptides explained.

FAQ

Is ipamorelin a GHRH analogue?

No. It is a ghrelin-receptor (GHS-R1a) agonist. Sermorelin and tesamorelin are GHRH analogues [R3][R5].

What is the main difference between sermorelin and tesamorelin?

Length and modification: sermorelin is GHRH 1–29; tesamorelin is GHRH 1–44 with an N-terminal hexenoyl group [R1][R4].

Which of the three is FDA-approved?

Only tesamorelin, for one indication. Sermorelin was approved but its products were discontinued and approval withdrawn in 2009. Ipamorelin was never approved [R4][R6][R8].

Why are GHRH analogues and ipamorelin studied together?

They reach the pituitary through two different receptors, the GHRH receptor and GHS-R1a, so researchers use them to study both pathways [R9][R10].

Is CJC-1295 more like sermorelin or ipamorelin?

Sermorelin. CJC-1295 is a modified GRF(1–29) that acts on the GHRH receptor [R16].

References

How we select and verify sources: Research Sources & Editorial Standards

1. KEGG DRUG. Sermorelin, D08509. kegg.jp/entry/D08509
2. KEGG DRUG. Tesamorelin, D06655. kegg.jp/entry/D06655
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4. U.S. Food and Drug Administration. Tesamorelin prescribing information, BLA 022505, revised 3/2025. accessdata.fda.gov (PDF)
5. FDA Global Substance Registration System. Ipamorelin, UNII Y9M3S784Z6. precision.fda.gov
6. U.S. Food and Drug Administration. Determination that sermorelin acetate (GHRH 1–29) drug products were not withdrawn from sale for reasons of safety or effectiveness. Fed Regist. 2013;78(42):14095–14096. govinfo.gov (PDF)
7. U.S. Food and Drug Administration. Drugs@FDA: BLA 022505 (tesamorelin acetate). accessdata.fda.gov
8. U.S. Food and Drug Administration. Pharmacy Compounding Advisory Committee, October 29, 2024: final summary minutes. fda.gov
9. Mayo KE. Molecular cloning and expression of a pituitary-specific receptor for growth hormone-releasing hormone. Mol Endocrinol. 1992;6(10):1734–1744. doi:10.1210/mend.6.10.1333056. PMID 1333056.
10. Howard AD, Feighner SD, Cully DF, et al. A receptor in pituitary and hypothalamus that functions in growth hormone release. Science. 1996;273(5277):974–977. doi:10.1126/science.273.5277.974. PMID 8688086.
11. Kojima M, Hosoda H, Date Y, Nakazato M, Matsuo H, Kangawa K. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature. 1999;402(6762):656–660. doi:10.1038/45230. PMID 10604470.
12. Teichman SL, Neale A, Lawrence B, Gagnon C, Castaigne JP, Frohman LA. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. J Clin Endocrinol Metab. 2006;91(3):799–805. doi:10.1210/jc.2005-1536. PMID 16352683.
13. Falutz J, Allas S, Blot K, et al. Metabolic effects of a growth hormone-releasing factor in patients with HIV. N Engl J Med. 2007;357(23):2359–2370. doi:10.1056/NEJMoa072375. PMID 18057338.
14. Falutz J, Mamputu JC, Potvin D, 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. doi:10.1210/jc.2010-0490. PMID 20554713.
15. Beck DE, Sweeney WB, McCarter MD; Ipamorelin 201 Study Group. Prospective, randomized, controlled, proof-of-concept study of the ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. Int J Colorectal Dis. 2014;29(12):1527–1534. doi:10.1007/s00384-014-2030-8. PMID 25331030.
16. Jetté L, Léger R, Thibaudeau K, et al. 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;146(7):3052–3058. doi:10.1210/en.2004-1286. PMID 15817669.
17. Sigalos JT, Pastuszak AW. The safety and efficacy of growth hormone secretagogues. Sex Med Rev. 2018;6(1):45–53. doi:10.1016/j.sxmr.2017.02.004. PMID 28400207.
18. U.S. Food and Drug Administration. Bulk drug substances nominated for use in compounding under section 503B of the FD&C Act (updated March 21, 2025). fda.gov

This article summarizes published research and public regulatory documents for educational purposes. Sequora Peptides supplies research chemicals for laboratory use only; nothing here describes use in humans or animals.

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