The short version
The research peptides grouped as "growth hormone peptides" act on one hormone through two different receptors on the same pituitary cells. One family copies growth-hormone-releasing hormone (GHRH) and acts at the GHRH receptor: sermorelin, CJC-1295 without DAC and tesamorelin. The other family acts at the ghrelin receptor, GHS-R1a, and is known as the growth-hormone secretagogues: ipamorelin and hexarelin. None of these is growth hormone itself, and none is licensed as a medicine in the UK.
All are supplied by BuyUK Peptides as research chemicals for in-vitro laboratory use only. Nothing here is guidance for any other use.
Two receptors, one hormone
| GHRH receptor | Ghrelin receptor (GHS-R1a) | |
|---|---|---|
| Natural ligand | Growth-hormone-releasing hormone, from the hypothalamus | Ghrelin, mainly from the stomach |
| Receptor family | Class B GPCR | Class A GPCR |
| Main signalling | Gs, cAMP | Gq, intracellular calcium |
| Peptides in our catalogue | Sermorelin, CJC-1295 (no DAC), tesamorelin | Ipamorelin, hexarelin |
GHRH is the body's main "on" signal for growth-hormone release. The ghrelin receptor came the other way round: it was found in 1996 as the target of synthetic secretagogues that already existed [1], and its natural ligand, ghrelin, was identified three years later [2]. Because the two receptors use different signalling routes on the same cells, their effects on growth-hormone release add together and are often synergistic in the systems studied, which is why the two families are so often researched together and why we also list a CJC-1295 and ipamorelin blend.
The five peptides side by side
| Sermorelin | CJC-1295 (no DAC) | Tesamorelin | Ipamorelin | Hexarelin | |
|---|---|---|---|---|---|
| Family | GHRH analogue | GHRH analogue | GHRH analogue | Secretagogue | Secretagogue |
| What it is | GHRH(1–29), the shortest fully active fragment | GHRH(1–29) with four substitutions | Full GHRH(1–44) with an N-terminal hexenoyl cap | Pentapeptide | Hexapeptide |
| Residues | 29 | 29 | 44 | 5 | 6 |
| Average mass | 3,357.9 Da | 3,367.9 Da | 5,135.9 Da | 711.9 Da | 887.0 Da |
| Licensing history | Licensed in the US as Geref, discontinued | Never licensed | Licensed in the US for one indication; not in the UK | Never licensed | Never licensed |
| Catalogue | 5 mg | 5 and 10 mg | 10 mg | 5 and 10 mg | 5 mg |
The masses are the quickest way to tell them apart on a certificate. Sermorelin and CJC-1295 without DAC differ by only about 10 Da, so the LC-MS line has to be read carefully; every other pair is separated by hundreds or thousands.
The GHRH analogues
The weakness of native GHRH in the laboratory is that it is cut quickly. Dipeptidyl peptidase-4 removes its first two residues within minutes in plasma, leaving an inactive fragment [3]. The three analogues are three different answers to that problem.
Sermorelin is the native sequence, unchanged: GHRH(1–29) with a C-terminal amide. It was licensed in the United States as Geref for the diagnosis and treatment of growth-hormone deficiency in children and later discontinued; the US regulator recorded that it was not withdrawn for reasons of safety or effectiveness [4]. It is the reference compound for the family, and the least stable in solution, because its asparagine and methionine residues deamidate and oxidise.
CJC-1295 without DAC, also called modified GRF(1–29), carries four substitutions, including D-alanine at position 2, developed to resist DPP-4 cleavage and the side-chain reactions that limit the native sequence [5]. It should not be confused with CJC-1295 with DAC, a different molecule that binds albumin and lasts for days: in healthy adults that version had a half-life of about six to eight days after one administration [6]. We supply only the no-DAC peptide, and the mass separates them, about 3,368 Da without DAC against about 3,647 Da with it.
Tesamorelin takes a different route: it keeps the full 44-residue sequence of GHRH and adds a trans-3-hexenoyl group to the N-terminus, which shields the bond DPP-4 attacks [7]. It is the only one of the three with a current licence anywhere, in the United States for a single indication, based on trials such as Falutz and colleagues' 2007 study [8]. It is not licensed in the UK.
Our comparison of sermorelin and tesamorelin goes further into the two.
The secretagogues
Ipamorelin is a five-residue peptide described by Raun and colleagues in 1998 as the first selective growth-hormone secretagogue: in their experiments it released growth hormone without the rise in ACTH and cortisol that earlier secretagogues produced at comparable potency [9]. That selectivity is the reason it is the cleanest ghrelin-receptor tool in the catalogue.
Hexarelin is an older and more potent hexapeptide from the same chemical series. In early human studies it released growth hormone strongly by several routes of administration, but less selectively, with small rises in prolactin, ACTH and cortisol as well [10]. It also binds a second receptor, CD36, found in the heart, which is why it appears in cardiovascular research that has nothing to do with growth hormone [11].
Ipamorelin vs CJC-1295 compares the most studied pair, one from each family.
Where IGF-1 LR3 fits
IGF-1 LR3 is often listed alongside these peptides but works at a different point. Growth hormone acts on the liver and other tissues to produce insulin-like growth factor 1 (IGF-1); IGF-1 LR3 is a modified form of that downstream factor, an 83-residue protein of about 9,111 Da, which acts at the IGF-1 receptor directly. It does not cause growth-hormone release, and it belongs to cell-culture and growth-factor research rather than pituitary pharmacology.
Regulatory and anti-doping status in the UK
None of the five peptides is a licensed medicine in the UK, and none is a controlled drug. All are supplied as chemicals for in-vitro laboratory use under our Terms of Sale; research peptides and UK law explains the framework. All are prohibited in sport at all times under section S2.2 of the WADA Prohibited List, which covers GHRH and its analogues and the growth-hormone secretagogues.
Handling and the certificate
The secretagogues are small and robust; they dissolve at once in water or bacteriostatic water. The GHRH analogues are larger and dissolve more slowly, and sermorelin in particular keeps less well in solution, so cold storage and prompt aliquoting matter more. Storage and stability covers the details, and the peptide bond explained shows the chemistry behind them.
On a certificate, look for RP-HPLC purity of 98 per cent or above and an LC-MS mass that matches the table above. For a CJC-1295 certificate, check that the mass is the no-DAC molecule; for sermorelin against CJC-1295, check the mass to the nearest few daltons. The full set of compounds is in the growth hormone peptides category.
References
- 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.
- 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.
- Frohman LA, Downs TR, Williams TC, Heimer EP, Pan YC, Felix AM. Rapid enzymatic degradation of growth hormone-releasing hormone by plasma in vitro and in vivo to a biologically inactive product cleaved at the NH2 terminus. Journal of Clinical Investigation. 1986;78(4):906–913. doi:10.1172/JCI112679.
- Prakash A, Goa KL. Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency. BioDrugs. 1999;12(2):139–157. doi:10.2165/00063030-199912020-00007.
- Campbell RM, Stricker P, Miller R, et al. Enhanced stability and potency of novel growth hormone-releasing factor (GRF) analogues derived from rodent and human GRF sequences. Peptides. 1994;15(3):489–495. doi:10.1016/0196-9781(94)90211-9.
- 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. The Journal of Clinical Endocrinology & Metabolism. 2006;91(3):799–805. doi:10.1210/jc.2005-1536.
- Ferdinandi ES, Brazeau P, High K, Procter B, Fraser S, Dubreuil P. 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.
- Falutz J, Allas S, Blot K, et al. Metabolic effects of a growth hormone-releasing factor in patients with HIV. New England Journal of Medicine. 2007;357(23):2359–2370. doi:10.1056/NEJMoa072375.
- Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology. 1998;139(5):552–561. doi:10.1530/eje.0.1390552.
- Ghigo E, Arvat E, Gianotti L, et al. Growth hormone-releasing activity of hexarelin, a new synthetic hexapeptide, after intravenous, subcutaneous, intranasal, and oral administration in man. Journal of Clinical Endocrinology & Metabolism. 1994;78(3):693–698. doi:10.1210/jcem.78.3.8126144.
- Bodart V, Febbraio M, Demers A, et al. CD36 mediates the cardiovascular action of growth hormone-releasing peptides in the heart. Circulation Research. 2002;90(8):844–849. doi:10.1161/01.RES.0000016164.02525.B4.
This monograph summarises the published literature for laboratory researchers. It is not medical advice, and nothing on this site is for human or veterinary use.