October 2026 · 6 min read
Sermorelin and the GHRH pathway: the first 29 residues, and the analogues built from them
A summary of published research, with citations. It states no amount, schedule or route, and makes no claim about what this compound does in a person. Supplied for laboratory research use only.
Sermorelin is the simplest member of a family that this catalog carries several relatives of. It is the first 29 amino acids of growth hormone-releasing hormone, and almost every GHRH analogue discussed on this site — CJC-1295, tesamorelin — is either that fragment with substitutions or the full hormone with a modification. Knowing what sermorelin is makes the rest of the family readable.
NovaEvum does not carry sermorelin. This page is about the molecule, its history as an approved medicine, and what its literature examined.
Where GHRH came from
Growth hormone-releasing hormone was found the hard way. Two groups in 1982, working from pancreatic tumours that had caused acromegaly by secreting a growth-hormone-releasing factor, isolated and sequenced it: Guillemin and colleagues (PMID 6812220) and Rivier and colleagues (PMID 6292724). The tumour was producing, in excess, a hormone the hypothalamus makes in trace amounts.
The native hormone is 44 amino acids long. It acts at the GHRH receptor on the somatotroph cells of the anterior pituitary, which release growth hormone in response. That receptor is separate from the ghrelin receptor that ipamorelin acts at; the two pathways converge on the same cells by different routes.
Why 29 residues
The biological activity of GHRH sits at its N-terminal end. A fragment of the first 29 amino acids, amidated at the C-terminus, retains the activity of the full hormone at its receptor. That fragment is sermorelin: GHRH(1-29)-NH2, the shortest fully active form.
Its limitation is the native hormone's limitation. GHRH is cleaved quickly in circulation, most notably by dipeptidyl peptidase-4 at the second residue, and sermorelin's half-life is in the range of minutes. Everything that came after it is an attempt to keep the activity and lose that short life.
The family, in one table
| Molecule | What it is | What changed |
|---|---|---|
| Native GHRH | 44 amino acids | — |
| Sermorelin | GHRH(1-29)-NH2 | Truncated to the active fragment |
| CJC-1295 without DAC, also sold as modified GRF(1-29) | GHRH(1-29) with four amino-acid substitutions | Substitutions resist enzymatic cleavage; half-life around thirty minutes |
| CJC-1295 with DAC | The same, plus an albumin-binding linker | Half-life measured in days |
| Tesamorelin | Full GHRH(1-44) with a trans-3-hexenoyl group on the N-terminus | N-terminal modification resists cleavage |
So the "CJC-1295" sold as research material is, in structural terms, sermorelin with four residues changed. The CJC-1295 and ipamorelin guide sets out why the DAC and no-DAC versions have almost no shared literature; the same caution applies one step further back, because a sermorelin paper does not describe either of them.
Sermorelin was an approved medicine
Unusually for a compound in this family, sermorelin completed a registration programme. Serono marketed it as Geref, approved in the United States for the diagnostic assessment of pituitary growth-hormone secretion and for the treatment of idiopathic growth hormone deficiency in children. Prakash and Goa reviewed that clinical use (PMID 18031173).
It was then discontinued by its manufacturer in 2008. Recombinant growth hormone had become the standard approach for children with GH deficiency, and Geref left the market.
That history is worth stating precisely, because it is routinely blurred in both directions. Sermorelin is not a compound that was never tested in people; it had an approved indication in a defined paediatric population. It is also not a currently approved medicine, and its approval never extended beyond that population.
What was studied in older adults
The age-related decline in growth hormone secretion made GHRH an obvious research tool for asking whether the pituitary of an older adult still responds. Vittone and colleagues studied GHRH(1-29) in healthy older men, measuring growth hormone and IGF-I over the course of the study (PMID 9005976). Walker later argued in a short commentary that the approach deserved more attention in adult-onset GH insufficiency (PMID 18046908).
Two things to note about that literature. The studies are small and short, and a commentary is an argument, not a trial. And the endpoints are hormone concentrations — what happened to growth hormone and IGF-I — not outcomes in the people studied. What follows from a change in those markers is a separate question that this literature does not settle.
Where the evidence stops
The approval is historical and narrow. Geref was approved for children with idiopathic GH deficiency and for diagnostic testing. It was never approved for adults, and it is no longer marketed. Health Canada's Drug Product Database is the place to check for any current authorisation in Canada.
Sermorelin data is not CJC-1295 data. Four substitutions change how long the molecule survives in circulation, which changes the pharmacology the papers describe. Results for one do not transfer to the other.
It is prohibited in sport. GHRH and its analogues are a named category on the World Anti-Doping Agency's prohibited list, which matters to anyone who competes at any level.
Hormone release is an endpoint, not a result. Every study described here measures what the pituitary did. That is a fact about a pathway, and it is where the published evidence ends.
Common questions
Is sermorelin the same as CJC-1295? No, though they are close relatives. CJC-1295 without DAC is GHRH(1-29) with four amino acids substituted to resist enzymatic breakdown, which extends its half-life from minutes to around thirty minutes. Sermorelin is the unmodified fragment.
How is sermorelin different from tesamorelin? Sermorelin is the 29-residue active fragment. Tesamorelin is the full 44-residue hormone with an N-terminal modification, and it is the GHRH analogue that holds a current approval, for one indication in one population. The tesamorelin guide covers what that approval does and does not mean.
Is sermorelin a growth hormone? No. It is a releasing hormone: it acts at the pituitary to prompt the body's own growth hormone release, which is why its literature is about pituitary responsiveness rather than about growth hormone itself.
Does NovaEvum sell sermorelin? No. For the GHRH analogues we do carry, see CJC-1295 and tesamorelin in the growth hormone category. Nothing here is medical, dosing, or therapeutic guidance.
Selected Research References
- Guillemin R, Brazeau P, Böhlen P, Esch F, Ling N, Wehrenberg WB. Growth Hormone-Releasing Factor from a Human Pancreatic Tumor That Caused Acromegaly. Science. 1982;218(4572):585-587. pubmed.ncbi.nlm.nih.gov/6812220
- Rivier J, Spiess J, Thorner M, Vale W. Characterization of a Growth Hormone-Releasing Factor from a Human Pancreatic Islet Tumour. Nature. 1982;300(5889):276-278. pubmed.ncbi.nlm.nih.gov/6292724
- 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. pubmed.ncbi.nlm.nih.gov/18031173
- Vittone J, Blackman MR, Busby-Whitehead J, et al. Effects of Single Nightly Injections of Growth Hormone-Releasing Hormone (GHRH 1-29) in Healthy Elderly Men. Metabolism. 1997;46(1):89-96. pubmed.ncbi.nlm.nih.gov/9005976
- Walker RF. Sermorelin: A Better Approach to Management of Adult-Onset Growth Hormone Insufficiency? Clinical Interventions in Aging. 2006;1(4):307-308. pubmed.ncbi.nlm.nih.gov/18046908
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