Quick answer: Growth-hormone secretagogues are compounds that prompt the pituitary to release growth hormone, and they fall into two families that act on two different receptors. GHRH analogs, such as sermorelin, tesamorelin, and CJC-1295, bind the growth-hormone-releasing-hormone receptor. GHRPs, such as ipamorelin, bind the ghrelin receptor (GHS-R1a). Because the two families act through independent pathways that converge on the same cells, they are often studied together. These are research compounds, not approved therapies except where noted, and Velora supplies them for in vitro, ex vivo, and in silico work only.
Research use only: what this article is, and what it isn’t
This is a mechanism-education reference for researchers on the two families of growth-hormone secretagogues. It is not medical advice, not a dosing or self-administration guide, and not a document about any human or veterinary use.
The research compounds referenced are supplied by Velora Research for in vitro, ex vivo, and in silico laboratory research only, not for human consumption, veterinary use, in vivo use in any species, or any personal application. Where a compound has an approved drug form, that is noted for context only; Velora’s research-grade material is not the approved drug. Mechanisms described come from published research and are reported for research orientation. Researchers are responsible for compliance with applicable law, including the Federal Food, Drug, and Cosmetic Act (21 U.S.C. § 331, § 355, § 360bbb-3), and institutional review requirements.
Two families, two receptors
The whole subject becomes clearer once you separate the two families by the receptor they act on, because that single fact explains most of their behavior.
GHRH analogs are synthetic versions of growth-hormone-releasing hormone, the hypothalamic hormone that normally tells the pituitary to release growth hormone. They bind the GHRH receptor. Sermorelin is essentially the first 29 residues of native GHRH; tesamorelin is a stabilized GHRH analog; and CJC-1295 is a modified GHRH analog engineered for a longer functional window. The published pharmacokinetics of the long-acting CJC-1295 form (with DAC) illustrate how far that engineering can go (Teichman et al., *Journal of Clinical Endocrinology and Metabolism*, 2006).
GHRPs, growth-hormone-releasing peptides, act on a completely different receptor, the growth-hormone secretagogue receptor 1a (GHS-R1a), better known as the ghrelin receptor. In preclinical studies, Ipamorelin showed greater selectivity for GH release than some earlier GHRPs, with substantially less ACTH and cortisol stimulation under the conditions tested (Raun et al., *European Journal of Endocrinology*, 1998).
Why the two are studied together
Here is the mechanistic payoff. A GHRH analog and a GHRP act on two distinct receptors, the GHRH receptor and the ghrelin receptor, but both converge on the same pituitary somatotrophs that manufacture and release growth hormone. In published preclinical literature, combining a GHRH analog with a GHRP has been described as producing additive or synergistic effects on growth-hormone release compared with either alone. That convergence on independent pathways is the reason research designs so often pair the two families, and it is why Velora’s CJC-1295 No DAC and ipamorelin blend puts one from each family in a single vial.
The two families side by side
| Attribute | GHRH Analogs | GHRPs (Ghrelin-Receptor Agonists) |
|---|---|---|
| Receptor | GHRH receptor | GHS-R1a (ghrelin receptor) |
| Natural Counterpart | Growth-hormone-releasing hormone | Ghrelin |
| Research Examples | Sermorelin, tesamorelin, CJC-1295 | Ipamorelin |
| Selectivity Note | Vary by analog | Ipamorelin showed GH selectivity with limited ACTH/cortisol stimulation in preclinical studies |
| Common Research Pairing | Combined with a GHRP for convergent signaling | Combined with a GHRH analog for convergent signaling |
A note on approval status
One point of accuracy matters when these compounds come up. Tesamorelin is FDA-approved as Egrifta for a specific indication (HIV-associated lipodystrophy), and sermorelin has a history as an approved product as well. That approval context is worth stating, but it does not extend to Velora’s research-grade material: those products are supplied strictly for laboratory research, not as the approved drugs, and ipamorelin and the CJC-1295 forms are not FDA-approved for any use. An approved drug’s regulatory status does not extend to a separately manufactured research-grade product, even when the state active molecule is the same.
Handling and verification
Across both families, the peptides are supplied as lyophilized powder, reconstituted with bacteriostatic water, stored sealed at -20°C, and refrigerated at 2 to 8°C once in solution. The compounds differ widely in size and half-life, so per-compound molar concentrations should be computed from the molecular weight on each batch Certificate of Analysis. The ipamorelin research reference and the tesamorelin, sermorelin, and ipamorelin comparison go deeper on the individual compounds, and the peptide half-life explainer covers why the GHRH-analog engineering matters.
“The GHRH-analog-versus-GHRP distinction is the first thing I explain when someone is designing growth-hormone-axis work, because it organizes much of the underlying biology. The two classes act through distinct receptors that converge on pituitary somatotroph signaling and GH release, which provides a mechanistic rational for studying them individually or together. As always, interpreting those experiments also depends on confirming the identity and quality of the material being studied through the Certificate of Analysis.”
Clark Jones, PhD, Velora Research
Working with verified material
Velora Research supplies growth-hormone-secretagogue research compounds including tesamorelin, ipamorelin, and the CJC-1295 No DAC and ipamorelin blend, each with a batch-specific third-party Certificate of Analysis reporting identity by mass spectrometry and purity by HPLC, published through the Certificates of Analysis hub. The same release protocol applies across the research peptide catalog, and the quality and testing process is documented end to end. For convergent-pathway research, verified identity on both the GHRH-analog and the GHRP side is what makes a combined result interpretable.
Frequently asked questions
1. What is a growth-hormone secretagogue?
A compound that prompts the pituitary to release growth hormone. The two families are GHRH analogs, which act on the GHRH receptor, and GHRPs, which act on the ghrelin receptor (GHS-R1a).
2. What is the difference between a GHRH analog and a GHRP?
The receptor. GHRH analogs (sermorelin, tesamorelin, CJC-1295) mimic growth-hormone-releasing hormone at the GHRH receptor; GHRPs (ipamorelin) act at the ghrelin receptor. Both drive growth-hormone release from the same pituitary cells.
3. Why are GHRH analogs and GHRPs combined in research?
Because they act on independent receptors that converge on the same cells, and preclinical literature reports additive or synergistic effects on growth-hormone release when the two are combined.
4. Are these compounds FDA-approved?
Tesamorelin is FDA-approved as Egrifta for a specific indication, and sermorelin has an approval history, but Velora’s research-grade versions are not those drugs. Ipamorelin and CJC-1295 are not FDA-approved. All are supplied for laboratory research only.
5. Which is more selective?
Among the GHRPs, ipamorelin is a selective example, demonstrating relative selectivity for GH release in preclinical studies, including limited ACTH an cortisol stimulation under the conditions tested. Selectivity among GHRH analogs varies by analog.
Sources and further reading
- Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology. 1998;139(5):552-561. PubMed
- 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. Journal of Clinical Endocrinology and Metabolism. 2006;91(3):799-805. PubMed
This article is provided for laboratory and scientific reference. Except where an approved drug form is noted for context, the compounds referenced are research compounds, not approved drugs, and Velora’s research-grade material is never the approved product. Products sold by Velora Research are for in-vitro, ex-vivo, and in-silico research use only and are not intended for human use, veterinary use, or in vivo use in any species. Researchers are responsible for compliance with applicable laws and institutional protocols.
