Research use only. The compounds discussed here are sold strictly as reference materials for in-vitro and laboratory research. Nothing on this page is medical advice, a dosing protocol, or a statement of human efficacy — it summarises how the published literature characterises these molecules at the receptor level. Every batch we list is published with its independent Janoshik HPLC certificate.
The short version
“Growth hormone secretagogue” is an umbrella term for compounds that prompt the anterior pituitary to release growth hormone (GH). In the research literature they fall into two distinct receptor families, and almost every practical question about this class comes down to telling them apart:
- GHRH-receptor analogs — sermorelin and CJC-1295. They mimic growth-hormone-releasing hormone and act on the GHRH receptor.
- Ghrelin-receptor agonists (GHRPs) — ipamorelin, GHRP-2, and hexarelin. They act on the GHS-R1a (ghrelin) receptor through a separate pathway.
Because the two families hit different receptors, they are frequently co-studied rather than treated as substitutes — the single most important point on this page.
Family 1 — GHRH-receptor analogs
These are analogs of growth-hormone-releasing hormone (GHRH), the hypothalamic signal that drives GH release. They bind the GHRH receptor on pituitary somatotrophs.
- Sermorelin — a GHRH(1–29) analog, the shortest functional fragment of native GHRH. Short half-life; studied as the classic pulsatile GHRH-receptor reference. See the Sermorelin research guide.
- CJC-1295 without DAC (mod GRF 1–29) — a modified GHRH analog with amino-acid substitutions that resist enzymatic breakdown, but still short-acting.
- CJC-1295 with DAC — adds a Drug Affinity Complex that binds serum albumin, substantially extending the molecule’s half-life in research models. The DAC vs no-DAC distinction is covered in depth in our CJC-1295 DAC vs No DAC guide.
Family 2 — ghrelin-receptor agonists (GHRPs)
GH-releasing peptides act on the GHS-R1a (ghrelin) receptor — the same receptor the hunger hormone ghrelin uses. They drive GH release through a pathway parallel to GHRH, and also suppress somatostatin (the brake on GH). The literature distinguishes them mainly by receptor selectivity:
- Ipamorelin — characterised as the most selective GHRP: in the literature it triggers GH release with minimal reported effect on cortisol, prolactin, or ACTH. It is the “clean signal” reference compound.
- GHRP-2 — a potent GH-releaser; the literature also notes measurable effects on cortisol, prolactin, and appetite (consistent with ghrelin-pathway activity).
- Hexarelin — among the most potent for acute GH release, but studies report pronounced receptor desensitisation with continued exposure, plus a separate strand of cardiac-tissue research interest independent of GH.
Why GHRH analogs and GHRPs are studied together
This is the defining theme of the secretagogue literature. Because a GHRH analog and a GHRP act on different receptors, combining them is reported to produce a larger, synergistic GH pulse in research models than either compound alone — the GHRH arm stimulates release while the GHRP arm both stimulates release and lifts the somatostatin brake. The canonical research pairing is CJC-1295 (no DAC) with ipamorelin — a short-acting GHRH analog plus the most selective GHRP, chosen so the combined signal is studied without the confounding cortisol/prolactin movement that less selective GHRPs introduce.
Side-by-side
| Compound | Family | Receptor | Literature note |
|---|---|---|---|
| Sermorelin | GHRH analog | GHRH-R | GHRH(1–29); short half-life |
| CJC-1295 no DAC | GHRH analog | GHRH-R | protease-resistant, short-acting |
| CJC-1295 with DAC | GHRH analog | GHRH-R | albumin-binding; extended half-life |
| Ipamorelin | GHRP | GHS-R1a | most selective; minimal cortisol/prolactin |
| GHRP-2 | GHRP | GHS-R1a | potent; some cortisol/prolactin/appetite |
| Hexarelin | GHRP | GHS-R1a | most potent acute; desensitisation noted |
This summarises receptor targets and selectivity as reported in the literature — not potency rankings, outcomes, or suitability for any use.
How researchers choose
- Studying the GHRH pathway alone? Sermorelin or CJC-1295 (no DAC) isolate it; the DAC variant is for designs needing an extended half-life.
- Studying the ghrelin pathway with the fewest confounders? Ipamorelin’s selectivity is why it is the default GHRP reference.
- Studying GHRP-specific cortisol/appetite effects? GHRP-2 is the compound where those show up.
- Studying GHRH + GHRP synergy? The CJC-1295-no-DAC + ipamorelin pairing is the literature standard.
What the literature does NOT establish
No standard human dosing, no long-term human safety data, and no validated translation of rodent secretagogue data to other contexts. “Synergy” between the two families is mechanism-plausible and reported in research models, but the specifics depend heavily on the model, compound pair, and exposure pattern studied. Treat all of these strictly as laboratory research compounds.
Handling and reconstitution
All of these ship as lyophilised powder and must be reconstituted before laboratory work — reconstitution volume sets the concentration per unit, so calculate it rather than estimate. Our peptide reconstitution guide includes a calculator and handling notes.
Verifying what you receive
For every batch we list, the independent Janoshik HPLC certificate that accompanies it is published — see the lab results archive. Every task ID resolves on Janoshik’s own domain, so results are independently checkable before checkout.
Frequently asked questions
What is the difference between a GHRH analog and a GHRP?
They act on different receptors. GHRH analogs (sermorelin, CJC-1295) bind the GHRH receptor; GHRPs (ipamorelin, GHRP-2, hexarelin) bind the GHS-R1a ghrelin receptor. That is why the two families are complementary rather than interchangeable.
Why are CJC-1295 and ipamorelin studied as a pair?
They engage separate pathways, so in research models the combination produces a larger GH pulse than either alone — and ipamorelin’s selectivity keeps cortisol and prolactin out of the picture, making the combined signal cleaner to study.
Which GHRP is the most selective?
Ipamorelin. The literature characterises it as releasing GH with minimal effect on cortisol, prolactin, or ACTH, which is why it is used as the reference GHRP.
What is the difference between CJC-1295 with and without DAC?
The DAC (Drug Affinity Complex) binds serum albumin and substantially extends half-life; the no-DAC form (mod GRF 1–29) is short-acting. See the dedicated CJC-1295 guide linked above.
How do I verify the purity of the batch I receive?
Each batch we list is published with the independent Janoshik HPLC certificate that accompanies it, with a public verify link on Janoshik’s own domain. The full set is on the lab results page.
Are these for human use?
No. They are sold strictly as research-use-only reference materials and are not intended for human or veterinary use.
Summary
Sort the secretagogues by receptor first: GHRH analogs (sermorelin, CJC-1295) on one side, ghrelin-receptor GHRPs (ipamorelin, GHRP-2, hexarelin) on the other. Within the GHRPs, selectivity is the deciding variable; across the two families, complementarity is why they are co-studied. Pick the reference compound that matches the pathway your research isolates, reconstitute it correctly, and confirm the batch against its published Janoshik certificate.