Pillar · Endocrine research
Growth Hormone and Secretagogue Peptide Research
Growth hormone secretagogues fall into two mechanistic families: GHRH analogues acting at the growth hormone releasing hormone receptor, and ghrelin-receptor agonists acting at GHS-R1a. Both raise endogenous growth hormone rather than supplying it exogenously, which preserves pulsatility and negative feedback — the key pharmacological distinction from recombinant GH.
Evidence position
Emerging human research
Research evidence, established clinical evidence and regulatory approval are three different things. This page distinguishes them throughout and does not present research compounds as approved treatments.
Two receptors, two mechanisms
GHRH analogues such as Sermorelin, CJC-1295 and Tesamorelin amplify the natural GHRH signal to somatotroph cells in the anterior pituitary. Ghrelin-receptor agonists such as Ipamorelin, Hexarelin, GHRP-2 and GHRP-6 act on a separate receptor and additionally suppress somatostatin tone. Because the pathways are complementary, they are frequently studied in combination in the literature.
Selectivity differences
Within the ghrelin-receptor group, selectivity varies considerably. Some members produce measurable cortisol and prolactin release alongside growth hormone; others were specifically developed to minimise it. Selectivity, not potency, is usually the more informative comparison point in the published pharmacology.
IGF-1 as the mediator and the measurement
Most peripheral effects attributed to growth hormone are mediated by hepatic IGF-1. Because GH itself is secreted in pulses and has a short half-life, IGF-1 is the practical measure used in research to assess axis activity. Interpreting IGF-1 requires age- and sex-adjusted reference ranges.
Regulatory position
One GHRH analogue is an approved medicine for a specific indication in some jurisdictions. The remaining compounds in this hub are not approved general treatments, are prohibited in tested sport, and are supplied for research use only.
Compounds studied in this area
| Compound | What it is | Evidence tier |
|---|---|---|
| CJC-1295 | A long-acting GHRH analogue studied for extended GH-axis stimulation. | Emerging human research |
| Ipamorelin | A selective ghrelin-receptor agonist developed to limit cortisol and prolactin release. | Emerging human research |
| Sermorelin | A GHRH(1-29) fragment, historically used in diagnostic testing of the GH axis. | Established clinical evidence |
| Tesamorelin | A stabilised GHRH analogue with an approved indication in some jurisdictions. | Established clinical evidence |
| Hexarelin, GHRP-2, GHRP-6 | Earlier-generation ghrelin-receptor agonists with differing selectivity profiles. | Emerging human research |
Comparisons in this cluster
Key takeaways
- Growth hormone secretagogues fall into two mechanistic families: GHRH analogues acting at the growth hormone releasing hormone receptor, and ghrelin-receptor agonists acting at GHS-R1a. Both raise endogenous growth hormone rather than supplying it exogenously, which preserves pulsatility and negative feedback — the key pharmacological distinction from recombinant GH.
- Overall evidence position for this topic: emerging human research.
- Findings in cells or animals are hypotheses about humans, never demonstrations in humans.
- Nothing on this page is medical advice, a protocol, or a dosing recommendation.
Frequently asked questions
What is a growth hormone secretagogue?
A compound that prompts the pituitary to release its own growth hormone, rather than supplying growth hormone directly.
How is GH axis activity measured in research?
Usually through IGF-1, because growth hormone is released in pulses and has a very short half-life, making single GH measurements uninformative.
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About this page
Written and reviewed by the Peptide Intel Hub Editorial Team. Last reviewed 8 September 2026.
Scientific disclaimer: this page is educational and does not constitute medical advice. Research compounds referenced here are not approved treatments. See our research disclaimer.