EDUCATIONAL NOTICE: Peptidings provides information for educational and research purposes only. The compounds in this research cluster are subjects of ongoing scientific investigation at varying stages of development. None of the information presented here constitutes medical advice or a recommendation for use. Consult a qualified healthcare provider before making any decisions about peptide use.
Research Cluster
Growth Hormone Secretagogues
Growth hormone peptides make up the largest and most evidence-dense cluster on Peptidings. It covers every major growth hormone secretagogue—from FDA-approved sermorelin to the controversial oral ghrelin mimetic MK-677—and maps them by mechanism, selectivity, and strength of human evidence.
It also includes HGH Fragment 176-191, which isn’t actually a secretagogue at all. It’s a lipolytic fragment of growth hormone that the community uses for fat loss. It’s here because it’s sold alongside these compounds and readers expect to find it.
Cluster at a Glance
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11 Compounds Covered |
1 FDA Approved |
5 Clinical Trials |
2 Pilot Data |
1 Preclinical |
2 It’s Complicated |
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Approved Drug FDA-approved or equivalent regulatory approval |
Clinical Trials Human clinical trial data (Phase I+) |
Pilot / Limited Human Data Small or preliminary human studies |
Preclinical Only Animal models and cell culture only |
BLUF: Bottom Line Up Front
Growth hormone secretagogues are the most evidence-rich category in peptide research. Sermorelin has FDA approval history and real safety data. The CJC-1295 + ipamorelin stack has become the community standard for good reason—both have human trial data and complementary mechanisms. MK-677 has the most extensive long-term human data but is an oral non-peptide with metabolic trade-offs. Beyond this evidence core, the cluster thins quickly: hexarelin and GHRP-6 are pharmacologically interesting but largely superseded, and HGH-Frag 176-191 has essentially no human data for a compound the community uses daily.
In This Article
Compounds in This Cluster
All 9 compounds in the Growth Hormone Secretagogues cluster, organized by mechanism and editorial function. Each grouping reflects how these compounds relate to each other scientifically—not just alphabetically.
Group 1 of 3
The GHRH Pathway
These compounds stimulate GH release through the GHRH receptor. Sermorelin is the anchor—formerly FDA-approved, real safety data, the known quantity. The two CJC-1295 variants are half-life-optimized modifications with a critical pharmacological distinction.
Group 2 of 3
The Selectivity Spectrum
The ghrelin-receptor (GHS-R1a) peptides. All stimulate GH via the same receptor but with wildly different selectivity profiles—from ipamorelin’s clean GH release to GHRP-6’s broad hormonal activation. The selectivity gradient is the central pharmacological story.
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Group 3 of 3
The Outliers
Neither is a peptide. MK-677 is an oral non-peptide ghrelin mimetic—the most human data in the cluster but the most metabolic trade-offs. HGH-Frag 176-191 isn’t even a secretagogue—it’s a lipolytic hGH fragment.
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How These Compounds Relate
Growth hormone secretagogues share a common goal—stimulating the body’s own GH release—but they approach it through fundamentally different receptor systems with different selectivity profiles, half-lives, and trade-off structures.
The cluster divides cleanly into two pharmacological families: the GHRH-pathway compounds (sermorelin, both CJC-1295 variants) that work through the GHRH receptor, and the ghrelin-pathway compounds (ipamorelin, GHRP-2, hexarelin, GHRP-6, MK-677) that work through GHS-R1a. The standard community practice of stacking one from each pathway isn’t arbitrary—it exploits complementary signaling to achieve synergistic GH pulses.
| Shared Mechanism | Compounds |
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GHRH Receptor Agonism Direct stimulation of the growth hormone-releasing hormone receptor on pituitary somatotrophs. Preserves natural pulsatile GH secretion patterns. |
Sermorelin, CJC-1295 (No DAC), CJC-1295 with DAC |
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GHS-R1a (Ghrelin Receptor) Agonism Activation of the growth hormone secretagogue receptor, the same receptor that ghrelin—the “hunger hormone”—uses. Selectivity varies dramatically between compounds. |
Ipamorelin, GHRP-2, Hexarelin, GHRP-6, MK-677 |
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β3-Adrenergic Lipolysis Direct fat-burning via beta-3 adrenergic receptor activation—a completely different mechanism from GH secretion. |
HGH-Frag 176-191 |
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CD36-Mediated Cardioprotection A unique secondary mechanism where GHS-R1a activation also triggers cardioprotective effects through the CD36 scavenger receptor, independent of GH release. |
Hexarelin |
Plain English
Think of this cluster as two families that work well together. The GHRH compounds (sermorelin, CJC-1295) tell the pituitary “make growth hormone.” The ghrelin compounds (ipamorelin, GHRP-2) tell it “release what you’ve made.” Stacking one from each family is synergistic—it’s like pressing the gas pedal and releasing the brake at the same time.
Browse by Condition
Conditions Addressed by These Compounds
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Weight Management GH secretagogues influence body composition through increased lipolysis and lean mass preservation. |
Muscle Recovery GH accelerates tissue repair and protein synthesis, relevant to post-exercise and post-injury recovery. |
Sleep Disorders Several GH secretagogues enhance slow-wave sleep, the phase during which most GH is naturally released. |
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Disclaimer: This page is for educational and research purposes only. It does not constitute medical advice, diagnosis, or treatment. The compounds discussed are subjects of ongoing scientific research and have not been evaluated by the FDA for all applications described. Consult a qualified healthcare provider before making any decisions about your health.