GHRP-1 (Growth Hormone Releasing Peptide 1)
First-generation ghrelin-mimetic GH secretagogue — the historical predecessor to the more widely-used GHRP-2, GHRP-6, and ipamorelin.
At a glance
What it is: First-generation ghrelin-mimetic GH secretagogue — the historical predecessor to the more widely-used GHRP-2, GHRP-6, and ipamorelin..
Primary research applications:
- Historical research compound for GH stimulation
- Rare grey-market use compared to GHRP-2/6 or ipamorelin
Editorial summary: GHRP-1 is the first synthetic ghrelin-mimetic GH secretagogue developed in the 1980s, predating the more widely-used GHRP-2, GHRP-6, hexarelin, and ipamorelin. Its limited clinical development meant it was largely superseded by later, more selective GH secretagogues. It remains historically interesting as the founding compound of the GHRP class.
- Class / structure
- Hexapeptide (Ala-His-D-2NaphylAla-Trp-D-Phe-Lys-NH2)
- Half-life
- Short (minutes)
- First described
- 1980s (Bowers / Tulane research group)
- Regulatory status
- Not FDA-approved; rarely encountered in research-peptide channels
What is GHRP-1?
GHRP-1 is the prototype synthetic ghrelin-mimetic GH secretagogue — a hexapeptide that binds GHSR-1a and triggers pituitary GH release through the same pathway later utilized by ghrelin (the endogenous ligand discovered after GHRP-1's development).[1]
Discovery and development
GHRP-1 emerged from Cyril Bowers's foundational work at Tulane on synthetic peptides that release growth hormone independently of the GHRH receptor. The work eventually led to the broader characterization of the ghrelin receptor (GHSR-1a) as a distinct target for GH secretion, and to the development of GHRP-2, GHRP-6, hexarelin, ipamorelin, and the orally bioavailable MK-677.
GHRP-1 itself never advanced into substantial clinical development. The later GHRP-class members offered better pharmacologic profiles (selectivity, oral bioavailability, half-life), and GHRP-1 receded into historical reference rather than active research or clinical use.
Mechanism of action
Binds the growth hormone secretagogue receptor (GHSR-1a) on anterior pituitary somatotrophs and triggers GH release. The same mechanism shared by GHRP-2, GHRP-6, hexarelin, ipamorelin, and MK-677 — though the later members have improved selectivity and pharmacology.
Pharmacokinetics
Short plasma half-life consistent with the GHRP-class peptides. Subcutaneous and IV administration in research contexts.
What the research shows
The peer-reviewed literature on GHRP-1 is summarized below across two tiers: human research (the highest standard), and preclinical / emerging research (animal models and early-stage human work).
Claims and the evidence behind them
This table summarizes commonly discussed claims and how the published evidence weighs in. The aim is clarity — supported claims, claims that look promising but need more data, and claims that outrun the science.
| Claim | What the evidence shows | Verdict |
|---|---|---|
| Stimulates GH release through GHSR-1a | Mechanism established | Supported |
| Equivalent to or better than GHRP-2 / ipamorelin for GH stimulation | Limited comparative data; later compounds generally favored | Uncertain |
| Useful for body composition or anti-aging | No published RCTs | Unsupported |
Reported user experiences
How the research describes administration
Subcutaneous injection in historical research protocols. No standardized clinical dosing.
Editorial note
Administration details above describe how the peptide is given in published studies. We summarize this for educational completeness — these descriptions are not protocols, dosing recommendations, or instructions for personal use. Decisions about treatment require an appropriately licensed clinician.
Safety considerations and open questions
The takeaway
GHRP-1 is primarily of historical interest — the founding compound of the GHRP class that established the pharmacology of synthetic ghrelin mimetics for GH release. For users looking at the current ghrelin-receptor agonist landscape, GHRP-2/6 (more potent), ipamorelin (more selective), and MK-677 (orally bioavailable, longer-acting) are the more clinically and practically relevant options.
Frequently asked questions
Why is GHRP-1 less commonly discussed than GHRP-2 or GHRP-6?
The later GHRP-class members offered improved pharmacology — better potency for GHRP-2, the unique appetite-stimulating profile of GHRP-6, the selectivity of ipamorelin, the oral bioavailability of MK-677. GHRP-1 was a historical first step rather than the molecule that proved most useful.
Is GHRP-1 still available?
It can be sourced from research-peptide vendors but is uncommonly seen compared to the better-characterized members of the class.
References
- Bowers CY, et al. On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone. Endocrinology. 1984;114(5):1537-1545. https://pubmed.ncbi.nlm.nih.gov/6714155/
- Bowers CY. GH releasing peptides — structure and kinetics. J Pediatr Endocrinol. 1993;6(1):21-31. https://pubmed.ncbi.nlm.nih.gov/8348215/
- Smith RG. Development of growth hormone secretagogues. Endocr Rev. 2005;26(3):346-360. https://pubmed.ncbi.nlm.nih.gov/15814848/