Comparison
GHRP-6 vs. Mod GRF (1-29)
Two peptides side-by-side — identity, evidence base, legal status and known adverse events.
Identity
Category
Growth
Growth
CAS no.
87616-84-0
863288-34-0
Molecular weight
873.02 g/mol
3367.9 g/mol
Half-life
0.4 h
0.5 h
Sequence
His-D-Trp-Ala-Trp-D-Phe-Lys-NH2Tyr-D-Ala-Asp-Ala-Ile-Phe-Thr-Gln-Ser-Tyr-Arg-Lys-Val-Leu-Ala-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Leu-Ser-Arg-NH2Mechanism of action
GHRP-6
GHRP-6 is a high-affinity agonist of the growth-hormone secretagogue receptor 1a (GHSR-1a) — the same receptor later shown to bind the endogenous hormone ghrelin. The identification of GHRP-6 as a pharmacological anchor led to cloning of GHSR in 1996 and the discovery of ghrelin itself in 1999. GHRP-6 stimulates pituitary GH secretion via a pathway independent of GHRH and can be combined synergistically with GHRH. Via GHSR in the hypothalamus it additionally activates NPY/AgRP neurons, producing an orexigenic (appetite-stimulating) effect in animal models.
Mod GRF (1-29)
Synthetic analogue of the first 29 amino acids of growth-hormone-releasing hormone (GHRH 1-29). Four amino-acid substitutions (D-Ala at position 2, Gln at 8, Ala at 15, Leu at 27) are intended to slow degradation by dipeptidyl peptidase-IV and increase enzymatic stability relative to native GHRH. Like the native hormone and sermorelin, it binds the GHRH receptor on somatotroph cells of the anterior pituitary; mechanistically this is expected to stimulate endogenous growth-hormone release. Unlike the DAC-conjugated CJC-1295 variant, it lacks albumin binding, so its duration of action remains short.
Evidence base
Highest evidence
Human trial
Human trial
Studies
4
4
of which in humans
2
4
Effects recorded
4
3
Open conflicts
1
1
Documented adverse events
2
0
Legal status
Full entries
Frequently asked questions
- What is the difference between GHRP-6 and Mod GRF (1-29)?
- GHRP-6 is classified as "Growth", while Mod GRF (1-29) is classified as "Growth". GHRP-6: Synthetic hexapeptide that founded the class of growth-hormone-releasing peptides (GHRPs). Cyril Bowers identified GHRP-6 in the late 1970s as the first orally and parenterally active GH secretagogue with no structural similarity to GHRH. Never approved as a medicine; downstream analogs (GHRP-2, hexarelin, ipamorelin) were pursued clinically. Mod GRF (1-29): Tetrasubstituted synthetic analogue of GHRH(1-29), traded on the grey market as "CJC-1295 without DAC". Closely related to sermorelin (GHRH 1-29); a short-acting growth-hormone-releasing-hormone analogue often combined with a GHRP/ghrelin mimetic. Not approved as a medicinal product. Direct human trials of this exact analogue are essentially absent; the factual basis relies on related GHRH(1-29) analogues. This page contrasts both neutrally and source-based — with no usage or dosing recommendation.
- Which peptide is better supported by science, GHRP-6 or Mod GRF (1-29)?
- The highest available evidence level is "Human trial" for GHRP-6 and "Human trial" for Mod GRF (1-29). A higher evidence level means more robust data, but says nothing about suitability for an individual. The full body of evidence is on each peptide's own page.
- What is the legal status of GHRP-6 and Mod GRF (1-29) in Germany and the United States?
- Germany: GHRP-6 — Unapproved, Mod GRF (1-29) — Unapproved. United States: GHRP-6 — Unapproved, Mod GRF (1-29) — Research only. These are factual summaries with source and review date on the individual pages.