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FDA Approved Growth Hormone Axis

Pralmorelin

also known as: GHRP-1, KP-102, Growth Hormone Releasing Peptide 1

The original growth hormone secretagogue — the first synthetic hexapeptide shown to release GH via the GHS-R receptor, paving the way for the entire GHRP drug class.

A synthetic hexapeptide GH secretagogue that was the first GHRP discovered, demonstrating proof-of-concept for non-GHRH-mediated GH release via the then-unknown ghrelin receptor, and later developed as a GH deficiency diagnostic (approved in Japan).

Mechanism of action

Agonist at the growth hormone secretagogue receptor type 1a (GHS-R1a, later identified as the ghrelin receptor). Stimulates GH release from pituitary somatotrophs via a distinct mechanism from GHRH (Gq/11 → PLC → IP3 → Ca²⁺ release, vs. GHRH's Gs → cAMP pathway). Also modestly stimulates ACTH, cortisol, and prolactin.

Primary uses

  • GH deficiency diagnostic test (Japan)
  • GH secretagogue research
  • GHS-R pharmacology studies

Typical dosing

100 mcg single IV bolus (diagnostic) (intravenous)

Diagnostic use: single 100 mcg IV bolus with GH sampling at 15, 30, 45, 60 minutes.

Regulatory status

Approved in Japan as a diagnostic agent for GH deficiency (GHRP test). Not FDA-approved in the US.

References

  1. [pubmed] 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;114:1537-1545.

Related peptides

GHRP-2

A second-generation GHRP approved as a diagnostic agent in Japan, with more pronounced GH-releasing potency than GHRP-6 but a meaningful prolactin and cortisol rise at higher doses.

GHRP-6

The prototype GHRP — a hexapeptide ghrelin receptor agonist notable for pronounced hunger stimulation and less favorable cortisol/prolactin profile than newer GHRPs.

Hexarelin

A high-potency GHRP studied for cardiac protection via a CD36-mediated pathway independent of GH release — but demonstrates clear tachyphylaxis with chronic use.

Ghrelin

The 'hunger hormone' — the only known circulating appetite stimulant, and the endogenous ligand that GHRP-2, GHRP-6, and MK-677 were designed to mimic.

MK-677

An orally active non-peptide ghrelin receptor agonist — included here by convention because it is universally marketed alongside peptide GH secretagogues. FDA warns of heart failure risk.

Guides & tools

Disclaimer

This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.