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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.
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.