GHRP-2
Synthetic hexapeptide ghrelin receptor agonist (GHS-R1a)
- Class
- GH secretagogue
- Half-life
- ~30 min
- Route
- Subcutaneous (SubQ)
- Cadence
- Multiple per week
- Evidence
- Human clinical trials
Overview
GHRP-2 is the most-studied growth hormone secretagogue in its class — a synthetic six-amino-acid peptide that hits the ghrelin receptor and tells your pituitary to dump GH. It's approved in Japan as pralmorelin (brand name GHRP Kaken) for diagnostic testing of GH deficiency, which makes it the only GH secretagogue with regulatory approval anywhere in the world. That approval is narrow — it's a diagnostic agent, not a therapeutic — but it means the safety and GH-release profile is better-characterized than almost any other peptide in this category.
The appeal is simple: strong GH pulses without the downsides of injecting actual growth hormone. Peak GH hits about 60 minutes after injection, stays elevated for 2-3 hours, then drops. You get the pulse, not the flat pharmacological flood. Most people dose 2-3× daily on an empty stomach — morning fasted + pre-bed is the standard pattern. It's almost always stacked with a GHRH analog (CJC-1295 or tesamorelin) because the two pathways converge at the pituitary and the combined GH release is 3-10× higher than either alone.
The catch: appetite stimulation (you'll feel hungrier, especially in the first hour), moderate cortisol and prolactin elevation (more than ipamorelin, less than hexarelin or GHRP-6), and the research-chemical supply chain outside Japan is unregulated — purity varies wildly. If you're using it for body composition or recovery, you're doing so off-label with no long-term human safety data beyond the Japanese diagnostic trials.
Safety considerations
A few of the safety signals worth knowing — the full list, with dosing context and what to monitor, is inside AIx Core.
- Not approved for therapeutic use outside Japan. The research-chemical market is unregulated — actual peptide content and purity vary wildly.
- Contraindicated in active malignancy — GH and IGF-1 elevation could theoretically promote tumor growth. Hard no if you have a history of cancer or proliferative retinopathy.
- Moderate cortisol and prolactin elevation — usually transient, but chronic high-dose use could suppress gonadal function (via prolactin) or dysregulate HPA axis. If you're dosing 3× daily long-term, monitor these.
+ 3 more safety notes inside AIx Core →
Commonly monitored
Markers and signals people track when researching GHRP-2.
- IGF-1 (serum) — reflects sustained GH action over time
- Fasting glucose & HbA1c — GH can impair insulin sensitivity
- Prolactin — GHRP-2 elevates it transiently; chronic elevation is rare but worth tracking
- Cortisol (AM) — if you're dosing multiple times daily, check baseline isn't creeping up
- Body composition (DEXA or similar) — scale weight alone misses lean vs. fat changes
- Subjective recovery, sleep quality, hunger level
Frequently asked questions
What is GHRP-2?
Synthetic hexapeptide ghrelin receptor agonist (GHS-R1a). GHRP-2 is the most-studied growth hormone secretagogue in its class — a synthetic six-amino-acid peptide that hits the ghrelin receptor and tells your pituitary to dump GH. It's approved in Japan as pralmorelin (brand name GHRP Kaken) for diagnostic testing of GH deficiency, which makes it the only GH secretagogue with regulatory approval anywhere in the world. That approval is narrow — it's a diagnostic agent, not a therapeutic — but it means the safety and GH-release profile is better-characterized than almost any other peptide in this category.
How is GHRP-2 administered?
Subcutaneous (SubQ), typically multiple per week.
What is the half-life of GHRP-2?
~30 min — Short plasma half-life but pulsatile GH release lasts 2-3 hours.
Is GHRP-2 approved for human use?
GHRP-2 is investigational — not approved by the FDA, EMA, or MHRA for human use at the time of writing.
What does the evidence show for GHRP-2?
Evidence tier: Human clinical trials. Japan PMDA approved pralmorelin in October 2004 as a diagnostic agent for GH deficiency — 1 mcg/kg IV produces GH >15 ng/mL in healthy subjects, <15 ng/mL in severe GHD (PMID: 15646370, 15646371).
What is commonly monitored when researching GHRP-2?
Commonly tracked markers + signals: IGF-1 (serum) — reflects sustained GH action over time, Fasting glucose & HbA1c — GH can impair insulin sensitivity, Prolactin — GHRP-2 elevates it transiently; chronic elevation is rare but worth tracking, Cortisol (AM) — if you're dosing multiple times daily, check baseline isn't creeping up, Body composition (DEXA or similar) — scale weight alone misses lean vs. fat changes, Subjective recovery, sleep quality, hunger level.
Related compounds
Open this in AIx Core for the full picture
Mechanism breakdown, receptor pathway diagram, full safety list, monitored items, source citations, and one-tap add-to-protocol. Free with any account.