GHRP-2
Pralmorelin · GHRP2
Growth hormone secretagogue that acts on the ghrelin receptor to amplify GH pulses.
Key takeaways
- Ghrelin-receptor secretagogue; the strongest GH releaser of the common GHRPs.
- Less hunger than GHRP-6, but raises cortisol and prolactin unlike ipamorelin.
- ~1-hour half-life; reported protocols run 100–300 mcg 2–3× daily.
- Studied in humans (as pralmorelin) but never approved as a therapy.
Overview
What it is
GHRP-2 (pralmorelin) is a synthetic hexapeptide that activates the ghrelin receptor (GHS-R1a) on pituitary somatotropes, amplifying pulsatile growth hormone release. It is generally the strongest GH releaser in its class, with less appetite stimulation than GHRP-6 but more cortisol and prolactin elevation than ipamorelin.
Pharmacokinetics
The estimated half-life is roughly one hour with around 50% subcutaneous bioavailability, so reported protocols dose it two to three times daily, fasted.
What the evidence says
GHRP-2 has a genuine human study history, including Phase 1 PK work and GH-stimulation testing from a Japanese development program. It never reached approval as a therapeutic, and long-term safety data is lacking.
Reported dosing protocols
Protocols reported in research literature and clinic/community use — informational context, not a dosing recommendation.
| Use case | Dose | Route | Frequency | Duration |
|---|---|---|---|---|
| GH release (community) | 100–300 mcg | SubQ | 2–3× daily, fasted | 8–12 weeks |
Pharmacokinetic summary
- Model tier
- Simple (t½ + F, Tmax estimated)
- Half-life
- 58 min
- Bioavailability
- 50%
- Typical dose
- 0.1–0.3 mg
Frequently asked questions
GHRP-2 vs GHRP-6 — what's the difference?
Both hit the ghrelin receptor, but GHRP-2 releases more GH per dose with noticeably less hunger. The trade-off is somewhat more cortisol and prolactin elevation, which is why users watching those markers lean toward ipamorelin instead.
Why is GHRP-2 dosed fasted?
Elevated blood sugar and insulin blunt GH release, so dosing away from meals produces a bigger pulse. The fasted window matters most around the injection; normal eating can resume once the pulse passes.
Does GHRP-2 raise cortisol and prolactin?
Yes, modestly and dose-dependently, which is its main drawback versus ipamorelin. At typical reported doses the elevations are transient, but with frequent high dosing they are the markers most worth watching.
References
- Estimated — Growth hormone secretagogue; ~1 hour half-life.
- J Clin Endocrinol Metab 1998 — GHRP-2 phase I PK/PD — Phase 1 pharmacokinetic and dose-response study of GHRP-2 in children.
Related compounds
Ipamorelin
Selective GHRP secretagogue releasing growth hormone with relatively minimal cortisol/prolactin effect.
GHRP-6
Ghrelin-receptor secretagogue that increases GH and notably stimulates appetite.
MK-677 (Ibutamoren)
Orally active growth hormone secretagogue (ghrelin receptor agonist) that elevates GH and IGF-1; the non-peptide counterpart to injectable GHRPs.
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