GHRP-2

What it is

GHRP-2 (growth hormone-releasing peptide-2, also called pralmorelin) is a synthetic six-amino-acid peptide that acts as a ghrelin receptor agonist, stimulating endogenous GH release from the pituitary. It belongs to the GHRP class of GH secretagogues that also includes GHRP-6, hexarelin, and ipamorelin.

GHRP-2 was developed in the 1980s and has been studied in clinical trials for diagnostic use in pediatric GH deficiency. Pralmorelin (GHRP-2) is approved as a diagnostic agent in Japan but has not received FDA approval in the US. The peptide is available through licensed compounding pharmacies and is commonly seen in compounded GH-axis protocols.

Mechanism of action

GHRP-2 binds the ghrelin receptor (GHS-R1a) on pituitary somatotrophs, stimulating GH release through pathways that complement GHRH signaling. The mechanism is similar to ipamorelin in that both are GHRPs acting at the same receptor — but the receptor selectivity profile is different:

• GH release: potent and reliable, similar magnitude to ipamorelin at equivalent doses
• Cortisol elevation: GHRP-2 produces measurable increases in ACTH and cortisol, which is not seen with ipamorelin at standard clinical doses
• Prolactin elevation: GHRP-2 can produce modest prolactin elevation
• Appetite stimulation: mild compared to GHRP-6 but more than ipamorelin

Clinical use and evidence

GHRP-2 has well-characterized pharmacology from research and Japanese diagnostic use. The peptide reliably produces GH release and is effective at this purpose. The clinical question is whether the off-target effects (cortisol, prolactin, appetite) are worth the benefits compared to alternatives.

Why we don’t prescribe it at The Tide

For modern GH-axis protocols, ipamorelin offers the same GH-releasing effect as GHRP-2 without the cortisol and prolactin elevation. This makes ipamorelin clearly preferable for chronic clinical use:

• Cortisol elevation from GHRP-2 partially counteracts the metabolic and recovery benefits of GH-axis support — we don’t want to elevate cortisol while trying to optimize body composition and recovery
• Prolactin elevation can have undesirable hormonal effects in some patients
• Long-term cortisol elevation has known metabolic and cognitive consequences
• Ipamorelin’s clean profile represents a clear pharmacological improvement that supports chronic safe use

GHRP-2 is older-generation pharmacology that has been superseded by selective alternatives. We use ipamorelin in all our GH-axis protocols and do not see clinical scenarios where GHRP-2 would be preferred.

Side effects and contraindications

Side effects include cortisol elevation (with associated potential effects on metabolism, mood, sleep), prolactin elevation, mild appetite stimulation, and standard GH-axis side effects (joint discomfort, water retention with excessive dosing). Contraindicated in malignancy, pregnancy, severe pituitary disease, and uncontrolled diabetes.