GHRP-2 (Pralmorelin)

GHRP-2 (Pralmorelin) is a synthetic peptide hormone and ghrelin-receptor agonist from the growth-hormone secretagogue (GHS) class: the hexapeptide (D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2, ~818 Da) binds GHS-R1a and triggers pulsatile release of endogenous growth hormone (GH) from the pituitary - it does not deliver GH itself. In Japan it is approved as pralmorelin for the diagnosis of GH deficiency in adults and children aged 4 and over.

How does GHRP-2 work?

GHRP-2 acts on a different receptor than classical GHRH analogs such as tesamorelin or sermorelin. It activates the ghrelin receptor (GHS-R1a) in the anterior pituitary and hypothalamus. Downstream signaling runs primarily via cAMP, PLC and protein kinase C, producing:

• a sharp, short GH pulse (peak ~15-60 min),
• suppression of somatostatin tone,
• moderate co-stimulation of ACTH, cortisol and prolactin (weaker than GHRP-6, stronger than ipamorelin),
• increased appetite (ghrelin-like, but milder than GHRP-6).

What does the evidence say?

Compared with GHRP-6, GHRP-2 is the most potent classical GHRP by peak GH output while producing less appetite stimulation. The human evidence includes several small RCTs:

• Laferrère et al. (2005) showed that a subcutaneous GHRP-2 infusion increased ad-libitum food intake by ~36% in healthy lean men - a clear ghrelin-mimetic effect.
• Laferrère et al. (2006) confirmed that obese subjects also respond with increased food intake to the ghrelin agonist GHRP-2.
• Haruta et al. (2015) reported one year of intranasal GHRP-2 in a severely emaciated anorexia-nervosa patient, with improvements in body weight and hypoglycemia symptoms.
• Veldhuis et al. (2007) dissected how peripheral signals (e.g. estrogen receptor-α) modulate the waveform of GHRP-2-induced GH secretory bursts.

The Japanese diagnostic approval rests on Phase III data showing that a single IV bolus reliably separates GH-sufficient subjects (peak GH ≥ 15 µg/L) from those with severe adult GH deficiency (clearly below this cut-off).

What is GHRP-2 used for?

• Approved (Japan): diagnostic GH-stimulation test in adults and children ≥ 4 years (pralmorelin, Kaken Pharmaceutical).
• Clinically investigated: appetite stimulation in cachexia/anorexia, acute GH-pulse studies, combined provocation tests with GHRH/TRH.
• Off-label research: body composition, sleep architecture, recovery and tissue repair - none of these are FDA-approved indications.

In research protocols GHRP-2 is often combined with a GHRH analog such as CJC-1295 (without DAC) because the two receptor pathways are complementary and produce a stronger, more physiological GH pulse - a principle we also describe in the CJC-1295/Ipamorelin entry.

How safe is GHRP-2?

Published trial data show a generally favorable safety profile, but with the characteristic class effects of GHRPs:

• Increased appetite - sometimes desired, sometimes not.
• Moderate rises in cortisol and prolactin, clinically relevant with repeated high dosing.
• Flushing, water retention, tingling after bolus injection, usually transient.
• Possible glucose effects (transient insulin resistance, since GH is anti-insulinergic).

Long-term data on repeated use in healthy adults are sparse; diagnostic single doses are considered well tolerated.

Regulatory status

• Japan (PMDA, 10/2004): approved as pralmorelin for GH-deficiency diagnosis in adults and children ≥ 4 years.
• US / EU: no FDA or EMA approval; North American rights were once sublicensed to Wyeth but never progressed.
• Sport: GHRP-2 is on the WADA Prohibited List at all times (class S2: peptide hormones and growth factors).

How does GHRP-2 compare to GHRP-6 and ipamorelin?

• GHRP-2 vs GHRP-6: higher GH peak, less hunger, somewhat lower cortisol/prolactin rise.
• GHRP-2 vs ipamorelin: ipamorelin is far more selective (almost no cortisol/prolactin effect); GHRP-2 delivers a stronger raw GH pulse.
• GHRP-2 vs GHRH analogs such as tesamorelin: completely different receptor pathway (GHS-R1a vs GHRH-R), so the two are additive when combined.

Frequently asked questions about GHRP-2

Is GHRP-2 legal to buy?

Outside Japan there is no approved pharmaceutical form of GHRP-2. Depending on the country and formulation, it falls under different rules for peptide hormones; self-use without a medical indication and supervision is not recommended.

How long does a dose of GHRP-2 last?

Plasma half-life is very short (~15-60 min) and the GH pulse lasts roughly 1-2 hours. Research protocols therefore use multiple daily doses or combine GHRP-2 with a long-acting GHRH analog such as CJC-1295 with DAC for sustained GH-axis stimulation.

Is GHRP-2 the same as pralmorelin?

Yes. Pramlomrelin is the INN (International Nonproprietary Name) of GHRP-2 as a drug substance. In Japan it is marketed as GHRP Kaken by Kaken Pharmaceutical.

Disclaimer: Peptipedia provides general information on peptides - not medical advice and no dosing or sourcing recommendations. Talk to a clinician you trust before using any peptide.