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GHRP-2 and GHRP-6

Written by The Peptide Record editorialClinical review not yet completedLast reviewed 11 September 2026

GHRP-2 (pralmorelin) is a real, narrowly approved product in Japan — as a one-time diagnostic injection to test pituitary growth hormone reserve, not a treatment anyone takes repeatedly. GHRP-6 has never been approved anywhere. Neither has trial support for the muscle-building, fat-loss or anti-aging uses either is sold for in the grey market.

On this page
  1. What they are
  2. The one real approval — and what it actually covers
  3. What the evidence shows for the marketed use
  4. Doping status

In brief

Should you care? Yes — GHRP-2 has a real approval, but for something completely different from how it's sold in the wellness/bodybuilding market, and that distinction matters.

The short version

  • GHRP-2 (pralmorelin) is approved in Japan as a single-dose diagnostic test, not a repeated-use treatment.
  • GHRP-6 has never been approved anywhere, for anything.
  • Neither has trial support for the muscle-building or anti-aging claims they're actually sold on.

What they are

Both are synthetic growth hormone-releasing peptides from the same pharmacological family as hexarelin and ipamorelin — ghrelin-receptor (GHS-R1a) agonists. GHRP-2 is the hexapeptide; GHRP-6 is a related compound most associated with strong appetite stimulation.

The one real approval — and what it actually covers

GHRP-2, under the brand name GHRP Kaken, received Japanese regulatory approval (Kaken Pharmaceutical, October 2004) as a single-dose diagnostic agent — marketed as pralmorelin — to assess pituitary growth hormone reserve in both adults and children over four with suspected GH deficiency. It is a one-time provocative test administered and interpreted by a clinician, not a treatment taken repeatedly. It was sublicensed to Wyeth for potential North American development but never reached FDA approval there.

What the evidence shows for the marketed use

GHRP-6's marketed effect — strong appetite stimulation — has real mechanistic backing via the ghrelin-receptor pathway, and ghrelin itself has shown a real appetite benefit in a small controlled human trial: an acute, randomized, placebo-controlled crossover study in 7 cancer patients with impaired appetite found ghrelin infusion increased energy intake by 31% versus placebo (Neary et al., J Clin Endocrinol Metab 2004;89(6):2832-2836, PMID 15181065). But that trial tested ghrelin itself, not GHRP-6 — the same "borrowed evidence" pattern seen elsewhere on this site, where a related compound's trial gets treated as if it applies directly.

A related compound's trial isn't your compound's trial

Ghrelin's appetite trial is real. It is a test of ghrelin, not of GHRP-6 — the two are related but distinct molecules, and the trial doesn't transfer automatically.

Doping status

Both are named under the World Anti-Doping Agency's S2 GHRP category (GHRP-1 through GHRP-6, and pralmorelin/GHRP-2 by name), prohibited in and out of competition.

References

  1. Neary et al., "Ghrelin Increases Energy Intake in Cancer Patients with Impaired Appetite: Acute, Randomized, Placebo-Controlled Trial," J Clin Endocrinol Metab 2004;89(6):2832-2836, PMID 15181065 — a trial of ghrelin itself, not GHRP-6.
  2. Kaken Pharmaceutical Co., GHRP Kaken (pralmorelin) approval, Japan PMDA, October 2004.