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GHRP-2: What the Research Actually Shows

GHRP-2 (growth hormone-releasing peptide 2, generic name pralmorelin) is a synthetic six-amino-acid peptide, D-Ala-D-2Nal-Ala-Trp-D-Phe-Lys-NH2, that triggers growth hormone release from the pituitary by binding the ghrelin receptor, GHS-R1a. It was developed in the same Tulane University program that produced GHRP-6, and much of its published human work uses it to measure the pituitary’s capacity to release growth hormone.

Below is what the studies looked at, in what kind of model, and what they reported. This is a summary of published research, not a description of what the compound does in a person.

Quick facts

• Names: GHRP-2, growth hormone-releasing peptide 2, pralmorelin (the generic drug name), KP-102 as a development code.
• Sequence: D-Ala-D-2Nal-Ala-Trp-D-Phe-Lys-NH2. Six amino acids, three of them in the D form, with an amidated end. D-2Nal is D-2-naphthylalanine, a synthetic amino acid that does not occur in natural proteins (Doi et al., 2004).
• Molecular formula C45H55N9O6, molecular weight 818.0 g/mol, CAS 158861-67-7 (PubChem CID 6918245). These values describe the free peptide. Salt forms, such as the dihydrochloride, carry a different formula, weight and CAS.
• Class: a growth hormone secretagogue and ghrelin receptor agonist. It is not growth hormone, and not a GHRH analog.
• Relatives: GHRP-2 and GHRP-6 share their last four amino acids and differ in the first two. A 1997 human study described GHRP-2 and hexarelin as more potent analogs of GHRP-6 (Arvat et al., 1997). Ipamorelin, a later five-amino-acid compound, carries the same D-2-naphthylalanine and the same D-Phe-Lys-NH2 end.
• Approval status: GHRP-2 is not an approved drug in the United States, and the FDA’s Drugs@FDA database lists no product containing it. In Japan, pralmorelin is an approved drug (KEGG D02040). Etched Research does not sell the Japanese drug product.

What the research found

The record splits into animal pharmacology, a handful of short human hormone studies, and the diagnostic work that led to the Japanese approval. Results are listed as the authors reported them.

The family in people (Bowers, Journal of Pediatric Endocrinology, 1993). Cyril Bowers of Tulane, whose group made these peptides, reported that three of them had been given to people by then: GHRP-6, GHRP-1 and GHRP-2. In humans, as in rats, the three were increasingly effective at releasing growth hormone in that order, and all three released more of it than the natural hormone GHRH in his studies. A review of the group’s own work. PMID 8374685.

Children being tested for short stature (Pihoker, Journal of Clinical Endocrinology and Metabolism, 1995). Twenty-four children under evaluation for growth hormone deficiency received the standard test agents (arginine, insulin, L-dopa) as well as GHRH and GHRP-2. The growth hormone responses to GHRH and to GHRP-2 were similar within each child, and the authors found both were reliable predictors of how much growth hormone the pituitary could release. The conventional agents were less likely to predict it. Short-term testing. PMID 7559885.

Hormones beyond growth hormone (Arvat, Peptides, 1997). A Turin group gave GHRP-2 and hexarelin to six healthy young adults and compared them with GHRH and with the hormones that drive prolactin and cortisol. GHRP-2 and hexarelin produced similar, strong growth hormone responses, higher than GHRH in the comparison they ran. Both also raised prolactin, ACTH and cortisol. The ACTH and cortisol rise was similar to the one produced by CRH, the body’s own trigger for that axis. The authors concluded neither peptide is fully specific for growth hormone. Single sessions. PMID 9285939.

Eight months in six children (Mericq, Journal of Clinical Endocrinology and Metabolism, 1998). Six prepubertal children with growth hormone deficiency received GHRP-2 at rising doses across successive two-month periods. Overnight growth hormone release rose with the dose, but the effect of each injection was brief, with little effect later in the night. Blood IGF-I and IGFBP-3 did not rise. Growth rate was higher during the GHRP-2 periods than in the periods before and after them. The authors concluded that a form with a longer duration of action would likely be needed. Six children, compared with their own before and after periods. PMID 9661608.

The pig comparison (Raun, European Journal of Endocrinology, 1998). In the study that introduced ipamorelin, GHRP-2 was one of the benchmarks. In pigs, GHRP-2 was the most potent of the compounds tested but reached a lower peak growth hormone level than GHRP-6 or ipamorelin. None of them changed FSH, LH, prolactin or TSH in pigs. GHRP-2 and GHRP-6 both raised ACTH and cortisol, and ipamorelin did not beyond the levels seen with GHRH. Pigs. PMID 9849822.

The receptor, and the hormone it answers to (Howard, Science, 1996, and Kojima, Nature, 1999). A Merck team cloned the receptor that the synthetic growth hormone secretagogues act on, in the pituitary and hypothalamus of pigs and humans, and concluded these compounds were imitating a hormone nobody had found yet. Three years later a Japanese group isolated that hormone from rat stomach and named it ghrelin. PMIDs 8688086 and 10604470.

Animal pharmacology from the developer (Doi, Arzneimittelforschung, 2004). Researchers at Kaken Pharmaceutical, the company that developed pralmorelin in Japan, reported that in conscious rats GHRP-2 released more growth hormone than injected GHRH, and in conscious dogs it released growth hormone where GHRH did not. They read this as GHRP-2 being less sensitive to suppression by somatostatin. In pituitary cells in a dish, it was weaker than GHRH. It released no growth hormone in rats without a pituitary, and less in rats with a damaged hypothalamic connection. In rats it also raised ACTH and corticosterone, but not prolactin. Rats and dogs, written by the developer. PMID 15646370.

Food intake in healthy men (Laferrère, Journal of Clinical Endocrinology and Metabolism, 2005). Seven lean, healthy men received a four-and-a-half-hour infusion of GHRP-2 or saline on separate days, then ate from a buffet. All seven ate more during the GHRP-2 session, the mix of foods they chose did not change, and growth hormone rose as expected. The authors concluded GHRP-2 is a useful tool for studying how ghrelin affects eating in people. One meal per session, seven men. PMID 15699539.

The adult pituitary test (Chihara, European Journal of Endocrinology, 2007). A Japanese multicenter group gave a single GHRP-2 test dose to 77 healthy adults and 58 adults with severe growth hormone deficiency confirmed by the insulin tolerance test. Growth hormone peaked within 60 minutes in all participants, the peaks were far lower in the patient group, and repeat tests gave similar results. The authors proposed a cut-off value for telling the two groups apart. PMID 17609397.

How it works

Two separate signals act on the pituitary cells that release growth hormone. One is GHRH, a hormone from the hypothalamus. The other is the ghrelin receptor, GHS-R1a, which GHRP-2 binds. Ghrelin, isolated in 1999, is the body’s own partner for that receptor (Kojima et al., 1999).

The animal work suggests GHRP-2 depends on more than the pituitary alone. In the Kaken rat studies, it needed an intact pituitary to release any growth hormone, and released less when the hypothalamic connection was damaged, which the authors read as a need for the body’s own GHRH to reach its full effect (Doi et al., 2004). The receptor itself sits in the hypothalamus as well as the pituitary (Howard et al., 1996).

What the research does not establish

• The human studies we found are short, and most are small. Most measured hormone levels in a single session. The longest followed six children for eight months, compared only with their own periods before and after.
• GHRP-2 is not selective for growth hormone. Prolactin, ACTH and cortisol rose in healthy adults, ACTH and cortisol rose in pigs, and ACTH and corticosterone rose in rats.
• The food-intake result comes from one meal in each of two sessions, in seven men.
• Much of the early work comes from the groups that developed the compound, at Tulane and at Kaken.
• Nothing here is a safety conclusion, and this is not a claim that the compound is safe to use.

Common questions

What is GHRP-2?

GHRP-2 is a synthetic six-amino-acid peptide, D-Ala-D-2Nal-Ala-Trp-D-Phe-Lys-NH2, developed as a growth hormone-releasing compound that acts at the ghrelin receptor, GHS-R1a (Doi et al., 2004). Its generic drug name is pralmorelin. It is not growth hormone itself.

What is the difference between GHRP-2 and GHRP-6?

GHRP-2 and GHRP-6 share their last four amino acids, Ala-Trp-D-Phe-Lys-NH2, and differ in the first two. Both bind the ghrelin receptor. In the early human work from the Tulane group, GHRP-2 released more growth hormone than GHRP-6 (Bowers, 1993), and in pigs it was more potent but reached a lower peak (Raun et al., 1998).

Has GHRP-2 been studied in people?

GHRP-2 has been studied in people in short studies, most of them small and most measuring hormone release in a single session. They include pituitary testing in children (Pihoker et al., 1995) and adults (Chihara et al., 2007), an eight-month study in six children (Mericq et al., 1998), and a food-intake study in seven men (Laferrère et al., 2005). We did not find a long-term controlled trial.

Does GHRP-2 change hormones other than growth hormone?

In a study of six healthy young adults, GHRP-2 raised prolactin, ACTH and cortisol as well as growth hormone, and the authors concluded it is not fully specific (Arvat et al., 1997). ACTH and cortisol also rose in pigs (Raun et al., 1998).

Is GHRP-2 in the Etched Research shop?

No. GHRP-2 is not part of the Etched Research retail catalog. This page is in the research library because the compound is part of growth hormone axis research, and the library covers more compounds than the shop does.

More in this research area: Growth Hormone Signaling Research | Research Library

Last reviewed 2026-10-04.

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