Mechanism of action

GHRP-2 acts in the secretagogue pathway, rather than functioning as the full GH protein. Laferrère and colleagues describe ghrelin-receptor activity, and the PMDA's medicinal product information explains GH release involving the hypothalamus and pituitary. The receptor interaction, released hormone and an assessed outcome are different levels of evidence. In a small meal experiment, acute GHRP-2 exposure increased both circulating GH and food intake relative to saline. This shows more than a single hormone measurement in that setting, but does not establish sustained nutritional or body-composition benefits.

State of evidence

Chihara et al. (2007) evaluated a GHRP-2 stimulation test in 77 healthy subjects and 58 patients with adult GH deficiency. The groups differed in their GH responses, and the study assessed reproducibility. Interpretation was linked to the assay and comparison used; diagnostic-validation findings are not evidence that the stimulus treats the underlying deficiency. Laferrère's separate controlled experiment involved seven lean healthy men and measured acute intake at a test meal and GH responses. A pediatric peptide pharmacokinetic study addresses another population and endpoint. The PMDA identifies pralmorelin hydrochloride in GHRP Kaken 100 for diagnosis of impaired GH secretion. The specific authorization concerns that diagnostic medicine, and cannot be expanded into unrelated treatment indications or applied automatically to differently manufactured research material.

Questions about the research

What does the name pralmorelin identify?

It identifies the peptide also called GHRP-2. The cited Japanese medicine contains pralmorelin hydrochloride in a specified preparation. The peptide name alone does not establish equivalence among different salts, formulations or samples.

Does the diagnostic indication establish treatment of GH deficiency?

No. The diagnostic test investigates the endocrine system's response to a stimulus. Evidence that the stimulus treats the condition would be a separate question. The cited PMDA indication concerns diagnosis of impaired GH secretion.

Can the meal study predict long-term weight or recovery outcomes?

It measured acute intake and a GH response in seven lean healthy men with a saline comparison. The sample and short experimental setting constrain interpretation. It does not establish sustained body-composition, strength or recovery benefits or responses across other populations.

Sources

1. Laferrère et al., J Clin Endocrinol Metab 2005DOI: 10.1210/jc.2004-1719PMID: 15699539
2. Chihara et al., Eur J Endocrinol 2007DOI: 10.1530/EJE-07-0066PMID: 17609397
3. PMDA, GHRP Kaken 100 prescribing information, July 2025
4. PMDA, original pralmorelin hydrochloride approval record 2004
5. Pihoker et al., J Clin Endocrinol Metab 1998, pediatric intravenous peptide PKDOI: 10.1210/jcem.83.4.4744PMID: 9543135

Mechanism of action

GHRP-2 acts in the secretagogue pathway, rather than functioning as the full GH protein. Laferrère and colleagues describe ghrelin-receptor activity, and the PMDA's medicinal product information explains GH release involving the hypothalamus and pituitary. The receptor interaction, released hormone and an assessed outcome are different levels of evidence. In a small meal experiment, acute GHRP-2 exposure increased both circulating GH and food intake relative to saline. This shows more than a single hormone measurement in that setting, but does not establish sustained nutritional or body-composition benefits.

State of evidence

Chihara et al. (2007) evaluated a GHRP-2 stimulation test in 77 healthy subjects and 58 patients with adult GH deficiency. The groups differed in their GH responses, and the study assessed reproducibility. Interpretation was linked to the assay and comparison used; diagnostic-validation findings are not evidence that the stimulus treats the underlying deficiency. Laferrère's separate controlled experiment involved seven lean healthy men and measured acute intake at a test meal and GH responses. A pediatric peptide pharmacokinetic study addresses another population and endpoint. The PMDA identifies pralmorelin hydrochloride in GHRP Kaken 100 for diagnosis of impaired GH secretion. The specific authorization concerns that diagnostic medicine, and cannot be expanded into unrelated treatment indications or applied automatically to differently manufactured research material.

Questions about the research

What does the name pralmorelin identify?

It identifies the peptide also called GHRP-2. The cited Japanese medicine contains pralmorelin hydrochloride in a specified preparation. The peptide name alone does not establish equivalence among different salts, formulations or samples.

Does the diagnostic indication establish treatment of GH deficiency?

No. The diagnostic test investigates the endocrine system's response to a stimulus. Evidence that the stimulus treats the condition would be a separate question. The cited PMDA indication concerns diagnosis of impaired GH secretion.

Can the meal study predict long-term weight or recovery outcomes?

It measured acute intake and a GH response in seven lean healthy men with a saline comparison. The sample and short experimental setting constrain interpretation. It does not establish sustained body-composition, strength or recovery benefits or responses across other populations.

Sources

1. Laferrère et al., J Clin Endocrinol Metab 2005DOI: 10.1210/jc.2004-1719PMID: 15699539
2. Chihara et al., Eur J Endocrinol 2007DOI: 10.1530/EJE-07-0066PMID: 17609397
3. PMDA, GHRP Kaken 100 prescribing information, July 2025
4. PMDA, original pralmorelin hydrochloride approval record 2004
5. Pihoker et al., J Clin Endocrinol Metab 1998, pediatric intravenous peptide PKDOI: 10.1210/jcem.83.4.4744PMID: 9543135