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Terminus Peptides
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Research profile · Peptide

GHRP-6

Also known as Growth hormone-releasing peptide 6

Early human — evidence level 3 of 4: Early human evidenceExperimental — UK regulatory status: Experimental — not authorised for human use in the UK

Overview

The prototype synthetic hexapeptide growth hormone secretagogue, first described in 1984 and studied chiefly as a diagnostic probe.

Category
Peptide
Highest evidence level identified
Early human evidence
Last scientifically reviewed
20 August 2026
Last regulatory review
20 August 2026

Mechanism under investigation

GHRP-6 is the prototype synthetic hexapeptide growth hormone secretagogue, first described in 1984, acting as an agonist at the growth hormone secretagogue receptor. Its releasing action appears to depend on intact hypothalamic-pituitary connectivity and to act synergistically with growth hormone-releasing hormone, since that synergy is lost in patients with pituitary stalk disconnection. Like other peptides in the class it is not fully selective, and stimulation of the pituitary-adrenal axis is described alongside the growth hormone response.

Research areas

  • Pituitary endocrinology
  • Cytoprotection models

These are fields in which the compound has been investigated. Listing a field is not a statement that anything was demonstrated within it.

Current evidence

In-vitro evidence

Cells, tissues or biochemical systems outside a living organism.

Present. The peptide stimulates phosphatidylinositol turnover in human pituitary somatotroph cells, produces a biphasic calcium response in rat somatotrophs, and regulates transcription factor expression through its receptor. Separate work characterises derived ligands of the CD36 scavenger receptor.

Animal evidence

Studies in living non-human animals.

Extensive, and the strongest tier. Rodent studies address central growth hormone regulation, somatostatin interaction, feeding behaviour and hypothalamic gene expression. A substantial cytoprotection literature reports protection against ischaemia and reperfusion injury across several organs, reduced fibrosis and improved wound healing in rat and rabbit models.

Human observational evidence

Studies observing people without assigning an intervention.

Effectively absent. No cohort, registry or case-series data were located. Human-facing literature is confined to analytical methods for detecting the peptide in plasma and in athlete urine samples.

Clinical-trial evidence

Studies assigning an intervention to human participants.

Present, and confined to acute endocrine testing rather than therapeutic efficacy. The peptide has been evaluated as a diagnostic stimulation agent for adult growth hormone deficiency against the insulin tolerance test, studied in obese subjects, and used to probe hypothalamic-pituitary integrity in patients with stalk disconnection. A 2017 review notes human dose-escalation safety studies but describes clinical development as erratic and irregular. No controlled efficacy trial for any therapeutic indication was found, and no registered trials exist.

Study limitations

  • Human evidence is almost entirely acute diagnostic testing designed to measure a hormone response over minutes to hours. It was never structured to answer whether repeated use produces any clinical benefit.
  • The large cytoprotection literature is preclinical, and the review that consolidates it notes clinical development has not followed through.
  • Human studies are small and drawn from specific clinical groups, which limits generalisability.
  • No registered trials exist, and no long-term human exposure data of any kind were located.
  • The common claim that this peptide raises cortisol and prolactin more than GHRP-2 does is not well supported. The head-to-head study usually cited for it compares GHRP-2 against hexarelin, not against this compound, and no direct comparative trial establishing the difference was found.

UK regulatory context

Experimental — not authorised for human use in the UK

A compound appearing in research literature that holds no UK authorisation for human use in any indication.

Source: The Human Medicines Regulations 2012, regulation 46 — prohibition on sale or supply of an unauthorised medicinal product (opens legislation.gov.uk in a new tab) (legislation.gov.uk)

Regulatory classification is jurisdiction-specific. A compound authorised elsewhere is not thereby authorised in the UK, and a supplier’s description of a substance does not determine how it is classified in law. See safety and regulation for the framework and the authoritative sources.

Safety and interpretation

Acute administration in supervised diagnostic settings has been described as producing minimal side effects, but those studies observed participants over hours rather than weeks. A 2026 review attributes stimulation of the pituitary-adrenal axis, with corticotropin and cortisol elevation, and altered nocturnal hormone and sleep patterns to this compound. Because no controlled trial has assessed repeated administration, statements about the safety of sustained use are not supported by the available evidence in either direction.

References