Growth hormone-releasing peptide 1
Also known as: Ala-His-D-βNal-Ala-Trp-D-Phe-Lys-NH2, GH-releasing peptide 1, GHRP-1, Growth hormone secretagogue‑1, Growth hormone‑releasing peptide‑1
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Summary
Growth hormone‑releasing peptide‑1 (GHRP‑1) is a synthetic heptapeptide belonging to the growth hormone secretagogue family. It stimulates the release of endogenous growth hormone (GH) in humans and several animal species, and has been investigated in short‑term studies in children, adolescents, and in vitro thyroid tissue. The peptide is investigational and is not approved for therapeutic use.
Mechanism of Action
GHRP‑1 binds to the growth hormone secretagogue receptor (GHSR), a ghrelin‑responsive GPCR, and accumulates in the glandular stomach where ghrelin is produced. Animal studies suggest that part of its GH‑releasing effect is mediated by ghrelin release, as gastrointestinal resection markedly reduces the response. GHRP‑1 also appears to act directly at the pituitary, engaging intracellular pathways distinct from those used by GHRH, and exerts a dose‑dependent inhibition of TSH‑stimulated thyroid hormone secretion downstream of cAMP formation in cultured human thyroid follicles.
What the Research Shows
Human data are limited to a single paediatric trial in which an intravenous bolus of 1 µg/kg GHRP‑1 produced a rapid rise in plasma GH, with a larger response in pubertal versus prepubertal children. The same study reported a modest increase in free thyroxine, a decrease in thyrotropin, and a transient cortisol rise, while prolactin, LH and FSH remained unchanged. In rats, whole‑body autoradiography showed gastric accumulation of GHRP‑1, and gastrointestinal resection attenuated GH release by 60‑70%, implicating ghrelin as a mediator. In vitro, GHRP‑1 inhibited TSH‑stimulated T3 secretion and cAMP production in human thyroid follicles, indicating a direct thyroidal effect. No large‑scale or long‑term clinical trials have been reported.
Reported Benefits
Evidence from the paediatric study indicates that GHRP‑1 can acutely increase GH secretion, which may support growth in short‑term settings. The peptide also modulates thyroid axis markers (higher free T4, lower TSH) and elicits a transient cortisol rise, suggesting broader endocrine activity. In animal models, its interaction with ghrelin pathways may enhance GH release beyond direct pituitary stimulation.
Limitations of the Evidence
The clinical evidence is confined to small, short‑term studies with limited participant numbers and no data on long‑term efficacy or safety. Findings are derived from a single intravenous dosing protocol; oral or subcutaneous administration has not been evaluated in humans. The thyroidal inhibitory effects were observed only in vitro, and the relevance to in vivo thyroid function remains uncertain. No regulatory approval has been granted.
Safety Considerations
In the paediatric trial, GHRP‑1 caused a transient rise in cortisol and modest changes in thyroid hormones (increased free T4, decreased TSH) that remained within normal ranges. No alterations were seen in prolactin, LH, or FSH. Animal studies suggest that removal of the gastrointestinal tract diminishes the GH response, indicating dependence on ghrelin pathways. No serious adverse events were reported, but the short observation period limits safety conclusions.
How It Is Administered
Experimental use of GHRP‑1 has involved intravenous bolus injection (e.g., 1 µg/kg in children). The compound is also listed as investigational for oral and subcutaneous routes, though human data for these routes are not reported in the cited literature. Formulations are peptide‑based solutions suitable for injection.
Routes of Administration
Goals & Uses
- Study of GH secretory mechanismsBasic ScienceHigh
- Increase endogenous GH levelsEndocrineModerate
- IGF-1 elevationMetabolic / HormonalLow
- Growth hormone stimulationEndocrine / HormonalModerate
Contraindications
- Active malignancyOncologyHighUse caution or avoid depending on agent and context
- known hypersensitivity to peptideImmunologicModerate
- PregnancyPopulationHighPotential fetal risk or insufficient safety data
- Acromegaly or gigantismEndocrineHigh
- Diabetic retinopathy or uncontrolled diabetesMetabolicModerate
Adverse Effects
- EdemaFluid BalanceRareSwelling from fluid retention
- Injection site reactionsLocalCommon
- Water retention / edemaFluid BalanceUncommon
- Elevated cortisol and prolactinEndocrineCommon
- Transient hyperglycemiaMetabolic/EndocrineUncommon
- Increased appetite / hungerGastrointestinal / MetabolicCommon
- GH-related paresthesiasNeurologicalUncommon
- DizzinessNeurologicUncommonFeeling faint, lightheaded, or unsteady
- Increased appetiteMetabolicCommon
Drug Interactions
- InsulinLowMay increase risk of low blood sugar
- GlucocorticoidsModerate
- Somatostatin analogs (e.g., octreotide)Moderate
- Insulin / antidiabetic agentsModerate
Population Constraints
- PregnancyReproductive SafetyAbsolute
- Pediatric patientsAgeRelative
- Patients with pituitary tumorsOncologic / EndocrinologicAbsolute
- Elderly patientsAgeRelative
- Elderly with cardiovascular diseaseComorbidityRelative
Regulatory Status
- European UnionUnapprovedNo marketing authorization in European Union.
- United StatesInvestigationalInvestigational New Drug (IND) status; not FDA‑approved.
- United KingdomUnapprovedClassed as a research chemical; not licensed for clinical use.
Not approved by any regulatory authority (FDA, EMA, MHRA). Strictly a research compound used in preclinical and early clinical studies. Not scheduled as a controlled substance in most jurisdictions but is banned in sport by WADA.
Evidence & Sources
- Journal ArticleLowAhnfelt-Rønne I, Nowak J, Olsen UB2001-01-01T00:00:00.000000Z
- Journal ArticleLowLaron Z, et al.1993-01-01T00:00:00.000000Z
- Journal ArticleLowKraiem Z, et al.1995-01-01T00:00:00.000000Z
- Journal ArticleLowRico M, et al.1998-01-01T00:00:00.000000Z
Frequently Asked Questions
What is the primary pharmacological effect of GHRP‑1?
GHRP‑1 primarily stimulates the secretion of endogenous growth hormone by activating the growth hormone secretagogue receptor, with part of the effect mediated through ghrelin released from the stomach.
How has GHRP‑1 been administered in human studies?
In the only human study cited, GHRP‑1 was given as an intravenous bolus at a dose of 1 µg per kilogram body weight. Oral and subcutaneous routes are listed for investigational use but have not been evaluated in humans.
Does GHRP‑1 affect thyroid function?
In vitro experiments with cultured human thyroid follicles showed that GHRP‑1 dose‑dependently inhibits TSH‑stimulated T3 secretion and cAMP formation, suggesting a direct inhibitory effect on thyroid hormone production.
Is GHRP‑1 approved for medical use?
No. GHRP‑1 is classified as an investigational compound and has not received regulatory approval for any therapeutic indication.
What safety concerns are known from the available data?
Short‑term administration in children produced a transient cortisol increase and modest changes in thyroid hormones that stayed within normal limits. No serious adverse events were reported, but the limited duration and sample size mean that comprehensive safety information is lacking.
What is Growth hormone-releasing peptide 1 used for?
Growth hormone-releasing peptide 1 is educationally associated with: Study of GH secretory mechanisms, Increase endogenous GH levels, IGF-1 elevation, Growth hormone stimulation. Educational only — not medical advice.
How is Growth hormone-releasing peptide 1 administered?
Recorded routes of administration: Intravenous, Oral, Subcutaneous.
What are the potential side effects of Growth hormone-releasing peptide 1?
Reported adverse effects include: Edema, Injection site reactions, Water retention / edema, Elevated cortisol and prolactin, Transient hyperglycemia, Increased appetite / hunger, GH-related paresthesias, Dizziness, Increased appetite. This list is not exhaustive — consult a qualified clinician.
Who should avoid Growth hormone-releasing peptide 1?
Recorded contraindications: Active malignancy, known hypersensitivity to peptide, Pregnancy, Acromegaly or gigantism, Diabetic retinopathy or uncontrolled diabetes. Consult a qualified clinician before use.