Pralmorelin
Also known as: GHRP-2, GHRP‑2, Growth Hormone-Releasing Peptide-2, KP-102, Macimorelin precursor analog, Pralmorelin dihydrochloride
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Summary
Pralmorelin, also called GHRP‑2, is a synthetic six‑amino‑acid peptide that acts as a growth‑hormone‑releasing secretagogue. Developed as an oral and injectable diagnostic agent, it stimulates endogenous GH release by mimicking the natural hormone ghrelin. Research has explored its use for diagnosing GH deficiency, promoting growth in animal models, and as a potential treatment for short stature, and for scientific investigation of the GH axis.
Mechanism of Action
Pralmorelin binds to the growth‑hormone‑secretagogue receptor (GHS‑R), the same receptor activated by the endogenous peptide ghrelin. Activation of GHS‑R on somatotrophs in the anterior pituitary triggers intracellular signaling that leads to rapid GH secretion. In animal studies the peptide’s effect is less inhibited by somatostatin than that of GHRH and requires an intact median eminence, indicating dependence on endogenous GHRH signaling.
What the Research Shows
Preclinical work in rats showed that an intravenous bolus of pralmorelin (3 mg/kg) is cleared rapidly, displaying a biexponential plasma decline and extensive biliary excretion—about 80 % of the dose appears unchanged in bile within one hour. Tissue distribution is blood‑flow limited to liver and permeability‑limited elsewhere. In vivo studies demonstrated that pralmorelin provokes a greater GH surge than exogenous GHRH in conscious rats and dogs, and its effect persists under conditions of reduced somatostatin. The peptide directly stimulates GH release from cultured rat pituitary cells, albeit with lower potency than GHRH in vitro, and also raises ACTH and corticosterone without affecting prolactin. Clinically, oral administration in healthy volunteers produced marked GH increases irrespective of age, gender, or obesity, while patients with GH deficiency showed a blunted response, supporting its use as a diagnostic challenge test. Additionally, modified analogues with an N‑terminal glycine have been identified in illicit doping samples.
Reported Benefits
Pralmorelin reliably elicits a rapid rise in circulating GH in healthy individuals, making it a useful pharmacological challenge for diagnosing GH deficiency. In animal models it promotes growth‑accelerating effects, modestly increasing body weight and organ size after three weeks of treatment. Early clinical programs also investigated its potential to treat short stature associated with pituitary dwarfism, suggesting a therapeutic benefit beyond diagnostic use.
Limitations of the Evidence
Pralmorelin has never received regulatory approval; development in the United States was discontinued and its status remains investigational. Human data are limited to short diagnostic studies, and the GH response is markedly weaker in GH‑deficient patients than in healthy controls. Pharmacokinetic and safety information in humans are sparse, and most efficacy evidence derives from animal experiments, leaving substantial uncertainty about therapeutic value.
Safety Considerations
Animal investigations reported that pralmorelin stimulates ACTH and corticosterone release alongside GH, indicating activation of the hypothalamic‑pituitary‑adrenal axis. Rapid biliary excretion in rats suggests high clearance, but no systematic human safety assessments are described in the literature. Consequently, potential endocrine side effects and unknown tolerability warrant caution, and the peptide should only be used within controlled research settings under careful monitoring.
How It Is Administered
Pralmorelin is formulated as a dihydrochloride salt for parenteral use and has been studied as an intravenous or subcutaneous injection. Oral preparations have also been investigated, reflecting its reported oral activity in humans. In preclinical studies the peptide is administered as a solution for bolus injection. No depot or sustained‑release formulations are described in the available literature.
Routes of Administration
Goals & Uses
- Anti-aging / GH replacement researchResearchLow
- Muscle mass and body composition improvementPerformance/Body CompositionLow
- Increase endogenous growth hormone secretionEndocrineModerate
- Increase growth hormone secretionEndocrineModerate
- Diagnosis of growth hormone deficiencyDiagnosticHigh
- Appetite stimulationNutritionalLow
- Treat adult growth hormone deficiencyTherapeuticLow
Contraindications
- Hypersensitivity to pralmorelin or excipientsAllergyHigh
- Active malignancyOncologyModerateUse caution or avoid depending on agent and context
- PregnancyPopulationHighPotential fetal risk or insufficient safety data
- Untreated hypothyroidismEndocrineModerate
Adverse Effects
- EdemaFluid BalanceUncommonSwelling from fluid retention
- HyperglycemiaMetabolicCommonAbnormally high blood glucose
- FlushingVascularCommonWarmth and redness of the skin
- NauseaGastrointestinalCommonFeeling of sickness or urge to vomit
- Elevated cortisol/prolactinEndocrineUncommon
- Injection site reactionLocalCommonRedness, swelling, itching, bruising, or pain at the injection site
- Transient hypotensionCardiovascularUncommon
Drug Interactions
- InsulinModerateMay increase risk of low blood sugar
- GlucocorticoidsLow
- Somatostatin analogs (e.g., octreotide)Moderate
- Insulin / Hypoglycemic agentsModerate
Population Constraints
- Pediatric patientsAgeRelative
- Elderly (>75 y)AgeRelative
- Elderly patientsAgeRelative
- Obese individualsMetabolicRelative
- Patients with renal or hepatic impairmentOrgan FunctionRelative
Regulatory Status
- European UnionInvestigationalInvestigational use in clinical trials; no marketing authorization.
- United StatesInvestigationalNever submitted for FDA approval; only used in clinical research.
- United KingdomUnapprovedNot approved by the MHRA; no licensed indication in the UK.
Approved in Japan (Kaken Pharmaceutical) as a diagnostic agent for GH deficiency testing. Not approved by the FDA or EMA for therapeutic or diagnostic use. Widely used in research settings as GHRP-2.
Evidence & Sources
- Journal ArticleLowGajda PM, et al.2019-01-01T00:00:00.000000Z
- Journal ArticleModerateBayes M, Rabasseda X, Prous JR2002-01-01T00:00:00.000000Z
- Journal ArticleLowNasu R, et al.2005-01-01T00:00:00.000000Z
- Journal ArticleModerate2004-01-01T00:00:00.000000Z
- Journal ArticleLowBayés M, Rabasseda X, Prous JR2003-01-01T00:00:00.000000Z
- Journal ArticleLowDoi N, et al.2004-01-01T00:00:00.000000Z
Frequently Asked Questions
How does pralmorelin differ from traditional growth‑hormone‑releasing hormone (GHRH)?
Pralmorelin activates the growth‑hormone‑secretagogue receptor (GHS‑R), a ghrelin‑related pathway, whereas GHRH binds its own receptor on somatotrophs. In animal studies pralmorelin’s GH‑releasing effect is less suppressed by endogenous somatostatin and requires an intact median eminence, indicating a distinct regulatory profile.
What clinical applications have been investigated for pralmorelin?
The peptide has been studied as a diagnostic challenge test to assess GH reserve in healthy subjects and to differentiate GH deficiency. Early trials also examined its potential for treating short stature (pituitary dwarfism) and its oral formulation was evaluated for GH‑stimulating activity.
Why is pralmorelin not an approved medication?
Regulatory approval was never granted; development in the United States was discontinued and the compound remains classified as investigational. Available data are limited to short‑term diagnostic studies and animal experiments, with insufficient human safety and efficacy evidence for formal approval.
What safety concerns should be considered when using pralmorelin in research?
In animals, pralmorelin triggers ACTH and corticosterone release, suggesting activation of the adrenal axis. Rapid biliary clearance has been observed in rats. No comprehensive human safety data are published, so potential endocrine disturbances and unknown tolerability require careful monitoring and restriction to controlled study settings.
What is Pralmorelin?
Pralmorelin, also called GHRP‑2, is a synthetic six‑amino‑acid peptide that acts as a growth‑hormone‑releasing secretagogue. Developed as an oral and injectable diagnostic agent, it stimulates endogenous GH release by mimicking the natural hormone ghrelin. Research has explored its use for diagnosing GH deficiency, promoting growth in animal models, and as a potential treatment for short stature, and for scientific investigation of the GH axis.
What is Pralmorelin used for?
Pralmorelin is educationally associated with: Anti-aging / GH replacement research, Muscle mass and body composition improvement, Increase endogenous growth hormone secretion, Increase growth hormone secretion, Diagnosis of growth hormone deficiency, Appetite stimulation, Treat adult growth hormone deficiency. Educational only — not medical advice.
How is Pralmorelin administered?
Recorded routes of administration: Intravenous, Subcutaneous.
What are the potential side effects of Pralmorelin?
Reported adverse effects include: Edema, Hyperglycemia, Flushing, Nausea, Elevated cortisol/prolactin, Injection site reaction, Transient hypotension. This list is not exhaustive — consult a qualified clinician.
Who should avoid Pralmorelin?
Recorded contraindications: Hypersensitivity to pralmorelin or excipients, Active malignancy, Pregnancy, Untreated hypothyroidism. Consult a qualified clinician before use.