Try Calculator
← Back to Compound Library GH SECRETAGOGUES

GHRP-2

Research Guide

GHRP-2, formally known by its pharmaceutical name Pralmorelin, is a synthetic hexapeptide belonging to the family of growth hormone secretagogues (GHS). Its amino acid sequence — D- Ala-D-(β-naphthyl)-Ala-Trp-D-Phe-Lys-NH₂ — was developed in the 1980s and 1990s by researchers at Tulane University led by Dr. Cyril Bowers, in collaboration with Polygen in Germany. GHRP-2 holds the distinction of being the first growth hormone secretagogue introduced clinically and is currently approved in Japan under the brand name GHRP Kaken 100 as a diagnostic agent for growth hormone deficiency. Unlike exogenous synthetic human growth hormone (HGH) injections, which introduce an external hormone into the body, GHRP-2 works by stimulating the body’s own pituitary gland to produce and release growth hormone. This mechanism operates through the ghrelin receptor pathway, making GHRP-2 a ghrelin mimetic — a compound that replicates the actions of the naturally occurring hunger and growth hormone-regulating peptide, ghrelin. GHRP-2 has been studied via intravenous, subcutaneous, intranasal, and oral administration routes in both animal models and human clinical trials. Its applications have included research into growth hormone deficiency in children, diagnostic testing of pituitary function, appetite regulation, and recovery from critical illness. Clinical studies have documented peak plasma growth hormone concentrations of 30–100 ng/mL occurring approximately 15 to 30 minutes after subcutaneous administration, representing an 8 to 20-fold increase above baseline depending on dosage and individual response characteristics.

How It Works

The Ghrelin Pathway

To understand GHRP-2’s mechanism of action, it is helpful to first understand ghrelin, the endogenous hormone it mimics. Ghrelin is a 28-amino acid octanoyl peptide produced primarily in the stomach. Its primary functions include signaling hunger to the brain, regulating energy balance, and stimulating the release of growth hormone from the pituitary gland. These effects are mediated through the growth hormone secretagogue receptor, designated GHS-R1a. GHRP-2 binds to this same GHS-R1a receptor with high affinity. When it does so, it initiates a cascade of intracellular signaling events — including cyclic AMP (cAMP) activation via the cAMP/PKA pathway, protein kinase C (PKC) signaling through the IP3/DAG pathway, and calcium channel modulation — that collectively culminate in growth hormone release from the anterior pituitary gland.

Dual-Action Mechanism

GHRP-2 stimulates growth hormone through two complementary pathways:

triggers GH secretion.

stimulates the release of endogenous growth hormone-releasing hormone (GHRH), which in turn amplifies the GH signal to the pituitary. Additionally, GHRP-2 suppresses somatostatin, the inhibitory hormone that normally acts as a brake on growth hormone release. By simultaneously stimulating GH release through two mechanisms while reducing somatostatin-mediated inhibition, GHRP-2 produces robust and reliable growth hormone pulses. Research has also established that GHRP-2 requires an intact GHRH signaling system to achieve its full effect. Studies conducted in GHRH knockout mice demonstrated that GHRP-2 alone could not produce adequate GH stimulation without functional GHRH pathways. This biological dependency is the scientific basis for combining GHRP-2 with GHRH-analogue peptides such as CJC-1295.

The Growth Hormone Response

Following subcutaneous injection, GHRP-2 produces a rapid and predictable rise in circulating growth hormone. Studies consistently show that GH levels peak at approximately 15 to 30 minutes post-injection and return to baseline within 90 to 120 minutes. The plasma half-life of GHRP-2 is approximately 15 to 30 minutes. Because the active window is relatively brief, research protocols typically administer GHRP-2 two to three times daily to maintain elevated GH levels throughout the day and night.

Downstream Effects: IGF-1 and Anabolic Signaling

The growth hormone released in response to GHRP-2 travels to the liver, where it stimulates the production of insulin-like growth factor-1 (IGF-1). IGF-1 is the primary mediator of many of growth hormone’s downstream anabolic effects, including:

Benefits

Growth Hormone Stimulation

GHRP-2 is considered one of the most potent members of the GHRP family for stimulating growth hormone release. Clinical studies have demonstrated dose-dependent increases in plasma GH levels, with a single injection producing meaningful elevations above baseline for approximately 90 minutes. Its potency for GH stimulation exceeds that of GHRP-6 on a microgram-per- microgram basis, while producing a comparatively more moderate side effect profile.

Balanced Appetite Stimulation

Unlike GHRP-6, which is notorious for producing intense and difficult-to-manage hunger, GHRP- 2 produces a more moderate degree of appetite stimulation. A clinical study published in the Journal of Clinical Endocrinology and Metabolism found that subcutaneous GHRP-2 infusion increased food intake by approximately 35.9% compared to saline placebo in healthy men — a meaningful increase that is nonetheless manageable for most individuals. This balanced orexigenic effect can be advantageous in research contexts examining appetite regulation, or in applications where increased caloric intake is a desired outcome, such as supporting muscle building in hard-gainers.

Muscle Growth and Lean Body Composition

Elevated GH and IGF-1 levels support anabolic processes, including muscle protein synthesis and the inhibition of protein degradation pathways. Research in both animal models and human subjects supports GHRP-2’s role in promoting lean tissue accretion and favorable shifts in body composition.

Fat Loss and Metabolic Effects

Growth hormone is a potent stimulator of lipolysis — the mobilization and breakdown of stored triglycerides from adipose tissue. GHRP-2 users and research subjects have demonstrated improvements in body fat distribution, particularly reductions in visceral and abdominal adipose tissue, alongside elevated GH and IGF-1 signaling.

Tissue Repair and Recovery

Growth hormone plays a central role in tissue regeneration and cellular repair. Research suggests that GH-mediated signaling accelerates recovery from physical stress, reduces muscle soreness, and supports healing of connective tissue and minor injuries. These properties have made GHRP- 2 of interest in recovery research following injury or critical illness.

Sleep Quality Enhancement

Growth hormone is naturally secreted in its largest pulses during deep slow-wave sleep. Research protocols administering GHRP-2 in the evening have been associated with enhanced sleep quality and deeper sleep architecture. This bidirectional relationship between GH and sleep makes GHRP- 2 of particular interest in sleep disorder and recovery research.

Potential Cardioprotective Properties

Emerging preclinical research has suggested that GHRP-2 may exert protective effects on cardiac tissue. Studies using cardiomyocyte culture systems and animal myocardial injury paradigms have investigated GHRP-2’s role in reducing apoptosis-associated markers and oxidative stress pathways, though this application remains in early stages of investigation.

Diagnostic Applications

GHRP-2’s most clinically validated application is as a diagnostic agent for growth hormone deficiency. Its reliable and reproducible stimulation of GH release makes it well-suited for assessing pituitary function. In Japan, it is approved as a standardized diagnostic test under the brand name GHRP Kaken 100 and represents an alternative to insulin tolerance testing, which carries a risk of hypoglycemia.

What the Science Shows

Food Intake Study — Laferrère et al. (2005) Published in the Journal of Clinical Endocrinology and Metabolism, this study investigated whether GHRP-2 could stimulate appetite in healthy human subjects, mirroring the known orexigenic effects of ghrelin. Protocol: Seven lean, healthy adult males received subcutaneous GHRP-2 infusion at a rate of 1 mcg/kg/hour — or a saline placebo — for 270 minutes. Participants then had access to an ad libitum buffet-style meal, and caloric intake was precisely measured. Results:

vs. 101.3 kJ/kg)

responders

used as a research model for food intake behavior

Short Stature Treatment Study — Pihoker et al. (1997) Published in the Journal of Clinical Endocrinology and Metabolism, this study evaluated the therapeutic potential of intranasal GHRP-2 administration in children with growth hormone deficiency-related short stature. Protocol: Fifteen children with short stature received intranasal GHRP-2 at doses of 5 to 15 mcg/kg twice daily for the first three months, subsequently increasing to three times daily. Follow-up was extended to 18 to 24 months. Results:

mark

demonstrating durability of response

signaling

Swine Growth Performance Study — Azain et al. (2000) Published in Domestic Animal Endocrinology, this study examined the effects of GHRP-2 on growth hormone dynamics and growth performance metrics in a porcine model, which is a commonly used surrogate for human physiology. Results:

GH levels peaking at 15 minutes and returning to baseline within 120 minutes

some attenuation of the GH response was observed between day 1 and day 10

elevated GH signaling

GHRH Dependency Research — Alba et al. (2005) Published in the American Journal of Physiology: Endocrinology and Metabolism, this study used GHRH knockout mice to evaluate the extent to which GHRP-2’s GH-stimulating effects depend on an intact endogenous GHRH system. Results: GHRP-2 alone was unable to produce adequate GH secretion in mice lacking functional GHRH signaling. This established that GHRP-2’s full efficacy is contingent on a functional GHRH pathway, which is why co-administration with a GHRH analogue such as CJC-1295 produces significantly amplified and more sustained GH release compared to GHRP-2 administered alone.

Critical Illness Recovery — Van den Berghe et al. (2002) Published in Clinical Endocrinology, this study evaluated the use of GHRP-2 in combination with TRH and GnRH in critically ill patients with prolonged ICU stays, where hypothalamic-pituitary axis suppression is a significant clinical problem. Results: The combined administration of GHRP-2, TRH, and GnRH produced superior endocrine and metabolic outcomes compared to GHRP-2 alone. This demonstrated the utility of combination secretagogue protocols in restoring anabolic hormonal signaling in catabolic states.

University of Turin Comparative Study (1997) Research conducted at the University of Turin compared GHRP-2’s GH-stimulating efficacy against GHRP-6 in human subjects. Findings indicated that GHRP-2 stimulates GH secretion more effectively than GHRP-6 on a microgram-per-microgram basis, while producing comparatively smaller elevations in prolactin, ACTH, and cortisol. This established GHRP-2 as the more potent and relatively selective member of the two peptides for GH research applications.

Dosing Protocol

Standard Solo Protocol

bed (2+ hours after last meal)

Combined Protocol with CJC-1295 Without DAC (Preferred) The combination of GHRP-2 with a GHRH analogue such as CJC-1295 without DAC is the preferred research protocol. GHRP-2 delivers the GH pulse while CJC-1295 amplifies and extends the response. Research demonstrates that the combination produces significantly greater GH release than either peptide administered alone — potentially 5 to 10 times the output of GHRP-2 alone, according to some research estimates.

Dosing by Body Weight

Body Weight Recommended Dose Under 150 lbs 100–150 mcg per injection 150–200 lbs 150–200 mcg per injection Over 200 lbs 200–300 mcg per injection

Timing Considerations

GHRP-2 should always be administered in a fasted state. Food intake — particularly carbohydrates and fats — raises insulin levels, which blunts the growth hormone response. Best practices include:

any food or caloric beverages.

involved, the pre-workout window is ideal.

often considered the most important for sleep quality and overnight recovery. Wait at least 30 minutes before eating after injection.

Reconstitution

Materials needed:

Reconstitution instructions: 1. Wipe the rubber stopper of the peptide vial and the BAC water vial with separate alcohol swabs. Allow to air-dry briefly. 2. Draw the desired volume of bacteriostatic water (1 mL or 2 mL — see tables below) into a sterile reconstitution syringe. 3. Insert the needle through the rubber stopper at an angle and direct the stream of water to flow slowly down the interior wall of the vial. 4. Do not inject water directly onto the lyophilized powder, as this can degrade the peptide. 5. Swirl the vial gently until the powder is fully dissolved. Do not shake or vortex. 6. The resulting solution should be clear and colorless. If the solution is cloudy, particulate, or discolored, discard and do not use.

Draw Volume Reference Tables

5 mg Vial — Reconstituted with 2 mL BAC Water (Concentration: 2.5 mg/mL) Dose Volume Insulin Syringe Units 100 mcg 0.04 mL 4 units 150 mcg 0.06 mL 6 units 200 mcg 0.08 mL 8 units 250 mcg 0.10 mL 10 units 300 mcg 0.12 mL 12 units

5 mg Vial — Reconstituted with 1 mL BAC Water (Concentration: 5 mg/mL) Dose Volume Insulin Syringe Units 100 mcg 0.02 mL 2 units 150 mcg 0.03 mL 3 units 200 mcg 0.04 mL 4 units 250 mcg 0.05 mL 5 units 300 mcg 0.06 mL 6 units

Note: Very small draw volumes result from the 1 mL reconstitution. A 2 mL reconstitution is generally preferred for easier and more accurate measurement. Vial duration at 200 mcg twice daily (2 mL reconstitution): approximately 12 days.

Side Effects

GHRP-2 is generally well tolerated across research populations. Its side effect profile occupies a middle ground within the GHRP family: more selective than GHRP-6, which produces more pronounced hormonal and appetite effects, and slightly less selective than Ipamorelin, which is considered the cleanest member of the class.

Common Side Effects

intense than with GHRP-6. Most subjects find the effect manageable.

transient with continued use.

resolves within hours.

has been reported. This is a known effect of elevated GH levels.

considered beneficial for sleep quality in research contexts.

Hormonal Effects

higher doses. This effect is less pronounced than with GHRP-6 or Hexarelin and is generally manageable at standard research doses.

acceptable ranges at standard doses. Subjects with concerns about prolactin-related effects may prefer Ipamorelin.

Rare Side Effects

doses or longer cycles.

sensitivity. Subjects with pre-existing glucose metabolism concerns should monitor blood sugar.

Clinical Trial Safety Data

Human clinical trials including the Pihoker et al. (1997) study in children with short stature reported that intranasal GHRP-2 was well tolerated over an extended 18-to-24-month follow-up period with no serious adverse events. The food intake study by Laferrère et al. (2005) similarly reported no adverse events. These findings support a favorable short-term safety profile at studied doses, though long-term data in healthy adults using supraphysiological protocols remains limited.

Contraindications and Precautions

Do Not Use If You Have

proliferation, which may stimulate tumor growth

Use With Caution If You Have

blood sugar monitoring is recommended

symptoms

Drug Interactions

Growth hormone can significantly affect insulin sensitivity. Research subjects using insulin or oral diabetes medications may need to adjust their glucose management protocols. Glucocorticoid medications (corticosteroids) have been shown to blunt the growth hormone response to GHRPs and may reduce GHRP-2’s efficacy.

GHRP-2 Compared to Related Peptides

GH Release Appetite Cortisol/Prolactin Side Effect

Peptide

Potency Stimulation Effects Burden GHRP-2 Very High Moderate Mild-Moderate Moderate GHRP-6 High Very High Moderate-High Highest Ipamorelin Moderate-High Minimal Minimal Lowest Hexarelin Highest Moderate High High

Choosing Between GHRP-2 and GHRP-6: Both produce strong growth hormone release. GHRP- 2 produces slightly higher GH output on a microgram-per-microgram basis while inducing far less intense hunger. For research applications where appetite stimulation is a confounding variable, GHRP-2 is generally the preferred option. Choosing Between GHRP-2 and Ipamorelin: Ipamorelin is the most selective GHRP, with essentially no effect on cortisol, prolactin, or appetite. If side effect minimization is the primary concern and maximizing GH output is secondary, Ipamorelin is a cleaner option. GHRP-2 is preferred when stronger GH stimulation is required.

Success Tips

Combine with a GHRH Peptide

Research consistently shows that GHRP-2 achieves significantly greater GH output when co- administered with a GHRH analogue such as CJC-1295 without DAC. The science behind this is clear: GHRP-2 initiates the GH pulse while GHRH amplifies and extends it. The combination exploits both known GH secretion pathways simultaneously. Administer both peptides in the same injection or within a short timeframe for maximum synergy.

Always Dose Fasted

Food intake — especially carbohydrates — raises insulin, which directly inhibits GH secretion. For optimal research outcomes, administer GHRP-2 in a fasted state and wait at least 30 minutes after injection before consuming any food. The three ideal administration windows are morning upon waking, pre-workout (if 2+ hours fasted), and before bed (2+ hours after the last meal).

Use the Appetite Effect Strategically

Unlike GHRP-6, where hunger can become overwhelming, GHRP-2’s moderate orexigenic effect is manageable and can be used to advantage. Administering a dose 30 minutes before a planned large meal — particularly for research subjects studying muscle growth requiring high caloric intake — can enhance total food consumption without the discomfort associated with GHRP-6.

Be Patient and Consistent

Research timelines for GHRP-2 outcomes vary by application. Improvements in sleep quality and recovery are typically among the first changes observed, often within 1 to 2 weeks of consistent administration. Changes in body composition — fat loss and muscle accretion — generally become measurable at 6 to 8 weeks. The full spectrum of effects, particularly those mediated by sustained IGF-1 elevation, develops over 3 to 6 months of consistent use.

Support with Appropriate Nutrition and Training

GHRP-2 creates a favorable hormonal environment for muscle growth and fat loss, but it does not replace the fundamental requirements of adequate training stimulus and proper nutrition. Research subjects in muscle growth protocols should incorporate resistance training 3 to 4 times per week and consume adequate dietary protein — approximately 0.8 to 1.0 grams per pound of body weight daily.

Cycle Appropriately

Research on closely related peptides such as Hexarelin has documented receptor desensitization with continuous long-term use. While daily dosing protocols are supported by the existing GHRP- 2 literature (including the 30-day swine study), cycling 12 to 16 weeks on followed by a 4-week off period is a common practice to mitigate potential receptor downregulation and manage cortisol and prolactin exposure over time.

Storage and Handling

Before Reconstitution (Lyophilized Powder)

After Reconstitution (Liquid Solution)

immediately

Legal Status

United States

GHRP-2 is not approved by the U.S. Food and Drug Administration for any therapeutic use in humans. In the United States, it is classified as a research chemical and is legally permitted for in vitro research and laboratory use only. It is not approved for human administration. Phase II clinical trials were conducted in the U.S. by Wyeth for growth hormone deficiency treatment, but development was discontinued.

WADA and Athletic Competition

GHRP-2 is prohibited at all times under the World Anti-Doping Agency (WADA) Prohibited List, categorized under growth hormone secretagogues. Detection methods for GHRP-2 and related peptides have been developed. Competitive athletes subject to anti-doping testing should not use this compound.

Frequently Asked Questions

Is GHRP-2 better than GHRP-6?

The two peptides produce comparable growth hormone release, but GHRP-2 does so with significantly less intense hunger stimulation and a slightly more favorable hormonal profile. On a microgram-per-microgram basis, research from the University of Turin indicates GHRP-2 is actually the more potent GH stimulator. For most research applications, GHRP-2 is the preferred option unless the study design specifically requires the more pronounced appetite stimulation of GHRP-6.

Can GHRP-2 be used alone? Yes, GHRP-2 produces meaningful GH release when administered alone. However, research clearly demonstrates that its effects are significantly amplified when combined with a GHRH analogue such as CJC-1295 without DAC. The combination exploits both the GHSR pathway (via

GHRP-2) and the GHRH receptor pathway (via CJC-1295), producing a synergistic GH pulse that can be 5 to 10 times greater than either compound alone.

Why is GHRP-2 approved in Japan but not the United States? GHRP-2’s approval in Japan is specifically limited to its use as a diagnostic agent — a single-dose test to assess pituitary function — not as an ongoing therapeutic treatment. The U.S. FDA has not approved GHRP-2 for any indication. Phase II therapeutic trials in the U.S. were discontinued. Regulatory approval pathways differ significantly between countries, and Japan’s approval reflects a narrowly defined diagnostic application.

How long until results are observed? In research settings, improvements in sleep quality and subjective recovery are often among the earliest changes noted, typically emerging within 1 to 2 weeks of consistent administration. Changes in body composition become measurable at approximately 6 to 8 weeks. Full effects — particularly those dependent on sustained IGF-1 elevation and cumulative anabolic signaling — generally develop over 3 to 6 months of consistent use.

Does GHRP-2 cause significant hunger? Yes, but moderately. The food intake study by Laferrère et al. (2005) quantified an average 35.9% increase in food intake. In practice, this is experienced as a noticeable but manageable increase in appetite — significantly less intense than the appetite response characteristic of GHRP-6. Most research subjects find the hunger effect controllable.

Does GHRP-2 raise cortisol significantly? GHRP-2 can produce mild, dose-dependent increases in cortisol. The University of Turin’s comparative study found that GHRP-2’s effects on cortisol and prolactin were less pronounced than those of GHRP-6. At standard research doses of 100 to 300 mcg, cortisol elevation is typically within manageable ranges. Subjects concerned about cortisol exposure may consider Ipamorelin as an alternative, which produces essentially no cortisol elevation.

Can GHRP-2 be combined with other peptides beyond CJC-1295? Yes. Research has explored GHRP-2 in combination with TRH (thyrotropin-releasing hormone) and GnRH (gonadotropin-releasing hormone) in critically ill patients, with superior outcomes compared to GHRP-2 alone. In general research contexts, GHRP-2 is most commonly paired with GHRH analogues (CJC-1295 without DAC or Sermorelin) to maximize GH output.

References

1. Laferrère B, et al. Growth Hormone Releasing Peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men. Journal of Clinical Endocrinology and Metabolism. 2005;90(2):611– 614.

2. Pihoker C, et al. Treatment effects of intranasal growth hormone releasing peptide-2 in children with short stature. Journal of Clinical Endocrinology and Metabolism. 1997. 3. Azain MJ, et al. The effects of growth hormone-releasing peptide-2 (GHRP-2) on the release of growth hormone and growth performance in swine. Domestic Animal Endocrinology. 2000. 4. Alba M, et al. Effects of long-term treatment with growth hormone-releasing peptide-2 in the GHRH knockout mouse. American Journal of Physiology — Endocrinology and Metabolism. 2005. 5. Van den Berghe G, et al. The combined administration of GH-releasing peptide-2 (GHRP-2), TRH and GnRH to men with prolonged critical illness evokes superior endocrine and metabolic effects compared to treatment with GHRP-2 alone. Clinical Endocrinology. 2002;56(5):655–669. 6. Berlanga-Acosta J, et al. Synthetic Growth Hormone-Releasing Peptides (GHRPs): A Historical Appraisal of the Evidences Supporting Their Cytoprotective Effects. SAGE Open Medicine. 2017. 7. National Center for Biotechnology Information. PubChem Compound Summary for CID 6918245, Pralmorelin. https://pubchem.ncbi.nlm.nih.gov/compound/Pralmorelin 8. Wikipedia. Pralmorelin. https://en.wikipedia.org/wiki/Pralmorelin 9. Bowers CY, et al. Growth hormone-releasing peptide (GHRP). Endocrinology. 1990;126(3):1223–1228. 10. Smith RG, et al. A receptor for growth hormone-releasing peptide. Science. 1997;275(5304):1261–1264.

Property Support

Our Property Support services are designed to help homeowners, property managers, and businesses maintain safe, clean, and well-functioning properties year-round.

Get In Touch