GHRP-2
GHRP-2 (Pralmorelin)
A balanced growth hormone releasing peptide with moderate appetite stimulation -- the middle ground between clean Ipamorelin and aggressive GHRP-6.
GHRP-2 (Growth Hormone Releasing Peptide 2), also known by its pharmaceutical name Pralmorelin, is a synthetic hexapeptide that stimulates your pituitary gland to release growth hormone. It was the first growth hormone secretagogue to be introduced clinically and holds the distinction of being approved in Japan as a diagnostic agent for growth hormone deficiency under the brand name GHRP Kaken 100. This makes it one of the few GHRPs with any form of regulatory approval anywhere in the world.
GHRP-2 works by binding to ghrelin receptors in the pituitary gland and hypothalamus, triggering a cascade that leads to growth hormone release. Unlike synthetic HGH injections, it stimulates your body's own production rather than introducing an external hormone. The peptide is notable for being orally active and has been studied via intravenous, subcutaneous, intranasal, and oral administration routes, making it one of the most versatile GHRPs from a research perspective.
In terms of its side effect profile, GHRP-2 occupies a middle ground between the clean selectivity of Ipamorelin and the aggressive hormonal effects of GHRP-6. It produces strong growth hormone release with moderate appetite stimulation, less intense hunger than GHRP-6, and mildly increases cortisol and prolactin at higher doses. This balanced profile makes it a popular choice for people who want stronger GH release than Ipamorelin provides but do not want the overwhelming hunger and hormonal disruption of GHRP-6.
How It Works
GHRP-2 acts as a ghrelin mimetic, meaning it copies the actions of the natural hormone ghrelin that your stomach produces. Ghrelin serves several functions: it signals hunger to your brain, influences energy balance, and stimulates growth hormone release from the pituitary. When GHRP-2 binds to the ghrelin receptor (GHS-R1a), the pituitary gland releases growth hormone through several pathways including calcium channel modulation, cyclic AMP activation, and protein kinase C signaling.
GHRP-2 stimulates growth hormone through two mechanisms simultaneously. First, it acts directly on the pituitary gland to release growth hormone. Second, it acts on the hypothalamus, specifically the arcuate nucleus, to regulate growth hormone release. Additionally, like other GHRPs, GHRP-2 suppresses somatostatin, the hormone that normally inhibits growth hormone release. This dual action of stimulating release while reducing inhibition is why GHRPs produce such strong growth hormone pulses.
After injection, GHRP-2 produces a rapid increase in growth hormone. Studies show GH levels peak at approximately 15 minutes and return to baseline within 90 to 120 minutes. The half-life is approximately 15 to 30 minutes. Research has shown that GHRP-2 requires an intact GHRH system to fully stimulate growth hormone release. Studies in GHRH knockout mice showed that GHRP-2 alone could not stimulate adequate growth hormone secretion without functional GHRH signaling, which is why GHRP-2 is often combined with GHRH peptides like CJC-1295 for maximum effect.
Potential Benefits
Strong Growth Hormone Release
GHRP-2 produces strong, reliable growth hormone release with clinical studies showing dose-dependent increases in plasma growth hormone levels across all tested doses. A single injection can elevate growth hormone significantly above baseline for approximately 90 minutes, providing a potent anabolic signal for muscle growth and recovery.
Balanced Appetite Stimulation
Unlike GHRP-6 which causes intense, sometimes overwhelming hunger, GHRP-2 produces more moderate appetite stimulation. Clinical studies showed it increased food intake by approximately 36 percent compared to placebo. This effect can be helpful for people trying to eat more to support muscle gain without the extreme hunger spikes that make GHRP-6 difficult to tolerate.
Muscle Growth and Strength
Higher growth hormone and IGF-1 levels support muscle protein synthesis, the process your body uses to build new muscle. Users typically report improved ability to build lean mass, increased strength, and better muscle fullness over time when GHRP-2 is combined with consistent resistance training and adequate protein.
Fat Loss
Growth hormone promotes lipolysis, the breakdown of stored fat for energy. GHRP-2 users commonly report improvements in body composition with reduced body fat, particularly around the midsection, as elevated growth hormone shifts your metabolism toward using fat for fuel.
Improved Recovery
Growth hormone accelerates cellular repair and tissue regeneration at the cellular level. This translates to faster recovery between training sessions, reduced muscle soreness, and improved healing from minor injuries, allowing for more consistent and productive training.
Better Sleep
Many users report improved sleep quality with GHRP-2, especially when taken before bed. Growth hormone naturally peaks during deep sleep, and GHRP-2 may enhance this process, leading to deeper rest and better overnight recovery.
Diagnostic Utility
GHRP-2 is approved in Japan as a diagnostic test for growth hormone deficiency because its reliable, predictable stimulation of growth hormone release makes it useful for assessing whether your pituitary gland is functioning properly.
What the Research Shows
A study published in the Journal of Clinical Endocrinology and Metabolism examined GHRP-2's effect on food intake in 7 lean, healthy males who received subcutaneous GHRP-2 infusion followed by a buffet-style meal. Subjects ate 35.9 percent more food when given GHRP-2 versus placebo, and every single subject increased their intake. Food intake increased from 101.3 to 136.0 kJ/kg, confirming that GHRP-2, like ghrelin, stimulates appetite in humans, though less intensely than GHRP-6.
Pihoker and colleagues published a study in 1997 examining intranasal GHRP-2 in 15 children with short stature. Children received GHRP-2 at 5 to 15 mcg/kg twice daily for 3 months, then three times daily, with follow-up extending to 18 to 24 months. Height velocity increased from 3.7 cm/year to 6.1 cm/year at 6 months and was maintained at 6.0 cm/year at 18 to 24 months. The treatment was well tolerated and GH binding protein concentrations increased significantly.
Azain and colleagues published a study in Domestic Animal Endocrinology in 2000 examining GHRP-2's effects on growth performance. A single intravenous injection stimulated growth hormone release in a dose-dependent manner, with GH levels peaking at 15 minutes and returning to baseline by 120 minutes. Chronic daily administration for 30 days consistently stimulated GH release, average daily gain increased by 22.35 percent, and feed efficiency improved by 20.64 percent. Some attenuation of the GH response between day 1 and day 10 of chronic use was noted.
What to Know
Increased appetite that is moderate but less intense than GHRP-6, water retention, injection site redness or irritation, tingling or numbness in the hands that is transient, and drowsiness especially with evening dosing are the most frequently reported side effects.
GHRP-2 causes mild cortisol and prolactin increases at higher doses, though these effects are dose-dependent and generally manageable at standard doses. It has less appetite stimulation than GHRP-6 and slightly more hormonal effects than the more selective Ipamorelin, occupying a middle ground in the GHRP family.
Do not use if you have active cancer or history of cancer, diabetic retinopathy, or are pregnant or breastfeeding. Use caution with diabetes or pre-diabetes as growth hormone can affect insulin sensitivity, cardiovascular disease, or history of carpal tunnel syndrome. Joint stiffness from elevated growth hormone and headache are rare side effects.
Research References
Treatment effects of intranasal growth hormone releasing peptide-2 in children with short stature
Pihoker C, et al. · Journal of Clinical Endocrinology and Metabolism · 1997
Study of 15 children receiving intranasal GHRP-2 showing height velocity increased from 3.7 to 6.1 cm/year at 6 months, maintained at 6.0 cm/year at 18-24 months. Well tolerated with significantly increased GH binding protein concentrations.
View StudyThe effects of growth hormone-releasing peptide-2 (GHRP-2) on the release of growth hormone and growth performance in swine
Azain MJ, et al. · Domestic Animal Endocrinology · 2000
Demonstrated dose-dependent GH release peaking at 15 minutes, consistent GH stimulation over 30 days of chronic daily administration, 22.35 percent increase in average daily gain, and 20.64 percent improvement in feed efficiency.
View StudyEffects of long-term treatment with growth hormone-releasing peptide-2 in the GHRH knockout mouse
Alba M, et al. · American Journal of Physiology: Endocrinology and Metabolism · 2005
Showed that GHRP-2 requires an intact GHRH system to fully stimulate growth hormone release, as GHRP-2 alone could not stimulate adequate GH secretion in GHRH knockout mice, supporting the rationale for combining GHRPs with GHRH peptides.
View Study