Both are synthetic hexapeptide agonists of the ghrelin receptor GHS-R1a that push the pituitary to release growth hormone. GHRP-2 is the more potent of the two by weight and raises prolactin and cortisol noticeably at higher doses; in Japan it is approved as pralmorelin, but only as a diagnostic. GHRP-6 is older, strongly appetite-stimulating and approved nowhere.
Key parameters side by side
Parameter
GHRP-2
GHRP-6
Molecular weight
817.97 Da
873.01 Da
Same for both: Category — Growth Hormone; Evidence status — Clinical Trial; Sequence length — 6
Frequently asked questions
In potency and side profile. GHRP-2 produces the strongest growth hormone release in the GHRP family but also raises prolactin and cortisol more. GHRP-6 was the first peptide described in the series and is marked by pronounced appetite stimulation.
GHRP-2 has the only approved use in the world — a diagnostic growth hormone stimulation test in Japan. GHRP-6 remained a research tool: it was the compound used to characterise the GHS-R1a receptor and ghrelin itself.
Growth Hormone
GHRP-2
Clinical Trial
GHRP-2 (Growth Hormone Releasing Peptide-2), also known as pralmorelin, is a synthetic hexapeptide growth hormone secretagogue that stimulates growth hormone release through activation of the ghrelin receptor (GHS-R1a). Developed in the 1990s as part of the GHRP series of peptides, GHRP-2 is considered one of the most potent GH secretagogues, producing robust GH release with relatively consistent dose-response characteristics.
GHRP-2 acts as a ghrelin mimetic, binding to the same receptor as the endogenous hunger hormone ghrelin (GHS-R1a) on pituitary somatotrophs and hypothalamic neurons. It produces the strongest GH release among the GHRP family (GHRP-2 > GHRP-6 > hexarelin by weight), but unlike the more selective ipamorelin, GHRP-2 also significantly stimulates prolactin and cortisol release at higher doses.
Pralmorelin (GHRP-2) is approved in Japan as a diagnostic agent for GH deficiency. It has been extensively studied in clinical research and remains one of the most referenced GH secretagogues in the scientific literature, with particular attention to its effects on body composition, sleep, and GH axis restoration.
GHRP-6 (Growth Hormone Releasing Peptide-6) is a synthetic hexapeptide and one of the first generation growth hormone secretagogues discovered by Dr. Cyril Bowers in the 1980s. It was among the earliest peptides identified to potently stimulate GH release from the pituitary gland, and its discovery ultimately led to the identification of the ghrelin receptor (GHS-R1a) and the endogenous hormone ghrelin itself.
GHRP-6 acts as a potent ghrelin receptor agonist, producing robust GH release along with significant appetite stimulation and modest cortisol/prolactin increases. It was the foundational compound that demonstrated peptidic GH secretagogues could effectively stimulate GH release independent of GHRH, opening an entirely new avenue for GH axis research and therapy.
While newer, more selective GH secretagogues have been developed (ipamorelin, MK-677), GHRP-6 remains widely used in research and retains importance due to its well-characterized pharmacology, strong GH-releasing potency, and its historical role in elucidating the ghrelin signaling system.
GHRP-2 (Growth Hormone Releasing Peptide-2), also known as pralmorelin, is a synthetic hexapeptide growth hormone secretagogue that stimulates growth hormone release through activation of the ghrelin receptor (GHS-R1a). Developed in the 1990s as part of the GHRP series of peptides, GHRP-2 is considered one of the most potent GH secretagogues, producing robust GH release with relatively consistent dose-response characteristics.
GHRP-2 acts as a ghrelin mimetic, binding to the same receptor as the endogenous hunger hormone ghrelin (GHS-R1a) on pituitary somatotrophs and hypothalamic neurons. It produces the strongest GH release among the GHRP family (GHRP-2 > GHRP-6 > hexarelin by weight), but unlike the more selective ipamorelin, GHRP-2 also significantly stimulates prolactin and cortisol release at higher doses.
Pralmorelin (GHRP-2) is approved in Japan as a diagnostic agent for GH deficiency. It has been extensively studied in clinical research and remains one of the most referenced GH secretagogues in the scientific literature, with particular attention to its effects on body composition, sleep, and GH axis restoration.
GHRP-6 (Growth Hormone Releasing Peptide-6) is a synthetic hexapeptide and one of the first generation growth hormone secretagogues discovered by Dr. Cyril Bowers in the 1980s. It was among the earliest peptides identified to potently stimulate GH release from the pituitary gland, and its discovery ultimately led to the identification of the ghrelin receptor (GHS-R1a) and the endogenous hormone ghrelin itself.
GHRP-6 acts as a potent ghrelin receptor agonist, producing robust GH release along with significant appetite stimulation and modest cortisol/prolactin increases. It was the foundational compound that demonstrated peptidic GH secretagogues could effectively stimulate GH release independent of GHRH, opening an entirely new avenue for GH axis research and therapy.
While newer, more selective GH secretagogues have been developed (ipamorelin, MK-677), GHRP-6 remains widely used in research and retains importance due to its well-characterized pharmacology, strong GH-releasing potency, and its historical role in elucidating the ghrelin signaling system.