Growth hormone secretion is regulated by the interplay of GHRH (stimulatory) and somatostatin (inhibitory), with a third input from ghrelin receptor (GHSR-1a) agonists. This dual regulatory architecture creates an opportunity for synergistic pharmacological intervention using compounds from each class.
Ipamorelin: Selective GHRP
Ipamorelin is a pentapeptide GHSR-1a agonist developed by Novo Nordisk. Unlike earlier GHRPs such as GHRP-2 and GHRP-6, ipamorelin demonstrates high receptor selectivity — stimulating GH release without meaningfully elevating cortisol, prolactin, or ACTH at therapeutic doses. Its half-life of ~2 hours produces a discrete GH pulse that mimics natural pulsatile release.
CJC-1295 No DAC: GHRH Analog
CJC-1295 No DAC is a synthetic analog of GHRH(1-29) without the Drug Affinity Complex modification, giving it a shorter half-life than the DAC version and producing more discrete, physiological pulses more closely mimicking endogenous GHRH release. It acts at GHRH receptors on pituitary somatotrophs to prime and amplify GH secretory capacity.
Synergistic Combination
CJC-1295 acts at GHRH receptors, priming somatotrophs. Ipamorelin acts at GHSR-1a via a distinct Gq/11 pathway, providing an additional stimulatory input. Together they engage two independent GH-stimulatory pathways simultaneously — in vitro studies confirm the combination produces GH release exceeding the additive response from either compound alone. Ipamorelin also suppresses somatostatin tone, removing the primary brake on GHRH-stimulated release.
Related research compounds:
References
- Johansen PB, et al. (1999). Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol, 139(5), 552–561.
- Teichman SL, et al. (2006). Prolonged stimulation of GH and IGF-I secretion by CJC-1295. J Clin Endocrinol Metab, 91(3), 799–805.
- Smith RG. (2005). Development of growth hormone secretagogues. Endocr Rev, 26(3), 346–360.