Growth hormone secretion is regulated by the interplay of GHRH (stimulatory) and somatostatin (inhibitory), with a third input from ghrelin receptor (GHSR-1a) agonists. Evidence for each compound must be read in the context of the molecular form and experimental setting studied.
Ipamorelin: Selective GHRP
Raun et al. (1998) identified ipamorelin as a pentapeptide that stimulates GH release through a GHRP-like receptor. In swine, ipamorelin increased GH without affecting prolactin; ACTH and cortisol responses were not significantly different from those following GHRH stimulation. These selectivity findings are from swine, not humans.
Gobburu et al. (1999) reported a terminal half-life of about 2 hours in a pharmacokinetic study in healthy male volunteers. The study observed a single episode of GH release. These results do not establish the half-life under other study conditions or equivalence to natural GH pulsatility.
CJC-1295 No DAC: GHRH Analog
CJC-1295 No DAC is a GHRH analog without the Drug Affinity Complex (DAC) modification. Teichman et al. (2006) studied the long-acting DAC form of CJC-1295 in healthy adults and reported sustained GH and IGF-I increases and an estimated half-life of 5.8–8.1 days. Those findings do not establish the No-DAC analog's half-life or GH pulse pattern, or demonstrate that it more closely mimics endogenous GHRH release.
Combination Evidence: What Is Not Established
The Raun, Gobburu, and Teichman studies cited here do not establish that ipamorelin combined with CJC-1295 No DAC produces a greater-than-additive GH response. Evidence about either compound alone does not demonstrate synergy for this specific combination. These studies also do not establish that ipamorelin suppresses somatostatin tone.
Related research compounds:
References
- Raun K, et al. (1998). Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol, 139(5), 552–561. PMID: 9849822. DOI: 10.1530/eje.0.1390552.
- Teichman SL, et al. (2006). Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. J Clin Endocrinol Metab, 91(3), 799–805. PMID: 16352683. DOI: 10.1210/jc.2005-1536.
- Gobburu JV, Agersø H, Jusko WJ, Ynddal L. (1999). Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res, 16(9), 1412–1416. PMID: 10496658. DOI: 10.1023/a:1018955126402.
- Smith RG. (2005). Development of growth hormone secretagogues. Endocr Rev, 26(3), 346–360.
This article summarizes publicly available research for educational purposes and does not constitute medical advice, a therapeutic claim, or a recommendation for human use. Products referenced are sold for laboratory research use only.