CJC-1295 (without DAC) vs Ipamorelin

CJC-1295 (without DAC)

CJC-1295 without DAC, also called modified GRF (1-29), is a 29-residue synthetic analogue of growth hormone-releasing hormone (GHRH). Native GHRH has 44 residues, but its first 29 carry the receptor-binding activity, and this peptide is built on that shortened sequence with four amino-acid substitutions intended to slow breakdown. The name causes confusion: CJC-1295 originally referred to a version carrying a drug affinity complex (DAC), a reactive linker that binds albumin and greatly prolongs circulation. The form described here lacks that linker. Human studies of the DAC version exist but are few; published work on the form without DAC is thinner still, and much of what is said about it is inferred from the parent hormone.

Ipamorelin

Ipamorelin is a synthetic pentapeptide, Aib-His-D-2-Nal-D-Phe-Lys-NH2, that acts as an agonist at the ghrelin receptor, GHS-R1a. It was derived from earlier growth hormone-releasing peptides and is one residue shorter than GHRP-2 and GHRP-6. What set it apart in the original animal pharmacology was selectivity: growth hormone release was not accompanied by the rises in ACTH and cortisol recorded for older compounds in the class. Because ghrelin receptors are also present in the gut, it has been examined in rodent models of gastrointestinal motility, and it has been the subject of a small number of human clinical studies. Human data remain limited, and most of what is known comes from animal work.

How CJC-1295 (without DAC) acts

Like native GHRH, the peptide has been reported to bind the GHRH receptor, a class B G protein-coupled receptor on somatotroph cells of the anterior pituitary. Receptor activation couples to Gs, raising intracellular cAMP and releasing stored growth hormone; circulating growth hormone in turn drives IGF-1 production, mainly in the liver. The substitutions, D-alanine at position 2, glutamine at 8, alanine at 15 and leucine at 27, were chosen to resist cleavage by dipeptidyl peptidase-4 and to reduce deamidation and oxidation at vulnerable residues. Without the albumin-binding linker its half-life is short, and pharmacokinetic data specific to this form are sparse.

How Ipamorelin acts

Ipamorelin has been reported to bind GHS-R1a on somatotroph cells of the anterior pituitary, where receptor activation raises intracellular calcium and triggers growth hormone secretion. Its reported selectivity concerns other pituitary and adrenal hormones: in the animal studies that first characterised it, ACTH and cortisol did not rise appreciably, unlike with GHRP-6 or GHRP-2. The structural basis for this difference has not been fully explained. The receptor is also found in the gut wall and its nerve supply, which is the rationale for rodent studies of gastrointestinal transit using this compound.

The records side by side

• Type: CJC-1295 (without DAC), GHRH analog (Modified GRF 1-29); Ipamorelin, Growth hormone secretagogue (GHRP)
• Length: CJC-1295 (without DAC), not recorded; Ipamorelin, 5 amino acids
• Molecular weight: CJC-1295 (without DAC), 3647.2 g/mol; Ipamorelin, 711.9 g/mol
• Molecular formula: CJC-1295 (without DAC), C165H269N47O46; Ipamorelin, C38H49N9O5

Reading a comparison

A comparison places two records side by side; it does not merge them. Each description above is drawn from that compound's own record, and the two were not necessarily characterised by the same methods, at the same time, or to the same level of detail. Before comparing any attribute, it is worth establishing that both records describe the substance you think they describe — names are not identifiers, and two entries sharing a name can differ in salt form, stereochemistry or the convention used to state a mass. Where a figure carries no method beside it, the comparison is between two reported numbers rather than between two measurements.