What the CJC-1295 Ipamorelin Literature Has Established
CJC-1295 ipamorelin is a two-component growth-hormone secretagogue blend studied across more than two decades of peer-reviewed endocrinology research. CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH) that binds the GHRH receptor on anterior pituitary somatotrophs. Ipamorelin is a selective synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) that binds the ghrelin receptor (GHS-R1a). The two act on distinct receptor arms — the GHRH axis and the ghrelin axis — and their combination produces supraadditive GH release in preclinical and human models.[13]
In a published Phase I/II-context human study, CJC-1295 at 60–90 µg/kg subcutaneous increased mean GH by 46% and IGF-1 by 45% one week post-dose, with pulsatile GH secretion preserved and basal GH elevated 7.5-fold.[1] Ipamorelin, described in the first selectivity study as the first selective growth hormone secretagogue, did not elevate ACTH, cortisol, FSH, LH, prolactin, or TSH even at doses more than 200-fold above its GH-release ED50 in rat and swine models.[3]
The published literature spans six species: human, rat, mouse, swine, bovine, and canine — and has extended into equine anti-doping enforcement where an immuno-PCR assay confirmed CJC-1295-albumin conjugate in thoroughbred plasma at a 50 pg/mL threshold.[22] The evidence base encompasses mechanism-of-action studies, pharmacokinetic characterizations (including the albumin-bioconjugation half-life extension of the DAC form[2]), bone mineral content and longitudinal bone growth outcomes,[4][9] gastrointestinal motility restoration in postoperative ileus models,[10] sleep architecture modulation via ghrelin-receptor agonism,[12] and the proteomic downstream shifts of GH/IGF-1 axis activation in healthy men.[6]
REGULATORY STATUS
Neither CJC-1295 nor ipamorelin holds FDA approval for any human indication. Both appear on the WADA Prohibited List (Section S2: Peptide Hormones, Growth Factors, Related Substances and Mimetics). See the regulatory status section.
The CJC-1295 Ipamorelin Blend: Synergistic Growth Hormone Secretagogues
The rationale for combining CJC-1295 and ipamorelin rests on two independent receptor axes that produce greater GH output together than either compound achieves alone. CJC-1295 amplifies tonic GH secretion by binding the GHRH receptor (GHRH-R) on pituitary somatotrophs, increasing cAMP production and upregulating the protein kinase A cascade. Ipamorelin triggers acute pulsatile GH release by binding GHS-R1a — the ghrelin receptor — via a pathway that also suppresses hypothalamic somatostatin release and directly stimulates hypothalamic GHRH secretion.
In a cross-species analysis covering human, rat, swine, bovine, and canine models, a near-threshold GHS dose combined with a maximally effective GHRH dose produced supraadditive GH release.[13] Constant GHS infusion maintained pulsatile GH patterns, demonstrating that the ghrelin arm amplifies physiological GH rhythms rather than flattening them. The GHRH-R arm (CJC-1295) provides the elevated tonic baseline; the GHS-R1a arm (ipamorelin) provides the acute pulse amplitude. The IGF-1 negative feedback loop remains intact in both arms, which has been proposed as a safety advantage over exogenous recombinant human GH (rhGH), which bypasses hypothalamic regulation entirely.
For a full mechanistic account, see the mechanism of action section. For CJC-1295 ipamorelin dosage protocols studied in preclinical and human contexts, see the Dosage page. For an overview of CJC-1295 ipamorelin benefits across body composition, bone, and sleep endpoints, see the Benefits page.
A near-threshold GHS dose combined with a maximally effective GHRH dose produced supraadditive GH release in humans, rats, pigs, cows, and dogs — the foundation of the combination-secretagogue rationale.Farhy & Veldhuis, 2005 [13]
What is CJC-1295 Ipamorelin Good For?
The CJC-1295/ipamorelin blend has been studied in preclinical models and Phase I/II-context human trials for several endpoints. In rodent models, outcomes include: dose-dependent increases in longitudinal bone growth rate (42 to 52 µm/day over 15 days in adult female rats, p<0.0001[4]); 4-fold increases in periosteal bone formation rate when ipamorelin countered glucocorticoid-induced bone loss;[8] increased bone mineral content via expanded bone dimensions;[9] and restored gastrointestinal motility in postoperative ileus models via GHS-R1a agonism.[10]
In human models, CJC-1295 produced sustained GH and IGF-1 elevation[1] with downstream shifts in the serum proteome, including changes in apolipoprotein A1, transthyretin, and immunoglobulin-albumin isoforms that correlated linearly with IGF-1.[6] Ghrelin — the endogenous ligand at the same receptor ipamorelin binds — enhanced slow-wave sleep and delta-wave activity in human subjects while elevating GH and prolactin,[12] suggesting that GHS-R1a agonists may modulate sleep architecture. No FDA-approved indication for either compound exists.
What Are CJC-1295 and Ipamorelin?
CJC-1295 is a tetrasubstituted synthetic analog of human GHRH(1-29) with a maleimidopropionamide-lysine Drug Affinity Complex (DAC) appended at the C-terminus. After subcutaneous injection, the DAC moiety spontaneously forms a covalent bond with the free thiol on cysteine-34 of serum albumin, extending plasma half-life from under 13 minutes (the DPP-IV-limited half-life of native GRF(1-29)) to approximately 6–8 days.[2][16]
Ipamorelin is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2, MW 711.9 Da) that selectively binds GHS-R1a to trigger pulsatile GH release. Its plasma clearance in rats is 5-fold lower than GHRP-6; 60–80% of administered dose is recoverable from bile and urine as intact peptide, indicating moderate metabolic resistance. Intranasal bioavailability was approximately 20% in rat studies.[7] Human pharmacokinetic parameters for ipamorelin have not been formally published in peer-reviewed literature.
Synergistic Mechanism: Why These Two Peptides Are Combined
CJC-1295 amplifies the growth hormone baseline through GHRH receptor agonism while ipamorelin triggers acute GH pulses via ghrelin-receptor binding — the two axes work additively and supraadditively in preclinical models.[13] The Farhy and Veldhuis (2005) computational and experimental analysis confirmed three synergistic mechanisms: ghrelin/GHS-R1a agonism (a) directly stimulates pituitary GH release, (b) antagonizes somatostatin at the pituitary, and (c) induces additional hypothalamic GHRH secretion. A subthreshold GHS dose combined with a maximally effective GHRH dose produced supraadditive GH release across five species. Constant GHS infusion maintained pulsatile GH patterns rather than flattening secretion — a physiological outcome distinct from continuous exogenous GH delivery.
EST. 02 — THE TWO RECEPTOR ARMS
CJC-1295 as a GHRH Analog
CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH) — it mimics endogenous GHRH by binding pituitary GHRH receptors to amplify GH secretion. The DAC albumin-bioconjugation technology extends active plasma residence to approximately 6–8 days.[16] The class precedent is tesamorelin — a GRF(1-44) analog — which received FDA approval in 2010 for HIV-associated lipodystrophy and demonstrated significant visceral adipose tissue reduction over 26 weeks in human trials.[18] Tesamorelin establishes proof-of-concept for GHRH analogs in body composition endpoints, though it is a distinct compound studied in a distinct population.