CJC-1295 Ipamorelin: An Indexed Almanac of the Growth-Hormone-Secretagogue Literature

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]. This selectivity profile distinguishes ipamorelin from earlier GHRPs (GHRP-6, GHRP-2) and shapes the compound's safety record in published Phase I trials.

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], body composition in GH-knockout mice ^[5], and the proteomic downstream shifts of GH/IGF-1 axis activation in healthy men ^[6].

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). The regulatory and compliance record is indexed in the References and About sections of this almanac.

This site is an editorial digest of that literature — 22 numbered findings sorted as plates in a curated archive. Every quantitative claim maps to a numbered citation in the References index.

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.

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, ipamorelin, 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 rather than volumetric density change ^[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]. A CJC-1295 formulation without the DAC modification behaves pharmacokinetically closer to the native peptide.

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.

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. Native GHRH(1-44) is produced by the hypothalamus and acts on anterior pituitary somatotrophs to stimulate GH synthesis and release. The native peptide degrades rapidly in plasma via dipeptidylpeptidase-IV (DPP-IV) cleavage at the N-terminal dipeptide, limiting its utility as a research tool. CJC-1295 was engineered with four amino acid substitutions to resist DPP-IV degradation, and the DAC albumin-bioconjugation technology further extends active plasma residence to approximately 6–8 days ^[16].

The class precedent is tesamorelin — a GRF(1-44) analog with trans-3-hexenoic acid conjugation — 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.

What Are Peptides? A Research Overview

Peptides are short amino acid chains — by convention, fewer than 50 residues — that act as signaling molecules by binding specific receptors. Their receptor specificity makes them attractive research tools: a five-residue peptide like ipamorelin can bind a single receptor subtype (GHS-R1a) with nanomolar affinity while leaving adjacent receptor families unaffected. CJC-1295 illustrates a complementary design principle: a 29-residue GHRH fragment, engineered for metabolic stability and extended plasma residence through albumin bioconjugation.

Peptide research explores receptor-specific activity in biological models as alternatives or adjuncts to larger protein hormones — exogenous GH (MW ~22,000 Da) versus a 3,367 Da GHRH analog. The receptor-specificity and preserved endogenous-feedback arguments are central to the secretagogue literature reviewed on this site. For growth hormone secretagogue research background and the mechanistic literature, see the Research page.

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.

Regulatory Status

Neither CJC-1295 nor ipamorelin holds FDA approval for any human indication. CJC-1295 (with DAC) reached Phase I/II-context human studies with published results; ipamorelin reached Phase I/II for postoperative ileus (NCT00672074) and Phase I safety. No Phase III data for either compound have been published. Both appear on the WADA Prohibited List: CJC-1295 as a GHRH analog (Section S2) and ipamorelin as a growth hormone secretagogue (GHS-R1a agonist, Section S2; potentially also Section S0 Non-Approved Substances). As of December 2024 FDA Pharmacy Compounding Advisory Committee briefing documents, CJC-1295 acetate forms were proposed not to be included on the 503A Bulks List. For regulatory status detail, see the About page.