# CJC-1295 Research: Mechanism, Pharmacokinetics, and Phase I Outcomes > The CJC-1295 research record: GHRH-receptor mechanism, the DAC vs. no-DAC pharmacokinetic split, Phase I dose-escalation outcomes, and the gray-literature claims surrounding the molecule. _Mechanism, pharmacokinetics, Phase I outcomes, and what the compounding-pharmacy literature claims beyond them._ ## CJC-1295 Mechanism of Action The CJC-1295 mechanism of action is GHRH-receptor agonism on anterior-pituitary somatotrophs. The molecule binds the growth hormone-releasing hormone receptor (GHRHR) — a class B G-protein-coupled receptor — and activates the canonical Gs / adenylate cyclase / cAMP / PKA signaling cascade [7]. PKA phosphorylates CREB, which cooperates with the somatotroph-lineage transcription factor Pit-1 to drive growth-hormone gene transcription and release [7]. Cryo-EM structural work in 2020 mapped the activated GHRHR binding interface, confirming the two-domain architecture characteristic of class B GPCRs and clarifying the binding pocket engaged by GHRH(1-29)-derived analogs including CJC-1295 [8]. The downstream consequence is elevated growth-hormone secretion, which in turn drives hepatic IGF-1 production [1]. The DAC variant's distinguishing pharmacology is not at the receptor. CJC-1295 with DAC binds GHRHR with the same affinity as the unconjugated peptide; the difference is residence time in circulation. The maleimidopropionic-acid linker reacts with free thiol cysteine-34 on serum albumin within minutes of subcutaneous injection [4], producing a covalent albumin-peptide bioconjugate that resists renal clearance. The receptor sees more of the drug, for longer, at lower instantaneous concentrations. ## CJC-1295 with DAC vs. CJC-1295 without DAC The single most consequential structural distinction in the CJC-1295 literature is whether the DAC linker is present. The CJC-1295 DAC variant — sometimes notated DAC:GRF — carries the maleimide-modified linker and conjugates to serum albumin; the no-DAC variant — chemically identical to modified GRF (1-29) — does not [12]. The pharmacokinetic gap is large. With DAC: plasma elimination half-life of 5.8 to 8.1 days in healthy human Phase I subjects [2], cumulative IGF-1 elevation above baseline for up to twenty-eight days after repeat dosing [2], detection of the albumin-bound peptide in rat plasma beyond seventy-two hours after a single dose [4]. Without DAC: approximately thirty minutes [12]. The consequence for dosing logic — peer-reviewed or gray-literature — is direct. The DAC variant supports weekly subcutaneous dosing because the receptor remains occupied between doses. The no-DAC variant requires multiple daily doses to maintain any sustained GH-axis effect, which is why compounding-pharmacy protocols using 'CJC-1295 without DAC' typically prescribe one to three injections per day [12]. Anyone reading 'CJC-1295' without a specified DAC status is reading about two different drugs at once. ## CJC-1295 without DAC (modified GRF 1-29) CJC-1295 no DAC is functionally indistinguishable from modified GRF (1-29). Both names refer to tetrasubstituted GHRH(1-29) without the albumin-binding linker: D-Ala at position 2, Gln at position 8, Ala at position 15, Leu at position 27 [12]. The substitutions confer DPP-IV resistance but do not extend half-life beyond the order of thirty minutes [12]. ### Modified GRF (1-29) — the no-DAC parent molecule Modified GRF 1-29 is the chemistry-literature name for the no-DAC parent. It is the molecule that ConjuChem started with and the DAC linker was added to. The two names persist in parallel because the peptide-research community adopted 'modified GRF (1-29)' while the compounding-pharmacy community adopted 'CJC-1295 without DAC.' They are the same compound. ## CJC-1295 Half-Life and Pharmacokinetics ### CJC-1295 Half-Life and Pharmacokinetics The CJC-1295 half life is the defining pharmacokinetic property of the molecule, and it splits cleanly along DAC status. CJC-1295 with DAC: 5.8 to 8.1 days in healthy human plasma in the Teichman Phase I trial [2]. CJC-1295 without DAC (modified GRF 1-29): approximately thirty minutes [12]. The DAC variant produces sustained baseline GH elevation; the no-DAC variant produces brief pulses. The albumin-conjugation kinetics underlie the gap. The maleimide linker reacts with free thiol cysteine-34 on circulating albumin within minutes of subcutaneous injection; the resulting bioconjugate is too large for glomerular filtration and is cleared on the timescale of albumin turnover rather than peptide turnover [4]. Albumin's own half-life in human circulation is roughly nineteen days; CJC-1295-DAC therefore approaches a substantial fraction of that ceiling before falling off [4]. ## Outcomes Reported in CJC-1295 Studies The CJC-1295 results that exist in the peer-reviewed literature come almost entirely from the Teichman 2006 Phase I dose-escalation trial in healthy adults [1]. Across single subcutaneous doses of 30, 60, 125, and 250 µg/kg, mean plasma growth hormone rose 2- to 10-fold and remained elevated for six days or more; mean plasma IGF-1 rose 1.5- to 3-fold and remained elevated for nine to eleven days [1][2]. Repeat dosing every one or two weeks produced cumulative IGF-1 elevation extending to twenty-eight days [2]. The Jetté 2005 rodent characterization measured a 4-fold increase in GH area-under-the-curve over two hours relative to unmodified GRF following intravenous administration in rats, and detection of the albumin-bound peptide in plasma beyond seventy-two hours [4]. The Alba 2006 GHRH-knockout mouse study showed once-daily subcutaneous CJC-1295 normalized body weight, body length, pituitary GH-gene expression, and somatotroph proliferation — less-frequent dosing produced only partial restoration [5]. What the published record does not contain: a powered body-composition trial, a randomized controlled efficacy study, a long-term safety study, a head-to-head against tesamorelin or sermorelin, or any Phase III data. ConjuChem's Phase II HIV-lipodystrophy trial (n = 192) was halted in 2006 after a participant death from myocardial infarction — the death was clinically attributed by the investigator to pre-existing asymptomatic coronary artery disease, but commercial development was discontinued [13]. ## Reported Effects and Benefits in the Literature CJC-1295 benefits, in the strict sense the peer-reviewed literature supports, are the pharmacological endpoints measured in published trials: dose-dependent elevation of plasma growth hormone, sustained elevation of plasma IGF-1, and restoration of growth in the GHRH-knockout mouse [1][2][5]. These are pharmacodynamic findings, not clinical outcomes. The broader claims circulating in compounding-pharmacy and direct-to-consumer literature — fat loss, lean-mass gains, anti-aging effects, deeper sleep, skin and joint improvements — are extrapolations from general growth-hormone pharmacology, not measurements made specifically in a CJC-1295 trial. The class comparator that has been studied: tesamorelin, the only FDA-approved GHRH analog, produced approximately 15-20% reduction in visceral adipose tissue over twenty-six weeks in a 410-patient Phase III trial in HIV-associated lipodystrophy [11][18]. Tesamorelin is structurally adjacent to CJC-1295 but its trial results cannot be assumed to transfer. What is honest: the GH/IGF-1 axis is downstream of CJC-1295 administration, and the GH/IGF-1 axis is mechanistically associated with lipolysis, protein anabolism, and tissue repair. What is honest as a limit: no published CJC-1295 trial has measured those downstream clinical outcomes. ## Reported effects in the body ### Reported effects in the body In published Phase I trials, single doses of CJC-1295 with DAC elevated mean plasma growth hormone 2- to 10-fold and IGF-1 1.5- to 3-fold for six days or longer [1]. Clinical-level body composition data in humans remain limited — Phase I trials were not powered for body-composition endpoints, and no Phase II body-composition trial in healthy populations has been published [1]. ### Body-composition effects in studies No CJC-1295 trial has been adequately powered for body-composition endpoints. The mechanistic association between sustained GH/IGF-1 elevation and lipolysis is established in general growth-hormone pharmacology, but CJC-1295-specific human weight-loss data are limited and short-duration. Tesamorelin, the class comparator, reduced visceral adipose tissue ~15-20% over twenty-six weeks at 2 mg/day SC in a Phase III trial [11]. ## Receptor binding ### Receptor binding GHRH-receptor (GHRHR), a class B G-protein-coupled receptor expressed on anterior-pituitary somatotrophs [7]. Agonist binding activates the Gs / adenylate cyclase / cAMP / PKA pathway, leading to CREB phosphorylation and Pit-1-cooperative transcription of the GH gene [7]. The 2020 cryo-EM structure clarified the binding-pocket architecture engaged by GHRH(1-29)-derived analogs [8]. ## Effects on IGF-1 ### Effects on IGF-1 Phase I trials reported sustained 1.5- to 3-fold IGF-1 elevation lasting approximately six to eleven days after a single DAC-variant dose, with cumulative elevation extending to twenty-eight days under repeat-dose protocols [1][2]. IGF-1 is the downstream hepatic mediator of GH action, with an own plasma half-life of roughly twelve to fifteen hours — long enough to integrate GH exposure over hours-to-days, making it the canonical biomarker of GHRH-analog effect. ## Modified GRF (1-29) ### Modified GRF (1-29) The chemistry-literature name for CJC-1295 without DAC: GHRH (1-29) with four amino-acid substitutions (D-Ala, Gln, Ala, Leu) that protect against enzymatic degradation but lack the DAC linker [12]. Plasma half-life on the order of thirty minutes; brief, pulsatile growth-hormone effect; not albumin-bound. ## References [1] Teichman SL, Neale A, Lawrence B, Gagnon C, Castaigne JP, Frohman LA. 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. 2006;91(3):799-805. https://pubmed.ncbi.nlm.nih.gov/16352683/ [2] Teichman SL, et al. CJC-1295 Phase I pharmacokinetics — half-life and IGF-1 elevation duration data. J Clin Endocrinol Metab. 2006;91(3):799-805. https://pubmed.ncbi.nlm.nih.gov/16352683/ [3] Jetté L, Léger R, Thibaudeau K, et al. Human growth hormone-releasing factor (hGRF)1-29-albumin bioconjugates activate the GRF receptor on the anterior pituitary in rats: identification of CJC-1295 as a long-lasting GRF analog. Endocrinology. 2005;146(7):3052-3058. https://pubmed.ncbi.nlm.nih.gov/15817669/ [4] Jetté L, et al. CJC-1295 albumin-conjugation pharmacokinetics in rats — peptide detectable in plasma beyond 72 hours, 4-fold GH AUC over unmodified GRF. Endocrinology. 2005;146(7):3052-3058. https://pubmed.ncbi.nlm.nih.gov/15817669/ [5] Alba M, Fintini D, Sagazio A, Lawrence B, Castaigne JP, Frohman LA, Salvatori R. Once-daily administration of CJC-1295, a long-acting growth hormone-releasing hormone (GHRH) analog, normalizes growth in the GHRH knockout mouse. Am J Physiol Endocrinol Metab. 2006;291(6):E1290-E1294. https://pubmed.ncbi.nlm.nih.gov/16822960/ [7] Growth hormone-releasing hormone receptor (GHRH-R) and its signaling (review). Rev Endocr Metab Disord. 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC12137518/ [8] Zhou F, Zhang H, Cong Z, Zhao LH, et al. Structural basis for activation of the growth hormone-releasing hormone receptor. Nat Commun. 2020;11(1):5205. https://www.nature.com/articles/s41467-020-18945-0 [11] Falutz J, Allas S, Blot K, et al. Metabolic effects of a growth hormone-releasing factor in patients with HIV. N Engl J Med. 2007;357(23):2359-2370. https://www.nejm.org/doi/full/10.1056/NEJMoa072375 [12] Modified GRF (1-29) — chemistry and pharmacology overview (review compendium, citing primary GRF analog literature). https://en.wikipedia.org/wiki/Modified_GRF_(1-29) [13] Aidsmap editorial. Lipodystrophy study halted after patient death (news report on ConjuChem Phase II CJC-1295 trial). aidsmap.com. 2006. https://www.aidsmap.com/news/jul-2006/lipodystrophy-study-halted-after-patient-death [18] Stanley TL, Feldpausch MN, Oh J, Branch KL, Lee H, Torriani M, Grinspoon SK. Effect of tesamorelin on visceral fat and liver fat in HIV-infected patients with abdominal fat accumulation: a randomized clinical trial. JAMA. 2014;312(4):380-389. https://jamanetwork.com/journals/jama/fullarticle/1889139 --- A compounding-pharmacy reading room for the CJC-1295 research record — Phase I evidence rendered in solid rules, gray-literature claims in dashed ones, no scripts filled on the premises.