What does CJC-1295 do?

CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH) that stimulates the pituitary gland to produce and release growth hormone. A single injection of CJC-1295 with DAC produces dose-dependent GH increases of 2-10 fold lasting 6 or more days and IGF-1 increases of 1.5-3 fold lasting 9-11 days in healthy adults. It preserves the natural pulsatile pattern of GH secretion.

What is the difference between CJC-1295 with DAC and without DAC?

CJC-1295 with DAC includes a Drug Affinity Complex that binds to blood albumin, extending the half-life to 6-8 days, allowing weekly injections. CJC-1295 without DAC (Mod GRF 1-29) has the same amino acid substitutions but no albumin-binding group, giving it a half-life of approximately 30 minutes, requiring 2-3 daily injections. They produce different GH elevation patterns.

Is CJC-1295 FDA approved?

No. CJC-1295 has no FDA-approved indications for human use. Clinical development was discontinued after Phase II trials. It is available through research suppliers and some compounding pharmacies, but the FDA has taken regulatory action regarding compounded peptides. The only FDA-approved GHRH analog is tesamorelin (Egrifta), approved for HIV-associated lipodystrophy.

Why is CJC-1295 combined with ipamorelin?

CJC-1295 (a GHRH analog) and ipamorelin (a GH-releasing peptide) work through different receptors and signaling pathways on pituitary cells. Combining them produces synergistic GH release greater than either alone. This pairing is common in peptide therapy protocols, though no published clinical trial has specifically studied this combination in humans.

Does CJC-1295 build muscle or burn fat?

CJC-1295 elevates GH and IGF-1, hormones involved in body composition regulation. However, no controlled clinical trial has measured body composition, muscle strength, or fat loss as outcomes of CJC-1295 treatment. The assumption that GH elevation translates to meaningful body composition changes in GH-sufficient adults is based on GH biology, not CJC-1295-specific evidence.

CJC-1295 and IGF-1

CJC-1295: The GHRH Analog Explained

13 min read|March 21, 2026

CJC-1295 and IGF-1

6-8 day half-life

CJC-1295 with DAC maintains elevated growth hormone levels for nearly a week after a single injection, compared to minutes for native GHRH.

Teichman et al., Journal of Clinical Endocrinology & Metabolism, 2006

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CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH), the hypothalamic peptide that signals the pituitary gland to produce and release growth hormone. Developed by ConjuChem Biotechnologies (now ConjuChem LLC), it was designed to solve a fundamental pharmacological problem: native GHRH has a plasma half-life of less than 10 minutes, making it impractical as a therapeutic agent. CJC-1295 extends that half-life to 6-8 days through a technology called Drug Affinity Complex (DAC), which covalently binds the peptide to circulating albumin after injection. For the broader evidence on what this GH elevation produces downstream, see our pillar guide to CJC-1295 and IGF-1 elevation.

The result is a peptide that produces sustained, dose-dependent elevation of both growth hormone and insulin-like growth factor 1 (IGF-1) from a single weekly injection. This pharmacokinetic profile made CJC-1295 one of the most discussed peptides in the growth hormone optimization space. It is also one of the most misunderstood, with claims about its effects often running far ahead of the published evidence. This article covers what the actual clinical data shows, what the two versions of CJC-1295 are, how the compound compares to other GHRH analogs, and what remains unproven.

Key Takeaways

A single injection of CJC-1295 with DAC produced dose-dependent GH increases of 2-10 fold lasting 6+ days and IGF-1 increases of 1.5-3 fold lasting 9-11 days in healthy adults (Teichman et al., 2006)
CJC-1295 normalized growth in GHRH knockout mice through once-daily administration, confirming it activates the same pituitary pathway as native GHRH (Alba et al., 2006)
The DAC (Drug Affinity Complex) technology covalently binds the peptide to blood albumin after injection, extending half-life from minutes to approximately 6-8 days
CJC-1295 preserves the pulsatile pattern of GH secretion rather than producing a continuous flat elevation, which distinguishes it from exogenous GH injection
The peptide has no FDA-approved indications and is classified as a research compound; clinical development was discontinued after Phase II
"CJC-1295 without DAC" (also called Mod GRF 1-29) is a different compound with a much shorter half-life and different dosing requirements

What CJC-1295 Is and How It Works

Native GHRH is a 44-amino-acid peptide released by the hypothalamus in pulsatile bursts. It travels through the portal blood system to the anterior pituitary, where it binds GHRH receptors on somatotroph cells and triggers growth hormone synthesis and release. The biological activity of GHRH resides in its first 29 amino acids; the remaining 15 are not required for receptor binding.^[5]

CJC-1295 is based on this active 29-amino-acid fragment, with four amino acid substitutions that protect it from enzymatic degradation (specifically from dipeptidyl peptidase IV, which cleaves native GHRH at position 2). These modifications alone extend the half-life to approximately 30 minutes. The DAC technology adds a further extension: a reactive chemical group (a maleimido moiety) is attached to the peptide, which after subcutaneous injection reacts with a lysine residue on serum albumin, forming a stable covalent bond. This albumin conjugation is what produces the 6-8 day half-life.^[1]

The mechanism of action is identical to native GHRH: binding to GHRH receptors on pituitary somatotrophs, activating the cAMP/PKA signaling pathway, and stimulating GH gene transcription and GH release. In GHRH receptor knockout mice, CJC-1295 had no effect, confirming that it works exclusively through the GHRH receptor and does not have off-target activity on other GH-regulatory pathways.^[1]

The Clinical Data

The most important clinical study of CJC-1295 was a 2006 Phase I/II trial published in the Journal of Clinical Endocrinology & Metabolism. Teichman and colleagues administered single subcutaneous injections of CJC-1295 with DAC at doses of 30, 60, and 90 mcg/kg to healthy adults aged 21-61.

The results were striking. GH levels increased in a dose-dependent manner: 2-fold at the lowest dose and up to 10-fold at the highest dose, with elevations persisting for 6 or more days after a single injection. IGF-1 levels rose 1.5 to 3-fold and remained elevated for 9-11 days. The estimated half-life was 5.8-8.1 days, roughly 1,000 times longer than native GHRH.

A separate study confirmed that CJC-1295 preserved the pulsatile pattern of GH secretion. Rather than producing a constant flat elevation (as occurs with exogenous GH injection), CJC-1295 increased both the trough and peak levels of GH pulses while maintaining their rhythmic pattern. This is physiologically relevant because pulsatile GH secretion is believed to be important for the hormone's metabolic effects, including lipolysis and tissue repair. Continuous GH exposure downregulates GH receptors in target tissues, potentially reducing effectiveness over time. Pulsatile delivery, by contrast, allows receptor resensitization between pulses, which may maintain tissue responsiveness during chronic treatment.^[7]

The treatment was described as "safe and relatively well tolerated" at doses of 30 and 60 mcg/kg. The most common side effects were injection site reactions, transient flushing, and headache. At the highest dose (90 mcg/kg), some subjects experienced water retention and joint stiffness consistent with GH elevation.

CJC-1295 with DAC vs. Without DAC

Two compounds circulate under the CJC-1295 name, and the distinction matters.

CJC-1295 with DAC is the original compound developed by ConjuChem. It includes the Drug Affinity Complex that enables albumin binding and produces the 6-8 day half-life described above. This is the version studied in the published clinical trials.

CJC-1295 without DAC, commonly called Modified GRF (1-29) or Mod GRF 1-29, contains the same four amino acid substitutions but lacks the DAC moiety. Without albumin binding, its half-life is approximately 30 minutes. This version requires multiple daily injections (typically 2-3 times daily) to produce sustained GH elevation, and each injection produces a sharp GH pulse followed by rapid decline. For details on this shorter-acting version, see our article on Mod GRF 1-29.

The two versions produce qualitatively different GH profiles. CJC-1295 with DAC creates a sustained elevation that lasts days. Mod GRF 1-29 creates brief spikes that mimic (and amplify) the body's natural GH pulses. Some practitioners argue the pulsatile profile of Mod GRF is more physiological; others prefer the convenience of weekly dosing with DAC. No head-to-head comparison has been published, and the clinical significance of these different profiles is unknown.

The naming confusion has led to considerable misinformation. Many online discussions and peptide vendor descriptions conflate the two compounds, and research findings from one version are frequently attributed to the other. Understanding the mechanism of action requires knowing which version is being discussed.

Why Development Was Discontinued

Despite promising Phase I/II data, CJC-1295 with DAC did not progress to Phase III trials or FDA approval. ConjuChem Biotechnologies encountered financial difficulties, and clinical development was halted. A participant death during a clinical trial (attributed to a pre-existing cardiac condition unrelated to the drug by investigators, but still a regulatory setback) further complicated the development path.

The broader context is that the GHRH analog space has been difficult commercially. Tesamorelin (Egrifta), the only FDA-approved GHRH analog, received approval specifically for HIV-associated lipodystrophy, a narrow indication. Sermorelin, another GHRH analog that preceded CJC-1295, was approved for GH deficiency diagnosis and treatment in children but was commercially discontinued. The market dynamics favor direct GH replacement (which is well-established and covered by insurance for approved indications) over GHRH stimulation, despite the theoretical advantages of preserving physiological GH pulsatility.

CJC-1295 remains available through research chemical suppliers and compounding pharmacies, though the FDA has taken regulatory action regarding compounded peptides. It has no approved indications for human use in any country.^[2]

The GHRH vs. GHRP Distinction

CJC-1295 is frequently combined with GH-releasing peptides (GHRPs) like ipamorelin or GHRP-6 in research and clinical practice. Understanding why requires knowing how the two peptide classes differ.

GHRH analogs like CJC-1295 work by stimulating the GHRH receptor on pituitary somatotrophs, directly driving GH synthesis and release through the cAMP pathway. GHRPs work through a completely different receptor: the growth hormone secretagogue receptor (GHS-R1a), also known as the ghrelin receptor. GHRPs amplify GH release through a separate intracellular signaling cascade (the IP3/DAG pathway) and also suppress somatostatin, the peptide that inhibits GH release.^[3]^[9]

Because the two pathways converge on the somatotroph from different directions, combining a GHRH analog with a GHRP produces synergistic (greater than additive) GH release. Studies in animal models and in vitro pituitary cell preparations have demonstrated that simultaneous GHRH and GHRP stimulation produces GH release several fold greater than either stimulus alone.^[7]^[8]

This synergy is the rationale for the CJC-1295 + ipamorelin combination popular in peptide therapy clinics. The combination has no published human clinical trial data specifically evaluating the pairing, so evidence for this protocol relies on extrapolation from the mechanistic data and individual agent studies. For more on how growth hormone peptides affect sleep and body composition, the evidence base is similarly limited to individual peptide studies.

What Remains Unproven

The published clinical data for CJC-1295 establishes three things: it elevates GH and IGF-1, it does so for a sustained duration, and it preserves GH pulsatility. What it does not establish is whether these biochemical changes translate into meaningful clinical outcomes.

The Phase I/II trial measured hormone levels, not endpoints like body composition change, muscle strength, bone density, fat loss, sleep quality, or tissue repair. The assumption that elevating GH and IGF-1 will produce these outcomes is based on GH biology, not on CJC-1295-specific evidence. Growth hormone deficiency causes increased body fat, decreased lean mass, reduced bone density, and impaired quality of life. Replacing GH in deficient patients reverses many of these changes. But whether stimulating GH release via CJC-1295 in GH-sufficient adults produces meaningful improvements is an untested hypothesis.^[4]

The safety profile is similarly incomplete. The published trial data covers short-term use in a small number of healthy volunteers. Long-term effects of sustained GH elevation via CJC-1295, including potential impacts on insulin sensitivity, cancer risk (GH and IGF-1 are mitogenic), and joint health, have not been studied in controlled settings.^[6]^[10]

This evidence gap is not unique to CJC-1295. The entire growth hormone secretagogue class, from MK-677 to hexarelin, shares the same pattern: robust pharmacokinetic and pharmacodynamic data demonstrating GH elevation, but limited or absent controlled outcome data for the endpoints that users care about. The question of whether GH peptides can build muscle or reduce visceral fat remains open for all members of this drug class, not just CJC-1295. The role of somatostatin as the natural brake on GH secretion also raises questions about whether chronic GHRH stimulation might eventually trigger compensatory somatostatin upregulation that blunts the response over time, a phenomenon called tachyphylaxis that has not been adequately studied with CJC-1295.

The Bottom Line

CJC-1295 with DAC is one of the most pharmacologically impressive peptides in the growth hormone space: a single injection produces sustained GH and IGF-1 elevation for approximately one week while preserving the body's natural pulsatile secretion pattern. The Phase I/II clinical data is clean and compelling for what it measured (hormone levels and short-term safety). The gap between that data and the clinical outcomes attributed to the peptide (fat loss, muscle gain, improved recovery, better sleep) is large and unbridged by controlled trials. CJC-1295 remains a research compound with promising pharmacology but incomplete clinical evidence.