What is the difference between CJC-1295 with DAC and Modified GRF(1-29)?

Both are synthetic analogs of GHRH, but they are chemically distinct. CJC-1295 with DAC includes a maleimide-based modification that allows it to bind albumin in the bloodstream, extending its half-life to roughly six to eight days in human pharmacokinetic studies. Modified GRF(1-29), also called Mod GRF 1-29, uses amino acid substitutions to resist enzymatic degradation but does not bind albumin. Its active half-life is measured in minutes rather than days. In practice, CJC-1295 DAC is associated with sustained IGF-1 elevation between doses, while Mod GRF 1-29 is used for acute, pulse-style administration.

Why is ipamorelin considered more selective than GHRP-2 or GHRP-6?

Preclinical research published in 1998 by Raun and colleagues at Novo Nordisk showed that ipamorelin produced potent growth hormone release in animal models with substantially smaller increases in cortisol and prolactin compared to GHRP-2 and GHRP-6 at matched effective doses. The mechanistic explanation involves differences in how each peptide interacts with receptor subtypes and downstream signaling. Whether the same selectivity holds at the same magnitude in humans has not been established through a published head-to-head clinical trial.

Is there clinical evidence specifically for the CJC-1295 and ipamorelin combination?

No published randomized controlled trial has studied the combination as of early 2026. The rationale for pairing them is based on established pharmacology showing that GHRH analogs and ghrelin receptor agonists activate separate intracellular pathways in pituitary cells that produce a synergistic GH response when co-stimulated. This synergism is well-documented in animal models and fits the basic science, but the specific clinical evidence base for the human combination is extrapolated from individual compound data rather than from a controlled combination study.

Are CJC-1295 or ipamorelin approved for any medical use?

No. CJC-1295 was studied in a Phase 2 trial by ConjuChem but did not progress to approval. Ipamorelin entered human trials for postoperative ileus but also did not receive approval. Neither compound has an approved indication in the United States, European Union, or other major regulatory jurisdictions. They are not approved for human use, and products sold as research chemicals are not subject to pharmaceutical manufacturing or labeling standards.

CJC-1295 and Ipamorelin: The Research Behind the GH Stack

Published: May 1, 2026•Updated: May 1, 2026

Research use only. This article discusses compounds that include approved medications, investigational drugs, and research peptides. Material sold for research is not cleared for human administration and is not a substitute for medical advice.

CJC-1295 and ipamorelin are two of the most widely discussed research peptides in the growth hormone axis category. They act through different but complementary mechanisms, which is why researchers often study them together. This article covers what each compound is, what the published literature reports, and where the current evidence ends.

What CJC-1295 is

CJC-1295 is a synthetic analog of growth hormone releasing hormone (GHRH), the hypothalamic signal that tells the pituitary to produce and release growth hormone. The parent sequence that researchers started from is the first 29 amino acids of native GHRH, sometimes written as GRF(1-29). Native GRF(1-29) has a very short active half-life in circulation because it is rapidly cleaved by proteases including dipeptidyl peptidase IV.

The compound sold as CJC-1295 incorporates a technology called the Drug Affinity Complex (DAC), developed by ConjuChem. The DAC modification allows the peptide to form a covalent bond with albumin, the most abundant protein in blood plasma. Albumin has a much longer biological half-life than free peptides, so the albumin-bound form of the compound circulates for days rather than minutes. A related but distinct compound, sometimes called Modified GRF(1-29) or Mod GRF 1-29, uses a different set of amino acid substitutions to resist enzymatic degradation but does not include the DAC albumin-binding element and has a much shorter duration of action.

CJC-1295 versus Modified GRF(1-29)

These two names are sometimes used interchangeably in informal channels, but they refer to chemically distinct peptides with very different pharmacokinetics. CJC-1295 with DAC has an estimated half-life of around six to eight days in humans. Mod GRF 1-29 without DAC has a half-life measured in minutes, similar to GHRP peptides it is often paired with. The original ConjuChem Phase 2 clinical data refers specifically to the DAC version.

What ipamorelin is

Ipamorelin is a synthetic pentapeptide that acts as an agonist at the ghrelin receptor, also called the growth hormone secretagogue receptor type 1a (GHS-R1a). Compounds that bind this receptor stimulate the pituitary to release growth hormone, but they do so through a pathway that is distinct from and synergistic with the GHRH pathway. Ipamorelin was characterized by researchers at Novo Nordisk and published in the European Journal of Endocrinology in 1998.

What distinguished ipamorelin from earlier growth hormone releasing peptides like GHRP-2 and GHRP-6 was its selectivity profile. In preclinical studies, the older GHRPs produced substantial increases in cortisol and prolactin alongside growth hormone elevation, which raised questions about tolerability and application. Published animal data showed that ipamorelin produced strong growth hormone release at relatively low doses with considerably less effect on cortisol and prolactin secretion. Whether this selectivity translates cleanly to the same magnitude of difference in humans is an ongoing research question.

Why the two compounds are studied together

GHRH analogs and ghrelin receptor agonists work through different intracellular signaling pathways inside pituitary somatotroph cells, the cells responsible for growth hormone synthesis and secretion. GHRH signals primarily through cyclic AMP, while ghrelin receptor agonists work through a calcium-dependent pathway. When both pathways are activated simultaneously, the growth hormone response is larger than what either stimulus produces alone, a pharmacological interaction that researchers describe as synergism.

•GHRH analogs like CJC-1295 set the background secretory capacity of somatotroph cells by upregulating GH gene transcription
•Ghrelin receptor agonists like ipamorelin amplify the magnitude of individual GH pulses
•The two signals together produce GH release that is greater than the sum of each signal separately, based on animal models and pharmacological theory
•Mod GRF 1-29 (the short-acting version) is often timed with ipamorelin to produce a coordinated pulse, while CJC-1295 DAC is used for sustained background elevation
•Neither combination has been studied in a published randomized controlled trial as of early 2026

The synergistic concept is well-supported at the level of basic pharmacology and animal research. The specific optimization of dose timing and ratio for human use is extrapolated from first principles rather than from controlled human data, which is an important distinction for anyone evaluating the literature.

What clinical research has been published

The human trial data that exists is for CJC-1295 as a single compound, not for the combination with ipamorelin. The most significant published trial is a Phase 2 study from ConjuChem, published in the Journal of Clinical Endocrinology and Metabolism in 2006 by Teichman and colleagues.

CJC-1295 Phase 2 trial (Teichman et al., JCEM 2006)

This trial enrolled healthy adults and tested multiple single and repeat doses of CJC-1295 DAC. Across dose groups, the compound produced dose-dependent increases in mean 24-hour GH concentrations and IGF-1 levels. The GH and IGF-1 elevations persisted for several days after a single injection, consistent with the albumin-bound half-life. Multiple weekly injections produced further sustained increases. No serious adverse events were attributed to the compound in the report.

Ipamorelin progressed into human clinical trials at Novo Nordisk for a different indication. The compound was studied for its effects on gastrointestinal motility, specifically postoperative ileus, based on observations that ghrelin receptor agonists may accelerate gut recovery after surgery. Those trials did not advance to registration, and ipamorelin has not been approved by any regulatory agency for any indication.

For the CJC-1295 plus ipamorelin combination specifically, no published Phase 2 or Phase 3 human trial exists as of early 2026. The rationale for combining them is grounded in well-established pharmacology, but the clinical evidence base is extrapolated from individual compound data and animal research rather than from a controlled study of the combination.

Safety profile and known concerns

The safety signals reported in published research for each compound are relatively limited given the small number of human trials conducted. The adverse events noted in the CJC-1295 Phase 2 trial included mild injection site reactions and transient flushing. Water retention and peripheral edema are commonly reported with GH-elevating compounds generally and would be an expected area of monitoring.

Growth hormone elevation at any level raises a theoretical concern about effects on glucose metabolism. GH is counter-regulatory to insulin, meaning elevated GH can reduce insulin sensitivity. In the ConjuChem trial, glucose and insulin measures were collected, and no clinically significant changes were reported at the doses studied, but the trial was not powered or designed to evaluate metabolic safety as a primary endpoint.

A concern raised with any GH-stimulating compound is whether sustained elevation of IGF-1 could theoretically promote the proliferation of pre-existing tumors. This is a theoretical risk based on the known biology of IGF-1 signaling in cancer cell lines, not an observed clinical outcome in the limited human trials conducted. It is a standard cautionary note in the endocrinology literature on any intervention that raises IGF-1.

•Injection site reactions (redness, mild swelling) are the most commonly reported adverse event in published trials
•Transient flushing and headache have been reported
•Ghrelin receptor agonists including ipamorelin tend to stimulate appetite, though ipamorelin is reported to have a smaller appetite effect than GHRP-6
•Tingling or paresthesia in the hands is associated with growth hormone elevation generally and has been reported anecdotally with this class
•Long-term safety data in humans does not exist for either compound at the doses used in research chemical contexts

The research chemical market

Both CJC-1295 and ipamorelin are sold as research chemicals by peptide suppliers marketing them for laboratory and in vitro use. Neither compound has been approved by the FDA or any other major regulatory agency for human therapeutic use. Products from research chemical suppliers have not undergone the manufacturing controls, stability testing, or identity verification required for pharmaceutical products, and purity cannot be assumed without independent analytical testing.

The World Anti-Doping Agency (WADA) prohibits growth hormone releasing hormones and their analogs, including CJC-1295, under the Growth Hormone Releasing Factors category. Ghrelin mimetics and GHS-R1a agonists are prohibited under the Peptide Hormones category. Both classes are banned in competition and out of competition for athletes subject to WADA rules. This is not a medical safety judgment but reflects the regulatory framework governing competitive sport.