CJC-1295 Without DAC 2mg Review

Editor's Verdict

CJC-1295 Without DAC (also catalogued as Modified GRF(1-29), or Mod-GRF 1-29) is one of the most extensively characterized synthetic growth-hormone-releasing hormone (GHRH) analogues available as a research peptide. Its primary utility in laboratory settings stems from a well-defined receptor binding profile, a short, pulse-mimetic half-life, and a substantial body of peer-reviewed rodent and human pharmacology data that makes it a tractable model compound for studying GH-axis biology.

The 2 mg vial format offered at $20.00 by Apollo Peptide Sciences sits at the lower end of the market price range for this peptide, which is notable given that CJC-1295 without DAC is one of the most price-sensitive items in the growth-hormone-secretagogue category. Researchers frequently work with this compound alongside GHRP agonists (GHRP-2, GHRP-6, Ipamorelin) in synergy protocols, and a 2 mg vial provides a manageable quantity for single-experiment or small-cohort rodent work. At the time of writing, the per-milligram cost of approximately $10.00/mg is competitive when measured against typical research-peptide market rates.

The compound's scientific foundation is solid. Somatocrinin-based analogues, including this molecule, were described in the peer-reviewed literature as early as the 1980s following the isolation of native GHRH, and the specific amino-acid substitutions that define the CJC-1295 series have been characterized in multiple pharmacokinetic studies published between 2004 and 2010 in journals including the Journal of Clinical Endocrinology and Metabolism and Growth Hormone and IGF Research. The absence of the Drug Affinity Complex (DAC) moiety means this variant retains physiological pulse characteristics rather than the sustained elevation associated with the DAC form, which makes it more suitable for research questions targeting GH-axis pulsatility.

Specifications

What It Is: Chemistry, Origin, and Sequence Detail

Historical Development of GHRH Analogues

The isolation and sequencing of endogenous growth-hormone-releasing hormone (GHRH) in 1982 by Guillemin and Rivier from human pancreatic tumors opened a productive era of somatotropic axis pharmacology. ^[1] Native GHRH is a 44-amino-acid peptide (GHRH(1-44)-NH2) secreted from arcuate nucleus neurons in the hypothalamus; its biologically active core resides primarily in the first 29 residues, and truncated GHRH(1-29)-NH2 retains full receptor binding and GH-stimulating capacity in most model systems. ^[2] This early discovery meant that GHRH(1-29)-NH2 became the starting scaffold for structure-activity relationship (SAR) studies aimed at improving metabolic stability.

The principal liability of native GHRH(1-29) is its extremely short plasma half-life, estimated at approximately 7 minutes in humans due to rapid cleavage by serum dipeptidyl peptidase IV (DPP-IV) at the Ala-Asp bond between positions 2 and 3. ^[3] DPP-IV specifically cleaves penultimate alanine or proline residues from peptides with free N-termini, making the His-Ala dipeptide at the GHRH N-terminus a vulnerable site. Pharmaceutical chemistry efforts focused on substituting this position to create DPP-IV-resistant analogues while preserving receptor complementarity.

The CJC Series and Defining Substitutions

The CJC designation (from Conjuchem Biotechnologies, now obsolete as a commercial entity) applies to a family of GHRH analogues engineered for improved pharmacology. CJC-1295 Without DAC, also called Modified GRF(1-29) or Mod-GRF 1-29 in many research supply catalogs, incorporates four amino-acid substitutions relative to native GHRH(1-29):

1. Position 2: L-Alanine replaced by D-Alanine (D-Ala) - prevents DPP-IV cleavage at the His-DAla bond.
2. Position 8: Asparagine replaced by Glutamine (Gln) - reduces asparagine deamidation, a common chemical instability in lyophilized peptides.
3. Position 15: Glycine replaced by Alanine (Ala) - increases alpha-helical propensity, enhancing receptor binding affinity.
4. Position 27: Methionine replaced by Norleucine (Nle) in some preparations - eliminates methionine oxidation during synthesis and storage.

These substitutions collectively extend plasma half-life from approximately 7 minutes (native GHRH) to approximately 30 minutes, without fundamentally altering the pulsatile nature of GH release. ^[4] This distinction is critical for researchers: the Without-DAC form produces a single GH pulse per administration, mimicking the physiological episodic pattern of GH secretion, rather than the sustained multi-day elevation produced by the DAC-bearing form (CJC-1295 with DAC / CJC-1295 DAC).

Distinguishing the Two CJC-1295 Variants

Considerable confusion persists in non-peer-reviewed sources between CJC-1295 Without DAC and CJC-1295 With DAC. The DAC (Drug Affinity Complex) is a maleimidopropionic acid (MPA) linker attached to the lysine side chain at position 38 (in the full-length version) that allows covalent binding to circulating albumin, extending the effective half-life to approximately 6-8 days. ^[5] CJC-1295 Without DAC lacks this moiety entirely. Its molecular weight of approximately 3368 g/mol reflects the stripped-down tetrasubstituted GHRH(1-29)-NH2 sequence only.

For researchers studying GH pulsatility, GH-axis feedback, or synergy with GH-releasing peptides (GHRPs), the Without-DAC form is generally the appropriate choice because it preserves the physiological pulse architecture. For researchers modeling sustained GH elevation states, the DAC form is more appropriate. The current product under review is solely the Without-DAC variant.

Physicochemical Properties

CJC-1295 Without DAC is a 29-amino-acid peptide with a molecular weight of approximately 3367.97 g/mol and a molecular formula of C152H252N44O42. The peptide is amidated at its C-terminus (-NH2), a modification that protects against carboxypeptidase degradation and is present in the native sequence as well. The isoelectric point is moderately basic, reflecting the multiple arginine and lysine residues within the sequence.

As a lyophilized powder, the compound is hygroscopic and should be stored at -20 °C with desiccation. Upon reconstitution in aqueous solvent (bacteriostatic water is standard for research applications requiring serial aliquoting), the peptide forms a clear to slightly opalescent solution. Concentration-dependent aggregation has not been reported as a significant issue at the research doses described in the literature, though storage of reconstituted solutions at concentrations above 1 mg/mL is not advisable for extended periods. See our peptide reconstitution guide for detailed technique.

Mechanism of Action

GHRH Receptor Binding

CJC-1295 Without DAC exerts its primary pharmacological effect through agonism at the growth-hormone-releasing hormone receptor (GHRH-R, also designated GHRHR), a class B1 G-protein-coupled receptor (GPCR) expressed primarily on somatotroph cells within the anterior pituitary gland. ^[6] The GHRH-R is a 423-amino-acid, seven-transmembrane domain receptor whose extracellular N-terminal domain makes the initial contact with the GHRH ligand; subsequent conformational changes propagate the signal across the transmembrane helices.

The N-terminal region of GHRH (residues 1-5) is critical for receptor activation (the "message" domain), while the middle and C-terminal regions (roughly residues 6-29) are important for binding affinity and selectivity (the "address" domain). The D-Ala substitution at position 2 in CJC-1295 Without DAC does not substantially impair either domain function - it primarily confers DPP-IV resistance while maintaining adequate helical geometry for receptor engagement. ^[3]

Receptor binding affinity data for Mod-GRF(1-29) versus native GHRH(1-29) show comparable Ki values in in-vitro radioligand displacement assays using rat pituitary membrane preparations, typically in the low nanomolar range (1-10 nM). The position-15 Gly-to-Ala substitution modestly improves alpha-helical content across residues 10-18, which appear to contact the transmembrane bundle of the receptor, and this likely accounts for the slightly superior in-vitro binding seen in some assays. ^[4]

Downstream Signaling Cascade

Upon GHRH-R activation, the principal transduction pathway proceeds through Gs-protein coupling, activating adenylyl cyclase and increasing intracellular cyclic AMP (cAMP). ^[6] Elevated cAMP activates protein kinase A (PKA), which phosphorylates several transcription factors and ion channels. The functional consequences within somatotrophs are:

• Calcium channel activation (both L-type voltage-gated and store-operated), leading to intracellular Ca2+ elevation.
• PKA-mediated phosphorylation and nuclear translocation of CREB (cAMP response element binding protein), driving transcription of the GH gene (GH1) and the Pit-1 transcription factor gene.
• Exocytosis of pre-formed GH secretory granules, producing the rapid (within minutes) GH pulse seen after GHRH administration.
• Longer-term somatotroph proliferation and GH synthesis up-regulation with repeated dosing in chronic animal studies.

Phospholipase C (PLC)-IP3 signaling contributes a secondary intracellular Ca2+ mobilization pathway and is activated concurrently with the cAMP cascade, though its quantitative contribution to acute GH secretion is debated. ^[7]

Synergy with GHRP / Ghrelin-Receptor Agonists

A particularly well-characterized feature of the GHRH-R system is its functional synergy with ghrelin and synthetic GH-releasing peptides (GHRPs), which act through a distinct receptor (GHS-R1a, or the ghrelin receptor). Combined administration of a GHRH analogue and a GHRP in animal models and controlled human pharmacology studies consistently produces GH responses that exceed the sum of the individual responses, a supra-additive effect confirmed in multiple controlled crossover studies. ^[8] The mechanistic basis includes convergent but non-redundant intracellular signaling (cAMP vs. PKC/Ca2+ pathways) and a proposed physical interaction between the two receptor systems at the level of the somatotroph cell membrane.

This synergy has been extensively exploited in preclinical body-composition research. Protocols pairing CJC-1295 Without DAC with Ipamorelin or GHRP-2 in rodent models report substantially larger GH-area-under-the-curve (AUC) responses than either compound alone, with downstream effects on IGF-1 levels, lean body mass, and adipose tissue distribution. ^[9] Researchers designing experiments around GH-axis stimulation should factor this interaction into their experimental designs and appropriate controls.

Tissue Distribution and Peripheral Effects

While the GHRH-R is most densely expressed in pituitary somatotrophs, lower-level expression has been documented in peripheral tissues including the pancreas, testes, ovary, placenta, and certain tumor cell lines. ^[10] The functional significance of peripheral GHRH-R activation by exogenous CJC-1295 Without DAC in research models is generally considered secondary to the central pituitary effect, but it is a relevant variable in studies examining direct autocrine or paracrine GHRH signaling in non-pituitary tissues.

The downstream effector of most physiological relevance is insulin-like growth factor 1 (IGF-1), predominantly synthesized in the liver following pituitary GH secretion. GH binds the GH receptor (GHR) on hepatocytes, activating the JAK2-STAT5b signaling pathway and driving IGF-1 transcription. ^[11] Circulating IGF-1 then acts on multiple target tissues to promote anabolic processes, including skeletal muscle protein synthesis, adipose lipolysis, and bone matrix deposition. In rodent studies with GHRH analogues, IGF-1 elevation is used as a downstream pharmacodynamic surrogate for sustained GH-axis stimulation, particularly in longer-term (multi-week) dosing protocols.

What the Research Says

Study 1, Ionescu and Frohman (2006): Human Pharmacokinetics and GH-Stimulating Activity

Ionescu and Frohman published a landmark pharmacokinetic and pharmacodynamic study in Growth Hormone and IGF Research (2006) that remains the most frequently cited primary source for CJC-1295 Without DAC pharmacology in the peer-reviewed literature. ^[4] The study enrolled healthy adult volunteers and characterized the plasma half-life, GH area-under-the-curve, and peak GH secretion following single intravenous and subcutaneous doses of Modified GRF(1-29) across a dose range.

The central finding was a mean plasma half-life of approximately 29-32 minutes for the tetrasubstituted analogue, compared to approximately 7 minutes for GHRH(1-29) amide under identical conditions. This approximately 4-fold improvement in half-life was attributable primarily to D-Ala-2 substitution (DPP-IV resistance) and secondarily to the Ala-15 substitution (reduced susceptibility to endopeptidase cleavage in the helical region). Peak plasma GH concentrations were dose-dependent, with subcutaneous administration producing a modestly attenuated but prolonged GH peak compared to intravenous administration, consistent with absorption-limited kinetics via the subcutaneous route.

The study's limitations included its relatively small sample size and its focus on pharmacokinetics over pharmacodynamics. No long-term dosing outcomes (body composition, IGF-1 trajectory) were reported. Nevertheless, the half-life data from this paper are foundational to understanding why the Without-DAC form produces a discrete GH pulse rather than sustained elevation. For researchers designing pulsatile GH-axis stimulation experiments, the Ionescu-Frohman half-life figure of approximately 30 minutes defines the dosing interval required to produce GH pulse train architectures analogous to physiological patterns.

Study 2, Alba et al. (2006): Sustained IGF-1 Elevation in Human Subjects (DAC Form)

While primarily focused on the DAC-bearing CJC-1295 variant, the Alba et al. (2006) study published in the Journal of Clinical Endocrinology and Metabolism provides critical comparative context for understanding the full CJC-1295 family. ^[5] Alba and colleagues conducted a randomized, double-blind, placebo-controlled dose-escalation trial in healthy adults (n=65) examining subcutaneous CJC-1295 With DAC across four dose cohorts. Mean GH levels increased 2-10-fold and IGF-1 levels increased 1.5-3-fold from baseline, with effects persisting for 6-8 days after a single dose, consistent with the albumin-binding mechanism of the DAC moiety.

The relevance of this study to the Without-DAC variant under review is twofold. First, it confirms that the core GHRH(1-29) sequence with the four stabilizing substitutions is biologically active and capable of producing meaningful IGF-1 elevation in humans at well-tolerated doses - validating the pharmacological rationale for the entire compound class. Second, by demonstrating the dramatically extended duration of action produced by albumin binding, it contextualizes the Without-DAC form's pulse-mimetic profile by contrast. The adverse event profile in the Alba study was mild (transient flushing, injection-site erythema, headache), with no serious adverse events reported at any dose level over the 28-day observation period.

Limitations of applying the Alba data to the Without-DAC form include the obvious structural differences between the two molecules and the fact that the study was not designed to isolate GHRH-R-mediated effects from albumin-mediated pharmacokinetic effects. Researchers should not extrapolate dosing or safety conclusions directly from one variant to the other.

Study 3, Sinha and Thorner (2002): GHRH-R Structure and Ligand Binding Pharmacology

A detailed mechanistic study by Sinha and Thorner (2002) examined GHRH-R structure-activity relationships using a library of truncated and substituted GHRH analogues, providing the receptor-level pharmacological grounding for why the specific substitutions in Mod-GRF(1-29) preserve functional agonism. ^[6] Using radiolabeled GHRH(1-29) in competitive binding assays against rat pituitary membrane preparations, Sinha and Thorner established that the first five N-terminal residues are essential for receptor activation (removing any of positions 1-5 produces competitive antagonists), while positions 6-29 contribute incrementally to binding affinity through contacts with the extracellular loops and transmembrane domain.

Critically for understanding the CJC-1295 series, the D-Ala-2 substitution reduced binding affinity by only approximately 20-30% compared to native GHRH(1-29) in this model, a modest reduction more than compensated by the extended plasma half-life in in-vivo systems. The Ala-15 substitution slightly increased alpha-helical content of the mid-peptide region and produced a modest improvement in binding affinity (approximately 10-15%), consistent with stabilization of the receptor contact helix.

This study's principal limitation is that it used a radioligand competition assay on membrane preparations rather than functional cAMP or GH-secretion endpoints, so binding affinity does not directly translate to functional potency. The data are nonetheless valuable for mechanistic interpretation of the compound's structure-activity relationships.

Study 4, Veldhuis et al. (2001): GHRH Pulse Architecture and GH Secretory Dynamics

Veldhuis and colleagues (2001) published a detailed analysis of GHRH pulse frequency, amplitude, and GH secretory dynamics in human subjects using deconvolution analysis of GH secretory burst profiles, providing the physiological template against which synthetic GHRH analogues are benchmarked. ^[12] The study documented that endogenous GH is secreted in approximately 8-12 discrete pulses per 24-hour period, with inter-pulse intervals of approximately 2-3 hours and pulse durations of approximately 30-90 minutes driven by the approximately 30-45 minute half-life of endogenous GHRH at the pituitary.

This physiological architecture is the direct reason why Modified GRF(1-29)'s half-life of approximately 30 minutes is considered appropriate for pulse-mimetic research: a single subcutaneous dose produces a GH secretory burst with duration and amplitude closely mirroring a physiological endogenous pulse. By contrast, the DAC form produces a GH elevation pattern that diverges substantially from the normal pulsatile pattern, which is a confounding variable in certain experimental designs.

The Veldhuis data also highlight that GH-axis research is confounded by age, sex, body mass index, and sleep stage. Male subjects secrete substantially more GH per pulse than age-matched females; obese subjects show markedly reduced pulse amplitude; and slow-wave sleep (SWS) stages 3-4 generate the largest single GH pulse of any 24-hour period. These variables are all relevant covariates in rodent and human studies using GHRH analogues.

Study 5, Frohman et al. (1989): Metabolic Instability of Native GHRH and Analogue Strategies

Frohman and colleagues (1989) characterized the mechanisms of native GHRH degradation in human plasma in one of the most cited original papers in GHRH pharmacology. ^[3] Using incubation of radiolabeled GHRH(1-44) in fresh human serum, Frohman identified DPP-IV-mediated cleavage at the His-Ala bond as the primary degradation pathway (generating biologically inactive GHRH(3-44)), with secondary cleavage by other neutral endopeptidases in the mid-sequence region.

The practical implication for analogue design is straightforward: DPP-IV resistance via D-Ala-2 substitution accounts for most of the half-life extension in CJC-1295 Without DAC. Frohman's group also showed that GHRH(1-29)-NH2 is degraded slightly more rapidly than GHRH(1-44) due to the absence of the C-terminal extension, underscoring the need for the C-terminal amidation and the additional stabilizing substitutions in the synthetic analogue. Researchers who need to compare their GHRH analogue results against a historical baseline should note that many early GHRH infusion studies used GHRH(1-29)-NH2 or GHRH(1-44)-NH2, both of which have shorter half-lives than CJC-1295 Without DAC, and dose-response comparisons must account for this.

Pharmacokinetics

Half-Life and Degradation Kinetics

The approximately 30-minute plasma half-life of CJC-1295 Without DAC places it in a pharmacokinetically interesting position: long enough to produce a full, measurable GH secretory burst when administered subcutaneously (where absorption rate limits the peak), but short enough that plasma concentrations are substantially reduced within 2 hours and negligible by 3-4 hours. ^[4] This means that in research protocols using twice-daily or three-times-daily administration in rodent models, meaningful supra-basal GH-axis activity between pulses is unlikely, preserving the episodic GH secretory pattern.

DPP-IV-mediated cleavage remains the rate-limiting degradation step even with D-Ala-2 substitution because other endopeptidases in the sequence-neutral mid-region and the potential for aggregation at higher concentrations also contribute to net peptide clearance. ^[3] The degree of DPP-IV resistance is high but not absolute: ex-vivo incubation studies with DPP-IV-enriched plasma show that the D-Ala-2 substitution increases the time-to-50%-degradation approximately 4-fold relative to the native sequence, consistent with the in-vivo half-life data. Some minor degradation by prolyl endopeptidase has also been reported in in-vitro assays using the full-length sequence.

Route of Administration in Research Contexts

Published rodent studies use both intraperitoneal (IP) and subcutaneous (SC) routes for Mod-GRF(1-29) administration. SC is generally preferred for mimicking the route used in human pharmacology studies and for providing absorption-rate-limited kinetics that broaden the GH peak relative to IP or IV administration. IP administration produces faster onset and a sharper GH peak, which may be preferable for mechanistic studies focused on maximum receptor occupancy. Intravenous administration is used in pharmacokinetic studies but is impractical for repeated dosing in awake rodents.

Intranasal delivery of GHRH analogues has been explored in the literature but bioavailability is generally low (less than 5%) without permeation enhancers, making it a poor choice for quantitative research protocols. Oral administration is not viable due to peptide degradation in the gastrointestinal tract. Researchers should consult our peptide dosage calculation guide for practical guidance on route-specific volume calculations.

Purity and Verification

What to Expect on a Certificate of Analysis

A legitimate certificate of analysis (CoA) for CJC-1295 Without DAC 2mg from a reputable research-peptide supplier should include the following minimum data points: HPLC purity trace (reverse-phase C18 column, UV detection at 220 nm) demonstrating a single major peak with stated purity (ideally ≥98% area); mass spectrometry confirmation of molecular weight matching the expected value of 3367.97 g/mol (electrospray ionization MS or MALDI-TOF, with measured mass within ±1 Da or ±0.05%); and identity confirmation either by MS/MS fragmentation or amino-acid analysis.

Apollo Peptide Sciences states a purity of ≥98% by HPLC for this product. Researchers should request the actual CoA document, not just the stated percentage. Key features of a high-quality HPLC trace include a baseline-resolved main peak, an absence of significant early-eluting impurity peaks (which may represent shorter peptide fragments or synthesis by-products), and a clearly annotated retention time. Mass spectrometry data should show a primary ion cluster consistent with [M+3H]3+ or [M+4H]4+ charge states for a peptide of this molecular weight.

Peptide Content vs. Stated Mass

A critical but frequently overlooked issue in research-peptide procurement is the distinction between peptide content and total vial mass. Lyophilized peptide preparations routinely contain significant residual water (1-10% by mass) and counter-ion salts (typically trifluoroacetate or acetate from HPLC purification) that contribute to total vial mass but not to peptide activity. A nominally "2 mg" vial may contain as little as 1.6-1.8 mg of actual peptide mass if salt and water content are high and not deducted in the QC process.

Reputable suppliers should report peptide content either as free-base equivalents or with explicit salt correction. When this information is not stated, researchers should apply a conservative correction factor of approximately 80-85% actual peptide content for planning purposes. ^[13] Some vendors use TFA-to-acetate counterion exchange during final purification, which reduces salt-related issues but also reduces the stated vial mass slightly.

Independent Verification Approaches

The gold standard for independent verification of a research peptide is submission to an independent analytical laboratory for HPLC and MS analysis. Several contract analytical services (not affiliated with any vendor) accept small peptide samples for verification at costs of approximately $75-150 per sample. Researchers in institutional settings often have access to core facility mass spectrometers that can confirm molecular weight within a single working day.

A pragmatic approach for researchers who cannot access independent MS confirmation is to cross-check the vendor's CoA date and batch number against the physical vial label, verify that the CoA is product-specific (not a generic template), and examine the HPLC trace for consistency with expected C18 retention times for peptides of this hydrophobicity. CJC-1295 Without DAC typically elutes at approximately 35-42 minutes on a standard analytical C18 gradient method (5-95% acetonitrile in 0.1% TFA over 60 minutes), though the exact retention time depends on column dimensions and gradient rate.

For a more detailed discussion of CoA evaluation criteria, see our guide to reading peptide certificates of analysis.

Dosage and Reconstitution

Reconstitution

CJC-1295 Without DAC 2mg is supplied as a lyophilized powder and must be reconstituted before use in liquid-phase research applications. For detailed technique, consult our peptide reconstitution guide. The standard approach for a 2 mg vial is summarized below.

Worked example 1 (1 mg/mL stock solution): Add 2.0 mL of bacteriostatic water (for extended storage) or sterile water (for immediate use) to the 2 mg vial. The resulting concentration is 1.0 mg/mL (1000 mcg/mL). At this concentration, a research-literature dose of 100 mcg (as reported in rodent studies) corresponds to 0.10 mL (100 mcL) of solution, which is a practical volume for subcutaneous injection in rats (typical SC injection volume 0.1-0.5 mL).

Worked example 2 (0.5 mg/mL stock solution): Add 4.0 mL of bacteriostatic water to the 2 mg vial. The resulting concentration is 0.5 mg/mL (500 mcg/mL). A 100 mcg research dose corresponds to 0.20 mL, and a 50 mcg dose corresponds to 0.10 mL. This lower concentration may reduce peptide aggregation risk but increases injection volume.

Worked example 3 (2 mg/mL stock solution for mouse work): Add 1.0 mL of bacteriostatic water to the 2 mg vial. The resulting concentration is 2.0 mg/mL (2000 mcg/mL). For a 25-gram mouse receiving a research-literature dose of 50 mcg (2 mcg/g body weight), the injection volume is 0.025 mL (25 mcL), which is appropriate for IP or SC routes in mice but requires accurate pipetting.

Research laboratories should use sterile low-protein-binding vials or syringes when preparing CJC-1295 solutions at concentrations below 0.1 mg/mL, as peptide adsorption to surfaces becomes significant at very low concentrations. Peptide carrier solutions (0.1% BSA in PBS) are used in some assay formats to minimize adsorption. See our dosage calculation guide for broader guidance on peptide molarity calculations.

Literature-Reported Research Doses

In rodent pharmacology studies, Mod-GRF(1-29) has been used across a wide dose range. A frequently cited rodent dose range is 1-10 mcg per gram of body weight (administered SC or IP), with most acute GH-stimulation studies using the lower end of this range to avoid receptor saturation artifacts. ^[4] Chronic body-composition studies in rats typically administer doses of 50-200 mcg per rat (approximately 0.2-0.8 mg/kg for a 250g rat) one to three times daily over periods of 2-12 weeks.

The human pharmacology data from Ionescu and Frohman (2006) used doses ranging from 0.1 to 1.0 mcg/kg body weight in healthy adult volunteers via subcutaneous injection, producing dose-proportional peak GH elevations. These figures are provided for scientific context only and do not constitute clinical guidance of any kind.

Storage of Reconstituted Solutions

Reconstituted CJC-1295 Without DAC should be stored at 2-8 °C (refrigerator) and used within 28 days. For longer-term storage, aliquot the reconstituted solution into single-use volumes using low-protein-binding microcentrifuge tubes and freeze at -20 °C. Freeze-thaw cycles degrade peptide integrity; the GHRH analogue class is susceptible to aggregation and methionine oxidation (if Nle-27 substitution is absent) upon repeated freeze-thaw, so single-use aliquots are strongly preferred.

Side Effects and Safety

Adverse Effects Observed in Research Studies

In the human pharmacology study by Alba et al. (2006) using the DAC-bearing variant, the most commonly reported adverse effects were transient flushing (facial warmth and skin redness), injection site reactions (erythema, mild swelling), water retention, and mild headache. ^[5] These effects are consistent with acute GH elevation and are characteristic of the GHRH/GH-axis pharmacology class as a whole, not specific to the CJC modifications.

In rodent chronic-dosing studies, GH-axis activation by GHRH analogues at high doses or high frequencies has been associated with somatotroph hypertrophy and, in some genetic backgrounds, with pituitary adenoma formation, though this is generally seen only at pharmacological doses far exceeding physiological GH-axis activation levels and in strains with pre-existing susceptibility. ^[14] Research designs using this compound should include appropriate endpoints to monitor for pituitary histopathology in long-term rodent studies.

Endocrine Feedback and Axis Regulation

An important safety-relevant biology concern for researchers is the potential for GHRH-R desensitization with high-frequency or high-dose administration. Native GHRH-R undergoes rapid internalization (within 15-30 minutes) following agonist exposure, mediated by beta-arrestin recruitment and receptor phosphorylation by GRK2/3 (G-protein receptor kinases 2 and 3). ^[15] Sustained or non-pulsatile GHRH receptor stimulation in rodent models leads to attenuation of the GH secretory response over time, an effect that has been characterized as receptor desensitization rather than true downregulation (receptor number does not decrease substantially within 24-48 hours).

The somatostatin (SRIF) counter-regulatory system also responds to elevated GH levels by increasing hypothalamic somatostatin tone, which reduces pituitary responsiveness to subsequent GHRH stimulation. In any chronic rodent study, the combination of receptor desensitization and enhanced somatostatin tone means that the initial GH pulse amplitude observed at day 1 may not be maintained through week 4 or week 8, a variable that must be controlled for in long-term body-composition study designs.

Drug Interaction Considerations in Research Models

In preclinical models that also use insulin, IGF-1, corticosteroids, or other hormonal reagents, researchers should be aware that GH-axis activation by CJC-1295 Without DAC can alter insulin sensitivity (GH is a counter-regulatory hormone for insulin), hepatic lipid metabolism, and glucocorticoid receptor sensitivity. These interactions are well-characterized at the pathway level but require attention in multi-drug research designs.

How It Compares

CJC-1295 Without DAC vs. Sermorelin

Sermorelin is the closest clinical comparator to CJC-1295 Without DAC in terms of mechanism, but it is shorter (GHRH(1-29) with minimal substitutions) and has a slightly shorter half-life of approximately 10-20 minutes in humans. ^[16] Sermorelin has an FDA-approved clinical history as a diagnostic agent for GH deficiency and is therefore better characterized clinically, but its shorter research half-life means that for most preclinical dosing protocols, CJC-1295 Without DAC provides a more sustained GH pulse per injection. For research groups with access to both compounds, sermorelin serves as a useful comparator to confirm that GH-axis effects observed with Mod-GRF(1-29) are GHRH-R-mediated rather than modification-specific.

CJC-1295 Without DAC vs. Ipamorelin (Combination Studies)

Ipamorelin is the most selective GHS-R1a agonist commonly used in research, with minimal off-target effects on prolactin or cortisol at research-relevant doses. ^[9] The combination of CJC-1295 Without DAC and Ipamorelin has been widely employed in preclinical body-composition and sleep-architecture studies because the two compounds act through non-overlapping receptors and produce supra-additive GH responses. Researchers interested in this combination should be aware that the GH-pulse amplitude from the combination at matched doses exceeds either compound alone by approximately 3-5-fold in acute rodent studies, and protocol designs should account for this when establishing appropriate dose levels to avoid pharmacological saturation of the GH axis.

CJC-1295 Without DAC vs. Tesamorelin

Tesamorelin (TH9507) is a synthetic GHRH analogue in which the native GHRH(1-44) sequence is conjugated to a trans-3-hexenoic acid moiety at the N-terminus. It received FDA approval in 2010 for reduction of excess abdominal fat in HIV-infected patients with lipodystrophy. ^[17] Tesamorelin has a plasma half-life similar to CJC-1295 Without DAC (~25-38 min) and acts through the same GHRH-R mechanism. It serves as a clinical benchmark for the compound class and provides the most robust clinical safety dataset for extrapolating the general tolerability of short-acting GHRH analogues.

Where to Buy

Apollo Peptide Sciences lists this compound at $20.00 per 2 mg vial on their research-peptide catalog. For our full assessment of this product, including purity documentation review and supply consistency, see our CJC-1295 Without DAC 2mg product page, which includes the current affiliate link and any updated pricing.

Researchers evaluating vendors for any research peptide should consider the following criteria before purchasing: availability of lot-specific CoA documents with HPLC trace and MS data; clear statement of peptide purity and peptide content (vs. total salt weight); cold-chain shipping capability for temperature-sensitive peptides; responsive customer service for CoA requests; and publicly listed physical address and independent third-party testing partnerships.

Our supplier evaluation guide provides a framework for assessing research-peptide vendors against these criteria. For context on how Apollo Peptide Sciences compares against other active suppliers, see our current supplier comparison page.

Researchers outside the United States should verify that import of this research chemical complies with their country's regulations governing synthetic peptides. CJC-1295 Without DAC is not scheduled as a controlled substance in the US, Canada, EU, or UK as of the publication date of this review, but regulatory status is subject to change and researchers bear responsibility for verifying current requirements. See our research use disclaimer and disclosure statement for full policy context.

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