CJC-1295 / Ipamorelin: A Two-Receptor GH Research Stack

The short version

CJC-1295 / Ipamorelin is a two-peptide research combination. CJC-1295 is a long-acting analogue of growth-hormone-releasing hormone (GHRH), the pituitary's natural "make more GH" signal. Ipamorelin is a synthetic pentapeptide that activates a second, independent receptor on the same pituitary cells — the ghrelin receptor (GHS-R1a). Because the two arms use different molecular switches, co-stimulating them produces a GH pulse meaningfully larger than either peptide alone, which is the mechanistic rationale for the combination ^[5][7].

The honest assessment: a single subcutaneous dose of CJC-1295 raised GH two- to ten-fold for six or more days in healthy adults ^[3], and ipamorelin added a selective GH pulse without raising cortisol or ACTH even at large doses ^[6]. But the fixed CJC-1295 + ipamorelin combination has never been evaluated in a controlled clinical trial — its profile is inferred entirely from separate-component studies and general GHRH+GHRP synergy work ^[2]. Neither compound is FDA-approved for any human indication. This page summarizes what the literature shows; it lists no dose and gives no medical advice.

What it is

CJC-1295 is a tetrasubstituted analogue of the first 29 residues of human growth-hormone-releasing factor, hGRF(1-29)NH2. Four amino-acid substitutions stabilize the alpha-helix and block enzymatic breakdown. In the DAC (Drug Affinity Complex) variant, a C-terminal lysine carries a maleimidopropionyl linker that undergoes Michael addition with the free thiol on Cys34 of circulating serum albumin, forming a covalent peptide-albumin conjugate that extends the half-life toward albumin's own multi-day duration ^[4]. The no-DAC form (also called Modified GRF 1-29) keeps the four substitutions but lacks this albumin-binding chemistry and is therefore short-acting.

Ipamorelin is a synthetic pentapeptide, Aib-His-D-2-Nal-D-Phe-Lys-NH2, with D-configured residues conferring protease resistance. It is classified as a selective growth hormone secretagogue because, unlike earlier growth-hormone-releasing peptides, it activates GHS-R1a without meaningfully raising ACTH, cortisol, or prolactin ^[6].

The combination is sold as a research chemical under various names including "CJC-1295 with DAC + Ipamorelin" and "GHRH + GHRP stack"; it is not an approved pharmaceutical product.

How it works

The two components act through mechanistically distinct and complementary pathways on pituitary somatotroph cells.

CJC-1295 binds the GHRH receptor (a class-B GPCR), activating the Gs/cAMP/PKA cascade that drives GH synthesis and release. In the DAC form, covalent albumin binding in rat plasma produced approximately a four-fold increase in GH area under the curve over two hours versus plain hGRF(1-29), with detectable albumin-bound peptide in plasma beyond 72 hours ^[4]. In healthy adults, this translated to multi-day GH and IGF-1 elevation per dose ^[3].

Ipamorelin binds GHS-R1a (the ghrelin receptor) on the same pituitary cells, raising intracellular calcium via Gq rather than cAMP, and triggering a discrete GH pulse. Because this is a Gq/calcium pathway rather than a Gs/cAMP pathway, the two arms do not simply add — they converge on GH release through independent intracellular machinery.

Synergy. In transfected HeLa cells co-expressing both the GHRH receptor and GHS-R1a, co-activation produced a cAMP response approximately twice that of GHRH-receptor activation alone, demonstrating direct receptor-level cross-talk ^[5]. In healthy adult men, submaximal GHRP + GHRH doses each too small to produce maximal GH release together produced supra-additive GH output ^[7]. This dual-receptor convergence is the primary scientific rationale for studying the combination.

What the research shows

GHRH-analogue class human data. A 2026 meta-analysis of five RCTs of tesamorelin — a closely related GHRH analogue — found significant reductions in visceral adipose tissue (mean difference −27.71 cm²) and hepatic fat (−4.28%), increased lean body mass (+1.42 kg) and IGF-1, with no serious adverse events or glucose perturbation ^[1]. This is the freshest high-quality human evidence for GHRH-analogue stimulation of the GH/IGF-1 axis, providing read-across context for the GHRH arm of the combination.

CJC-1295 DAC pharmacodynamics. A single subcutaneous dose (30 or 60 micrograms per kilogram) in healthy adults aged 21–61 produced 2- to 10-fold increases in mean plasma GH for 6 or more days and 1.5- to 3-fold increases in IGF-1 for 9–11 days; after multiple doses, IGF-1 remained above baseline up to 28 days, with an estimated CJC-1295 half-life of 5.8–8.1 days ^[3].

Albumin-binding chemistry. In Sprague-Dawley rats, the DAC linker on CJC-1295 produced roughly a four-fold increase in GH AUC over two hours versus the unmodified hGRF(1-29) and detectable albumin-bound peptide beyond 72 hours — the mechanism that gives the DAC form its extended pharmacodynamic profile ^[4].

Receptor cross-talk. Co-activation of cloned GHRH and GHS receptors in HeLa cells produced a cAMP response approximately double that of the GHRH receptor alone, providing a receptor-level mechanistic explanation for the combination synergy ^[5].

Ipamorelin selectivity. Unlike GHRP-6 and GHRP-2, ipamorelin did not raise ACTH or cortisol above GHRH-stimulated levels at doses more than 200 times its GH ED50 in swine, while matching GHRP-6's GH efficacy — the founding characterization of ipamorelin as the first selective GH secretagogue ^[6].

Human GHRP + GHRH synergy. In eighteen healthy adult men, submaximal doses of GHRP (0.1 and 0.3 micrograms per kilogram) combined with GHRH (1 microgram per kilogram) stimulated GH release synergistically through independent mechanisms — the foundational human evidence base for combining a GHRP with a GHRH analogue ^[7].

Safety class review. A review of GH secretagogues found them generally well tolerated, with the chief safety concern being increased blood glucose from decreased insulin sensitivity; long-term data on cancer incidence and mortality remain outstanding ^[2].

Reported effects, cautions & safety

Community-reported effects (anecdotal, not clinical evidence). Research-use community accounts most consistently describe: deeper, more restorative sleep and faster workout recovery (both frequently reported); gradual shifts toward leaner body composition over weeks to months, increased appetite particularly in hours after injection, and improvements in skin, nail, and connective-tissue feel (all occasionally reported). Adverse effects include injection-site redness, itching, or mild swelling (frequently reported); water retention and puffiness, facial flushing, tingling or carpal-tunnel-like hand symptoms, lethargy or grogginess after dosing, and lightheadedness (all occasionally or sometimes reported). These are anecdotal, unverified, dose and source unknown — not clinical findings.

Cited safety cautions. The following arise directly from the literature:

• Active or recent malignancy. GH drives hepatic IGF-1 production; IGF-1 is a well-characterized mitogen. CJC-1295 raised IGF-1 1.5- to 3-fold for 9–11 days per dose in healthy adults ^[3], and ipamorelin potently releases GH ^[6]. The theoretical concern is that chronically elevating GH/IGF-1 could accelerate proliferative activity in pre-existing or occult tumors. This is mechanistic reasoning, not an observed event in any trial of the combination.
• Diabetes or impaired glucose tolerance. GH is a counter-regulatory hormone that reduces peripheral insulin sensitivity. The secretagogue class review identifies increased blood glucose and decreased insulin sensitivity as the chief metabolic concern ^[2]; the combination, designed to raise GH output, carries that class-level glycemic risk.
• Mismatched pharmacokinetics. CJC-1295 DAC produces multi-day GH and IGF-1 elevation ^[3][4], while ipamorelin has a terminal half-life of approximately 2 hours ^[15]. Pairing a multi-day agent with a short-acting one means the net GH exposure and the intended pulsatile synergy profile are not characterized for any specific protocol.
• Fluid retention, carpal tunnel, joint pain. GH excess classically causes sodium and water retention, soft-tissue swelling, and arthralgia ^[2]. The CJC-1295 component is documented to raise GH and IGF-1 substantially for days; these GH-mediated effects are the mechanistically expected nuisances.
• Cardiovascular vulnerability. Sustained GH-related fluid retention can worsen edema and volume-overload conditions. The secretagogue review notes cardiovascular and fluid-handling as considerations for sustained GH elevation ^[2].
• Unknown long-term safety; unverified purity. Neither component is approved for human use, the fixed combination has never been studied in a controlled human trial, and research-grade material from unregulated suppliers carries no pharmaceutical quality assurance ^[2].

Where it fits in GH-axis research

Among the three entries on this desk, CJC-1295 / Ipamorelin is the combined-pharmacology lead — the reason the stack concept exists — while CJC-1295 and Ipamorelin provide the individual component depth. The combination's story is ultimately a mechanistic inference built from two separate evidence bases and general GHRH+GHRP synergy work in normal men ^[7]. There are no completed controlled clinical trials of the fixed blend for any indication, which makes this also the clearest example of how far inference can travel from first-principles receptor pharmacology into community practice without the clinical checkpoint. See the comparison page for how the three stack up.