What Are Ipamorelin and CJC-1295?
Ipamorelin and CJC-1295 are synergistic growth hormone secretagogues — Ipamorelin is a selective ghrelin receptor agonist, CJC-1295 is a long-acting GHRH analogue — studied together for pulsatile GH release without cortisol or prolactin elevation.
Ipamorelin is a synthetic pentapeptide with the sequence Aib-His-D-2-Nal-D-Phe-Lys-NH2, developed by Novo Nordisk in the late 1990s and characterised in peer-reviewed literature from 1998 onwards. It belongs to the growth hormone releasing peptide (GHRP) class — synthetic compounds that mimic the endogenous hormone ghrelin by binding to the growth hormone secretagogue receptor type 1a (GHS-R1a) in the pituitary gland and hypothalamus. This receptor binding triggers GH release from somatotroph cells. What distinguishes Ipamorelin from earlier GHRPs (GHRP-2, GHRP-6, hexarelin) is its exceptional selectivity — it produces robust GH secretion at GHS-R1a without significantly elevating cortisol, prolactin, or ACTH at equivalent GH-stimulating doses.
CJC-1295 (most precisely referred to as Modified GRF 1-29, or Mod GRF 1-29 when supplied without the Drug Affinity Complex) is a synthetic analogue of the endogenous GHRH(1-29) fragment — the bioactive portion of full-length Growth Hormone Releasing Hormone (GHRH, 44 amino acids). The "CJC-1295 without DAC" variant incorporates four amino acid substitutions (at positions 2, 8, 15, and 27) that protect the molecule from rapid dipeptidyl peptidase IV (DPP-IV) degradation, extending its half-life from approximately 7 minutes (native GHRH) to 30–60 minutes. The compound acts exclusively at GHRH receptors (GHRHR) on pituitary somatotrophs to stimulate GH synthesis and release.
The combination of a GHRP (Ipamorelin) and GHRH analogue (CJC-1295) in research has become a widely used model for studying synergistic pituitary GH secretion. The two compounds operate through entirely different receptor systems and signal transduction pathways, meaning their effects are additive-to-synergistic rather than redundant — a property that has made this combination the dominant GHRP/GHRH pair in the research literature for studying the hypothalamic-pituitary-somatotroph axis. All compounds are supplied by Rainbow Peptide strictly For Research Use Only.
Mechanisms of Action
Ipamorelin selectively binds GHSR-1a (ghrelin receptor) triggering pulsatile GH release without elevating cortisol or prolactin. CJC-1295 binds and activates GHRH receptors with a half-life of 6–8 days via DAC technology. Together they produce amplified, physiological-pattern GH pulses.
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Ipamorelin — GHS-R1a Agonism (Ghrelin Receptor) Ipamorelin binds to GHS-R1a receptors on pituitary somatotroph cells and in the arcuate nucleus of the hypothalamus. GHS-R1a is a Gαq-coupled GPCR; its activation mobilises intracellular calcium stores through IP3-mediated pathways, triggering exocytosis of stored GH secretory granules. Ipamorelin's binding selectivity for GHS-R1a over other receptor types (including those mediating ACTH and cortisol release) makes it a particularly clean research tool for GH secretion studies.
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Ipamorelin — Somatostatin Inhibition In addition to direct pituitary stimulation, Ipamorelin appears to partially suppress somatostatin (SRIF) — the primary inhibitory regulator of GH secretion from the hypothalamus. By reducing somatostatin tone, Ipamorelin effectively lowers the threshold for GH release, amplifying pituitary responsiveness to GHRH. This dual mechanism contributes to Ipamorelin's potency relative to simple GHRH analogues.
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CJC-1295 — GHRHR Agonism (cAMP/PKA Pathway) CJC-1295 binds to the GHRH receptor (GHRHR), a Gαs-coupled GPCR that activates adenylyl cyclase, increasing intracellular cAMP concentrations. Elevated cAMP activates protein kinase A (PKA), which phosphorylates transcription factors including CREB, stimulating GH gene transcription and promoting synthesis of new GH stores in somatotrophs. This mechanism increases both the pool of releasable GH and the sensitivity of the pituitary to subsequent secretagogue stimulation.
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Downstream: IGF-1 Axis Activation GH released through either mechanism activates hepatic and peripheral GH receptors, stimulating insulin-like growth factor 1 (IGF-1) synthesis. IGF-1 mediates many of the downstream anabolic and tissue-remodelling effects attributed to GH axis activity in research models, including protein synthesis, lipolysis stimulation, and skeletal muscle satellite cell activation. Research using Ipamorelin and CJC-1295 frequently measures serum IGF-1 as a biomarker for GH axis activation.
Stack Synergy Research
The GHRP + GHRH research combination model is grounded in mechanistic complementarity. Ipamorelin (GHRP) acts through the Gαq/calcium pathway while CJC-1295 (GHRH analogue) acts through the Gαs/cAMP pathway. These two second messenger systems converge synergistically on the GH secretory machinery within pituitary somatotrophs, producing GH pulse magnitudes substantially larger than either compound administered individually.
Research data from GHRP/GHRH combination studies consistently demonstrates 3–5× amplification of GH peak concentrations when the two classes are combined versus equivalent doses of either alone. The combination also produces more physiologically patterned GH release — characterised by discrete pulse peaks followed by return to baseline — compared to sustained GH elevation, making it a valuable model for studying pulsatile GH secretion physiology.
Ipamorelin Alone
Selective GH pulse via GHS-R1a. No cortisol or prolactin elevation at research doses.
CJC-1295 Alone
GH Response: Moderate–High GHRHR-driven cAMP/PKA GH synthesis and release. Extended somatotroph priming.
Combined Research Model
GH Response: Synergistic Amplification Dual-pathway convergence produces supraadditive GH pulse. The standard research stack for GH axis studies.
Key Research Findings
1998
Ipamorelin: Selective GH Secretagogue Characterisation
The original pharmacological characterisation of Ipamorelin by Raun et al. at Novo Nordisk established its identity as the most selective GHRP studied at the time. In rat, swine, and dog models, Ipamorelin produced dose-dependent GH increases comparable to GHRP-6 but without the significant cortisol, ACTH, or prolactin elevations seen with earlier GHRPs. This selectivity profile established Ipamorelin as a preferred research tool for clean GH axis studies.
Raun K et al. — Eur J Endocrinol, 1998 2004
CJC-1295 Half-Life Extension via Amino Acid Substitutions
Jetté et al. characterised the pharmacokinetic profile of modified GHRH analogues incorporating DPP-IV-resistant substitutions. CJC-1295's four-substitution variant demonstrated a plasma half-life of 30–60 minutes versus 7 minutes for native GHRH — representing an 8× improvement in stability with preserved GHRHR binding affinity. This work established the structural basis for CJC-1295's utility in sustained pituitary stimulation research models.
Jette L et al. — J Pharm Sci, 2004 2006
Synergistic GH Pulse Amplification
Studies combining GHRP-class and GHRH-class compounds demonstrated 3–5× supraadditive amplification of GH peak concentrations compared to matched doses of either class alone. The synergistic effect was attributed to convergent signalling through calcium mobilisation (GHRP) and cAMP elevation (GHRH) pathways, both acting on the same somatotroph population. These findings established the mechanistic basis for the GHRP/GHRH combination research model.
Veldhuis JD et al. — J Clin Endocrinol Metab, 2006 2015
GH Axis Research in Body Composition Models
Research using GH secretagogue combinations in rodent models of sarcopenia and metabolic disease demonstrated significant effects on lean tissue preservation, fat mass reduction, and insulin sensitivity markers over 8-week treatment periods. Ipamorelin-containing protocols showed improved maintenance of muscle fibre cross-sectional area and reduced visceral adipocyte size compared to controls, providing research data relevant to GH axis biology in ageing tissue models.
Walker RF et al. — Growth Horm IGF Res, 2015 Reconstitution Reference
The following reference is provided for licensed research professionals only. All reconstitution must comply with your institution's biosafety protocols.
| Compound | Vial Size | BAC Water Volume | Concentration | Peptide Calculator |
| Ipamorelin | 2 mg | 1.0 mL | 2,000 mcg/mL | Calculate → |
| CJC-1295 (Mod GRF) | 2 mg | 1.0 mL | 2,000 mcg/mL | Calculate → |
Both peptides may be reconstituted separately or, in research protocols that require simultaneous administration, may be combined in a single vial after individual reconstitution. Store each at 2–8°C. Lyophilised powders are stable at -20°C for up to 24 months.
Competitive Pricing Comparison
Market price data from independent competitor analysis. All products are For Research Use Only.
| Compound / Supplier | Competitor Range | Market Average | COA Available |
| Ipamorelin (market) | $46 – $98 | $68 | Varies |
| CJC-1295 (market) | $41 – $119 | $80 | Varies |
| Rainbow Peptide — Ipamorelin | View Price → | ✓ HPLC + MS |
| Rainbow Peptide — CJC-1295 | View Price → | ✓ HPLC + MS |
Research Ipamorelin & CJC-1295
View our Ipamorelin and CJC-1295 research compound specifications, certificates of analysis, and current pricing for qualified research applications.
For Research Use Only. Not for human consumption.
Frequently Asked Questions
What are Ipamorelin and CJC-1295?
Ipamorelin is a synthetic pentapeptide GHRP that selectively stimulates GH secretion via GHS-R1a. CJC-1295 (Modified GRF 1-29) is a GHRH analogue with 4 amino acid substitutions that extend its half-life. Both are research compounds for studying the GH-IGF-1 axis. For Research Use Only.
Why are Ipamorelin and CJC-1295 studied together?
Ipamorelin acts through GHS-R1a (Gαq/calcium pathway) while CJC-1295 acts through GHRHR (Gαs/cAMP pathway). These complementary mechanisms produce synergistic GH pulse amplification when combined — making the combination a useful research model for studying GH secretion dynamics.
Does Ipamorelin elevate cortisol or prolactin in research models?
Compared to earlier GHRPs like GHRP-6, Ipamorelin is noted for selectivity — producing GH elevation without significant concurrent increases in cortisol or prolactin at doses that elicit comparable GH responses. This selectivity has made Ipamorelin a preferred GHRP for clean GH secretion research.
How is each peptide reconstituted for research?
Both Ipamorelin and CJC-1295 are typically supplied as 2mg vials. Each is reconstituted with 1mL bacteriostatic water to yield 2,000 mcg/mL. Store at 2–8°C and use within 28 days.
What is CJC-1295 with DAC vs without DAC?
CJC-1295 with DAC binds covalently to plasma albumin, extending half-life to 6–8 days. Modified GRF 1-29 (without DAC) has a half-life of 30–60 minutes, better suited for pulsatile GH secretion research. Rainbow Peptide supplies Modified GRF 1-29 for research use.
Published Research References
Studies cited for scientific reference. All data from preclinical models or Phase 1/2 human trials unless stated. Not medical advice.
- Raun K, et al. "Ipamorelin, the first selective growth hormone secretagogue." Eur J Endocrinol. 1998;139(5):552–561. PubMed 9849822 ↗
- Ionescu M, Frohman LA. "Pulsatile secretion of growth hormone after continuous subcutaneous infusion of CJC-1295." J Clin Endocrinol Metab. 2006;91(12):4792–4797. PubMed 16882766 ↗
- Teichman SL, et al. "Prolonged stimulation of growth hormone by continuous infusion of a long-acting growth hormone–releasing factor." J Clin Endocrinol Metab. 2006;91(3):799–805. PubMed 16368745 ↗