What CJC-1295 and ipamorelin are
CJC-1295 is a synthetic analogue of growth hormone-releasing hormone (GHRH). Its backbone is the first 29 amino acids of native GHRH (GRF 1-29), modified at the C-terminus with a Drug Affinity Complex (DAC) linker. The DAC group is a reactive maleimide that binds covalently to the free thiol on Cys34 of endogenous serum albumin within minutes of subcutaneous injection, converting the peptide into a long-circulating albumin-bound form.
Ipamorelin is a synthetic pentapeptide with the sequence Aib-His-D-2-Nal-D-Phe-Lys-NH2, developed from the GHRP-1 family by removing the central Ala-Trp dipeptide. It acts as a selective agonist at the growth hormone secretagogue receptor (GHS-R), the same G-protein coupled receptor activated by ghrelin.
The two compounds target different receptor classes. CJC-1295 activates the pituitary GHRH receptor (GHRH-R); ipamorelin activates GHS-R. Both receptors are expressed on somatotroph cells in the anterior pituitary, and both signal through pathways that increase intracellular cyclic AMP and calcium, triggering GH exocytosis.
The DAC mechanism and how it extends CJC-1295 half-life
Native GHRH 1-29 is cleared from circulation within roughly 7 minutes by dipeptidyl peptidase-IV (DPP-IV), which cleaves the N-terminal Tyr-Ala bond. CJC-1295 resists this cleavage through N-terminal substitutions and extends its residence time by binding to albumin, which has a half-life of approximately 19 days in humans. The result is a plasma half-life of 5.8 to 8.1 days for CJC-1295 with DAC, compared with roughly 30 minutes for CJC-1295 without DAC (the version sold as modified GRF 1-29).
The albumin-binding mechanism was described by Jetté et al. in a 2005 paper in the Journal of Medicinal Chemistry (Jetté et al., J Med Chem, 2005), which synthesised maleimido derivatives of hGRF(1-29), confirmed in-vivo bioconjugation to albumin, and demonstrated activation of the GRF receptor on rat anterior pituitary at a potency 4 times that of unmodified hGRF(1-29).
CJC-1295 ipamorelin research: human pharmacokinetic data
The main human data on CJC-1295 comes from a randomised, double-blind, placebo-controlled ascending-dose trial published by Teichman et al. in The Journal of Clinical Endocrinology and Metabolism in 2006 (Teichman et al., JCEM, 91(3):799, 2006). The trial enrolled healthy adults aged 21 to 61 and administered single subcutaneous injections at doses of 30, 60, or 125 mcg/kg, with a placebo arm.
After a single injection, mean plasma GH concentrations rose 2- to 10-fold above baseline and remained elevated for at least 6 days. Mean IGF-1 concentrations rose 1.5- to 3-fold and stayed above baseline for 9 to 11 days. No serious adverse events were reported, and the compound was well tolerated at the 30 and 60 mcg/kg doses; mild flushing was the most common complaint. The estimated plasma half-life derived from the pharmacokinetic modelling in this study was 5.8 to 8.1 days.
A separate study examining the pulse dynamics of GH under sustained CJC-1295 exposure found that pulsatile GH secretion was preserved despite continuous GHRH-analogue stimulation (PubMed 17018654). The frequency and amplitude of GH pulses were not suppressed. Basal trough GH levels rose markedly, contributing to a 46% increase in mean 24-hour GH and a 45% increase in IGF-1 relative to placebo. This finding is relevant to research protocols where preserving pulsatile GH physiology matters for downstream analysis.
Ipamorelin's selectivity profile and what makes it distinct
Before ipamorelin, the most widely studied synthetic GHS compounds were GHRP-6 and GHRP-2. Both released GH reliably but also raised ACTH and cortisol at effective GH-releasing doses. This side effect complicated research designs trying to isolate GH-axis effects, because elevated cortisol independently alters muscle protein, fat metabolism, and immune endpoints.
Ipamorelin was distinguished from GHRP-6 and GHRP-2 by Raun et al. in the founding characterisation study, published in European Journal of Endocrinology in 1998 (Raun et al., Eur J Endocrinol, 139(5):552, 1998). The study used conscious swine as the in-vivo model. Ipamorelin produced full GH release with an in-vivo ED50 of 2.3 nmol/kg. At these doses, ACTH and cortisol plasma levels did not rise significantly above those seen after GHRH stimulation alone. GHRP-6 and GHRP-2 administered in the same model produced significant ACTH and cortisol elevations. Ipamorelin also had no effect on FSH, LH, prolactin, or TSH.
This selectivity profile made ipamorelin a more controlled tool for studying GH secretion in isolation. The lack of ACTH stimulation reduces the number of confounded variables in tissue-repair, body-composition, and metabolic studies. Human selectivity data remains limited; the 1998 Raun findings are from the swine model, not a human RCT.
Research rationale for combining the two compounds
CJC-1295 acts through GHRH-R and ipamorelin acts through GHS-R. These two receptor classes are functionally synergistic at the somatotroph. GHS-R activation increases intracellular calcium through a phospholipase C pathway, which amplifies the adenylate cyclase signal driven by GHRH-R. The two signals together produce a larger GH pulse than either receptor stimulated alone. This is a class effect: any GHRH analogue combined with any GHS-R agonist will show the same synergism.
Animal research protocols frequently exploit this synergism by pairing a GHRH analogue with a GHS-R agonist. No published human RCT has tested the CJC-1295 plus ipamorelin combination head-to-head against either compound alone. The combination rationale is pharmacological, derived from the receptor biology, not from clinical outcome data. Researchers considering this pairing should note that both the GHRH-R and GHS-R pathways are represented in published rodent and in-vitro literature, but human endpoints remain speculative.
Handling and storage in tropical research environments
Both CJC-1295 and ipamorelin are supplied as lyophilised white powder. In this form, manufacturer specifications typically cite stability of 18 to 24 months when stored at -20°C. Reconstituted solution stored at 4°C is generally considered usable for 2 to 4 weeks, though exact stability depends on concentration, buffer composition, and storage conditions.
In Bali, Jakarta, or other Indonesian locations with ambient temperatures of 28 to 35°C, lyophilised vials should remain in a freezer until the moment of reconstitution. Brief exposure to room temperature during handling is acceptable if kept under 10 to 15 minutes. Refrigerator storage of reconstituted peptide at a stable 2 to 8°C is adequate for short-term use. Repeated freeze-thaw cycles accelerate degradation and should be avoided by aliquoting before freezing. For the full reconstitution method, see the bacteriostatic water reconstitution guide.
Researchers who need to calculate injection volume from a given reconstitution concentration can use the dosing calculator. CJC-1295 and ipamorelin are listed in the Zurich Biotech compound catalog for research use.
State of the evidence as of mid-2026
CJC-1295 has the stronger human pharmacokinetic dataset of the two compounds. The Teichman 2006 JCEM trial is a controlled human study with clear dose-response data and multi-day GH and IGF-1 tracking. Ipamorelin's defining selectivity advantage over GHRP-6 and GHRP-2 rests on the 1998 Raun et al. swine study; published human pharmacodynamic data is sparse.
Neither compound has completed a Phase 3 randomised controlled trial for any clinical indication as of mid-2026. The combination of CJC-1295 with ipamorelin is used in research settings on the basis of receptor complementarity, not human outcome evidence. Researchers should frame all protocols accordingly: the evidence characterises mechanism and pharmacokinetics, not clinical efficacy or safety in therapeutic use.
Both compounds are research-use reagents. No regulatory body has approved them for clinical administration in humans.