GH-Axis Secretagogue Reference Standards: CJC-1295, Ipamorelin, Tesamorelin Compared
Three growth-hormone-axis research peptides, three different mechanisms. How CJC-1295 (Mod GRF 1-29), Ipamorelin, and Tesamorelin differ by receptor pathway, sequence length, and synthesis difficulty — and what to specify when qualifying each as a reference standard.
Published June 3, 2026 · 8 min read · By Lyochem Regulatory Team
Growth-hormone-axis research peptides are often grouped because they all act, directly or indirectly, on GH release — but they do it through different receptors and they present different synthesis and verification problems. CJC-1295 and Tesamorelin are GHRH-receptor analogs; Ipamorelin works through the ghrelin/GHSR pathway. For a lab assembling a GH-axis panel, knowing which pathway each one engages, and how each behaves on the bench, is the difference between a clean comparison and a confounded one.
How do CJC-1295, Ipamorelin, and Tesamorelin differ as research standards?
They differ by receptor pathway and by molecular size. CJC-1295 without DAC (Mod GRF 1-29, CAS 863288-34-0) is a 29-residue GHRH analog with four stabilizing substitutions. Tesamorelin (CAS 218949-48-5) is a 44-residue full-length GHRH(1-44) analog with an N-terminal trans-3-hexenoyl modification for DPP-4 resistance. Ipamorelin (CAS 170851-70-4) is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH₂) acting as a selective ghrelin-receptor (GHSR) agonist. All three are supplied strictly as research reference standards, verified by RP-HPLC purity plus ESI-MS identity per lot.
Identity and mechanism reference
| Peptide | CAS | Length | Receptor pathway | Key feature |
|---|---|---|---|---|
| CJC-1295 (no DAC) | 863288-34-0 | 29 aa | GHRH receptor | Mod GRF 1-29; D-Ala2, Gln8, Ala15, Leu27 substitutions |
| Tesamorelin | 218949-48-5 | 44 aa | GHRH receptor | GHRH(1-44) analog, N-terminal trans-3-hexenoyl cap |
| Ipamorelin | 170851-70-4 | 5 aa (pentapeptide) | Ghrelin / GHSR | Aib-His-D-2-Nal-D-Phe-Lys-NH₂; C-terminal amide |
The CAS line for CJC-1295 refers to the no-DAC (Mod GRF 1-29) form; the DAC form carries a distinct identifier listed on the batch COA. Every Lyochem lot confirms identity by ESI-MS against the theoretical mass for the supplied form and reproduces the value on the batch COA so it can be cited directly in a methods section.
Two pathways, framed for research
In the published GH-axis literature, GHRH-receptor agonists and ghrelin-receptor agonists act through complementary mechanisms on the somatotroph, which is why a study may pair one of each:
- GHRH-receptor analogs (CJC-1295, Tesamorelin). Both are analogs of growth-hormone-releasing hormone. The stabilizing changes — CJC-1295's four amino-acid substitutions, Tesamorelin's N-terminal acyl cap — are described in the literature as resisting DPP-4 cleavage to extend the analog's working life relative to native GHRH. CJC-1295 is built on the GRF(1-29) fragment; Tesamorelin is the full GHRH(1-44) length.
- Ghrelin-receptor agonist (Ipamorelin). Ipamorelin is described as a selective growth-hormone secretagogue acting at the GHSR (ghrelin receptor), and the literature characterizes it as relatively clean — engaging GHSR without strongly activating some of the off-target pathways associated with earlier GHRP-class peptides.
This mechanism context explains why the three are studied together; it is not a claim about the reagent. Lyochem makes no therapeutic representation about any of these standards.
Why the synthesis difficulty differs
The three span a wide range of synthesis and verification difficulty:
- Ipamorelin (5 residues) is short, but it carries two D-amino acids (D-2-Nal, D-Phe), a non-coded Aib, and a C-terminal amide. Mass alone cannot confirm the D-/L-configuration, so for sequence-and-stereochemistry-sensitive work the verification question is chirality and the amide, not chain length.
- CJC-1295 (29 residues) is a medium-length GHRH analog with four specific substitutions; the verification priority is confirming those substitutions are present and correctly placed, which an intact mass partially but not fully addresses.
- Tesamorelin (44 residues) is a long synthesis with an N-terminal acyl modification. Longer chains accumulate more closely-related deletion by-products that co-elute near the target on RP-HPLC, so RP-HPLC purity plus ESI-MS plus — for first-lot qualification — LC-MS/MS sequence confirmation is the proportionate packet.
Counter-ion, water, and endotoxin
For all three, the handling questions are the standard set: counter-ion form (acetate by default; TFA suppresses some cell-based readouts), water content by Karl Fischer (which affects true peptide mass per vial), and lyophilized stability at minus 20 degrees Celsius protected from light. For in vivo work, request bacterial endotoxin (LAL) on the specific lot. For Ipamorelin specifically, ask that the COA reports the chiral/configuration verification when the study is stereochemistry-sensitive, since the two D-residues are central to its identity.
Sourcing scale and framing
Lyochem supplies CJC-1295 (no DAC), Tesamorelin, and Ipamorelin as reference-grade research standards at milligram scale, characterized lot-by-lot, and labelled strictly Research Use Only. The material is a research reagent, not a finished dosage form and not labelled for human administration; buyers are responsible for institutional biosafety review and verifying import eligibility in the destination market.
Talk to our regulatory team
Assembling a GH-axis research panel?
Send the molecules, target purity, intended assay, and whether this is first-lot qualification. Lyochem will map the analytical packet — including chirality verification where relevant — before quote.
Frequently asked questions
- What receptor pathways do CJC-1295, Ipamorelin, and Tesamorelin act through?
- CJC-1295 without DAC (Mod GRF 1-29, CAS 863288-34-0) and Tesamorelin (CAS 218949-48-5) are both GHRH-receptor analogs — CJC-1295 is built on the GRF(1-29) fragment with four stabilizing substitutions, and Tesamorelin is a full-length GHRH(1-44) analog with an N-terminal acyl cap. Ipamorelin (CAS 170851-70-4) is a pentapeptide acting through the ghrelin/GHSR pathway. The two pathways are complementary, which is why a study may pair a GHRH analog with a ghrelin-receptor agonist.
- Why does Ipamorelin need chirality verification and not just a mass check?
- Ipamorelin is the pentapeptide Aib-His-D-2-Nal-D-Phe-Lys-NH₂, which contains two D-amino acids and a C-terminal amide. Mass spectrometry confirms molecular weight but cannot distinguish a D-residue from its L-isomer, so a same-mass stereochemical error can pass an ESI-MS check. For stereochemistry-sensitive work, ask that the COA reports chiral/configuration verification because the two D-residues are central to the molecule's identity.
- Which of these GH-axis peptides is the hardest to verify, and how?
- Tesamorelin is the longest at 44 residues with an N-terminal acyl modification, so it accumulates the most closely-related deletion by-products that co-elute near the target on RP-HPLC. The proportionate packet is RP-HPLC purity plus ESI-MS plus LC-MS/MS sequence confirmation for first-lot qualification. CJC-1295's verification priority is confirming its four substitutions are correctly placed; Ipamorelin's is chirality and the C-terminal amide rather than chain length.
- Are these GH-axis secretagogue standards finished drugs?
- No. Lyochem supplies CJC-1295 (no DAC), Tesamorelin, and Ipamorelin as bulk research reference standards for Research Use Only, characterized lot-by-lot at milligram scale, not labelled for human administration and not finished dosage forms. The material is a research reagent; buyers are responsible for institutional biosafety review and verifying import eligibility in the destination market.