What are Ipamorelin and CJC-1295?
Ipamorelin is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) that acts as a selective agonist at the growth hormone secretagogue receptor GHS-R1a, the receptor for endogenous ghrelin. Its defining characteristic in the literature is selectivity: unlike earlier growth hormone-releasing peptides such as GHRP-2 and GHRP-6, ipamorelin showed minimal effect on cortisol and prolactin in the original characterization studies, which is why it became the reference ghrelin-mimetic for clean axis experiments.
CJC-1295 is a modified analog of GHRH(1-29). It exists in two distinct research forms that are routinely confused: CJC-1295 with DAC, which carries a drug-affinity complex enabling covalent binding to serum albumin and a substantially extended duration; and CJC-1295 without DAC (also called modified GRF 1-29), which retains four stabilizing amino-acid substitutions but has no albumin anchor and therefore a short duration. These are different test articles and should never be treated as interchangeable in a study design.
PX1 Research supplies both compounds individually and as the blended preparation, each released against a batch-specific certificate of analysis. Research use only — not for human or veterinary use.
Why the two are studied together
The somatotropic axis has two independent stimulatory inputs at the pituitary somatotroph: the GHRH receptor and GHS-R1a. Because the receptors are distinct and their signaling converges downstream, co-stimulation in preclinical models produces a response larger than either input alone — a synergy that is one of the better-replicated findings in the field.
That is the mechanistic rationale behind the CJC-1295 + ipamorelin blend, which is among the most commonly requested research preparations in the class. The GHRH analog raises the amplitude of the release pulse while the ghrelin-mimetic increases pulse frequency and suppresses somatostatin tone, and study designs frequently isolate each contribution by running the two singles alongside the blend.
Comparative designs also bring in tesamorelin (a hexenoyl-stabilized GHRH(1-44) analog) and sermorelin (unmodified GHRH(1-29)) to separate duration effects from receptor effects, since the three GHRH-side molecules differ mainly in how they resist DPP-4 cleavage and clearance.
Analytical characterization
Laboratories that work with Ipamorelin and CJC-1295 typically characterize incoming material on three axes before it enters a study: identity, purity and content. Identity is established by high-resolution mass spectrometry against the theoretical monoisotopic mass (711.9 Da for ipamorelin; ≈3,647.2 Da for CJC-1295 with DAC and ≈3,367.9 Da for the non-DAC form), usually supported by MS/MS fragmentation that walks the backbone and confirms the sequence rather than just the total mass. A matching intact mass alone can be satisfied by a scrambled or partially epimerized sequence, which is why fragmentation data is the stronger identity evidence.
Purity is quantified by reversed-phase HPLC with UV detection, integrating every resolved peak in the chromatogram and expressing the main peak as a percentage of total area. The gradient matters more than the headline number: a shallow, well-optimized gradient resolves closely eluting process impurities such as deamidation products, oxidation variants, truncated sequences and acetate adducts, while an aggressive gradient can co-elute them under the main peak and inflate the reported purity. PX1 publishes the chromatogram itself, not only the integrated figure, so the resolution behind the number is auditable.
Content — how much peptide is actually in the vial once counter-ions and residual water are subtracted — is the axis most often skipped by low-cost suppliers. Net peptide content is a function of the labeled mass, the water content measured by Karl Fischer titration, and the counter-ion (typically trifluoroacetate or acetate) load. A vial that is 99% pure by HPLC can still under-deliver on content if it carries a high salt and moisture fraction, which is why the COA reports both.
Solubility, reconstitution and stability behavior
Ipamorelin and CJC-1295 is supplied as a lyophilized white powder, supplied singly or as a co-lyophilized blend. The lyophilized cake is the most stable form of the molecule and should be kept sealed at −20°C or below, protected from light, until the study begins. The single most common handling error in a research setting is opening a cold vial: atmospheric moisture condenses onto the cake the moment the stopper is broken, and that water starts hydrolytic degradation before reconstitution has even happened. Always equilibrate the sealed vial to room temperature first.
Reconstitution should be performed aseptically with bacteriostatic or sterile water for research reconstitution, introduced slowly down the inner wall of the vial rather than streamed directly onto the cake. Swirl — never shake. Peptides are surface-active, and vigorous agitation drives them to the air-liquid interface where they unfold and aggregate; visible foaming is a sign that material has already been lost to interfacial denaturation. Full dissolution to a clear, particle-free solution normally takes under a minute of gentle swirling.
Once in solution the molecule is far more labile than it was as a powder. Reconstituted Ipamorelin and CJC-1295 should be held at 2–8°C, protected from light, and aliquoted immediately into single-use volumes so that the working stock is never subjected to repeated freeze-thaw cycling. Each freeze-thaw cycle contributes measurable loss through aggregation and adsorption to container surfaces. Low-binding polypropylene tubes reduce adsorptive loss at dilute concentrations, and a carrier protein is commonly added to very dilute working solutions for the same reason.
Purity and Certificate of Analysis (COA)
Each lot is USA-manufactured and released at ≥99% purity by reversed-phase HPLC with LC-MS identity confirmation, kinetic chromogenic LAL endotoxin, GC residual solvents and Karl Fischer water content. For the blend, the release method resolves both peptides in a single chromatographic run and mass spectrometry confirms both intact masses — a blend released against a single-analyte method has only been half-characterized.
The DAC and non-DAC forms of CJC-1295 differ by roughly 279 Da, which makes mass spectrometry an unambiguous check that the vial contains the form on the label. Confirming this is worth doing, because mislabeling between the two forms is one of the more common quality failures in the research-peptide market.
Sourcing, provenance and what separates lab-grade material
The research-peptide market is unusually wide in quality. The same nominal Ipamorelin and CJC-1295 listing can represent USA-manufactured material released against a documented specification, or repackaged bulk of unknown origin with a generic certificate that was never generated from the lot in the vial. The distinction is invisible from the product photo and only becomes visible in the paperwork.
The practical test is traceability: the lot number printed on the vial label should appear on the certificate of analysis, and that certificate should show the actual chromatogram and mass spectrum for that lot rather than a representative example. A COA without a lot number, without instrument traces, or dated years before the vial was filled is a document, not evidence. PX1 publishes the batch-specific report directly on the product page so the chain from manufacturing to vial is checkable before purchase.
Beyond the certificate, consistent lab-grade supply depends on synthesis and release happening under one controlled process: domestic solid-phase manufacturing, preparative HPLC purification, lyophilization under validated cycle parameters, and third-party confirmation of purity and endotoxin. Ipamorelin and CJC-1295 sold by PX1 Research is produced and released on that pathway and is supplied strictly for laboratory research use — not for human or veterinary use.
Study design considerations
A well-formed secretagogue experiment is factorial: vehicle, GHRH analog alone, ghrelin-mimetic alone, and the combination. Anything less cannot distinguish additivity from synergy, and synergy is the specific claim most often made about this pairing. Because the two receptor inputs differ in their kinetics, the sampling schedule must be dense enough to capture both the amplitude and the frequency components of the response.
Selectivity controls belong in the design when ipamorelin is chosen for its clean profile. Measuring cortisol and prolactin alongside growth hormone confirms in the specific model that the selectivity reported in the original characterization holds, and it provides the contrast that justifies using ipamorelin rather than GHRP-2 or GHRP-6.
The DAC question must be settled before the study starts, not after. CJC-1295 with DAC produces sustained exposure measured in days, while the non-DAC form is short-acting; a sampling schedule appropriate for one is wrong for the other, and a methods section that says only "CJC-1295" leaves the result uninterpretable. State the form, the lot and the confirmed mass.
Downstream, IGF-1 serves as the integrated readout that smooths pulsatile growth hormone data, but it lags the stimulus and saturates, so it complements rather than replaces direct sampling. Designs reporting both give a much clearer picture of whether an intervention changed pulse structure or only total output.
For in vitro work, somatotroph models should be characterized for both GHRH-receptor and GHS-R1a expression before use, since the synergy under investigation requires both receptors to be present at functional density. Verifying expression in the specific line prevents a null combination result that reflects receptor absence rather than pharmacology.
Common research questions about Ipamorelin and CJC-1295
What makes ipamorelin "selective"? Earlier growth hormone-releasing peptides such as GHRP-2 and GHRP-6 stimulate the secretagogue receptor but were also reported to raise cortisol and prolactin, confounding any experiment attempting to isolate the somatotropic axis. The original ipamorelin characterization reported minimal effect on both, which made it the preferred tool compound for clean axis studies and remains the reason it is chosen over the older GHRPs.
What is the difference between CJC-1295 with and without DAC? With DAC, the molecule carries a maleimidopropionic acid drug-affinity complex that binds covalently to serum albumin, creating a long-lived circulating reservoir. Without DAC — commonly labeled modified GRF 1-29 — the sequence keeps four stabilizing substitutions but has no albumin anchor and a much shorter duration. They are different test articles, differ by roughly 279 Da, and mislabeling between them is one of the most common quality failures in this category.
Why combine a GHRH analog with a ghrelin-mimetic? They act at two independent receptors on the same cell, and co-stimulation in preclinical models produces a response greater than either alone. The GHRH side raises pulse amplitude while the ghrelin side affects pulse frequency and somatostatin tone, so the combination is a mechanistic design choice rather than simply a larger stimulus.
Should the blend or the singles be purchased? For a study isolating each receptor's contribution, the singles are required and the blend serves as the combination arm — most rigorous designs use all three. For method development or as a reference standard, the singles are the more useful stock because their impurity profiles can be characterized independently.
What should the certificate show for a co-lyophilized blend? Both intact masses confirmed by mass spectrometry, both peptides resolved on a single HPLC run with their individual impurity profiles integrated, and the ratio between the two analytes reported. Endotoxin, residual solvents and water content apply to the finished blend as filled, not to the components before blending.
Where these compounds sit in the PX1 catalog
Ipamorelin and CJC-1295 are stocked individually and as the co-lyophilized blend, which is the configuration most often requested for co-stimulation designs. A factorial study needs all three listings — the two singles and the blend — plus vehicle, so laboratories working in this area typically order the set together.
On the GHRH side the catalog comparators are Tesamorelin, the hexenoyl-stabilized GHRH(1-44) analog, and Sermorelin, the unmodified 1-29 fragment. On the ghrelin side they are GHRP-2 and GHRP-6, the earlier and less selective secretagogues against which ipamorelin's selectivity is defined.
IGF-1 LR3 completes the group as the direct-acting comparator that bypasses the pituitary. Every listing in the group is released against the same specification with a lot-matched certificate, and for the blend the certificate resolves both peptides in a single chromatographic run.
References
- Raun 1998. Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology. 1998;139(5):552-561.
- Teichman 2006. Teichman SL, et al. Prolonged stimulation of growth hormone and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GHRH, in healthy adults. Journal of Clinical Endocrinology & Metabolism. 2006;91(3):799-805.
- Jetté 2005. Jetté L, et al. Human growth hormone-releasing factor conjugate stimulates GH secretion in rats and monkeys. Endocrinology. 2005;146(7):3052-3058.
All products are sold strictly for laboratory and research use only. Not for human or veterinary use, diagnosis, treatment or consumption. Statements have not been evaluated by the FDA.