CJC-1295 and Ipamorelin: What’s in a Blended Vial

CJC-1295 and ipamorelin are often supplied together in a single vial. The reasoning behind the pairing is real and comes out of 1990s endocrinology: two compounds that raise growth hormone through different receptors should, in principle, do more together than either alone. What is usually left unsaid is that the published synergy data involve a different peptide, and that no study has tested this particular pair at all.

This guide covers what each half of the blend is, where the combination idea comes from and how far the evidence actually goes, and then the question a blended vial creates that a single-peptide vial does not: how do you verify that two peptides are both present, both pure, and in the ratio the label claims?

Two peptides, two targets

Growth hormone is released from the anterior pituitary under two opposing hypothalamic signals: GHRH, which stimulates release, and somatostatin, which restrains it. The two halves of this blend enter that system at different points.

CJC-1295, a GHRH analogue

CJC-1295 is a modified version of the first 29 residues of GHRH. Its distinguishing feature is a chemical group called a DAC, for drug affinity complex: a maleimidopropionic acid moiety which, according to the developer, binds to a specific site on albumin, the most abundant protein in blood. Tethering a short-lived peptide to a long-lived blood protein is a standard way to extend its life in circulation; our guide to peptide half-life engineering covers the family of tricks it belongs to.

The effect was substantial. In the key published human study, Teichman and colleagues reported in the Journal of Clinical Endocrinology & Metabolism in 2006 that CJC-1295 had an estimated half-life of “5.8–8.1 d” in healthy adults, that growth hormone rose “by 2- to 10-fold for 6 d or more”, and that IGF-I, the downstream marker of growth hormone activity, rose “by 1.5- to 3-fold for 9–11 d”. A GHRH fragment on its own survives minutes in blood. This one lasted days.

Ipamorelin, a selective secretagogue

Ipamorelin was described in 1998 by Kirsten Raun and colleagues, in a paper titled “Ipamorelin, the first selective growth hormone secretagogue”. It is a pentapeptide, built partly from non-standard residues: Aib (a methylated alanine) and two D-amino acids, which are mirror images of the forms found in natural proteins. Our guides to amino acid codes and D-amino acids explain the notation.

“Selective” referred to what it did not do. Earlier growth hormone-releasing peptides such as GHRP-6 and GHRP-2 also raised ACTH and cortisol, the stress hormones. In the 1998 study, ipamorelin did not do so at exposures more than 200 times those needed for its growth hormone effect, and the authors concluded it was “the first GHRP-receptor agonist with a selectivity for GH release similar to that displayed by GHRH”.

One historical detail matters for reading older papers: the 1998 paper describes a “GHRP-like receptor”, because ghrelin, the natural hormone that binds that receptor, was not identified until 1999. Ipamorelin is classed today as a ghrelin-receptor agonist, or ghrelin mimetic, but its discovery predates the hormone it mimics. Our guide to ghrelin covers that discovery, and how peptide receptors work explains the receptor family both compounds act on.

Ipamorelin reached human trials for a non-hormonal use. A phase 2 study published by Beck and colleagues in 2014 tested it for postoperative ileus, the temporary shutdown of the bowel after abdominal surgery, in patients undergoing bowel resection. It did not work: the median time to the first tolerated solid meal was 25.3 hours against 32.6 hours on placebo, a difference that did not reach statistical significance (p = 0.15), and the authors reported “no significant differences between ipamorelin and placebo in the key and secondary efficacy analyses”. Development was discontinued after those results.

The CJC-1295 naming problem

“CJC-1295” is sold in two forms, and the difference is not cosmetic.

Two things follow. First, the multi-day figures from the 2006 study belong to the DAC version only; applying them to a no-DAC product is a mistake. Second, “CJC-1295 without DAC” is not sermorelin. Sermorelin is unsubstituted GHRH(1-29) amide; the no-DAC molecule carries four amino-acid substitutions. Anti-doping authorities list CJC-1295 and sermorelin as separate named substances. Our CJC-1295 with DAC guide covers the DAC chemistry in detail, and our sermorelin guide covers the unmodified fragment.

Where the combination idea comes from

The argument for pairing a GHRH analogue with a secretagogue is mechanistic, and it has genuine support in the literature — for a different peptide.

In 1990, Bowers and colleagues reported in the Journal of Clinical Endocrinology & Metabolism that submaximal amounts of a growth hormone-releasing peptide given with GHRH “stimulated GH release synergistically” in healthy men. The peptide in that study was the hexapeptide GHRP-6. A 1995 study by Popovic and colleagues then showed why the two classes complement each other: in patients whose hypothalamus was disconnected from the pituitary, the synergy disappeared, which the authors read as placing GHRP-6’s main action in the hypothalamus rather than the pituitary. By 1998, Micic and colleagues were describing GHRH plus GHRP-6 as among the most effective growth hormone-releasing stimuli tested.

So the two-class rationale is well founded. What does not follow is that it has been demonstrated for this blend. Every one of those studies used GHRP-6 or a close relative, not ipamorelin, and we could find no published study, human or animal, that administered CJC-1295 and ipamorelin together. Vendor and clinic pages that cite “studies showing synergy” for this pair are borrowing results from a different molecule. Our guide to GHRP-6, GHRP-2 and hexarelin covers the peptides that were actually tested, and how to read a peptide study covers this kind of substitution in general.

The two components side by side

Verifying two peptides in one vial

This is where a blend differs from a single-peptide reagent, and where documentation is most often thin. A certificate that reports one purity figure and one mass for a two-peptide vial has not characterised what is in it.

Regulatory guidance treats a product with more than one active substance as exactly that. ICH Q6A defines a “combination product” as “a drug product which contains more than one drug substance”, and requires that identity testing “establish the identity of the new drug substance(s)” — the bracketed plural is doing real work — with a stability-indicating assay for strength and acceptance limits stated for individual specified degradation products. ICH Q2(R2), the guideline on validating analytical procedures, defines selectivity as the extent to which particular analytes in mixtures can be measured “without interferences from other components with similar behaviour”, and notes that where one procedure cannot discriminate, “a combination of two or more procedures is recommended”.

Translated into what to look for on a report for a blended vial:

• A chromatogram that resolves both components. Reversed-phase HPLC separates peptides by how strongly they stick to the column, and two peptides as different as a 29-residue GHRH analogue and a pentapeptide should elute well apart. You want to see both main peaks identified, not one peak and a purity number. Our guide to reading an HPLC chromatogram explains retention time and peak assignment.
• Purity stated per component. A single percentage for a mixture is ambiguous: it cannot tell you whether an impurity belongs to one component or whether the two are present in the intended proportions.
• Two masses confirmed. Mass spectrometry identity work should find the expected mass of each peptide. Note what mass cannot tell you: it “cannot distinguish between isomers”, so it cannot confirm ipamorelin’s D-amino acids or its Aib residue against same-mass alternatives. That needs chiral or derivatisation methods. See how to read a peptide mass spectrum.
• A stated ratio, and how it was shown. Quantitation by HPLC assumes a quantitative reference standard for each component; where none exists, a gravimetric approach is used in which both standard and sample are “corrected for counterion content and water content”.
• Net peptide content, per component. Synthetic peptides are supplied as salts, carrying trifluoroacetate or acetate counter-ions, and peptides “are quite hygroscopic” so uncontrolled moisture “can lead to erroneous assay results”. In a blend, a single total labelled mass covers two peptides with two different counter-ion and water loads. Our guide to net peptide content works through the arithmetic.

What’s established and what isn’t

Sourcing a blended vial in Canada

Everything that applies to a single research peptide applies here, plus the per-component checks above. Before ordering, confirm that:

• The documentation names both peptides. Identity, purity and content should each be attributable to a component.
• You know which CJC-1295 you are getting. With DAC and without are different molecules with different published evidence.
• The batch number on the certificate matches your vial. See our COA guide.
• Storage is cold, dry and dark, and the vial is lyophilized on arrival. See the peptide storage guide and what lyophilized means.

CJC-1295 + IpamorelinThe two peptides in one vialView product CJC-1295 with DACThe DAC-bearing formView product CJC-1295 No DACModified GRF (1-29)View product IpamorelinThe pentapeptide on its ownView product

Frequently asked questions