CJC-1295 + Ipamorelin: Two Receptors, One Somatotroph, and the Arithmetic of a Blend

This blend combines, in a single vial, two peptides that act on separate receptors of the same hormonal axis. CJC-1295 (No DAC) is a stabilised 29-residue GHRH analogue that binds the GHRH receptor on pituitary somatotrophs; ipamorelin is a selective five-residue agonist of GHS-R1a, the ghrelin receptor. The rationale is that the two receptors drive different intracellular pathways in the same cell — Gs and cAMP downstream of the GHRH receptor, Gq and phospholipase C downstream of GHS-R1a — and published pituitary pharmacology describes a larger secretory output when a GHRH analogue and a secretagogue are present together than with either one alone.

We offer CJC-1295 (No DAC) + Ipamorelin freeze-dried together in a 1:1 ratio by weight, as 10 mg (5 mg/5 mg) and 20 mg (10 mg/10 mg) vials, listed with our growth hormone blends.

The two components

CJC-1295 (No DAC) is also sold under the name Mod GRF (1-29). It is the first 29 amino acids of human GHRH — the shortest piece that retains full activity at the receptor — carrying four deliberate substitutions, each aimed at a known weak point: D-Ala at 2 against DPP-4 cleavage, Gln at 8 to eliminate an asparagine that deamidates, Ala at 15 to stabilise the helix, and Leu at 27 in place of a methionine that oxidises. "No DAC" distinguishes it from the version fitted with a drug affinity complex linker that binds albumin; lacking that linker, this peptide is short-acting by design. Our explainer on what CJC-1295 is covers it in full.

Ipamorelin is a five-residue synthetic peptide developed at Novo Nordisk in the 1990s; its Aib and D-2-naphthylalanine residues give it both metabolic stability and affinity for the receptor. What it is known for is selectivity. The older GHRP compounds — GHRP-2, GHRP-6 and hexarelin — pushed up cortisol, ACTH and prolactin together with growth hormone, whereas pharmacology studies in animals and people found ipamorelin released growth hormone without those accompanying rises. See our ipamorelin explainer for its structure.

Why the combination is used

The idea is two complementary pathways converging inside one cell type. GHRH receptor activation works through Gs: cAMP goes up and protein kinase A is activated, which in the accepted model both prompts hormone release and keeps somatotroph gene transcription going. GHS-R1a activation works through Gq: phospholipase C is recruited, IP3 is produced and cytosolic calcium climbs. Because the two routes to secretion use different second messengers, studies in pituitary tissue and in human pharmacology report that GHRH plus a secretagogue gives more than the two responses added together — the finding that gave rise to this entire category of blends.

Another reported component is a functional opposition to somatostatin, the brake on the GH axis. GHS-R1a agonists are described as lowering somatostatin tone, which would let the GHRH-driven response run more fully. Both mechanisms describe pharmacology at the level of the pituitary; neither says anything about outcomes.

Any protocol should account for two things. First, GHS-R1a loses responsiveness under constant stimulation, so how exposure is timed shapes the size of the combined response. Second, freeze-drying the two at 1:1 by weight fixes the molar ratio at roughly 4.7 parts ipamorelin to each part CJC-1295 — their molecular weights are almost fivefold apart, so equal milligrams are far from equal moles. If your study needs to vary the ratio, you will need separate single-peptide vials; our guide to peptide blends versus single vials explains the trade-off.

Research to date

Combined GHRH and secretagogue pharmacology

The strongest data support the general principle, not this specific commercial combination. Since the 1990s, animal and human studies giving GHRH together with a GHRP-type secretagogue have reported greater growth hormone release than either alone — the synergy on which blend products rest.

Ipamorelin selectivity data

In Novo Nordisk's preclinical work, ipamorelin was compared with GHRP-6 and other secretagogues and matched them on growth hormone release while producing no corresponding increase in ACTH or cortisol. That clean profile is the reason current blends pair CJC-1295 with ipamorelin instead of an older GHRP.

Stability work on the GHRH analogue

Other papers tested each of the four Mod GRF (1-29) substitutions against the breakdown pathway it was meant to prevent, and compared persistence of the DAC and non-DAC forms. The distinction is important: the short-acting analogue allows designs built around pulses, whereas the albumin-binding form produces continuous exposure.

What has not been shown

This exact co-formulation has never been tested in controlled studies, and no publication shows a 1:1 weight ratio to be the best choice for any experimental question. Here, as across the whole catalogue, blend ratios are a formulation habit, not a specification backed by evidence. For the broader class, see the GH secretagogue landscape explained.

Formats and sizes

Both vial sizes contain the two peptides freeze-dried together, so one reconstitution gives a solution with both at the labelled ratio. The 10 mg (5 mg/5 mg) vial suits shorter series of experiments; for a longer study that should run on a single lot, the 20 mg (10 mg/10 mg) vial is better value. Each lot's certificate reports purity separately for each peptide, ≥99% by HPLC. Ordering information is in our CJC-1295 + Ipamorelin buying guide, and both peptides are also sold individually as CJC-1295 (No DAC) and Ipamorelin.

Reconstitution and storage in the lab

Treat the blend as one material during reconstitution. Choose bacteriostatic water when the vial will be entered repeatedly and sterile water when a preservative would disturb the assay. Add solvent down the vial wall and swirl instead of shaking.

The vial mass refers to total peptide unless the label says otherwise. Add 2 mL of diluent to a 10 mg (5/5) vial and the combined concentration is 5 mg/mL — that is 2.5 mg/mL of each peptide — so 0.1 mL (the 10-unit line on a U-100 syringe) delivers 250 mcg of CJC-1295 and 250 mcg of ipamorelin. A 20 mg (10/10) vial made up to 4 mL gives the same figures per volume. Working from the combined total rather than the per-peptide amount is the textbook blend error; the reconstitution guide walks through the full method.

Keep sealed vials at −20 °C away from light and moisture, hold reconstituted solution at 2-8 °C for the study period, and aliquot and freeze for longer projects. The essentials are summarised in how to store peptides.

Reading a blend certificate

With a blend, the certificate has to answer something a single-peptide certificate never needs to: what exactly is in the vial, and in what proportion? Look for three things. First, purity stated for each peptide on its own, not as a single blended figure. Second, mass spectrometry showing both expected masses — 3,367.93 g/mol and 711.85 g/mol — which together confirm identity much more strongly than one mass would. Third, an HPLC trace in which the two peptides appear as distinct peaks, so their area ratio can be compared with the stated blend ratio. A two-peptide product documented with one purity value and one mass has an incomplete certificate.

Regulatory position

Neither peptide, and not the blend, holds a marketing authorisation as a medicine in the EU or the United States. Growth hormone itself is a prescription biological product; these peptides are secretagogues investigated for how they influence its release and are not a substitute for it. In sport, anti-doping regulations ban both GH secretagogues and GHRH analogues.

Related blends and further reading

The closest alternatives keep ipamorelin and swap the GHRH-side partner. Tesamorelin + Ipamorelin uses a stabilised analogue of the full 44-residue hormone; Sermorelin + Ipamorelin uses the unmodified native GHRH (1-29) sequence.

Matching catalogue section: Growth Hormone Blends