Ipamorelin vs CJC-1295 vs Sermorelin: the GH axis compared

Research context (RUO): Ipamorelin, CJC-1295 and sermorelin are three peptides that stimulate the growth hormone axis (GH axis) in laboratory research via different points of engagement. All products on this page are supplied exclusively for in-vitro laboratory research (Research Use Only) and are not intended for human or animal use.

Ipamorelin vs CJC-1295 vs Sermorelin: the GH axis compared

The comparison Ipamorelin vs CJC-1295 vs sermorelin revolves around one central question: in what way do these peptides prompt the pituitary to release growth hormone (GH)? All three are used in research to stimulate the GH axis, but they do so via two fundamentally different receptors. Ipamorelin mimics the hunger hormone ghrelin, while CJC-1295 and sermorelin are analogues of growth hormone-releasing hormone (GHRH). That difference in mechanism explains their divergent half-life, selectivity and the reason why researchers often study the two classes together.

Two routes to the same GH peak

The pituitary releases growth hormone under the influence of two natural signals. The first is GHRH, which via the GHRH receptor drives the production and release of GH. The second is ghrelin, which via the growth hormone secretagogue receptor (GHS-R) gives a separate, amplifying stimulus. Scientists call substances that mimic these routes “growth hormone secretagogues”. The three peptides in this comparison fall into two groups:

• Ghrelin agonist (GHRP class): ipamorelin binds to the GHS-R, the same receptor as ghrelin.
• GHRH analogues: CJC-1295 and sermorelin bind to the GHRH receptor and are structurally derived from the body's own GHRH.

Because the two receptors work independently of each other, the peptides act on different links of the same axis — which forms the basis for the combined research further on in this article.

What is ipamorelin? — the selective ghrelin agonist

Ipamorelin is a pentapeptide from the family of growth hormone-releasing peptides (GHRPs). It binds to the GHS-R and thereby mimics the action of ghrelin on the pituitary. In the original publication by Raun and colleagues (1998), ipamorelin was described as “the first selective growth hormone secretagogue”: in preclinical research it stimulated GH release without a notable rise in adrenocorticotropic hormone (ACTH), cortisol or prolactin. That selectivity is precisely what distinguishes ipamorelin within the GHRP class from older compounds such as GHRP-6, which also influenced hunger and cortisol in research. The reported half-life is around two hours, so that ipamorelin gives a short, pulse-like stimulus.

What is CJC-1295? — the long-acting GHRH analogue

CJC-1295 is a modified variant of GHRH(1-29). The best-known form contains a so-called Drug Affinity Complex (DAC): a chemical group that binds to albumin in the blood and thus protects the peptide against rapid breakdown. Where natural GHRH is broken down within minutes, for CJC-1295 DAC a half-life of about six to eight days is reported in research. In a study by Ionescu and Frohman (2006), GH release nevertheless remained pulsatile despite this continuous stimulation: the pituitary released GH in waves rather than in one flat stream. Researchers regard that as an indication that the physiological feedback is partly retained. In addition to the DAC form, there is also a variant without DAC (modified GRF 1-29), which acts much more briefly and is closer to sermorelin in profile.

What is sermorelin? — the short GHRH analogue

Sermorelin is the 1-29 fragment of human GHRH, generally regarded as the shortest fully functional part of the molecule. It binds to the GHRH receptor and stimulates the pituitary to release GH in natural bursts. The half-life is short — on the order of minutes — so that sermorelin, like natural GHRH, gives a rapidly rising and rapidly fading stimulus. Historically, sermorelin was approved in 1997 for research into and diagnostics of growth hormone deficiency in children; commercial production was discontinued around 2008. In the comparison with CJC-1295, sermorelin represents the “unmodified” GHRH analogue, while CJC-1295 shows what DAC technology does to the duration of action.

Ipamorelin vs CJC-1295 vs sermorelin: the core differences at a glance

• Receptor & class: ipamorelin acts on the GHS-R (ghrelin agonist / GHRP); CJC-1295 and sermorelin act on the GHRH receptor (GHRH analogues).
• Half-life: sermorelin minutes, ipamorelin around two hours, CJC-1295 DAC about six to eight days.
• Selectivity: ipamorelin stood out in research for its minimal influence on ACTH, cortisol and prolactin; GHRH analogues already act selectively by nature via the GHRH receptor.
• Release pattern: sermorelin and ipamorelin give short pulses; CJC-1295 DAC sustains the GHRH stimulus for days, whereby the pulsatility was retained in research.
• Origin: ipamorelin is a synthetic pentapeptide; sermorelin and CJC-1295 are derived from the body's own GHRH.

Why GHRH analogue and GHRP are studied together

The most studied combination in this field is a GHRH analogue together with a ghrelin agonist — for example CJC-1295 with ipamorelin. The reason lies in the two independent receptors. Because GHRH analogues and GHRPs act on different points of engagement, their signals reinforce each other: research on growth hormone secretagogues describes that the greatest increase in natural GH release occurs through the synergistic action of GHRPs and GHRH at the level of the GHS-R and the GHRH receptor respectively. In a study in hypogonadal men (published in 2017), researchers combined a GHRH analogue (sermorelin) with GHRPs and reported a significant rise in IGF-1, the downstream marker of GH activity, from an average of 159.5 to 239.0 ng/mL. The GHRH analogue provides the “production” stimulus, while the GHRP component further drives release via a separate route — two keys that together open more than each alone. This explains why the CJC-1295 + Ipamorelin blend is a widely studied research model.

These peptides in laboratory research: handling & dissolving

Ipamorelin, CJC-1295 and sermorelin are supplied as freeze-dried (lyophilised) powder and must first be reconstituted for in-vitro research, usually with bacteriostatic or sterile water. Because of the short half-lives of ipamorelin and sermorelin, correct, sterile handling is important for reproducible results. A detailed explanation of the right fluid and ratios is in the pillar reconstitute peptides and in dissolve peptide: which liquid.

Quality & purity

For peptides that act on the GH axis, purity is decisive for reliable research: contaminants or degradation products can distort receptor binding and therefore the outcomes. Every relevant batch is independently HPLC-tested by an external laboratory; the certificate of analysis (CoA) is publicly verifiable per batch. In the pillar why we rejected a batch it is described how that control works in practice.

Frequently asked questions about ipamorelin vs CJC-1295 vs sermorelin

What is the main difference between ipamorelin and CJC-1295 or sermorelin?
Ipamorelin is a ghrelin agonist that acts on the GHS-R, while CJC-1295 and sermorelin are GHRH analogues that act on the GHRH receptor. They stimulate the same GH axis via different receptors, which distinguishes their research profiles.

Why does CJC-1295 have a much longer half-life than sermorelin?
CJC-1295 DAC contains a Drug Affinity Complex that binds to albumin in the blood and protects the peptide against rapid breakdown. In research, a half-life of about six to eight days is therefore reported, compared to minutes for sermorelin.

What makes ipamorelin “selective”?
In the study by Raun and colleagues (1998), ipamorelin stimulated GH release without a notable rise in ACTH, cortisol or prolactin. This selectivity distinguishes it from older GHRPs such as GHRP-6.

Why are CJC-1295 and ipamorelin often studied together?
Because a GHRH analogue and a ghrelin agonist act on different, independent receptors. Research describes that their signals work together synergistically, with the combined GH release being greater than with each peptide separately.

Is sermorelin the same as CJC-1295 without DAC?
They are closely related but not identical. CJC-1295 is derived from GHRH(1-29) — just like sermorelin — but contains amino acid substitutions that increase stability. The variant without DAC (modified GRF 1-29) is close to sermorelin in duration of action.

May these peptides be used for anything other than research?
No. Ipamorelin, CJC-1295 and sermorelin are supplied exclusively for in-vitro laboratory research (Research Use Only) and are not intended for diagnostic or therapeutic use in humans or animals.

Read more & research at Peplife

• Research Ipamorelin at Peplife
• Research CJC-1295 DAC at Peplife
• Research Sermorelin at Peplife
• Researching the CJC-1295 + Ipamorelin blend at Peplife
• View all GH axis peptides
• Ipamorelin research: the selective GH secretagogue
• CJC-1295 research: DAC and duration of action
• Sermorelin research: the GHRH analogue
• Growth hormone peptides: the complete overview
• Sermorelin vs tesamorelin
• CJC-1295 with DAC vs without DAC

Sources: Raun K. et al. (1998), Ipamorelin, the first selective growth hormone secretagogue, Eur J Endocrinol · Ionescu M. & Frohman L.A. (2006), Pulsatile secretion of GH persists during continuous stimulation by CJC-1295, J Clin Endocrinol Metab · Growth Hormone Secretagogue Treatment in Hypogonadal Men Raises Serum IGF-1 Levels (2017), PMC · Sermorelin — overview GHRH(1-29)

Research Use Only. All products are supplied exclusively for in vitro laboratory research. Not intended for diagnostic or therapeutic use in humans or animals, and not approved by the EMA or FDA.