Sermorelin vs CJC-1295 ipamorelin: three molecules, one axis

The comparison on one screen

"Ipamorelin vs sermorelin" is searched about 4,400 times a month in the United States and "sermorelin vs CJC-1295" about 1,000 times, usually by someone choosing between clinic offers. The chart is built to answer that person with published numbers only; the rest of the page says where each cell comes from.

One family, one stranger

Sermorelin and CJC-1295 are relatives. Both are the N-terminal 29 residues of human growth-hormone-releasing hormone, the fragment identified as fully active when the hormone was first characterised from a pancreatic tumour in 1982 [Rivier et al., 1982]. Sermorelin is that fragment as found, amidated; it was reviewed as a licensed product in 1999 and used both as a stimulation test for growth hormone deficiency and as a once-daily bedtime treatment for prepubertal children with idiopathic GH deficiency [Prakash et al., 1999]. CJC-1295 is the fragment with four residues swapped for stability and a maleimide tail that binds serum albumin, which is the whole reason its numbers differ (the chemistry is in Mod GRF 1-29 and DAC versus no DAC).

Ipamorelin is not a relative. It is a five-residue synthetic peptide from an entirely different programme, at Novo Nordisk, built to mimic the GHRPs and to act on what is now called the ghrelin receptor, GHS-R1a, without the cortisol and prolactin release of its predecessors [Raun et al., 1998]. It shares nothing with the other two except the cell it acts on: the pituitary somatotroph carries both receptors, and a GHRH signal and a ghrelin signal arriving together release more GH than either alone. That synergy was shown in men by Bowers in 1990, with GHRH(1-44) and GHRP-6 [Bowers et al., 1990]; it is the reason CJC-1295 and ipamorelin are sold as a pair and sermorelin usually is not.

Minutes, hours, days

The largest single difference among the three is how long each lasts. Sermorelin is cleared in minutes; the practical evidence is that Corpas and colleagues, at the National Institute on Aging, had to inject GHRH(1-29) subcutaneously twice a day for 14 days to raise 24-hour GH and IGF-1 in ten men aged 68, and only the 1 mg dose did so, not 0.5 mg.

At the higher dose the older men's GH and IGF-1 no longer differed from those of nine men aged 26, and fasting glucose, blood pressure and blood chemistry were unchanged [Corpas et al., 1992]. Ipamorelin lasts about two hours after an intravenous dose and produces one GH episode that peaks at 40 minutes [Gobburu et al., 1999]. CJC-1295 with its albumin tail lasts 5.8 to 8.1 days, and a single dose held GH 2 to 10-fold above baseline for 6 days or more and IGF-1 1.5 to 3-fold for 9 to 11 days [Teichman et al., 2006].

The consequence for the GH rhythm is the second difference. Sermorelin and ipamorelin each produce a pulse and leave. CJC-1295 raised the trough between pulses 7.5-fold without changing the number or size of the pulses, so mean GH rose 46 % and IGF-1 45 % one week after a single injection [Ionescu et al., 2006]. Whether a raised trough or a bigger pulse is the better way to raise IGF-1 is a physiological argument, made for GHRH analogues in general by Walker in 2006 on the ground that they preserve pituitary feedback where recombinant GH does not [Walker, 2006]; the argument applies to all three molecules equally, since all three work through the pituitary.

Who has human data, and how much

Swipe sideways to see the whole table.

The table is the part of the comparison most pages leave out. Sermorelin was a licensed medicine with a paediatric programme long enough to follow height velocity for 36 months; its most frequent adverse events were transient facial flushing and injection-site pain [Prakash et al., 1999]. CJC-1295 has two well-designed but small trials in healthy adults. Ipamorelin's largest trial had nothing to do with growth hormone. And the pair has no trial at all. What the trials recorded is set out in the dosage guide.

Regulatory status

Sermorelin is the only one of the three that has ever been an approved drug, and the product reviewed in 1999 is no longer marketed. CJC-1295's phase 2 trial in HIV-associated visceral fat was terminated in 2006 and ipamorelin's ileus programme stopped in 2014, so neither reached approval anywhere. All three are prohibited in sport: the WADA list names CJC-1295, sermorelin and tesamorelin among GHRH analogues and ipamorelin among growth hormone secretagogues, class S2 [World, 2026]. The molecule that did complete a programme, tesamorelin, is the subject of CJC-1295 ipamorelin versus tesamorelin.

What the comparison cannot settle

It cannot say which is "better", because no study has compared them. It can say that sermorelin is the best-documented, that CJC-1295 is the longest-acting and the only one shown to raise trough GH without flattening pulses, that ipamorelin is the most selective GHRP by the criteria its designers set, and that combining a GHRH analogue with a GHRP has a 36-year-old proof of principle in humans with different molecules. Anyone who tells you more than that is not reading the same literature.

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