CJC-1295 vs Ipamorelin: what the published research shows

At a glance

Two routes to the same hormone

The pituitary gland releases growth hormone in response to two separate signals. GHRH, made in the hypothalamus, acts on the GHRH receptor. Ghrelin, a hormone mostly made in the stomach, acts on a different receptor, GHS-R1a. CJC-1295 is built to copy the first signal and ipamorelin the second. That is the reason the two are so often discussed together: they act on separate receptors that both lead to growth hormone release.

CJC-1295 with DAC vs without DAC

The name CJC-1295 originally belonged to one specific molecule. In 2005 the Canadian company ConjuChem described a modified GHRH(1-29) carrying a chemical linker called a Drug Affinity Complex (DAC). Once in the blood, the DAC bonds to albumin, the most common blood protein, so the peptide stays in circulation far longer. In rats, CJC-1295 was found attached to albumin within 15 minutes and was still present in plasma more than 72 hours later.

"CJC-1295 without DAC" (also sold as Modified GRF (1-29) or tetrasubstituted GRF(1-29)) is the same 29-amino-acid chain with four substitutions but no albumin linker. The substitutions make it more resistant to breakdown than natural GHRH(1-29). Without the linker, though, it cannot attach to albumin, so it would not be expected to share the multi-day half-life measured for the DAC version.

This is worth knowing when reading the research. Every human study published under the name CJC-1295 used the DAC version. The version without DAC has not yet been studied in published human trials, which makes it one of the more open research areas in this group of peptides. Its close relative sermorelin, the unmodified GHRH(1-29), is the usual comparison point.

CJC-1295 in the research

In two randomised, placebo-controlled, double-blind trials in healthy adults aged 21 to 61, a single injection of CJC-1295 with DAC raised average growth hormone levels 2- to 10-fold for six days or more. It also raised IGF-I, the main hormone produced in response to growth hormone, 1.5- to 3-fold for 9 to 11 days. The estimated half-life was 5.8 to 8.1 days, and no serious adverse reactions were reported.

A follow-up study measured growth hormone every 20 minutes overnight in healthy men. Growth hormone is normally released in pulses, and those pulses kept the same frequency and size after CJC-1295. The baseline level between pulses, however, rose 7.5-fold, average growth hormone rose 46% and IGF-I rose 45%. In other words, CJC-1295 lifted overall growth hormone levels while keeping the body's natural pulse pattern intact.

Ipamorelin in the research

Novo Nordisk described ipamorelin in 1998 as the first selective growth hormone secretagogue. In swine, older ghrelin-receptor peptides (GHRP-6 and GHRP-2) also raised the stress hormones ACTH and cortisol. Ipamorelin did not, even at doses more than 200 times higher than needed for growth hormone release, and none of the compounds tested changed FSH, LH, prolactin or TSH.

In a dose-escalation study with eight healthy men at each of five dose levels, ipamorelin had a terminal half-life of about two hours. Each dose produced a single pulse of growth hormone, peaking at about 40 minutes and then falling away. That short, clean pulse is the opposite profile to CJC-1295 with DAC, which is one reason the two are so often compared.

Ipamorelin was later tested for a different use: helping the gut recover after bowel surgery, since the ghrelin receptor also affects gut movement. In a randomised, double-blind, placebo-controlled phase 2 trial in 114 patients, patients given ipamorelin reached their first tolerated solid meal about 7 hours sooner (a median of 25.3 hours vs 32.6 hours with placebo). The difference was not statistically significant in a trial of this size (p = 0.15). The treatment was well tolerated, with a similar rate of side effects to placebo.

Where the research stands

The published human research on both compounds is still small: a handful of trials from the late 1990s to 2014. A 2026 review in Frontiers in Endocrinology noted that the version of CJC-1295 without DAC "remains essentially uncharacterised in the peer-reviewed human literature", and that the ipamorelin surgery result slowed further clinical work for that use. Both remain research compounds rather than approved medicines, including in Australia.

Both are named on the WADA Prohibited List under S2 (growth hormone releasing factors): CJC-1295 as a GHRH analogue and ipamorelin as a growth hormone secretagogue. Both are banned at all times, in and out of competition. Anti-doping researchers have published methods for detecting CJC-1295, both with and without DAC, in laboratory-prepared urine samples.

Sources

• Jetté et al., Endocrinology (2005) — hGRF(1-29)-albumin bioconjugates: identification of CJC-1295 as a long-lasting GRF analogue
• Teichman et al., J Clin Endocrinol Metab (2006) — Prolonged stimulation of GH and IGF-I secretion by CJC-1295 in healthy adults
• Ionescu & Frohman, J Clin Endocrinol Metab (2006) — Pulsatile GH secretion persists during continuous stimulation by CJC-1295
• Raun et al., Eur J Endocrinol (1998) — Ipamorelin, the first selective growth hormone secretagogue
• Gobburu et al., Pharm Res (1999) — Pharmacokinetic-pharmacodynamic modelling of ipamorelin in human volunteers
• Beck et al., Int J Colorectal Dis (2014) — Randomised, controlled study of ipamorelin for postoperative ileus (NCT00672074)
• Dominikowski et al., Front Endocrinol (2026) — Performance-enhancing peptides modulating the GH-IGF-1 axis: clinical evidence vs self-administration
• Memdouh et al., Drug Test Anal (2021) — Advances in the detection of GHRH synthetic analogues, including CJC-1295 with and without DAC
• WADA — The Prohibited List (S2.2.4 growth hormone releasing factors)
• PubChem — Ipamorelin (CID 9831659)
• PubChem — CJC-1295 with DAC (CID 91971820)
• PubChem — Sermorelin, GHRH(1-29)NH2 (CID 16132413)