CJC-1295 and ipamorelin: two doors to growth hormone, one confusing name

Two molecules, two doors

In 2009, Norwegian police and customs sent the national doping laboratory an unidentified pharmaceutical preparation. Mass spectrometry showed a 29-amino-acid peptide with an amidated end, a sequence consistent with a product marketed as CJC-1295 ^[5]. The catch: the CJC-1295 tested in clinical trials is not a plain 29-residue peptide. It carries an extra lysine and a chemical anchor that lets it latch onto albumin ^[1,6].

That mismatch is the first thing to understand about this blend. The second is its logic. The pituitary cells that make growth hormone (GH) respond to two separate "go" signals: growth-hormone-releasing hormone (GHRH) from the brain, and ghrelin, a hormone made mostly in the stomach ^[11]. CJC-1295 copies the first signal and ipamorelin copies the second. Our sermorelin article explains the full GH axis, including the brakes that keep it in check.

Origins

CJC-1295: a peptide that rides on albumin

CJC-1295 was developed by ConjuChem in Montreal using its Drug Affinity Complex (DAC) technology ^[1,4,13]. The idea was to fix GHRH's biggest weakness, a half-life of minutes, by bolting on a reactive maleimide group that bonds to a free sulphur atom on serum albumin, the dominant protein in blood ^[1,4].

The peptide part starts from the first 29 amino acids of human GHRH, with four substitutions (D-Ala at position 2, Gln at 8, Ala at 15, Leu at 27) and an extra lysine at position 30 that carries the maleimidopropionyl anchor ^[6]. In rats, it attached to albumin within 15 minutes and was still present in plasma beyond 72 hours ^[1].

Ipamorelin: the selective one

Ipamorelin came out of a chemistry programme at Novo Nordisk in Denmark, described in 1998 ^[7]. It is a pentapeptide, Aib-His-D-2Nal-D-Phe-Lys-NH2, derived from the older growth-hormone-releasing peptide GHRP-1 ^[7]. In rat pituitary cells it was about as potent as GHRP-6. The surprise came in pigs: GHRP-6 and GHRP-2 raised ACTH and cortisol, while ipamorelin did not, even at doses more than 200 times higher than those needed for GH release ^[7].

Its target, the growth hormone secretagogue receptor, turned out to be the receptor for ghrelin, a stomach hormone discovered in 1999 ^[11]. In healthy volunteers, intravenous ipamorelin had a terminal half-life of about 2 hours and produced a single burst of GH that peaked at around 40 minutes ^[8].

The naming problem

"CJC-1295 without DAC", also widely called "Modified GRF (1-29)" or "Mod GRF 1-29", is the same 29-residue backbone with the four substitutions but without the lysine anchor. The sequences are:

• CJC-1295 (with DAC): Tyr-D-Ala-Asp-Ala-Ile-Phe-Thr-Gln-Ser-Tyr-Arg-Lys-Val-Leu-Ala-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Leu-Ser-Arg-Lys(maleimidopropionyl)-NH2 ^[6]
• CJC-1295 without DAC: the same sequence ending at Arg29-NH2
• Ipamorelin: Aib-His-D-2Nal-D-Phe-Lys-NH2 ^[7]

A 2026 review of GH-axis peptides treats the two CJC-1295 forms as separate compounds and found no peer-reviewed human studies of the version without DAC ^[13]. This matters because all the multi-day pharmacology described below was measured with the albumin-binding version ^[2,3]. Without the anchor there is no albumin binding, so those results cannot simply be transferred. A mass-spectrometry identity result tells the two apart; our guide to reading a certificate of analysis explains what to look for.

How two signals add up

Picture the GH-producing cell as a shop with two doors. GHRH opens one; ghrelin and its mimics open the other. Opening both at once lets in more customers than the two doors manage separately, added together.

That intuition comes from physiology studies with older molecules. In 1990, Bowers and colleagues gave 18 healthy men natural GHRH and the hexapeptide now known as GHRP-6, alone and together ^[10]. Low doses of GHRP-6 plus GHRH released GH synergistically, more than the sum of each, and the authors concluded that the two act through independent pathways ^[10]. The same study showed the drawback of the older peptides: at the highest GHRP-6 dose, prolactin and cortisol roughly doubled ^[10]. Ipamorelin's appeal was that, in animal tests, it did not show that effect ^[7].

The synergy has been shown for the two classes of molecule, using natural GHRH and GHRP-6. It has never been tested in a published study with CJC-1295 and ipamorelin themselves ^[10,13].

What the research shows

CJC-1295 in healthy adults

Two randomised, placebo-controlled, double-blind trials in healthy adults aged 21 to 61 tested single and repeated doses ^[2]. After a single injection, mean GH rose 2- to 10-fold for 6 days or more and IGF-1 rose 1.5- to 3-fold for 9 to 11 days. The estimated half-life was 5.8 to 8.1 days, IGF-1 stayed above baseline for up to 28 days after multiple doses, and no serious adverse reactions were reported ^[2].

A follow-up study sampled blood every 20 minutes overnight in healthy men aged 20 to 40, before and one week after a single injection ^[3]. GH still came in pulses of unchanged frequency and size, but the trough level between pulses rose 7.5-fold, mean GH rose 46% and IGF-1 rose 45% ^[3].

The 2006 trial halt

ConjuChem also ran a phase 2 trial in people with HIV-associated lipodystrophy: international, randomised, placebo-controlled and double-blind, with 192 patients enrolled for 12 weeks of weekly dosing ^[4]. In July 2006, a patient at a site in Argentina reported chest discomfort about two hours after the eleventh weekly dose; an ECG confirmed an acute heart attack, and the patient died about an hour later ^[4].

The attending physician's most likely explanation was undiagnosed coronary artery disease with a ruptured plaque, and the company reported no evidence of heart toxicity in earlier studies ^[4]. ConjuChem nevertheless terminated the trial ^[4]. We found no published efficacy results from it.

Ipamorelin in patients

Beyond the volunteer study ^[8], ipamorelin's main clinical test was in postoperative ileus, the gut shutdown that can follow bowel surgery. Helsinn sponsored a phase 2 trial ^[14] that enrolled 117 adults undergoing bowel resection ^[9]. Median time to the first tolerated solid meal was 25.3 hours with ipamorelin and 32.6 hours with placebo, a difference that was not statistically significant (p=0.15) ^[9]. Adverse events were common in both groups (87.5% versus 94.8%), and the authors reported no significant differences in any efficacy analysis ^[9].

The combination itself

A PubMed search in October 2026 found no clinical trial of CJC-1295 combined with ipamorelin. The 2026 review describes the pairing as driven largely by anecdotal rationale, with limited controlled evidence for synergy or for body-composition effects in healthy people ^[13].

What we don't know yet

• How the pair behaves together. There are no data on interactions, dose-response or safety for the combination ^[13].
• Constant versus pulsed stimulation. CJC-1295 with DAC kept the pulses but raised the troughs between them 7.5-fold ^[3]. The long-term consequences of keeping baseline GH elevated for days at a time are unknown.
• What the 2006 death means. The investigator judged coronary disease the likely cause, but the trial stopped early, so its safety and efficacy picture is incomplete ^[4].
• Regulatory safety concerns. The FDA's compounding review lists serious adverse events associated with CJC-1295, including increased heart rate and a systemic vasodilatory reaction, and notes that clinical data are limited ^[12]. For ipamorelin, it flags possible immune reactions, peptide impurities and unnatural amino acids, and cites a published study in which serious adverse events, including death, occurred when ipamorelin was given intravenously for gut motility ^[12].
• The form usually paired with ipamorelin. The 2026 review notes that the CJC-1295 used alongside ipamorelin is typically the version without DAC, which has no peer-reviewed human data at all ^[13].

Regulatory status

• Approval. Neither compound has been approved as a medicine; both circulate as unregulated "research compounds" ^[13].
• US compounding. Ipamorelin has been in the FDA's Category 2 (substances that may present significant safety risks) for outsourcing facilities since 29 September 2023. As of April 2026, the FDA listed the nominations for CJC-1295, and for ipamorelin under the pharmacy-compounding route, as withdrawn ^[12]. Neither status amounts to an FDA approval.
• Sport. WADA names CJC-1295 as a prohibited GHRH analogue and ipamorelin as a prohibited GH secretagogue under S2.2.4, banned at all times ^[15].

In the lab: handling and storage

The CJC-1295 and ipamorelin blend is supplied as a lyophilised powder. Common practice is long-term storage at −20 °C, with 2–8 °C acceptable for short periods, protected from light and moisture. After reconstitution, solutions are usually kept cold and split into single-use aliquots to avoid repeated freeze-thaw cycles. If the DAC form is present, remember that its maleimide group is designed to react with free thiols ^[1], so buffers containing reducing agents or free cysteine can consume it. For a blend, identity testing should confirm both components separately.

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