Ipamorelin and CJC-1295

01 · What it is

This guide covers two compounds administered together: ipamorelin, a synthetic pentapeptide and selective agonist at the growth hormone secretagogue receptor GHS-R1a ³, and CJC-1295, a GRF(1-29) analogue acting at the growth hormone-releasing hormone receptor — in its most-studied form carrying a drug affinity complex that binds covalently to serum albumin, extending its half-life from minutes to days ^8,9.

The pairing is unusual in this roadmap, and it is worth being precise about why. Every other combination covered on this site was assembled in commerce and tested afterwards, if at all. This one has a genuine mechanistic rationale that predates it by decades and rests on a proper experiment.

GHRH analogues and ghrelin receptor agonists act through partly separate pathways. Antisera depletion in rats established that growth hormone-releasing peptides work through a combination of endogenous GHRH release and somatostatin withdrawal rather than acting on somatotrophs in isolation ¹, and combined GHRH plus GHRP administration produces a larger growth hormone response than either component alone ^1,2,5. Two different receptors, two different mechanisms, a demonstrated supra-additive response. That is what a real combination rationale looks like.

No study has tested this pairing. Not in humans, not in animals, not in vitro. The synergy evidence is for GHRH plus growth hormone-releasing peptides as classes, in acute endocrine testing — not for ipamorelin with CJC-1295, at any dose, for any duration, measuring any outcome.

And there is a finding from elsewhere in this family that anyone reading about the pairing should have in view: in a randomised controlled trial of a growth hormone secretagogue in 123 patients, IGF-1 rose by 51.4 ng/mL with p < 0.001 while stair climbing power did not improve (p = 0.292), and the trial was terminated early for a safety signal ¹⁰. Raising the axis reliably is not the same as producing a benefit, and in this family the two have come apart wherever they have been measured together.

As of September 2026 neither compound holds a marketing authorisation from any regulator.

02 · Evidence at a glance

Evidence grade

Preclinical

Studies of this combination

None, in any species

Human pharmacokinetic or interaction data for the pairing

None

Combination toxicology

None

Mechanistic rationale

Genuine — GHRH and GHRP pathways are partly separate and synergistic ^1,2,5

Evidence for that synergy

Class-level, in acute endocrine testing; not for these two compounds ^1,5

Ipamorelin’s own controlled trial

Phase 2 in postoperative ileus, 117 patients, null on primary and secondary endpoints ¹¹

CJC-1295’s own human data

One phase 1 in healthy adults; half-life 5.8–8.1 days, IGF-1 elevated to 28 days ⁸

Efficacy trials of either compound in body composition or recovery

None

Approval status

None, either compound, any jurisdiction

03 · Mechanism of action

Two receptors, two pathways

CJC-1295 acts at the growth hormone-releasing hormone receptor on pituitary somatotrophs. Ipamorelin acts at the growth hormone secretagogue receptor, the ghrelin receptor, expressed on somatotrophs and on hypothalamic neurons ^3,7. These are distinct receptors with distinct signalling and distinct regulatory inputs.

Why the combination should work, on paper

The classical account is that a GHRH analogue increases the amplitude of growth hormone pulses while a ghrelin receptor agonist increases their frequency and suppresses somatostatin tone. The experimental support is real: antisera depletion in rats showed that growth hormone-releasing peptide responses depend on both endogenous GHRH and somatostatin withdrawal ¹, and combined GHRH plus GHRP administration in humans produces responses larger than either alone, a finding reproduced across populations including type 2 diabetes under clamp conditions ⁵ and obesity ⁴.

This is the strongest combination rationale in the entire roadmap. It is not marketing; it is receptor pharmacology with a depletion experiment behind it.

Why that is not sufficient

A synergy demonstrated between two drug classes, in acute testing, on a hormonal endpoint, does not establish anything about two specific compounds administered together over time for a functional outcome. Three things separate the two situations.

Kinetics do not match. CJC-1295 with DAC has an estimated half-life of 5.8 to 8.1 days and keeps IGF-1 elevated for up to 28 days after dosing ⁸. Ipamorelin’s effect is short-acting; its trial used twice-daily intravenous administration ¹¹. Combining a compound that produces sustained receptor stimulation with one producing brief pulses is not the same experiment as the acute co-administration studies that demonstrated synergy, and nobody has characterised what the combined exposure profile looks like.

The acute studies measured hormone release, not outcomes. Growth hormone area under the curve over hours is the endpoint that established synergy ^1,5. No study has followed the combination to body composition, strength, recovery or anything else.

The dissociation is documented in this very family. Ibutamoren raised IGF-1 decisively and did not improve function in either trial that measured function ^6,10. Ipamorelin’s own trial was null on its efficacy endpoints ¹¹. If the components do not produce outcomes individually, a larger hormonal response from combining them is not evidence that outcomes will follow.

What has never been measured

Whether the two compounds interact pharmacokinetically. Whether combined stimulation desensitises either receptor over time — a specific and plausible concern given that one component provides continuous stimulation for days. What the combined growth hormone and IGF-1 profile actually looks like in a human. Whether co-formulation is chemically stable. None of these has been studied.

04 · Key research findings

The combination. No study. No in vitro work, no animal study, no human data, no case series.

The synergy evidence, stated precisely. Antisera depletion in rats established the dual GHRH and somatostatin dependence of growth hormone-releasing peptide action ¹. Human studies of combined GHRH plus GHRP-6 administration characterised the response under euglycaemic and hyperglycaemic clamp in type 2 diabetes ⁵, and in obesity showed GHRP-6 and hexarelin responses greater than GHRH alone though still below those in lean subjects ⁴. Reviews of the family document the synergy as a established property of the two classes ^2,7.

Real, reproducible, class-level, acute, and about hormone release.

What each component brings individually. CJC-1295 with DAC: one phase 1 study in healthy adults, half-life 5.8 to 8.1 days, IGF-1 above baseline for up to 28 days after multiple doses, with the authors concluding the data supported potential utility as a therapeutic agent ⁸; and a demonstration that pulsatile secretion persists despite continuous stimulation ⁹. Ipamorelin: the characterisation study establishing selectivity without adrenocorticotropic or cortisol release ³, and one phase 2 trial in postoperative ileus in 117 patients that found no significant difference from placebo on key or secondary efficacy analyses ¹¹.

Between them, two human studies and one null trial.

The cautionary result from within the family. In a multicentre randomised placebo-controlled phase IIb trial of the growth hormone secretagogue ibutamoren in 123 elderly patients, IGF-1 increased by 51.4 ng/mL (95% CI 34.42–68.44, p < 0.001) while stair climbing power did not improve (+12.5 W, 95% CI −10.95 to 35.88, p = 0.292), several other functional measures were unchanged, and the trial was terminated early due to a congestive heart failure safety signal, with the authors concluding an unfavourable safety profile in that population ¹⁰. An earlier trial in the same indication had also found no significant functional improvement ⁶.

This is the most important context for the combination: the endpoint the pairing is designed to move has been moved, decisively, without producing benefit.

Where the pairing appears in the literature. Reviews written for orthopaedic and sports medicine audiences name CJC-1295 combined with ipamorelin among the injectable peptide protocols most commonly encountered, and report that its benefits are largely unvalidated in human trials ^15,16. A 2026 review of performance-enhancing peptides modulating the GH-IGF1 axis lists both components among agents met in self-administration protocols ¹⁷.

Every one of these documents a pattern of use. None reports a study of the pairing, because none exists.

05 · Evidence overview

06 · Safety profile

Animal data. No combination toxicology exists. For the components individually, no repeat-dose toxicology, genotoxicity, reproductive or carcinogenicity programme was identified for either compound.

Human data on the combination. None.

Human data on the components. Ipamorelin: treatment-emergent adverse events in 87.5% of the ipamorelin group versus 94.8% of placebo across seven days of intravenous administration in post-surgical patients, described by the investigators as well tolerated ¹¹. CJC-1295: a phase 1 programme in healthy adults ⁸, with FDA separately citing serious adverse events including increased heart rate and systemic vasodilatory reaction in its account of the substance, and describing available clinical data as limited ¹⁸.

What combination specifically adds. Two problems beyond the sum of the components.

The first is attribution, which applies to every combination in this roadmap: when two investigational compounds are given together, no observation can be assigned to either, to an interaction, or to neither.

The second is specific to this pairing and more serious. One component keeps the growth hormone axis stimulated for weeks after dosing stops ⁸. Adding a second secretagogue to a background of sustained receptor stimulation is not a situation any published study describes, and the exposure cannot be adjusted quickly if something goes wrong. A short-acting compound can be stopped; a 28-day IGF-1 tail cannot.

What is genuinely unknown. Receptor desensitisation under combined chronic stimulation. Combined effects on glucose tolerance, given that growth hormone antagonises insulin action and both components raise growth hormone ^13,14. Whether the cardiac signal seen with a different secretagogue in this family ¹⁰ has any bearing on sustained combined stimulation — untested in either direction. Immunogenicity of either compound or the pair. What a co-formulated preparation contains.

07 · US regulatory status

Current as of 6 September 2026. Neither compound is approved as a drug in the United States or any other jurisdiction, and neither is a controlled substance. No combination product has been evaluated by any regulator.

Ipamorelin acetate appears in FDA’s category 2 bulk drug substances material in the active 503B table since 29 September 2023 and in the table of substances nominated but subsequently withdrawn by the nominators; CJC-1295 appears in the withdrawn table ¹⁸. Neither was among the seven substances reviewed by the Pharmacy Compounding Advisory Committee on 23–24 July 2026, and no combination was ¹⁹.

Under the World Anti-Doping Code, growth hormone-releasing factors and growth hormone secretagogues are both prohibited at all times, and validated urinary detection methods exist for both compounds ¹². Competitors should consult the current Prohibited List directly rather than rely on secondary summaries, including this one.

08 · Limitations of the evidence

1. No study of the combination exists. Every claim about the pairing is an extrapolation from class-level acute endocrine data and from the components studied separately.
2. A real rationale is not evidence of benefit. The GHRH-plus-GHRP synergy is genuine ^1,5 and it concerns hormone release measured over hours. Extending it to body composition or recovery over weeks is an inference nobody has tested.
3. The kinetics of the two components do not match the studies that demonstrated synergy. Those were acute co-administration experiments ^1,5. CJC-1295 with DAC produces receptor stimulation lasting days and IGF-1 elevation lasting weeks ⁸. The combination being used is not the combination that was studied.
4. The components have not produced outcomes individually. Ipamorelin’s only controlled trial was null ¹¹; CJC-1295 has no efficacy trial at all ⁸. Adding two compounds without demonstrated benefit does not produce demonstrated benefit.
5. The family’s own best-tested compound shows why hormonal response is not enough. IGF-1 up 51.4 ng/mL at p < 0.001, function unchanged, trial stopped for a cardiac signal ¹⁰. Any argument for this pairing that runs through IGF-1 elevation has to account for that result.
6. Attribution is impossible in combination use, and the long-acting component means exposure cannot be withdrawn quickly if a problem emerges ⁸.
7. No toxicology, no interaction data, no formulation characterisation for either compound alone or for the pair.

09 · References

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2. Ghigo E, Arvat E, Muccioli G, Camanni F. Growth hormone-releasing peptides. Eur J Endocrinol. 1997;136(5):445–460.

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3. Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552–561.

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4. Scacchi M, Pincelli AI, Cavagnini F. Growth hormone in obesity. Int J Obes Relat Metab Disord. 1999;23(3):260–271.

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5. Micic D, Kendereski A, Sumarac-Dumanovic M, Cvijovic G, Popovic V, Dieguez C, Casanueva F. Growth hormone response to GHRH + GHRP-6 in type 2 diabetes during euglycemic and hyperglycemic clamp. Diabetes Res Clin Pract. 2004;63(1):37–45.

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6. Bach MA, Rockwood K, Zetterberg C, et al. The effects of MK-0677, an oral growth hormone secretagogue, in patients with hip fracture. J Am Geriatr Soc. 2004;52(4):516–523.

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7. Smith RG. Development of growth hormone secretagogues. Endocr Rev. 2005;26(3):346–360.

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8. Teichman SL, Neale A, Lawrence B, Gagnon C, Castaigne JP, Frohman LA. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. J Clin Endocrinol Metab. 2006;91(3):799–805.

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9. Ionescu M, Frohman LA. Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog. J Clin Endocrinol Metab. 2006;91(12):4792–4797.

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10. Adunsky A, Chandler J, Heyden N, et al. MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study. Arch Gerontol Geriatr. 2011;53(2):183–189.

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11. Beck DE, Sweeney WB, McCarter MD; Ipamorelin 201 Study Group. Prospective, randomized, controlled, proof-of-concept study of the ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. Int J Colorectal Dis. 2014;29(12):1527–1534.

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12. Semenistaya E, Zvereva I, Thomas A, Thevis M, Krotov G, Rodchenkov G. Determination of growth hormone releasing peptides metabolites in human urine after nasal administration of GHRP-1, GHRP-2, GHRP-6, hexarelin, and ipamorelin. Drug Test Anal. 2015;7(10):919–925.

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13. Sigalos JT, Pastuszak AW. The safety and efficacy of growth hormone secretagogues. Sex Med Rev. 2018;6(1):45–53.

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14. Sinha DK, Balasubramanian A, Tatem AJ, et al. Beyond the androgen receptor: the role of growth hormone secretagogues in the modern management of body composition in hypogonadal males. Transl Androl Urol. 2020;9(Suppl 2):S149–S159.

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15. Mayfield CK, Bolia IK, Feingold CL, et al. Injectable peptide therapy: a primer for orthopaedic and sports medicine physicians. Am J Sports Med. 2026;54(1):223–229.

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16. Rahman OF, Lee SJ, Seeds WA. Therapeutic peptides in orthopaedics: applications, challenges, and future directions. J Am Acad Orthop Surg Glob Res Rev. 2026;10(1):e25.00236.

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17. Dominikowski A, Rękoś Z, Olejarz M, Szczepanek-Parulska E, Domin R, Ruchała M. The emerging landscape of performance-enhancing peptides modulating the GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration. Front Endocrinol (Lausanne). 2026;17:1822475.

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18. US Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks. Page current as of 22 April 2026. Regulatory document; no PMID.

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19. US Food and Drug Administration. July 23–24, 2026: Meeting of the Pharmacy Compounding Advisory Committee. Docket FDA-2025-N-6895. Regulatory document; no PMID.

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