Search any research-peptide vendor and the same pair appears near the top: CJC-1295 with ipamorelin, usually sold as a blend, usually described as the entry-level growth-hormone stack. Searches for cjc-1295 and ipamorelin stack have risen more than five-fold year on year.
The pairing is not arbitrary. It rests on a pharmacological argument that is thirty years old and correct as far as it goes. What it does not rest on is a study.
The census: ten papers, and what each one is
PubMed, searched 19 September 2026 for records mentioning both compounds: ten.
| Year | Record type | What it is |
|---|---|---|
| 2026 | Review | Injectable peptide therapy: a primer for orthopaedic and sports medicine physicians |
| 2026 | Review | Therapeutic peptides in orthopaedics: applications, challenges, future directions |
| 2026 | Review | Safety and efficacy of approved and unapproved peptide therapies for musculoskeletal injuries |
| 2026 | Review | Therapeutic peptides in gerontology |
| 2026 | Review | A new era of doping? Peptide and peptide-analog drugs in sport and bodybuilding |
| 2026 | Review | Therapeutic peptides in aesthetic, metabolic and endocrine conditions |
| 2026 | Review | Injectable peptides in sports medicine: a structured narrative review |
| 2026 | Review | Performance-enhancing peptides modulating the GH–IGF1 axis |
| 2026 | Journal article | Peptide supplements and their therapeutic applications in sports medicine |
| 2013 | Evaluation study | Doping control analysis of seven bioactive peptides in horse plasma |
Nine of the ten were published in 2026, which says something about how recently the clinical literature noticed this market. Not one is a study of the combination. Reviews cite other papers; the only primary research in the list is an analytical method developed in horse plasma (Kwok WH, Ho EN, Lau MY, et al., Anal Bioanal Chem 2013;405(8):2595–606, PMID 23318763).
The trial registry agrees:
| Intervention | Registered studies |
|---|---|
| Tesamorelin (approved GRF analogue, control) | 24 |
| Ipamorelin | 3 |
| CJC-1295 | 1 |
| The combination | 0 |
The control at the top is what makes the bottom row readable: registrations exist for this hormone class, so the absence is an absence and not a gap in the query.
Why the pairing makes pharmacological sense
The argument predates both molecules by more than a decade.
Growth hormone release is governed by two opposing switches: growth-hormone-releasing hormone (GHRH), which drives secretion, and somatostatin, which suppresses it. A separate receptor — the one ghrelin uses, and the one the synthetic growth-hormone-releasing peptides (GHRPs) were built for — acts through a different route. Pushing both at once does more than pushing either.
That was demonstrated in humans in 1993: combined intravenous administration of GHRP-1 and GHRH produced synergistic growth-hormone release, not merely additive (Bowers CY, J Pediatr Endocrinol 1993;6(1):21–31, PMID 8374685).
CJC-1295 is the GHRH side of that pair; ipamorelin is the GHRP side. The stack is a thirty-year-old endocrinology result applied to two newer molecules — which is a reasonable hypothesis and is not the same thing as a tested product. It also predicts a hormone concentration, not a change in muscle, fat, recovery or sleep. The gap between a raised hormone level and an outcome a person would notice is the subject of growth hormone secretagogues, where the class ceiling is set out in full.
What each compound's own evidence actually is
CJC-1295: one human trial, and it studied a molecule many buyers are not getting
The published human data is a pair of randomised, placebo-controlled, double-blind ascending-dose trials of 28 and 49 days in healthy adults aged 21 to 61. After a single subcutaneous injection, mean plasma growth hormone rose 2- to 10-fold for six 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, and after multiple doses IGF-1 remained above baseline for up to 28 days. No serious adverse reactions were reported (Teichman SL, Neale A, Lawrence B, et al., J Clin Endocrinol Metab 2006;91(3):799–805, PMID 16352683).
That multi-day half-life is the whole point of the molecule, and it comes from the drug affinity complex — a chemical group that binds the peptide covalently to blood albumin so it is not cleared in minutes.
Here is the distinction almost nothing in the retail market observes. Material sold as "CJC-1295 without DAC" is modified GRF(1-29), a different molecule. It does not carry the albumin-binding group, so it cannot have the pharmacokinetics the 2006 paper describes. Any page that quotes the 5.8-to-8.1-day half-life beside a no-DAC product is quoting a study of something else. The endpoints the trial did measure were hormone concentrations, pharmacokinetics and safety — not muscle, not strength, not body composition.
Ipamorelin: a selectivity result, in rats and pigs
Ipamorelin is a pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH₂) identified by removing the central Ala-Trp dipeptide from GHRP-1. Its foundational paper characterised it in primary rat pituitary cells, anaesthetised rats and conscious swine, where it released growth hormone with potency and efficacy similar to GHRP-6. Its distinguishing finding was selectivity: in swine, none of the secretagogues tested moved FSH, LH, prolactin or TSH, and ipamorelin did not produce the cortisol and prolactin rise that limited earlier compounds (Raun K, Hansen BS, Johansen NL, et al., Eur J Endocrinol 1998;139(5):552–61, PMID 9849822).
That is a clean pharmacology result and it is the reason ipamorelin displaced GHRP-6 in the market. It is also a result about hormone selectivity in animals. Our entries on ipamorelin and CJC-1295 carry each compound's record in full.
What a buyer is actually purchasing
Stated plainly, and this is the finding of the page:
- A combination with no human trial of the combination.
- One component whose only human trial measured hormone levels, not outcomes, in a form that may not match what is sold.
- One component whose defining study was run in rats and pigs.
- A rationale borrowed from a 1993 experiment with different molecules.
None of that makes the pharmacology wrong. GHRH-analogue plus GHRP almost certainly does raise growth hormone more than either alone, because that is what the receptor biology predicts and what the 1993 work showed for the class. It means the step from "raises a hormone" to "does something for a lifter" has never been taken in public, for this pair, by anyone. The same distinction runs through do peptides work for muscle growth and through the honest comparison on creatine versus peptides, where the compound with the weaker story has the stronger evidence.
Testing and status
Detection is not a future problem. The 2013 horse-plasma method detected both compounds among seven bioactive peptides by liquid chromatography and tandem mass spectrometry — in racing, before the human retail market was large. Growth-hormone secretagogues fall within the prohibited peptide-hormone class for tested athletes; how that class is handled, and what a tested athlete is exposed to, is on peptides and drug testing and are peptides legal for athletes.
What would change this page
A single registered trial giving both compounds to people and measuring a body-composition or performance endpoint. There is currently one registration for CJC-1295 and three for ipamorelin against 24 for tesamorelin, so the class is not unregistrable — these two simply have not been. Until then the honest description of the stack is a plausible mechanism with an empty outcome column.
This page is documentary journalism about what has and has not been published. It contains no clinical guidance, recommends nothing, and describes no protocol, per our editorial standards.
Key figures
- Publications naming both compounds: 10 — nine 2026 reviews, one 2013 horse assay
- Studies of the combination: 0 published, 0 registered
- Registrations: CJC-1295 1 · ipamorelin 3 · tesamorelin (control) 24
- CJC-1295 half-life in the one human trial: 5.8–8.1 days, from albumin binding
- Growth hormone: 2- to 10-fold for ≥6 days · IGF-1: 1.5- to 3-fold for 9–11 days
- Human trials of either compound measuring muscle or strength: none
Sources
- Teichman SL, Neale A, Lawrence B, et al. 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 — PMID 16352683 · doi:10.1210/jc.2005-1536
- Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol 1998;139(5):552–61 — PMID 9849822 · doi:10.1530/eje.0.1390552
- Bowers CY. GH releasing peptides — structure and kinetics. J Pediatr Endocrinol 1993;6(1):21–31 — PMID 8374685 · doi:10.1515/jpem.1993.6.1.21
- Kwok WH, Ho EN, Lau MY, et al. Doping control analysis of seven bioactive peptides in horse plasma by liquid chromatography-mass spectrometry. Anal Bioanal Chem 2013;405(8):2595–606 — PMID 23318763 · doi:10.1007/s00216-012-6697-9
- ClinicalTrials.gov API v2 — intervention census for CJC-1295, ipamorelin and tesamorelin, run 2026-09-19 — clinicaltrials.gov
- National Library of Medicine. PubMed E-utilities — census of records naming both compounds, with publication types, run 2026-09-19 — pubmed.ncbi.nlm.nih.gov
All sources retrieved 2026-09-19. Literature and registry counts are as of that date.