GROWTH HORMONE AXIS / MATRIX
Three Entries, Side by Side
Where the CJC-1295 + ipamorelin research stack, its GHRH-analogue arm, and its selective GHRP arm converge, diverge, and — most importantly — what the evidence behind each actually amounts to.
The short version
This page lines up CJC-1295 / Ipamorelin, CJC-1295, and Ipamorelin on the dimensions that matter most for reading this class of research peptides: mechanism, evidence model, pharmacokinetics, regulatory standing, and the single defining caution for each. The headline is efficient. All three stimulate the GH/IGF-1 axis, but through distinct mechanisms and from very different evidence positions: CJC-1295 has published human pharmacodynamic data documenting sustained multi-day GH and IGF-1 elevation [3]; ipamorelin has one published Phase 2 trial that missed its endpoint [14]; and the combination has never been studied as a fixed blend in any controlled trial. None is an approved medicine, and none is presented here with a human dose.
The comparison matrix
| Dimension | CJC-1295 / Ipamorelin | CJC-1295 | Ipamorelin |
|---|---|---|---|
| Peptide class | GHRH analogue (CJC-1295) + GHS-R1a agonist / GHRP (ipamorelin) — research combination | Tetrasubstituted hGRF(1-29) analogue; DAC and no-DAC variants | Synthetic pentapeptide; selective GHS-R1a / ghrelin receptor agonist |
| Most-studied in | Combination synergy (receptor cross-talk); GHRH-analogue class human body composition [1][5][7] | GH and IGF-1 pharmacodynamics; serum proteomics; anti-doping detection [3][10][11] | GH selectivity; bone growth (rats); postoperative ileus (humans); chemotherapy weight loss (ferrets) [6][14][16] |
| Evidence base (model) | Separate component studies + receptor cross-talk cell work; no fixed-blend human trial [2][5] | Human PK/PD studies (healthy adults) + rat albumin-binding chemistry [3][4] | Rat and ferret animal work; 1 human PK study (IV, n=8/dose); 1 Phase 2 RCT (missed endpoint) [14][15] |
| Pharmacokinetics | DAC half-life 5.8–8.1 days vs. ipamorelin ~2 h IV terminal half-life — fundamentally mismatched timescales [3][15] | DAC: half-life 5.8–8.1 days, GH elevated ≥6 days, IGF-1 elevated ≥9 days per dose [3] | Terminal half-life ~2 h (IV); GH pulse peaking ~40 min post-dose; no subcutaneous human PK data [15] |
| Regulatory / WADA status | Not approved; both components WADA S2 prohibited; compounding status: removed from Category 2, PCAC review 2024 | Not approved; WADA S2 prohibited; not recommended for 503A compounding bulks list [9] | Not approved (Phase 2 failed); WADA S2 prohibited; removed from 503A Category 2, PCAC reviewed Oct 2024 |
| Key caution | Fixed blend never clinically tested; mismatched half-lives make net GH exposure uncharacterized [2][3][15] | DAC vs. no-DAC confusion; sustained multi-day IGF-1 elevation; limited long-term human safety data [2][3] | Phase 2 missed endpoint; class-level cardiac signal from related GHS-R1a agonist; no long-term human safety database [13][14] |
Peptide class
All three work on the GH/IGF-1 axis, but through distinct molecular mechanisms. CJC-1295 is a GHRH analogue: it binds the GHRH receptor (a class-B GPCR) on pituitary somatotrophs and activates the Gs/cAMP/PKA cascade [8]. Ipamorelin is a synthetic pentapeptide that binds the ghrelin receptor (GHS-R1a) on the same cells and raises intracellular calcium via a Gq pathway — mechanistically independent from the GHRH receptor [6]. The combination exploits that independence: because the two arms use different intracellular switches, co-stimulating both produces a GH pulse larger than either alone [5][7].
Most-studied in
Each entry has a distinct research territory. CJC-1295 / Ipamorelin research centers on the synergy concept — dual-receptor co-stimulation for enhanced GH release — contextualized by the GHRH-analogue class human evidence on body composition [1][5][7]. CJC-1295 alone is most studied for its pharmacodynamic profile in humans: how much GH and IGF-1 it raises, for how long, with what kinetics [3][11]. Ipamorelin's most-cited contribution is its selectivity characterization in animal models [6], plus a single human trial in a bowel-resection context and the most recent ferret chemotherapy weight-loss study [12][14].
Evidence base (model)
This is where the three genuinely separate. CJC-1295 has the strongest individual human pharmacodynamic dataset: published PK/PD studies in healthy adults documenting multi-day GH and IGF-1 elevation, plus a serum proteomic shift study in young men [3][10][11]. Ipamorelin has the only published Phase 2 human trial of any compound on this desk — but that trial enrolled 114 adults in a bowel-resection context and missed its primary endpoint [14]. The combination has no controlled human trial of the fixed blend at all; its combined pharmacology is inferred from the component data and receptor cross-talk cell work [5]. In short: CJC-1295 is the most pharmacodynamically characterized, ipamorelin is the most clinically tested (but without demonstrated efficacy), and the combination is the most widely discussed but the least directly studied.
Pharmacokinetics
The pharmacokinetic mismatch between the two components is one of the underappreciated complications of the stack. CJC-1295 with DAC has a half-life of 5.8–8.1 days in humans, with GH elevated for 6 or more days and IGF-1 for 9–11 days or more per dose [3]. Ipamorelin has a terminal half-life of approximately 2 hours from IV infusion studies, with GH peaking around 40 minutes post-dose [15]. The no-DAC form of CJC-1295 (Mod GRF 1-29) has a half-life of roughly 30 minutes, which puts it closer to ipamorelin's timescale but far from the DAC form. Pairing a multi-day agent with a 2-hour agent means the intended pulsatile synergy profile and the net GH exposure are not characterized for any specific dosing interval. Community protocols choose a protocol from among several circulating options with no controlled-trial basis for choosing between them [2].
Regulatory / WADA status
None of the three entries is approved by the FDA, EMA, or any major regulator as a human medicine. All are prohibited in sport at all times under WADA Section S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics). Both CJC-1295 and ipamorelin acetate were added to the FDA's interim 503A Category 2 bulk-substances list (restricting compounding pharmacy use) in September 2023, then removed from Category 2 in September 2024 after nominator withdrawal; both were reviewed at the October 29, 2024 Pharmacy Compounding Advisory Committee meeting, where they were not recommended for the approved 503A bulks list [9]. Research-grade versions are sold only for laboratory research use.
Key caution
Each entry carries a defining caveat. For the combination, it is the absence of any fixed-blend clinical trial combined with the fundamentally mismatched half-lives of its two components, meaning the net GH exposure profile is unknown for any specific protocol [2][3][15]. For CJC-1295, it is the sustained multi-day IGF-1 elevation it produces — a real pharmacodynamic effect that lacks long-term safety data, compounded by routine DAC/no-DAC confusion that understates how different the two forms actually are [2][3]. For ipamorelin, it is that its one human Phase 2 trial failed [14] and a 28-day preclinical study of a related GHS-R1a agonist found dose-dependent myocardial degeneration in rats [13] — a class-level cardiovascular signal with no equivalent long-duration ipamorelin safety study in any species to either replicate or rule it out. Reading the three together, the pattern is consistent: compelling pharmacological mechanisms, real human pharmacodynamic data for one component, and a widening gap between mechanism and clinical evidence as one moves toward the combined protocol and its long-term implications.