GHRH analogs and GHRPs are mechanistically distinct compounds that both result in pituitary GH release — through different receptors that act synergistically. This page covers the two classes, their compounds, and why the combination approach is studied.
Research reference only. Not medical advice or dosing guidance.
Both stimulate pituitary GH release — via different receptors that converge downstream
GHRH analogs
Receptor: GHRHR (pituitary)
Mimic the hypothalamic signal that prompts pituitary somatotrophs to synthesize and release GH. DPP-4-resistant substitutions extend stability from the native ~7-minute half-life. The DAC addition to CJC-1295 further extends to ~7 days via albumin binding.
GHRPs (ghrelin-axis)
Receptor: GHS-R1a (pituitary + hypothalamus)
Act on the ghrelin receptor via a separate intracellular pathway. They amplify GH release synergistically when combined with a GHRH analog — the two receptor classes converge downstream. Ipamorelin is the most selective GHRP, releasing GH without meaningfully raising cortisol or prolactin.
Synergy: When a GHRH analog and a GHRP are combined, the downstream cAMP (GHRH pathway) and IP₃/Ca²⁺ (ghrelin pathway) signals converge on the same somatotroph, producing larger GH pulses than either alone. This is why CJC-1295 (no DAC) + ipamorelin is the most studied combination in the GH-secretagogue literature.
Sermorelin
GRF 1-29 · Geref
Shortest active GHRH fragment; historically the first GHRH analog FDA-approved (pediatric GH deficiency), later discontinued commercially.
CJC-1295 (no DAC)
Mod GRF 1-29
Four DPP-4-resistant substitutions extend stability vs sermorelin. The preferred pairing with ipamorelin for pulsatile GH research.
CJC-1295 (DAC)
CJC-1295 DAC
Albumin-binding DAC moiety extends half-life to ~a week. Studied for sustained IGF-1 elevation; blunts natural GH pulsatility.
Tesamorelin
Egrifta
Only currently FDA-approved GH-axis peptide. Approved for HIV-associated visceral lipodystrophy. Also studied for cognition and hepatic fat.
Ipamorelin
Most selective GHRP: GH release with minimal ACTH/cortisol/prolactin impact. Standard pairing with CJC-1295 (no DAC) in synergy research.
Hexarelin
More potent than ipamorelin but less selective. Distinctive CD36-mediated cardioprotective thread in preclinical literature, independent of GH release.
Endogenous GH is released in pulses — the largest occurring during deep sleep — and this pulsatility is functionally important for the GH/IGF-1 axis. Short-acting compounds (sermorelin, CJC-1295 no DAC, ipamorelin) reproduce this pulsatile pattern by producing brief receptor activation.
The DAC addition to CJC-1295 shifts the pharmacokinetic profile from pulsatile to sustained: albumin binding keeps the peptide in circulation for days, producing prolonged GHRHR occupancy. This raises baseline GH and IGF-1 but blunts the natural peak-to-trough rhythm. Whether blunting pulsatility is clinically consequential for the endpoints studied — body composition, IGF-1, fat distribution — is the central research question distinguishing the two CJC-1295 forms.
CJC-1295 vs ipamorelin — detailed comparisonWhat is a growth hormone secretagogue?
A growth hormone secretagogue is any compound that stimulates the pituitary gland to release growth hormone (GH). The term covers two mechanistically distinct classes: GHRH analogs, which mimic hypothalamic growth-hormone-releasing hormone at the GHRHR receptor, and GHRPs (growth-hormone-releasing peptides), which act on the ghrelin receptor (GHS-R1a). Both classes are studied separately and in combination.
What is the difference between a GHRH analog and a GHRP?
GHRH analogs (sermorelin, CJC-1295, tesamorelin) bind the GHRH receptor on pituitary somatotrophs and prompt GH synthesis and release, mimicking the hypothalamic pulse. GHRPs (ipamorelin, hexarelin) bind the ghrelin receptor (GHS-R1a) via a separate intracellular pathway. The two classes act synergistically — combining them produces more GH release than either alone because the downstream pathways converge.
Why is CJC-1295 (no DAC) commonly paired with ipamorelin?
CJC-1295 (no DAC) provides a short GHRH-receptor signal; ipamorelin provides a simultaneous ghrelin-receptor signal. Together they converge on the same pituitary somatotroph and produce a larger, synergistic GH pulse than either alone. The short half-life of both compounds keeps the pulse physiologic rather than sustained — preserving natural GH pulsatility.
What is the difference between CJC-1295 with DAC and without DAC?
The DAC (Drug Affinity Complex) is a maleimidopropionic acid group that allows the peptide to bind covalently to serum albumin, extending half-life from ~30 minutes (no DAC) to ~6–8 days (DAC). The no-DAC form produces brief, pulsatile GH pulses. The DAC form produces sustained GH and IGF-1 elevation but blunts the natural pulsatility of the GH axis — a trade-off studied in body-composition and IGF-1 research.
What makes ipamorelin different from other GHRPs?
Ipamorelin is defined by its selectivity: it releases GH with minimal effect on ACTH, cortisol, or prolactin, unlike earlier GHRPs (GHRP-6, hexarelin) that raise these hormones alongside GH. This cleaner profile has made it the most studied GHRP in combination protocols. It is not FDA-approved.
Is tesamorelin FDA-approved?
Yes — tesamorelin (Egrifta) is the only currently FDA-approved GH-axis peptide in this catalog. It is approved for reduction of excess visceral abdominal fat in people with HIV-associated lipodystrophy. Other uses described here are research contexts, not approved indications.
How do GH secretagogues differ from injecting growth hormone directly?
Secretagogues prompt the pituitary to release the body's own GH, preserving the natural feedback loop (IGF-1 suppresses further GH release when levels rise). Direct GH injection bypasses this feedback. Whether preserving pulsatility and feedback is clinically meaningful depends on the indication and is an active research question. Secretagogues are studied partly because they are peptides that require pituitary integrity to work, while direct GH does not.
Research reference only. Except for tesamorelin (Egrifta, specific indication only), none of the compounds on this page are FDA-approved. Nothing here constitutes medical advice, dosing guidance, or an offer for sale.