Guide
Growth hormone secretagogues stimulate the pituitary’s own GH release rather than replacing it, and the compounds in this category fall into a few clean mechanistic groups. This guide covers how they relate to each other, what actually distinguishes them, and where the naming gets misleading — particularly around CJC-1295.
Quick summary
- Two receptor families: GHRH analogs (CJC-1295, Tesamorelin, Sermorelin) and ghrelin receptor agonists / GHRPs (Ipamorelin, Hexarelin).
- GHRH analogs and GHRPs act on separate, non-competing receptors — pairing one from each is the standard combination logic.
- “CJC-1295” is ambiguous: with DAC it lasts about a week; without DAC (Mod GRF 1-29) it lasts about 30 minutes. Confirm which is meant.
- Ipamorelin is the most receptor-selective GHRP; Hexarelin is more potent but raises cortisol and prolactin more.
- Tesamorelin is the one compound in this group with a genuine FDA approval — for HIV-associated lipodystrophy, not general GH support.
- Pulsatile release, not sustained elevation, is the physiological pattern these compounds are designed to preserve.
The two mechanistic families
GHRH receptor analogs mimic growth hormone releasing hormone, the hypothalamic “go” signal for pituitary GH release. This group includes CJC-1295, Tesamorelin, and Sermorelin — they differ mainly in structural modifications that affect stability and half-life, not in which receptor they engage.
Ghrelin receptor agonists, also called growth hormone releasing peptides (GHRPs), engage GHS-R1a, stimulating GH release through a separate pathway while also suppressing somatostatin, the hormone that normally restrains pituitary output. Ipamorelin and Hexarelin belong here.
Because the two families act on different, non-competing receptors, pairing one from each — most commonly a GHRH analog with Ipamorelin — produces a larger combined effect than either alone. That is the mechanistic logic behind essentially every secretagogue combination in this category.
The compounds, briefly
CJC-1295 exists in two functionally different forms that share a name. With its Drug Affinity Complex (DAC) intact, it binds serum albumin and persists roughly a week, producing sustained GH elevation. Without DAC — correctly called Modified GRF (1-29) — it lasts around 30 minutes, producing a discrete pulse. These behave as different compounds and the distinction is frequently lost in casual use of the name.
Tesamorelin is a stabilized GHRH analog and the one compound in this group with an actual FDA approval: as Egrifta, for reduction of excess abdominal fat in HIV-associated lipodystrophy. That approval is specific and does not extend to general GH support or other indications — it is worth being precise about what was actually demonstrated in the trials that earned it.
Sermorelin is a shorter GHRH(1-29) fragment, historically the first GHRH analog studied clinically, with a short half-life on its own.
Ipamorelin was developed specifically for receptor selectivity: it stimulates GH release with comparatively little effect on cortisol or prolactin, unlike earlier GHRPs. This selectivity is why it became the default combination partner.
Hexarelin is an older, more potent GHRP that produces a stronger GH response but also raises cortisol and prolactin more than Ipamorelin — a real trade-off between potency and selectivity that is worth knowing when comparing the two.
Why pulsatility is the design goal
Endogenous GH is released in discrete pulses, concentrated during slow-wave sleep, with low levels between them — and there is good evidence that the pulsatile pattern itself, not just total exposure, carries biological signal. This is the core argument for secretagogues over administered growth hormone: secretagogues amplify a pattern the body already generates and remain subject to negative feedback from rising IGF-1 and somatostatin, while exogenous GH overrides the pattern and the feedback ceiling entirely.
This is also why the short-acting, pulse-shaped forms (Mod GRF 1-29, Ipamorelin) are frequently preferred in combination over the long-acting DAC form — the goal is amplifying a physiological rhythm, not flattening it.
What the evidence actually supports
That these compounds raise GH and IGF-1 in humans is well established pharmacology. What is not established, outside Tesamorelin’s specific approved indication, is that the resulting hormone elevation translates into meaningful long-term functional outcomes. None of the others in this group has completed development to approval, and the gap between “raises the hormone” and “improves an outcome” remains open. All compounds in this category are also prohibited in competitive sport under WADA rules.
Frequently asked questions
Which compound is actually approved?
Only Tesamorelin, as Egrifta, and only for a specific indication — abdominal fat reduction in HIV-associated lipodystrophy. None of the others in this group has FDA or EMA approval.
Why does “CJC-1295” need clarification?
Because the name is used for two pharmacologically different molecules — with DAC (week-long half-life) and without DAC, correctly called Mod GRF 1-29 (roughly 30-minute half-life). Confirming which is meant changes what to expect entirely.
Why pair a GHRH analog with a GHRP?
They act on separate, non-competing receptors — GHRH receptor and ghrelin receptor — so combining them produces a larger GH pulse than either alone, without one blocking the other’s binding site.
References
- Teichman SL, et al. Prolonged stimulation of growth hormone and IGF-I by CJC-1295. J Clin Endocrinol Metab. 2006;91(3):799–805.
- Falutz J, et al. Effects of tesamorelin on visceral fat and liver fat in HIV-infected patients. JAMA. 2014;312(4):380–389.
- Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552–561.
Read our CJC-1295 and Ipamorelin breakdown →
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For laboratory and research use only. Not for human consumption. Only tesamorelin (as Egrifta) is FDA approved, and only for its specific indication; all compounds are prohibited in competitive sport under WADA rules. This article summarizes published research for informational purposes and is not medical advice, nor a recommendation or protocol for use.
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