Every compound in this family ends in -morelin or gets stacked with one that does, and the names hide a clean two-way split. One group copies growth-hormone-releasing hormone (GHRH) and acts on its receptor: sermorelin, tesamorelin, and CJC-1295 in both of its forms. The other group mimics ghrelin at a different receptor entirely: ipamorelin, GHRP-2, GHRP-6 and hexarelin, with MK-677 as the oral, non-peptide member.
Two receptors, one pulse
Growth hormone is released in pulses, and the two families act on different levers of the same pulse. A GHRH analog raises the amplitude of a pulse the body was already going to produce. A ghrelin mimetic helps initiate the pulse and eases somatostatin, the brake that limits it. That is the entire logic of pairing one from each family: the combination works two mechanisms rather than doubling one, and the physiology literature on GHRH-plus-GHRP co-administration reports a larger release than either alone.
The map
| Compound | Family | Half-life | Distinguishing note |
|---|---|---|---|
| Sermorelin | GHRH analog | ~12 min | Formerly FDA-approved (Geref), withdrawn 2008 |
| Tesamorelin | GHRH analog | ~30 min | FDA-approved (Egrifta), visceral-fat outcome data |
| CJC-1295 (no DAC) | GHRH analog | ~1–2 h | Also sold as Mod GRF 1-29; pulse-shaped |
| CJC-1295 with DAC | GHRH analog | ~7 days | Albumin-bound; continuous elevation, not pulses |
| Ipamorelin | Ghrelin mimetic | ~2 h | Selective — little cortisol or prolactin signal reported |
| GHRP-2 / GHRP-6 | Ghrelin mimetic | ~30–35 min | Appetite stimulation; cortisol and prolactin at higher amounts |
| Hexarelin | Ghrelin mimetic | ~90 min | Most potent of the GHRPs; desensitisation reported fastest |
| MK-677 | Ghrelin mimetic (oral) | ~24 h | Non-peptide; continuous action, marked appetite effect |
Ipa/CJC versus Ipa/Tesa
The two stacks share the same ghrelin-mimetic half. Ipamorelin earns that seat on selectivity: in its original characterisation it released growth hormone without the cortisol, prolactin and appetite signals of the earlier GHRPs. The choice is really about the GHRH half.
CJC-1295 without DAC is the shorter instrument — it rises and clears on roughly the timescale of a natural pulse, which is why protocols built around pulsatility prefer it. The DAC version is a different proposition altogether: a week-long half-life produces continuous GHRH tone rather than pulses, with the sustained IGF-1 elevation that implies. Tesamorelin is the only compound in the table with current FDA approval, and the only one with published outcome data on a body-composition endpoint — visceral adipose tissue in HIV-associated lipodystrophy. It carries the strongest single-compound evidence in the family; what it does not carry is stack evidence.
What the debate leaves out
None of the named modern stacks has been studied as a stack. The co-administration literature is older physiology work on GHRH and GHRP given together, not trials of Ipa/CJC or Ipa/Tesa as protocols — so this library records both stacks as their components, and the graded evidence lives on the component monographs. Receptor desensitisation with continuous stimulation, and IGF-1 as the axis-level readout, are the recurring cautions across the family's safety sections.
Half-lives are reference figures from each monograph's cited sources. Nothing here is an endorsement of any stack, and no figure is a dose for a person.