Peptides for growth hormone.
A category where the mechanism is well understood, the compounds reliably do something measurable, and what that something is worth remains largely unproven.
Growth hormone secretagogues are unusual among research peptides because they demonstrably work at the level they claim to work. Administer one and growth hormone rises. That is measurable, reproducible, and well documented in short human studies. The receptors involved are identified, the pathways are characterized, and the pharmacology is not in serious dispute.
The category splits along two pathways. GHRH analogs act on the growth hormone releasing hormone receptor, which is the body's own primary lever for GH release. Ghrelin mimetics, usually called GHRPs, act on a completely separate receptor that was discovered partly through these compounds themselves. Because the two levers are independent, they are often discussed together, and combining them produces a larger GH release than either alone.
What almost none of these compounds have is outcome evidence. Raising growth hormone is a biomarker change, not a clinical result. The trials that would show whether that translates into better body composition, faster recovery, improved sleep or anything else people actually want have mostly not been run. The one clear exception is tesamorelin, which is FDA-approved for a specific indication and has the trial package to match, and its approval covers HIV-associated lipodystrophy rather than general body composition in healthy adults.
The safety considerations follow directly from the mechanism. Sustained supraphysiological growth hormone signalling raises IGF-1, and elevated IGF-1 over long periods carries theoretical concerns around insulin resistance and growth-promoting effects on existing tissue. Several compounds in this category also raise cortisol and prolactin as an off-target effect. None of this is a demonstrated harm in this population, because the studies do not exist, which is a description of an evidence gap rather than a clean bill of health.
These compounds move the biomarker they claim to move. Whether moving that biomarker produces the outcomes people are buying them for is a separate question that mostly has not been answered.
More growth hormone is better.
GH release is pulsatile and tightly regulated. Higher sustained levels are not simply better and carry their own metabolic consequences.
It raised my IGF-1, so it is working.
IGF-1 confirms the compound engaged the pathway. It does not confirm any downstream benefit.
Every compound in this category.
Graded on what has actually been published, with the regulatory reality on each one.
ACE-031 (ramatercept) is not a peptide but a recombinant fusion protein that joins the extracellular domain of the human activin receptor type IIB (ActRIIB) to the Fc region of IgG1.
CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH), based on the first 29 amino acids of human GHRH (GRF 1-29) with several amino-acid substitutions that resist enzymatic degradation.
CJC-1295 with DAC (also written DAC:GRF, CJC-1295 DAC) is a synthetic, long-acting analog of growth hormone-releasing hormone (GHRH).
Follistatin-344 (FS-344) is an alternatively spliced isoform of human follistatin, a naturally occurring secreted glycoprotein that acts as a high-affinity antagonist of several TGF-beta superfamily ligands.
GHRP-1 is a synthetic heptapeptide, one of the earliest growth hormone-releasing peptides (GHRPs) developed by Cyril Bowers' group in the 1980s and 1990s alongside GHRP-2 and GHRP-6.
GHRP-2 (growth hormone-releasing peptide-2; international nonproprietary name pralmorelin; development codes KP-102/GPA-748) is a synthetic hexapeptide with the sequence D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2.
GHRP-6 (growth hormone-releasing peptide-6) is a synthetic hexapeptide with the sequence His-D-Trp-Ala-Trp-D-Phe-Lys-NH2.
Hexarelin (examorelin) is a synthetic hexapeptide growth hormone secretagogue (GHS), structurally derived from the GHRP-6 family of growth hormone-releasing peptides.
Human growth hormone (hGH, also called somatotropin) is a 191-amino-acid, single-chain polypeptide hormone secreted by somatotroph cells of the anterior pituitary gland.
IGF-1 LR3 (Long R3 IGF-1) is a synthetic, recombinant analog of human insulin-like growth factor-1.
Ipamorelin is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) belonging to the growth hormone-releasing peptide (GHRP) class, sometimes described as a "third-generation" GHRP.
MGF is a splice variant of insulin-like growth factor 1 (IGF-1), designated IGF-1Ec in humans and IGF-1Eb in rodents, produced locally in skeletal muscle in response to mechanical loading or damage.
Mod GRF 1-29 (commonly sold as "CJC-1295 without DAC") is a synthetic 29-amino-acid analog of growth hormone-releasing hormone (GHRH).
PEG-MGF is a PEGylated synthetic peptide based on the unique C-terminal E-domain of mechano growth factor (MGF), an alternatively spliced isoform of insulin-like growth factor-1 known as IGF-1Ec (the rodent equivalent is IGF-1Eb).
Sermorelin is a synthetic 29-amino-acid peptide corresponding to the N-terminal 1-29 fragment of human growth hormone-releasing hormone (GHRH), the hypothalamic hormone that signals the pituitary to release growth hormone (GH).
Tesamorelin is a synthetic 44-amino-acid analog of human growth hormone-releasing hormone (GHRH/GRF 1-44), stabilized by a trans-3-hexenoic acid group attached to its N-terminus.
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