Metabolic · 5mg × 10 vials
Native C-terminal fragment of growth hormone. Studied for lipolytic signalling in adipocyte models without the growth or IGF-1 pathways.
HGH Fragment 176-191 is a synthetic 16-amino-acid peptide corresponding to the C-terminal residues 176 to 191 of human growth hormone in the unmodified native sequence (Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe). It is the parent fragment from which AOD-9604 was derived. AOD-9604 carries an additional N-terminal tyrosine, added by Metabolic Pharmaceuticals to improve serum stability and permit radiolabelling; the native fragment has no such modification.
The two compounds act through the same pathway. In adipocyte models the fragment stimulates lipolysis and inhibits lipogenesis, and in rodent studies it upregulates beta-3 adrenergic receptor expression, reproducing the lipolytic arm of full-length GH without engaging the growth, IGF-1, or insulin pathways. The adipose receptor it binds is high-affinity but remains uncharacterised in humans; it is not GH-R and not beta-3-AR directly. The human evidence for a fat-reduction effect is thin, mirroring the AOD-9604 Phase 2b result, while the absence of growth and metabolic side effects held up. The native fragment is less stable in circulation than the tyrosine-modified AOD-9604 and has a shorter functional half-life.
What the published studies measured.
Peer-reviewed studies and clinical guidelines — tap any to read the source.
of human growth hormone, Horm Res 2000](https://pubmed.ncbi.nlm.nih.gov/11146376/) — mechanism work on the C-terminal fragment lineage, Bornstein/Ng Metabolic Pharmaceuticals origin, foundational native-fragment lipolytic characterization
Read study ↗PubMedNg FM, Bornstein J et al, The lipolytic effects of a synthetic peptide corresponding to residues 177-191 of human growth hormone in adipocytesHeffernan/Ng acute-dose lipolysis characterization, the original native-fragment in-vitro and rodent work
Read study ↗PubMedNg FM et al, A novel anti-obesity peptide, AOD9604, in pre-clinical and clinical evaluationdevelopment summary including beta-3 adrenergic receptor upregulation finding and the native-to-modified transition
Read study ↗PubMedStier et al, Safety and tolerability of the hexadecapeptide AOD9604 in humans, J Endocrinol Invest 2013 (PMC3979506)](https://pmc.ncbi.nlm.nih.gov/articles/PMC3979506/) — Phase 2a safety study on the tyrosine-modified analog, the closest formal human safety reference for the fragment family
Read study ↗Clinical contextMetabolic Pharmaceuticals AOD-9604 Phase 2b 12-week obesity trial archivePhase 2b missed primary endpoint, 536 patients, no statistically significant weight loss vs placebo. Native 176-191 has no equivalent Phase 2 of its own, this is the closest human efficacy reference for the lineage.
Read study ↗Physician commentaryPeptide Sciences HGH Fragment 176-191 referenceclinical profile summary; oversold marketing tone, useful as counter-reference for honest framing
Read study ↗Storage: refrigerated, ~30 days after reconstitution; unreconstituted vials stable refrigerated long term