Research use only. The materials discussed on this page are sold exclusively for in vitro laboratory research. They are not for human or veterinary use, and nothing here is medical advice or a claim of benefit. Animal-model and clinical data are mentioned only as cited published literature.
AOD-9604 and HGH Fragment 176-191 are two peptides derived from the C-terminal portion of human growth hormone, studied for their lipolytic action without somatotropic effects. Although structurally very close, their pharmacological profiles differ. This comparison synthesizes preclinical data.
The two compounds
- AOD-9604 — view the AOD-9604 research product page
- HGH Fragment 176-191 — view the HGH Fragment 176-191 research product page
Comparison table
| Property | AOD-9604 | HGH Fragment 176-191 |
|---|---|---|
| Origin | HGH fragment 177-191 + Tyrosine at N-terminal | HGH fragment 176-191 (native sequence) |
| Structure | Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe (16 AA) | Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe (16 AA, 176-191) |
| Industrial origin | Metabolic Pharmaceuticals (Australia) — obesity research | Academic research on HGH fragments |
| Somatotropic effects | Absent (no GH or IGF-1 stimulation) | Absent (no GH or IGF-1 stimulation) |
| Lipolytic mechanism | Activates adipocyte β3-adrenergic (in vitro) | Stimulates adipocyte lipolysis (similar mechanism) |
| Half-life | Short (~30 min) | Short (~30 min) |
| Research stage | Clinical development discontinued after phase 2 | Primarily preclinical research |
| Applications | Obesity models, lipolysis, metabolic research | Obesity models, lipolysis, metabolic research |
| Purity documentation | Batch CoA (HPLC) | Batch CoA (HPLC) |
Research contexts
Literature contexts for AOD-9604
Studies on β3-stimulated adipocyte lipolysis, diet-induced obesity models, research on HGH fragments lacking somatotropic effects.
Literature contexts for HGH Fragment 176-191
Comparative studies with AOD-9604, research on native 176-191 fragment sequence, in vitro metabolic models.
Mechanisms of action
AOD-9604
AOD-9604 adds an N-terminal Tyrosine to HGH fragment 176-191, increasing stability and bioavailability. It stimulates lipolysis via adipocyte β3-adrenergic receptor activation, without stimulating endogenous GH or IGF-1 production. Phase 2 obesity development was later discontinued.
HGH Fragment 176-191
HGH Fragment 176-191 is the native C-terminal sequence of human HGH, studied for its lipolytic properties. It acts similarly to AOD-9604 (the precursor without Tyr) on adipocytes, but without the stabilization conferred by the N-terminal modification.
Combined research context
AOD-9604 and Fragment 176-191 are essentially the same molecule minus one amino acid (N-terminal Tyr). Choice depends on the protocol: AOD-9604 is more stable, Fragment 176-191 corresponds to the native sequence. Neither is clinically approved despite trials.
Related research products
Axion Research Peptides supplies research-grade peptides for in vitro use, with a batch certificate of analysis. Browse AOD-9604, HGH Fragment 176-191 or the full research catalog.
Frequently asked questions
Are AOD-9604 and Fragment 176-191 identical?
Almost — AOD-9604 is Fragment 176-191 with an added Tyrosine at the N-terminal. This modification improves stability and bioavailability.
Do they stimulate GH or IGF-1?
No — that’s their main characteristic. Unlike full HGH, these fragments have no somatotropic effect and stimulate neither GH nor IGF-1.
Why were the AOD-9604 clinical trials stopped?
The sponsor (Metabolic Pharmaceuticals) discontinued phase 2 development in obesity. Clinical development was abandoned, but preclinical research continues.
Which to choose for an in vitro lipolysis study?
Both are valid. AOD-9604 offers better solution stability. Fragment 176-191 corresponds to the native sequence. Choice depends on experimental design.
Are these peptides approved in the USA?
No — neither AOD-9604 nor Fragment 176-191 is approved by the FDA, EMA, or MHRA. Available exclusively for in vitro scientific research.
Scientific references
- Heffernan M et al., 2001 — AOD-9604 lipolytic activity, Endocrinology.
- Ng FM et al., 2000 — HGH 176-191 fragment, Endocrine.
Regulatory disclaimer
The peptides discussed in this comparison are not approved by the FDA, EMA, MHRA, or any regulatory agency for human or veterinary clinical use, except where a specific approved product is named (for example, tesamorelin as Egrifta). They are sold by Axion Research Peptides exclusively for in vitro scientific research. This page summarizes published literature and is neither medical advice nor a recommendation for clinical use.
