Bottom line
A boundary-case entry: AOD-9604 and HGH Fragment 176-191 are not a "blend" of distinct peptides but two variant forms of the same C-terminal fragment of human growth hormone, often confused or marketed interchangeably. AOD-9604 (Tyr-hGH 177-191) is a pharmaceutical optimisation with published Phase II human data; HGH Fragment 176-191 is the unmodified native sequence with no independent human trial data.
No established or recommended human dose.
Name and formulation variability
| Observed source/date | Claimed components | Claimed amounts | Verification limits |
|---|---|---|---|
| Various vendors | "AOD-9604 + HGH Frag 176-191" | Variable | Often sold as a "stack" not a single-vial blend |
| Various vendors | "AOD-9604" alone | 2–5 mg per vial | Research-grade; COA varies |
| Various vendors | "HGH Frag 176-191" alone | 2–5 mg per vial | Often labelled as AOD-9604 interchangeably |
These are often marketed as a "stack" for fat loss but are chemically distinct variants of the same GH region, not complementary peptides.
Component evidence
| Component | Separate evidence | Evidence for combination | Compatibility/stability evidence |
|---|---|---|---|
| AOD-9604 (Tyr-hGH 177-191) | Phase IIb RCT: ~1.8–2 kg fat loss over placebo at 1 mg/day oral; 6 Phase I/II trials (~900 participants); Phase IIb 24-week trial (n=536) failed primary endpoint; no IGF-1 elevation; development discontinued 2007 | No rationale for combining both forms — they compete for the same receptor | N/A — same binding site |
| HGH Fragment 176-191 (native) | Preclinical only; no published human trial; data often erroneously attributed from AOD-9604 | No rationale for combining | N/A |
AOD-9604 is distinguished by an N-terminal tyrosine that improves stability. The grey-market HGH Frag 176-191 lacks this modification.
Combination-specific studies
No study has tested AOD-9604 + HGH Frag 176-191 as a combination because they are variant forms of the same peptide, not complementary agents.
Safety and interaction uncertainties
AOD-9604 well-tolerated in Phase I/II; no IGF-1 elevation; no glucose disruption
Unmodified HGH Frag 176-191 has no human safety data
GRAS notice (GRN 000792) for food ingredient use — not a drug approval
WADA: both prohibited as GH fragments (S2 class)
Regulatory and product-quality notes
Neither is FDA-approved for any indication
AOD-9604 was an investigational drug; development terminated 2007
Mislabeling between AOD-9604 and HGH Frag 176-191 is widespread
FDA enforcement actions against compounders marketing unapproved peptides
Evidence gaps
No human trial data for HGH Frag 176-191 specifically
AOD-9604's published trial data never appeared in PubMed-indexed journals
No validated human dosing protocol for either compound
Widespread vendor confusion between the two variants
Sources
Clinical Peptide. AOD-9604 vs HGH Fragment 176-191. https://clinicalpeptide.org/compare/aod-9604-vs-hgh-frag-176-191/ accessed 2026-08-06.
PeptideBase. AOD-9604 Research Guide. https://peptidebase.io/peptides/aod-9604 accessed 2026-08-06.
HealthRX. HGH Frag 176-191 Evidence. https://healthrx.com/peptides-specialty/hgh-frag-176-191 accessed 2026-08-06.
Useful Vitamins. AOD-9604 Explained. https://usefulvitamins.com/aod-9604-explained/ accessed 2026-08-06.
Heffernan M, et al. Endocrinology. 2001;142(11):4723-4730. PMID 11713213.