AOD-9604 vs HGH Fragment 176-191
Research Comparison

Research Overview

Is AOD-9604 the same as HGH Fragment 176-191? Not quite: the gap is one amino acid. Both are 16-residue peptides from the C-terminal end of human growth hormone (hGH), closed by the same disulfide ring. Native hGH 176-191 starts with phenylalanine, the hormone's own residue 176. AOD-9604 is the 177-191 sequence with an added N-terminal tyrosine (Cox et al., 2015), so it matches the native fragment everywhere except position one.

That swap is why the names blur, and why most AOD-9604 vs HGH Frag questions come down to sequence. A 2026 review notes that the tyrosine analog sometimes carries the hGH 176-191 label and lists the two as one entry (Dominikowski et al., 2026), while a 2026 doping-control method measures them as separate analytes (Mazzarino et al., 2026).

Their research records differ more than the molecules: most adipose tissue and rodent work, and all human trial work, belongs to AOD-9604 and its 177-191 parent. Disguised Alpha supplies AOD-9604 and HGH Frag 176-191 as 5MG lyophilized powders for laboratory research use only.

Structure and Class

PubChem records the native fragment as FLRIVQCRSVEGSCGF (CID 16131230) and AOD-9604 as YLRIVQCRSVEGSCGF (CID 71300630), each cyclized by a disulfide between cysteines 7 and 14, which are cysteines 182 and 189 in the hormone's numbering. A third peptide shares the core: the 15-residue 177-191 domain, called AOD9401 in rat work (Ng et al., 2000).

Tyrosine carries one more oxygen than phenylalanine, a hydroxyl on its ring, and that is the entire chemical difference: AOD-9604 is C78H123N23O23S2 at 1815.07 g/mol (product page), the native fragment C78H123N23O22S2 at 1799.1 g/mol (PubChem). Mass spectrometry separates a 16 g/mol gap easily.

The AOD-9604 product page files its class as hGH fragment (176-191), which fits the 16-residue span; by sequence it is 177-191 plus tyrosine. The HGH Frag 176-191 product page prints no formula or weight, so those values come from PubChem. Since papers and catalogs swap the names, confirm identity against the lot certificate rather than the name.

Side by Side

Research Context: AOD-9604

The adipose tissue program began before the tyrosine was added. In rat adipose tissue, synthetic hGH 177-191 matched intact hGH in antilipogenic activity, with no significant lipolytic effect by glycerol release (Wu and Ng, 1993). As AOD9401, the same domain stimulated hormone-sensitive lipase and inhibited acetyl-CoA carboxylase in isolated rat adipose tissue (Ng et al., 2000), and raised lipolytic while lowering lipogenic activity in isolated adipose tissue from obese rodents and humans (Heffernan et al., 2000). Models: rat and human adipose tissue in vitro.

Rodent studies then moved to the tyrosine analog. In obese Zucker rats on a 19-day oral regimen, adipose tissue lipolytic activity rose, body weight gain fell by more than half against control, and euglycemic clamps showed no adverse effect on insulin sensitivity, unlike intact hGH (Ng et al., 2000).

In obese mice on 14-day osmotic pumps, it raised fat oxidation and plasma glycerol without hyperglycemia, and in BaF-BO3 cells carrying the hGH receptor it neither competed for the receptor nor induced proliferation (Heffernan et al., 2001). In beta-3 adrenergic receptor knockout mice, chronic exposure did not reproduce the body weight and lipolysis changes seen in wild-type mice (Heffernan et al., 2001).

Of the two, only AOD-9604 has a human trial record. Phase IIa trials were under way by February 2002 (Wilding, 2004). A 2026 review reports that, as an oral candidate, it showed no significant effect on the primary body weight endpoint of a 24-week study with 502 participants randomized. The review notes that this rests mainly on sponsor-reported outcomes rather than peer-reviewed randomized trials, cites the sponsor's 2007 announcement ending the program, and lists no reported human half-life and no meaningful IGF-1 elevation (Dominikowski et al., 2026). Model: human phase 2 trials.

No major regulator has approved AOD-9604 for any indication (Dominikowski et al., 2026). An FDA page on bulk drug substances that may present significant safety risks lists it among former category 2 substances whose compounding nominations were withdrawn, citing a possible immunogenicity risk for certain routes, impurity and characterization complexities, little or no safety-related information, and serious adverse events that may be associated with it, though causality is not clear.

Research Context: HGH Fragment 176-191

The native sequence has a short, older record. In normal rats, synthetic hGH 172-191, 176-191, 177-191 and 178-191 each produced a short-lived rise in blood glucose and a more sustained rise in plasma insulin, while 179-191 and 180-191 were inert; the authors concluded that activity needed both the core sequence and the correct physical configuration (Ng and Bornstein, 1978). Model: normal rats, in short-term experiments.

Beyond that work, its PubMed record is thin and largely analytical. Most lipolysis and lipogenesis findings that catalogs attach to Fragment 176-191 come from the 177-191 and AOD-9604 studies above, and the label travels: a 2022 nanoparticle study in MCF-7 breast cancer cells, titled for hGH fragment 176-191, specified the tyrosine sequence in its methods (Habibullah et al., 2022).

The newest work is analytical: a 2026 doping-control method using liquid chromatography and high-resolution mass spectrometry found hGH 176-191 and AOD9604 both extensively degraded after one week in serum and plasma at 4 and 22 degrees Celsius, stable for at least two months at -20 degrees Celsius, and detectable throughout in dried blood matrices (Mazzarino et al., 2026). Model: dried blood spots, serum and plasma.

Choosing Between Them for a Research Question

Questions that build on the published adipocyte and rodent lipid-metabolism work point to AOD-9604, because that work used AOD-9604 or its 177-191 parent. Questions about the unmodified C-terminal sequence point to the native fragment, which is also the natural comparator for isolating position one: run both side by side and the only structural variable is a single hydroxyl group.

Do not borrow findings across the pair. The 1978 rise in blood glucose came from short-term experiments in normal rats, while the later absence of hyperglycemia came from 14-day AOD-9604 exposure in obese mice (Heffernan et al., 2001); peptide, duration and model all differ. Molar amounts barely differ: one milligram holds about 0.551 µmol of AOD-9604 and 0.556 µmol of the native fragment, so the certificate's measured net content matters more than formula weight.

Handling and Storage

Both ship as lyophilized powder, and both product pages list -20°C for the powder as shipped and 2 to 8°C after reconstitution, protected from light, with freeze/thaw cycles avoided. Let the sealed vial reach room temperature before opening, add diluent slowly down the wall, and swirl rather than shake.

Both carry the same 7 to 14 disulfide, and early structure-activity work found that configuration mattered (Ng and Bornstein, 1978), so keep reducing agents such as dithiothreitol and 2-mercaptoethanol out of stock solutions unless the experiment calls for them. Given the serum and plasma stability data above (Mazzarino et al., 2026), keep liquid holding times short. Aliquot into single-use volumes, record the lot number, and use the measured content from the COA portal, not the label mass.

Questions Researchers Ask

Is AOD-9604 the same as HGH Fragment 176-191?

No. AOD-9604 is hGH 177-191 with an added N-terminal tyrosine (Cox et al., 2015); native hGH 176-191 begins with phenylalanine (PubChem CID 16131230). They share 15 of 16 residues and the disulfide ring, and differ by one oxygen atom: 1815.07 versus 1799.1 g/mol. Some papers and catalogs still use the names interchangeably (Dominikowski et al., 2026).

AOD-9604 vs Fragment 176-191: which one did the adipose tissue studies use?

AOD-9604 or its 15-residue 177-191 parent. The in vitro adipose tissue findings came from hGH 177-191 and AOD9401 (Wu and Ng, 1993; Heffernan et al., 2000), and the obese rat and mouse studies used AOD-9604 (Ng et al., 2000; Heffernan et al., 2001).

Did AOD-9604 reach human trials?

Yes. Phase IIa trials were under way by February 2002 (Wilding, 2004), and a 2026 review reports that a 24-week study did not meet its primary endpoint, based mainly on sponsor-reported outcomes; the compound holds no approval for any indication (Dominikowski et al., 2026).

HGH Fragment 176-191 vs AOD-9604: are both prohibited in sport?

Yes. The 2026 WADA Prohibited List names AOD-9604 and hGH 176-191 as examples of growth hormone fragments under S2.2.3, in class S2, which is prohibited at all times.