HGH Frag 176-191 Dosage: The Sequence, the Trials, No Approval

Human growth hormone is a 191-amino-acid protein. "176-191" names its last 16 residues, the C-terminal tail that early laboratory work in the 1980s and 1990s linked to growth hormone's effects on fat and glucose metabolism, separately from its growth-promoting effects. The sequences below are taken from the UniProt record for human growth hormone (P01241, mature chain) and from PubChem and Cox et al. (2015) for AOD-9604.

The two cysteines (C) form a disulfide bond in the native hormone. The only difference between native 176-191 and AOD-9604 is the first residue: phenylalanine (F) in the hormone, tyrosine (Y) in AOD-9604.

AOD-9604 is described in the anti-doping literature as "the C-terminal fragment of human growth hormone from amino acids 177-191 with an additional tyrosine residue at the N-terminus" (Cox et al., Drug Testing and Analysis, 2015). Because the tyrosine sits where phenylalanine 176 would be, AOD-9604 is the same length as hGH 176-191 and differs from it at one position. Some review articles simply call AOD-9604 "hGH 176-191", for example Dominikowski et al. (Frontiers in Endocrinology, 2026).

The practical consequence is that the label "fragment 176-191" is used loosely. A vial sold under that name could contain the native phenylalanine sequence or the tyrosine version that was tested as AOD-9604. Only the sequence printed on a certificate of analysis tells you which, and that certificate is itself the seller's document. If the sequence starts with Y, the AOD-9604 data are the relevant evidence; if it starts with F, a PubMed search turns up no human trial of that exact peptide.

Stier, Vos and Kenley (Journal of Endocrinology and Metabolism, 2013) summarised six randomized, double-blind, placebo-controlled trials of AOD-9604 run between 2001 and 2006 in 893 obese adults. Their reported findings:

• No effect on serum IGF-1, consistent with the idea that the fragment does not act through IGF-1 the way full growth hormone does.
• No negative effect on glucose tolerance in oral glucose tolerance testing, in contrast with full-length growth hormone.
• No anti-AOD-9604 antibodies in the patients tested.
• A safety and tolerability profile described as indistinguishable from placebo, with no withdrawals or serious adverse events related to the drug.

What the summary does not do, at least in its abstract, is report the doses, routes or durations used, or any weight-loss efficacy result. It is a safety paper. None of the trials appears on ClinicalTrials.gov (a search for AOD9604 returns no records), and the fragment never reached approval as an obesity drug. Before the human work, Ng et al. (2000) reported reduced weight gain in obese rats given 500 micrograms/kg orally, and Heffernan et al. (2001) reported reduced body weight and fat in obese mice; animal results do not translate into a human dose.

No approval means no label, and no label means no authorised dose, interval or maximum. The FDA's list of bulk drug substances that may present significant safety risks in compounding records AOD-9604 as previously placed in category 2 and later withdrawn by its nominator. The FDA's stated concerns were possible immunogenicity, peptide impurities and characterisation problems, and that it had "no, or only limited, safety-related information" and had identified serious adverse events that may be associated with AOD-9604, "though causality is not clear." AOD-9604 is also prohibited in sport by the World Anti-Doping Agency, according to Cox et al.

Searches for a "2mg", "5 mg" or "10mg" fragment dosage are usually asking about vial size, which changes the concentration and therefore the syringe reading, not the dose. The formula on a U-100 syringe is units = dose in mg ÷ (vial mg ÷ mL of water) × 100. The table shows units per 100 micrograms (0.1 mg) as a scaling reference; it is arithmetic, not a recommended dose.

Note how small the volumes become with a 10 mg vial: 2 units is hard to read accurately, which is why more water is often used. See the reconstitution guide and the syringe measurement guide.

This site does not have a separate fragment 176-191 calculator. Because the tested peptide is AOD-9604, the AOD-9604 dosage page and the AOD-9604 calculator are the closest match; the arithmetic is identical for any peptide once you enter the vial mass and water volume. The mg to mL to units converter works for any concentration. For full growth hormone, which is a different molecule with approved labels, see HGH dosage for women, and for how fat-loss peptides compare on evidence, see peptides for weight loss.