AOD-9604 Side Effects: Rare But Serious Adverse Events Explained

What has FDA said about serious AOD-9604 reactions?

On its page about bulk drug substances that may present significant safety risks when compounded, FDA lists AOD-9604 among substances that were nominated and later withdrawn by their nominators [1]. FDA states three concerns: compounded drugs containing AOD-9604 may pose significant immunogenicity risk for certain routes of administration from peptide impurities and characterization problems; it has identified no, or only limited, safety information; and it has identified serious adverse events that may be associated with AOD-9604, though causality is not clear [1].

FDA gives no details about the events [1]. Removal from the category 2 list followed the nominators' withdrawal; it was not a finding that AOD-9604 is safe [1].

How much human safety data is there?

The 24-week study of AOD-9604 as an oral anti-obesity drug candidate enrolled 534 people and randomized 502; it failed to show a significant benefit on the primary weight-loss endpoint [2]. A 2026 review notes that this conclusion rests on sponsor-reported phase 2 results rather than peer-reviewed randomized trials [2]. There is no approved dose, and that trial tested an oral candidate, not the injected products sold online [2].

What about immune reactions and product quality?

FDA's immunogenicity concern relates to peptide impurities and characterization problems for certain routes of administration [1]. Compounded drugs are not FDA-approved; FDA does not review their safety, effectiveness or quality before marketing [4]. Belgian authorities identified AOD-9604 in unknown pharmaceutical preparations they seized, and US investigators found it in confiscated vials [6][7].

It appears in none of the three categories on FDA's interim policy list for state-licensed pharmacies and physicians, or on FDA's list for outsourcing facilities, so FDA's category 1 policy does not cover it [8][9][10].

Is AOD-9604 growth hormone, and is it approved?

AOD-9604 is hGH amino acids 177 to 191 with an extra tyrosine at the N-terminus, 16 amino acids, which is why it is also called hGH fragment 176-191 [7]. Preclinical work found no growth-hormone-receptor binding, and human data on IGF-1 and body composition are too limited to say more [2].

It is not FDA-approved. Metabolic Pharmaceuticals developed it as an anti-obesity candidate; phase IIa trials were under way by February 2002, it never reached approval, and the obesity programme was later dropped [3][2]. FDA's GRAS notice inventory shows no AOD-9604 notice or FDA no-questions letter [11].

WADA names AOD-9604 and hGH 176-191 in section S2.2.3 (growth hormone fragments); it is prohibited at all times, in and out of competition, and appears on the 2026 and 2027 Lists [5][12].