AOD-9604 (hGH Fragment 176–191, Anti-Obesity Drug 9604) is a synthetic 16-amino-acid C-terminal fragment of human growth hormone with an elimination half-life of approximately 30 minutes, based on human Phase 2 metabolic trial pharmacokinetic data[1]. AOD-9604 retains the lipolytic domain of hGH without the IGF-1-stimulating N-terminal receptor-binding region. It progressed through Phase 2 clinical trials for obesity but failed to demonstrate significant weight loss in Phase 3. AOD-9604 is not FDA-approved for any indication and is classified as a research compound.
| Parameter | Value | Source |
|---|---|---|
| Elimination Half-Life | ~30 minutes | Heffernan MA et al. 2001 [1] |
| Time to Peak (Tmax) | ~15–30 minutes (SC, human) | Heffernan MA et al. 2001 [1] |
| Route(s) of Administration | Subcutaneous injection, Oral | — |
| Plasma Protein Binding | Not published | — |
| Full Clearance (5 half-lives) | ~150 minutes (~2.5 hours) | Calculated |
| Standard Research Protocol | 250–500 mcg SC once daily | Phase 2 trial protocols [1] |
| Approval Status | Not FDA-approved; Phase 3 failed for obesity | — |
| Data Quality | Human PK Study — Heffernan MA et al. J Endocrinol 2001, PMID 11566598 | — |
AOD-9604 has an elimination half-life of approximately 30 minutes, established in a human pharmacokinetic study by Heffernan MA et al. published in the Journal of Endocrinology in 2001 (PMID 11566598)[1]. This is one of the few research peptides for which human PK data has been published in peer-reviewed literature — a higher-confidence data point than the animal-derived estimates available for most research peptides.
AOD-9604 is the C-terminal fragment (residues 176–191) of human growth hormone. Its short half-life reflects its molecular structure as an unmodified 16-amino-acid peptide: no albumin-binding fatty acid moiety, no PEGylation, no cyclization or structural stabilization. These properties make it susceptible to rapid proteolytic degradation by serum and tissue peptidases, producing the observed ~30-minute plasma half-life[1].
In the Heffernan et al. 2001 human study[1], participants received subcutaneous doses of AOD-9604 across a range used in Phase 2 obesity trials. Serial plasma samples were collected post-injection and analyzed for AOD-9604 concentration. The half-life of approximately 30 minutes was determined from the terminal elimination phase of the plasma concentration-time curve. The study also characterized dose-proportional increases in AUC, confirming linear pharmacokinetics across the dose range studied.
AOD-9604's plasma half-life of approximately 30 minutes describes when the intact peptide clears from circulation. Its lipolytic biological effects may persist beyond plasma clearance through intracellular signaling cascades downstream of peptide-receptor interaction. However, because AOD-9604 failed to show statistically significant weight loss in Phase 3 trials, the clinical significance and duration of these downstream effects remains uncertain in the literature[1].
Based on the human pharmacokinetic data from Heffernan et al. 2001[1], AOD-9604 follows first-order elimination kinetics with an approximately 30-minute half-life following subcutaneous injection:
| Half-Lives Elapsed | Time After Last Dose | % Remaining in Plasma |
|---|---|---|
| 1 | ~30 minutes | 50% |
| 2 | ~60 minutes | 25% |
| 3 | ~90 minutes | 12.5% |
| 4 | ~120 minutes | 6.25% |
| 5 (clinical clearance threshold) | ~150 minutes (~2.5 hours) | ~3% |
After a single subcutaneous dose of AOD-9604, plasma concentrations peak within approximately 15–30 minutes and fall to less than 3% of peak within approximately 2.5 hours. The rapid clearance means AOD-9604 does not produce sustained plasma levels between once-daily doses. Unlike compounds with half-lives measured in days (such as semaglutide or tirzepatide), AOD-9604 does not accumulate to a clinically meaningful steady state; each day's injection begins essentially from baseline[1].
AOD-9604's ~30-minute plasma half-life means that a single injection produces a transient pulse of circulating peptide rather than sustained plasma levels. Phase 2 clinical trials used once-daily subcutaneous administration, typically in the morning in a fasted state, consistent with producing a discrete lipolytic stimulus rather than continuous peptide exposure[1]. The once-daily interval — approximately 1,440 minutes between doses, against a 30-minute half-life — means plasma AOD-9604 is fully cleared (more than 97%) many hours before the next dose.
Because AOD-9604 fully clears within approximately 2.5 hours of each injection, a missed dose produces no residual carryover effect from the prior dose. Unlike long-acting compounds where a missed dose modestly affects trough levels, with AOD-9604 each day is pharmacokinetically independent. There is no accumulation to dilute or disrupt — the next day's injection starts from a clean pharmacokinetic baseline.
| Compound | Half-Life | Data Quality | Approval Status |
|---|---|---|---|
| AOD-9604 | ~30 min (human) | Human PK Study | Not approved |
| hGH | ~20–30 min (SC) | Human PK Study | FDA-approved |
| IGF-1 | ~10–20 min (free) | Human PK Study | Research use |
| BPC-157 | ~15 min (animal) | Animal Study | Not approved |
| Route | Half-Life | Bioavailability | Tmax | Notes |
|---|---|---|---|---|
| Subcutaneous | ~30 min (human) | Not formally published | ~15–30 min | Primary route in Phase 2 trials; most research protocols |
| Oral | No published data | No published data | No published data | Some protocols use oral tablets; systemic PK not established |
| Intravenous | No published data | 100% | Minutes | Reference route; not used in clinical or research protocols |
AOD-9604 is not detected by standard workplace urine drug screens, WADA anti-doping panels, or broadly deployed immunoassay testing platforms. Standard panels target classes of controlled substances and have no cross-reactivity with small peptides. AOD-9604 would also not trigger hGH immunoassay tests, as it is a fragment lacking the intact hGH epitopes detected by standard hGH assays.
No published forensic or anti-doping detection study has characterized the urinary detection window specifically for AOD-9604. Specialized LC-MS/MS peptide detection methods could in principle detect AOD-9604 or its fragments, but no method targeting AOD-9604 specifically has been published in the anti-doping or forensic chemistry literature as of May 2026. Given the ~30-minute plasma half-life, urinary detection windows — if characterized — would likely be short.
AOD-9604 is a 16-amino-acid peptide corresponding to residues 176–191 of human growth hormone (Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe), with a disulfide bridge between the two cysteine residues. The disulfide bridge provides some structural stability relative to fully linear peptides, but AOD-9604 lacks the half-life extension mechanisms present in therapeutic biologics: no albumin-binding fatty acid chain (as in semaglutide or liraglutide), no PEGylation, and no Fc fusion. This means it remains subject to circulating serum peptidases and renal filtration, producing the observed ~30-minute elimination half-life[1].
AOD-9604's mechanism of lipolytic action is distinct from the IGF-1-mediated anabolic effects of full-length hGH. The 176–191 fragment retains the C-terminal region involved in lipolysis stimulation, activating fat cell receptors in a manner that stimulates triglyceride breakdown while not binding the canonical growth hormone receptor in the way that triggers IGF-1 secretion from the liver. This selectivity was the pharmacological rationale for AOD-9604's development as an anti-obesity agent[1].
Despite this selectivity rationale and the favorable human PK profile, AOD-9604 failed to replicate Phase 2 lipolytic effects at scale in Phase 3 trials, leading to termination of its obesity indication development program. The human PK data is reliable — rare for a research peptide — but clinical efficacy at standard doses was not established in the larger randomized controlled trial setting.
Log injection timing, dose, and protocol notes on-device. No account required. Free iOS app.
Download on App StoreThe Halflife app tracks AOD-9604 alongside 44 other compounds — all with citation-backed PK data. Free on iOS.
Download on the App Store