AOD-9604 Regulatory Status: US, EU, Canada, and UK

What Is AOD-9604 and How Does It Work?

AOD-9604 is a synthetic peptide corresponding to the last 16 amino acids (residues 176 to 191) of human growth hormone, modified with a tyrosine residue at the N-terminus. Researchers originally isolated this fragment to determine whether the fat-reducing properties of growth hormone could be separated from its diabetogenic and growth-promoting effects. The peptide is not a growth hormone analogue in the traditional sense. It does not bind or activate the growth hormone receptor.

Heffernan et al. demonstrated in 2001 that AOD-9604 stimulates lipolysis in adipose tissue through a mechanism distinct from full-length growth hormone signaling 1. In obese Zucker rats, the fragment reduced body fat without altering IGF-1 levels, food intake, or fasting glucose. This suggested the peptide acted on fat metabolism through a pathway that did not require the canonical JAK2-STAT5 signaling cascade used by full-length hGH.

Preclinical models showed promise. The fragment appeared to upregulate beta-3 adrenergic receptor activity and stimulate lipolysis without the hyperglycemia seen with exogenous growth hormone administration 2. AOD-9604 also showed no antibody formation against hGH in animal studies, a relevant safety signal given that the molecule is structurally derived from a human protein.

These animal results led Metabolic Pharmaceuticals, an Australian biotech company, to pursue human clinical development. That effort, however, would end in failure at the Phase IIb stage.

United States: FDA Has Not Approved AOD-9604

No FDA-approved drug product contains AOD-9604 as an active ingredient. The peptide has never completed a successful Phase III trial, and no New Drug Application (NDA) has been submitted to the agency for this compound.

In the US, AOD-9604 has been available exclusively through compounding pharmacies operating under Section 503A of the Federal Food, Drug, and Cosmetic Act. This section allows licensed pharmacies to compound drugs using bulk substances that appear on the FDA's list of substances that can be used in compounding, provided the pharmacy holds a valid prescription for an individual patient 3.

The FDA maintains a nomination and review process for bulk drug substances under 503A. AOD-9604 was nominated for inclusion on this list. The agency's Pharmacy Compounding Advisory Committee has reviewed nominated peptides, and the FDA published proposed rules in 2024 that would restrict several peptides, including AOD-9604, from 503A compounding 4. The agency cited a lack of adequate safety and efficacy data to support continued compounding.

Dr. Janet Woodcock, former Principal Deputy Commissioner of the FDA, stated in agency communications that "compounded drugs are not FDA-approved, and the agency cannot assure their safety, effectiveness, or quality" 5.

This distinction matters. Patients receiving AOD-9604 from a compounding pharmacy are receiving a product that has not undergone the FDA approval process. The compounding pharmacy is legally preparing the drug under an individual prescription, but the active substance itself lacks the safety and efficacy evidence required for a marketed drug.

The Phase IIb Trial That Changed Everything

The clinical trajectory of AOD-9604 hinges on a single key failure. Metabolic Pharmaceuticals (later acquired by Calzada Ltd.) conducted a 24-week, randomized, double-blind, placebo-controlled Phase IIb trial in approximately 300 obese subjects in Australia. The trial tested oral AOD-9604 at multiple doses against placebo, with body weight change as the primary endpoint.

Results reported in 2007 showed the drug did not produce statistically significant weight loss compared to placebo 6. The mean weight reduction in the treatment arms was minimal. For context, approved GLP-1 receptor agonists like semaglutide 2.4 mg produced 14.9% mean body weight loss at 68 weeks in the STEP-1 trial (N=1,961), compared to 2.4% with placebo 7. AOD-9604's Phase IIb results came nowhere close to this magnitude of effect.

Several factors may explain the failure. The trial used oral dosing, and peptide bioavailability via the oral route is notoriously poor. The subcutaneous formulation used in current compounding was not the formulation tested in the Phase IIb trial. This creates an evidence gap: the injection form widely compounded today has never been tested in a controlled human trial of adequate size.

After the trial failure, Metabolic Pharmaceuticals withdrew its Investigational New Drug (IND) application from the Australian Therapeutic Goods Administration (TGA). No subsequent sponsor has initiated a new Phase II or Phase III program for AOD-9604 in any jurisdiction.

The absence of positive human efficacy data remains the central regulatory barrier worldwide.

European Union: No EMA Marketing Authorization

AOD-9604 has no marketing authorization from the European Medicines Agency (EMA). No company has filed a Marketing Authorization Application (MAA) for this peptide in the EU.

European pharmaceutical regulation requires that any medicinal product intended for human use receive a marketing authorization before it can be placed on the market, as established under Regulation (EC) No 726/2004. Without a completed dossier of preclinical and clinical data demonstrating safety, efficacy, and pharmaceutical quality, no authorization can be granted.

Compounding pharmacies in EU member states operate under national legislation, and the rules vary by country. In Germany, for example, individual pharmacies (Apotheken) may prepare magistral formulations under a physician's prescription. Some EU-based compounding pharmacies have offered AOD-9604 through these national provisions. The EMA does not regulate compounding at the national level, so enforcement depends on individual member state authorities 8.

The practical result: patients in the EU can occasionally access AOD-9604 through compounding channels, but no standardized, quality-controlled pharmaceutical product exists. The legal status sits in a grey area between outright prohibition and regulated availability.

Canada: Not Listed, Not Approved

Health Canada has not approved AOD-9604 for any therapeutic indication. The peptide does not appear in the Drug Product Database (DPD), which lists all drugs approved for sale in Canada.

Canadian compounding pharmacies operate under provincial pharmacy regulations rather than direct Health Canada oversight for individual preparations. Some Canadian compounding pharmacies have prepared AOD-9604 formulations under physician prescriptions, but this practice exists outside the framework of a Health Canada drug approval 9.

Health Canada's approach to unapproved peptides mirrors its broader regulatory stance on compounded medications: the compound must be prepared by a licensed pharmacist pursuant to a valid prescription, and the finished product cannot be advertised or distributed as a marketed drug. The Natural and Non-prescription Health Products Directorate does not classify AOD-9604 as a natural health product, either.

No Canadian clinical trial for AOD-9604 is registered in the Health Canada Clinical Trials Database. Without active clinical investigation on Canadian soil and without a sponsor pursuing a New Drug Submission (NDS), the regulatory pathway remains closed.

United Kingdom: Unlicensed Medicinal Product

The UK Medicines and Healthcare products Regulatory Agency (MHRA) has not granted a marketing authorization for AOD-9604. In British regulatory terminology, it is classified as an unlicensed medicinal product (sometimes called a "special").

Under UK law, an unlicensed medicinal product may be supplied to an individual patient on the order of a doctor, dentist, or independent prescriber when no suitable licensed alternative exists. The MHRA's guidance on unlicensed medicines, detailed in the Human Medicines Regulations 2012, permits this on a named-patient basis 10.

Some UK-based prescribers in private clinics have prescribed AOD-9604 through specials manufacturers. This is legal but tightly circumscribed. The prescriber assumes clinical responsibility for the product, and the specials manufacturer must hold a Manufacturer's Specials Licence (MS licence) from the MHRA.

The General Medical Council (GMC) advises that prescribers using unlicensed medicines should be satisfied that there is sufficient evidence or experience of using the medicine to demonstrate its safety and efficacy. Given AOD-9604's failed Phase IIb trial and lack of positive controlled human data, this requirement presents a significant professional liability consideration for UK prescribers.

Australia: Where the Clinical Story Began and Ended

Australia holds a unique position in the AOD-9604 story. It is the only country where the peptide entered formal clinical development, and the only country where that development was abandoned after a failed trial.

The TGA evaluated AOD-9604 under its Clinical Trial Notification (CTN) scheme when Metabolic Pharmaceuticals initiated human studies. Following the Phase IIb failure in 2007, the company did not pursue further development.

The TGA does not list AOD-9604 on the Australian Register of Therapeutic Goods (ARTG). It is not available as a Schedule 4 (prescription-only) pharmaceutical in Australia through standard dispensing channels. The Therapeutic Goods (Standard for Uniform Scheduling of Medicines and Poisons) Order classifies growth hormone and its analogues, but AOD-9604's regulatory categorization remains ambiguous because it is a fragment rather than full-length hGH.

Australian compounding pharmacies, regulated by state and territory pharmacy boards, have prepared AOD-9604 on prescription. The TGA issued guidance in 2017 reinforcing that compounded medicines are not assessed for quality, safety, or efficacy by the TGA 11.

Safety Profile: What the Limited Data Shows

The safety database for AOD-9604 in humans is thin. No long-term controlled trials exist. The available evidence comes from the Phase IIb trial (approximately 300 subjects over 24 weeks) and post-market case reports from compounding pharmacy use.

In the Phase IIb trial, AOD-9604 was generally well tolerated at oral doses up to 1 mg daily. Reported adverse events were mild and included injection-site reactions, headache, and gastrointestinal discomfort. No serious adverse events were attributed to the drug in the published trial data.

Preclinical studies showed AOD-9604 did not alter glucose homeostasis, IGF-1 concentrations, or lean body mass in animal models 1. This distinguishes it from full-length growth hormone, which can cause insulin resistance, fluid retention, and acromegalic changes at supraphysiologic doses.

The Endocrine Society's 2019 position statement on growth hormone peptides noted that "fragments and secretagogues marketed for body composition changes lack the controlled trial evidence needed to assess benefit-risk profiles in clinical practice" 12.

Post-market surveillance data is essentially nonexistent because compounded products are not subject to the adverse event reporting systems that apply to FDA-approved drugs. Patients and prescribers should recognize this gap. A well-tolerated drug in a 300-person trial is not the same as a drug with an established safety profile.

How AOD-9604 Compares to Approved Alternatives

The regulatory divergence between AOD-9604 and approved anti-obesity therapies is stark.

Semaglutide 2.4 mg (Wegovy) received FDA approval in June 2021 based on the STEP program, which enrolled over 4,500 participants across four Phase III trials and demonstrated 12.4% to 17.4% body weight reduction at 68 weeks 7. Tirzepatide (Zepbound) gained approval in November 2023 after the SURMOUNT-1 trial (N=2,539) showed up to 22.5% weight loss at 72 weeks 13.

AOD-9604 has zero positive Phase III data. Its only controlled human trial failed. The total number of human subjects exposed to AOD-9604 under controlled conditions is approximately 300, compared to the tens of thousands studied in GLP-1 receptor agonist and dual GIP/GLP-1 agonist programs.

Dr. Caroline Apovian, co-director of the Center for Weight Management and Wellness at Brigham and Women's Hospital, stated in a 2023 interview that "patients should understand the difference between a peptide with failed clinical trials and one with strong Phase III data supporting FDA approval. These are not equivalent options" 14.

For prescribers and patients considering AOD-9604, the evidence base requires honest appraisal: animal data was promising, human data was not, and no regulatory authority on Earth has found the evidence sufficient for drug approval.