AOD-9604 Peptide Calculator

AOD-9604 is a synthetic peptide derived from the C-terminal end of human growth hormone (hGH), corresponding to residues 177–191 of the native 191-amino acid sequence. A tyrosine residue was added at the N-terminus during development to increase metabolic stability and facilitate radiolabeling in early pharmacokinetic studies—this is the structural basis of the 'Tyr-hGH177-191' designation sometimes used interchangeably with AOD-9604. The peptide also contains a disulfide bridge between Cys182 and Cys189 that maintains the loop conformation of the native hGH C-terminal domain, which is required for its biological activity.

Its molecular weight is approximately 1,815 Da, placing it in the mid-range of research peptides. This size is large enough to contain meaningful secondary structure (the disulfide-stabilized loop) but small enough to dissolve rapidly in bacteriostatic water under gentle handling. The peptide was developed at Monash University in Australia and advanced through Phase I–III clinical trials for obesity, making it one of the more clinically characterized research peptides. Despite not receiving final regulatory approval as a pharmaceutical, AOD-9604 remains an active subject of preclinical metabolic research.

Stimulating Lipolysis: Fat Breakdown at the Adipocyte Level

AOD-9604's primary metabolic activity is the stimulation of lipolysis—the enzymatic hydrolysis of stored triglycerides within adipocytes into glycerol and free fatty acids for energy substrate release. In animal models, AOD-9604 activates beta-3 adrenergic receptors on adipocyte membranes, triggering a cAMP-mediated signaling cascade that activates hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL). These enzymes catalyze the sequential breakdown of triglycerides, diacylglycerols, and monoacylglycerols, liberating fatty acids into circulation for mitochondrial beta-oxidation.

Inhibiting Lipogenesis: Blocking de Novo Fat Synthesis

Complementing its lipolytic activity, AOD-9604 also inhibits lipogenesis—the metabolic process by which non-fatty substrates (primarily excess carbohydrates and amino acids) are converted into new fatty acids and stored as triglycerides in adipose tissue. This dual action—simultaneously accelerating fat release and blocking new fat storage—mirrors the fat-metabolizing activity of the full-length growth hormone molecule without requiring systemic GH receptor activation. In diet-induced obesity rodent models, this combination produces measurable reductions in adipose tissue mass over the study period.

The No-IGF-1 Advantage: Why This Fragment Is Different from Full-Length hGH

Full-length human growth hormone activates the GH receptor primarily through its receptor-binding domains in the N-terminal region (residues 1–176). This activation triggers hepatic IGF-1 production, which drives the anabolic, anti-lipolytic, and diabetogenic effects associated with GH excess: insulin resistance, fluid retention, soft tissue growth, and increased proliferative signaling. AOD-9604, comprising only residues 177–191 with the N-terminal tyrosine, lacks the receptor-binding domains entirely. It does not bind the classical GH receptor, does not stimulate IGF-1 production, and does not alter blood glucose or insulin sensitivity in animal models at research-relevant doses. This separation of the fat-metabolizing activity from the insulin-disrupting activity is the central pharmacological rationale for AOD-9604 research.

Common Research Vial Sizes

• 2mg vials: suitable for short pilot studies or low-dose range-finding experiments. At standard concentration (2mg + 2ml BAC water = 10mcg/unit), provides 20 × 100mcg doses or 10 × 200mcg doses.
• 5mg vials: the standard workhorse for AOD-9604 research protocols. At the reference concentration (5mg + 2ml BAC water = 25mcg/unit), a 300mcg dose = 12 units and a 500mcg dose = 20 units.

AOD-9604 Dosage Chart: Calculation Example

The AOD-9604 calculator above uses the standard concentration formula. The reference preparation for most published research protocols is the 5mg vial with 2ml BAC water:

Critical Handling: AOD-9604 Is an Extremely Fragile Peptide

AOD-9604 requires more careful handling than most research peptides. Its disulfide bridge (Cys182–Cys189) is the structural foundation of its biological activity—disruption of this bond through mechanical stress, oxidation, or pH shifts renders the peptide inactive. The tyrosine residue at the N-terminus also undergoes oxidative degradation under suboptimal handling conditions. Two specific failure modes must be avoided:

• Vigorous shaking or vortexing: The air-liquid interface generated by shaking creates surface-induced mechanical stress that denatures small cyclic peptides with disulfide bonds. Even brief vigorous mixing is sufficient to cause aggregation and activity loss in AOD-9604 preparations.
• Vacuum-pressure 'jetting': When a syringe is inserted into a vial under vacuum, the pressure differential can force BAC water to jet directly onto the lyophilized cake at high velocity. This hydromechanical impact disrupts the powder structure and can denature the peptide on contact. Always inject slowly along the vial wall—never directly at the cake, and never at speed.

1. 1Equilibrate the vial to room temperature (15–20 minutes). Do not speed this up with body heat—slow, controlled warming is essential for this peptide.
2. 2Disinfect the stopper with a 70% isopropyl alcohol swab. Allow to air dry fully—residual alcohol can break disulfide bonds.
3. 3Calculate your target BAC water volume using the AOD-9604 calculator before drawing. Minimize stopper punctures per session.
4. 4Insert the needle at an angle and inject BAC water in a very slow, controlled stream directed at the inner glass wall—not at the peptide cake. If resistance is felt from vial vacuum, release pressure slowly; never allow pressure differential to force rapid BAC water entry.
5. 5Gently roll or swirl the vial between fingers with minimal force until dissolved. The solution should clarify within 30–60 seconds. Refrigerate immediately at 2–8°C.

Dose Range in Published Animal Model Literature

Published preclinical AOD-9604 research most commonly employs doses in the 300–500mcg range per administration in rodent models, expressed as absolute dose or normalized to body weight depending on the study design. This range represents the dose-response window where lipolytic activity is consistently measurable without producing non-specific effects. The AOD-9604 dosage chart above (generated from your specific vial size and BAC water volume) translates these reference doses into precise syringe units for your preparation.

Fasted-State Administration and Lipolytic Maximization

A consistent finding across AOD-9604 animal model studies is that administration timing relative to the fed/fasted cycle significantly modulates lipolytic output. In a fasted state, circulating insulin is low and lipolytic signaling is upregulated—adipocytes are already primed for triglyceride release, and AOD-9604's beta-3 adrenergic stimulation produces amplified HSL and ATGL activation under these conditions. Administration in a fed state—where elevated insulin actively suppresses HSL activity—attenuates the lipolytic response. Research protocols designed to maximize lipolytic readout therefore consistently control for fasting duration before administration, typically 4–6 hours in rodent models.

AOD-9604 is more thermally labile than most peptides of comparable size due to the temperature sensitivity of the disulfide bridge and the tyrosine residue. Its cold chain requirements are stricter than general research peptide guidelines:

• Lyophilized powder at −20°C: Stable for up to 24 months. Recommended long-term storage format. Store as single-use aliquots to avoid repeat freeze-thaw cycles on the same vial.
• Lyophilized powder at 2–8°C: Stable for up to 6 months. The disulfide bond and tyrosine residue begin degrading faster than in frozen storage beyond the 3-month mark—plan active research batches accordingly.
• Reconstituted solution at 2–8°C (36°F–46°F): For peak potency, use within 7–14 days. Unlike most research peptides where 28 days is the standard window, AOD-9604's solution-phase stability is significantly shorter due to the reactivity of the disulfide bond and tyrosine residue in aqueous conditions.
• Do not freeze reconstituted solution: Ice crystal formation disrupts the Cys182–Cys189 disulfide bridge conformation, causing partial or complete loss of the structural loop required for biological activity.
• Temperature excursions: Even brief exposure above 25°C for the reconstituted solution accelerates disulfide bond oxidation and tyrosine degradation. Do not leave reconstituted vials at room temperature beyond the time required for dose preparation.
• UV and light exposure: Both the disulfide bond and tyrosine residue are photosensitive. Protect from all UV sources—store in amber vials or foil-wrapped containers from reconstitution through to use.

Is AOD-9604 the same as Fragment 177-191?

Yes, with one important modification. 'hGH Fragment 177-191' refers to the raw C-terminal peptide sequence of human growth hormone spanning residues 177 through 191. AOD-9604 is this same fragment with a tyrosine (Tyr) residue added at the N-terminus, making the full sequence Tyr-hGH177-191. This tyrosine addition was incorporated during development to improve peptide stability in biological media—the N-terminal amine is capped by the bulkier tyrosine side chain, reducing susceptibility to exopeptidase cleavage. In most research literature, AOD-9604 and hGH Frag 177-191 are used interchangeably, though strictly speaking AOD-9604 refers to the tyrosine-modified form. When using the AOD-9604 calculator, both forms can be treated as equivalent for reconstitution math purposes, as their molecular weights differ by only ~181 Da (the mass of one tyrosine residue).

Why did the reconstituted solution turn cloudy?

Cloudiness in a reconstituted AOD-9604 preparation is the most reliable visual indicator that the peptide has been compromised, and it is almost always caused by one of three mechanisms. First, pH-induced solubility collapse: AOD-9604 has optimal aqueous solubility in the pH 4.5–6.0 range. Bacteriostatic water (pH ~5.5) falls within this window, which is why it is the preferred reconstitution vehicle. If sterile saline (pH ~7.0) or other neutral-to-alkaline diluents are used, the peptide can precipitate as insoluble aggregates, producing visible cloudiness. Second, disulfide bond disruption and aggregation: vigorous shaking, fast injection, or exposure to reducing agents (including trace residual alcohol from an incompletely dried stopper) can break the Cys182–Cys189 bridge, causing the peptide to unfold and aggregate into visible particulates. Third, thermal denaturation: if the vial was stored improperly before reconstitution, partial denaturation produces a cloudy solution upon rehydration. In all three cases, a cloudy solution should be discarded—filtering removes the aggregated peptide mass along with the particulates, resulting in an underdosed and potentially compromised preparation.