AOD-9604 10mg Pérdida de Peso

Functional uncoupling of growth hormone

Full human growth hormone (hGH, 191 aa, 22 kDa) exerts a diversified spectrum of biological activities including:

1. Anabolic effects mediated by hepatic IGF-1 synthesis (skeletal growth, muscle protein synthesis);
2. Anti-insulin and hyperglycemic effects on adipose tissue and liver (plasma glucose elevation, decreased insulin sensitivity);
3. Direct lipolytic effects on adipocytes (hormone-sensitive lipase activation, free fatty acid mobilization);
4. Water retention effects (documented peripheral edema);
5. Mitogenic effects on various cell lines.

Foundational work by Ng and Borstein (Horm Res 1978; Biochem J 1989; Diabetes 1990) experimentally demonstrated that the hGH 177-191 fragment (15 aa) fully retains lipolytic activity of the whole hormone in isolated adipocyte models.while losing IGF-1-dependent anabolic activities and hyperglycemic effects. Adding an N-terminal tyrosine (tyrosylated 176-191 fragment, i.e. AOD-9604) improves peptide stability and subcutaneous bioavailability without altering the selective lipolytic activity profile.

Documented lipolytic mechanisms

Three mechanistic pathways are established in rodents and on isolated adipocytes:

1. Beta-3 adrenergic receptor activation (ADRB3) — AOD-9604 increases beta-3 receptor expression on adipocytes (Heffernan 2001 Endocrinology), sensitizing the adipose cell to endogenous catecholamines and hormone-sensitive lipase (HSL) activation.
2. Mitochondrial beta-oxidation stimulation — AOD-9604 increases expression of beta-oxidation enzymes (CPT-1, acyl-CoA oxidase) in liver and adipocytes, directing released fatty acids toward energy combustion rather than re-storage (Heffernan 2001 Biochim Biophys Acta).
3. Hepatic lipogenesis inhibition — Via the AMPK / ACC pathway, AOD-9604 decreases hepatic acetyl-CoA carboxylase activity, reducing de novo triglyceride synthesis (demonstrated in obese ob/ob mice, Ng 2000).

Selectivity vs full GH: absence of anabolic and metabolic effects

The critical and scientifically remarkable point of AOD-9604 is the absence of undesirable collateral effects of full GH:

- No plasma IGF-1 elevation — no effect on hepatic GHR/JAK2/STAT5 axis generating IGF-1. Verified by plasma measurement in Metabolic Pharmaceuticals clinical trials (Ng 2008).
- No glycemic elevation — no anti-insulin activity, no fasting glucose or HbA1c rise over 12 weeks.
- No water retention — no peripheral edema reported at tested doses (0.25 to 1 mg/day).
- No carpal tunnel syndrome — classical adverse effect of exogenous GH, absent with AOD-9604.
- No mitogenic cell proliferation — favorable safety profile on murine tumor models.

This pure lipolytic selectivity explains why AOD-9604 obtained self-affirmed GRAS status in the US for dietary use in 2014 — a status inaccessible to recombinant GH.

Secondary chondroprotective activity (later discovery)

Work subsequent to the obesity program's discontinuation revealed anti-inflammatory and chondroprotective activity of AOD-9604 in osteoarthritis models (Kwak 2015 Tissue Eng Regen Med; Kim 2020). The peptide appears to stimulate proteoglycan synthesis by articular chondrocytes and reduce pro-inflammatory cytokine expression (IL-1beta, TNF-alpha) in degenerative cartilage. This pathway has revived pharmaceutical interest in AOD-9604 for a second indication (knee osteoarthritis), with Australian and Korean preclinical trials underway.

Foundational preclinical work — Melbourne and Howard Florey Institute

The AOD-9604 scientific corpus begins in the 1970s with Michael Wallis and Ronald Heap (Biochem J 1968) on proteolytic fractionation of hGH and the demonstration that peptide fragments retain differential biological activities. Frank Ng's team at the Howard Florey Institute (Melbourne, Australia) systematically refined this hypothesis:

- Ng and Borstein (Horm Res 1978) — First identification of the 177-191 fragment as carrier of hGH lipolytic activity, on isolated rat adipocytes.
- Ng et al. (Biochem J 1989) — Chemical synthesis of the fragment and demonstration of pure lipolytic activity (FFA release > 3x control on isolated adipocytes).
- Ng et al. (Diabetes 1990) — Demonstration of the absence of diabetogenic effect of the fragment, contrasting with full GH.
- Heffernan et al. (Endocrinology 2001, 142:11) — Mechanism elucidation via the beta-3 adrenergic receptor in obese ob/ob mice. 80 to 200% ADRB3 upregulation depending on dose.
- Heffernan et al. (Biochim Biophys Acta 2001, 1533:3) — Demonstration of increased mitochondrial beta-oxidation and CPT-1 expression in adipose and hepatic tissue.

Human clinical trials — Metabolic Pharmaceuticals program

Metabolic Pharmaceuticals, an ASX-listed Australian biotech startup, conducted clinical development of AOD-9604 between 2001 and 2008. Key stages:

- Phase I (Ng et al. 2003) — Tolerability and pharmacokinetics in healthy subjects, dose escalation 0.1 to 1 mg SC. Excellent tolerance profile, plasma half-life approximately 30 min, no IGF-1 elevation, no prolactin rise.
- Phase IIa (2005) — 12 weeks, N = 50 obese patients (BMI > 30), doses 0.5 and 1 mg/day SC. Modest reduction of total fat mass by DXA (2-3% vs placebo), confirmed lipolytic signal.
- Phase IIb (Ng et al. 2008) — Randomized placebo-controlled pivotal trial.N = 300 obese patients, 12 weeks, oral doses 1, 5, 10, 15, 30 mg/day. Primary result: absence of statistically significant difference on body weight vs placebo at all tested doses. Modest reduction of abdominal fat mass at the highest dose. Excellent tolerance maintained, no significant toxicity.
- Consequence — Metabolic Pharmaceuticals discontinued the obesity program in 2008. The molecule was licensed in 2014 to Phosphagenics (transdermal cream based on AOD-9604, osteoarthritis indication).

Subsequent work — Osteoarthritis indication

- Kwak et al. (Tissue Eng Regen Med 2015, 12:6) — AOD-9604 stimulates glycosaminoglycan synthesis by human chondrocytes in culture. Reduction of IL-1beta-induced MMP-13 expression.
- Kim et al. (2020 Korean publications) — Murine models of knee osteoarthritis induced by MIA (mono-iodoacetate). Histological reduction of cartilage lesions with local AOD-9604.
- FDA GRAS status (2014) — Self-affirmed GRAS status granted for dietary use in the US, based on phase II tolerance data. AOD-9604 may appear as a dietary supplement ingredient in some US jurisdictions.

Limitations and controversies

The main limitation of the AOD-9604 corpus is the phase IIb trial failure (Ng 2008) to demonstrate a clinically significant weight effect in humans, contrasting with encouraging preclinical results in mice. Discussed explanatory hypotheses: (1) limited oral bioavailability at tested doses, (2) poorly calibrated non-linear dose-response, (3) human pharmacokinetics different from rodent, (4) lipolytic effect present but insufficient to overcome homeostatic compensation of energy expenditure. No human randomized clinical trial in subcutaneous administration at adequate doses has been conducted to date.