A quiet analytical research laboratory at night, racks of glass vials along a dim bench.

Body Composition and the Growth Hormone Axis

The growth hormone axis has approved drugs at every level, from weekly GH to an oral diagnostic ghrelin agonist, and a larger gray market of unapproved peptides. Every GH-axis compound is prohibited in sport. Vegalab describes the science and the regulatory map and works only with licensed partners on approved or investigational programs.

How the axis works

The hypothalamus releases growth hormone releasing hormone (GHRH) and somatostatin; the stomach releases ghrelin, which acts on the GH secretagogue receptor. Together they set pulsatile GH release from the pituitary. GH acts directly on fat and muscle and indirectly through IGF-1 from the liver. GH secretion falls with age and with visceral fat. Interventions can target the receptor (GH itself), the releasing signal (GHRH analogs) or the secretagogue receptor (ghrelin mimetics).

Approved and unapproved compounds

Somatropin and long-acting versions (somapacitan, somatrogon, lonapegsomatropin) are approved for GH deficiency. Tesamorelin (Egrifta), a GHRH analog, is FDA approved to reduce excess abdominal fat in HIV-associated lipodystrophy. Macimorelin (Macrilen), an oral ghrelin agonist, is FDA approved only as a diagnostic test for adult GH deficiency. CJC-1295, ipamorelin, GHRP-2, GHRP-6, hexarelin and AOD-9604 have no approved use in the US or EU. All GH, GHRH analogs, secretagogues and GH fragments are on the WADA Prohibited List under S2.

Delivery reality

GH is a 22 kDa protein and is injected. GHRH analogs are peptides of about 29 to 44 amino acids and are injected. Macimorelin shows that a small peptidomimetic can be orally active, but it was designed for oral use from the start. Converting an injectable GH-axis peptide to an oral or nasal format faces protease degradation, poor permeability and very low bioavailability, the same barriers that hold oral semaglutide to about 1%.

Key facts

Tesamorelin is FDA approved to reduce excess abdominal fat in HIV-infected patients with lipodystrophy (FDA label, Egrifta 2010)
Macimorelin, an oral ghrelin receptor agonist, is FDA approved for the diagnosis of adult growth hormone deficiency (FDA label, Macrilen 2017)
Somapacitan, a once-weekly GH derivative, is FDA approved for adult growth hormone deficiency (FDA label, Sogroya 2020)
Growth hormone, GHRH and its analogs, GH secretagogues and GH fragments such as AOD-9604 are prohibited at all times (WADA Prohibited List 2026, S2)

How our delivery technology applies

For GH-axis peptides the barriers are proteolysis and permeability. Multi-layer encapsulation can shield a peptide in the gut and co-locate a permeation enhancer at the mucosal surface, the same principle used with SNAC in oral semaglutide. Realistic oral bioavailability for a peptide of this size is low single digits at best. Vegalab offers this as a research collaboration with licensed sponsors, not as a product.

Licensed sponsors: discuss a GH-axis delivery research collaboration with Vegalab.