IGF-DES

The IGF-DES evidence base cited here is 6 sources — 5 preclinical, 1 review. Critically, that evidence is almost entirely preclinical (animal and in-vitro) — no human clinical trials are cited, so efficacy and safety in people remain unproven. Regulatory status: Not FDA-approved.

• Des(1-3)IGF-I lacks the N-terminal Gly-Pro-Glu tripeptide and has been isolated from bovine colostrum, human brain tissue, and porcine uterus as a natural post-translational processing product; it demonstrates approximately 10-fold greater cellular potency than full-length IGF-I primarily because it binds negligibly to IGF-binding proteins (IGFBPs), leaving more free peptide available at the receptor.
• A 1989 Biochemical Journal study established the core mechanism: IGFBP preparations that potently inhibited IGF-1 and IGF-2 bioactivity had no inhibitory effect on des-(1-3)-IGF-I, directly demonstrating that biological potency inversely correlates with IGFBP binding affinity.
• Pharmacokinetic studies in rats showed des(1-3)IGF-I clears plasma roughly 3–4× faster than native IGF-I, accumulates preferentially in peripheral tissues including brain and adrenals, and produces greater anabolic effects locally despite its shorter systemic half-life.

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