IGF-1 is produced primarily in the liver in response to GH signalling via the GH receptor, though local autocrine and paracrine synthesis occurs in many other tissues. Its circulating form is almost entirely bound to a family of insulin-like growth factor binding proteins (IGFBPs), particularly IGFBP-3, which regulate its bioavailability and half-life. Free IGF-1 binds the IGF-1 receptor (IGF-1R), a receptor tyrosine kinase, activating downstream pathways including PI3K/Akt and MAPK/ERK cascades that regulate cell proliferation, differentiation, and survival.
In clinical medicine, recombinant human IGF-1 (rhIGF-1) is an approved therapy in a narrow set of diagnosed conditions involving severe primary IGF-1 deficiency or GH gene deletion. In Australia, access to approved rhIGF-1 preparations is governed by the Therapeutic Goods Administration (TGA) under the Therapeutic Goods Act 1989. Prescribing outside the registered indication may involve the TGA's Special Access Scheme (SAS) or Authorised Prescriber framework, and supply requires a valid prescription under the relevant state and territory poisons legislation.
IGF-1 peptide preparations marketed outside the approved pharmaceutical pathway , including products sold or promoted for performance enhancement or anti-ageing purposes , are considered unapproved therapeutic goods in Australia. Supplying such products without TGA approval is illegal under the Therapeutic Goods Act 1989, and the TGA actively enforces against the import, supply, and advertisement of unapproved peptides in this category. Individuals found supplying or importing these goods without authorisation face significant civil and criminal penalties.
Research into IGF-1's physiological roles is ongoing; studies have examined its involvement in normal growth across the lifespan, bone mineral regulation, and neurological development. Interpretation of this research requires careful attention to study design: many findings come from cell culture or animal models, and results do not automatically translate to clinical outcomes in humans. No therapeutic claims for unapproved IGF-1 products are supported by the TGA-regulated evidence base.
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