Drug delivery of Insulin-like growth factor I.

This review starts off outlining the control of Insulin-like growth factor I (IGF-I) kinetics in Nature and by virtue of a complex system of 6 binding proteins controlling half-life and tissue distribution of this strong anabolic peptide. In addition, alternative splicing is known to result in IGF-I variants with modulated properties in vivo and this insight is currently translated into advanced IGF-I variants for therapeutic use. Insights into these natural processes resulted in biomimetic strategies with the ultimate goal to control pharmacokinetics and have recently propelled new developments leading to optimized pharmaceutical performance of this protein in vivo. Aside from parenteral administration routes, IGF-I was successfully delivered across various epithelial barriers from liquid as well as from solid pharmaceutical forms opening novel and more convenient delivery modalities. IGF-I decoration yielded effective targeting upon systemic administration expanding the options for optimally deploying the growth factor for therapy. This review summarizes the exciting biotechnological and pharmaceutical progress seen for IGF-I delivery in recent years and critically discusses outcome in light of translational application for future IGF-I therapeutics.