Release mechanism studies on TFu nanoparticles-in-microparticles system

► N3-O-toluyl-fluorouracil (TFu) was synthesized as a new and potential antitumor prodrug of 5-fluorouracil. ► A nanoparticles-in-microparticles delivery system (NiMS) for TFu as a practical preparation was prepared. ► The in vitro release properties of TFu from NiMS were fit diffusion controlled drug release and matrix dissolution dual mechanism. ► The TFu-NiMS were valued to develop as a practical preparation for oral or i.v. administration.