Core–shell electrospun fibers for enhanced dissolution and stability of amorphous empagliflozin

Core-shell electrospun fibers represent a promising platform for formulating poorly water-soluble drugs as amorphous solid dispersions with enhanced dissolution and physical stability. This study developed and characterized coaxial electrospun fibers containing the antidiabetic drug empagliflozin (EMPA) with drug loadings up to 22% w/w, using a Soluplus-EMPA core and Kollicoat Smartseal shell architecture. Comprehensive solid-state characterization confirmed complete amorphization across all compositions and intimate molecular-level mixing stabilized by drug-polymer hydrogen bonding. Raman microscopy mapping verified the intended core-shell structure with spatial separation of drug-rich core from polymer shell. Systematic comparison against film-cast amorphous solid dispersions and physical mixtures of identical composition (18% w/w) confirmed faster dissolution and higher drug release performance of the electrospun fibers. Under accelerated stability conditions (3 months at 40°C/75% RH) the electrospun fibers showed the same stability as the film-cast formulation, in contrast to the physical mixture crystallizing within one week. Notably, dynamic vapor sorption analysis revealed that electrospun fibers absorbed less moisture than film-cast ASD despite their higher surface area and porous structure, attributed to the protective barrier function of the Kollicoat shell. These findings establish core-shell electrospun fibers as an advantageous platform combining rapid dissolution with moisture-resistant stability for empagliflozin formulation.