Tunable Release of Combined Contraceptive Steroids from Core-shell Gelatin/PCL Fibers

Abstract

The present study investigates simultaneous release of two hydrophobic contraceptive steroids from core-shell fibers made by coaxial electrospinning. The contraceptive steroids levonorgestrel (LNG) and ethinylestradiol (EE) were incorporated in gelatin/poly(e-caprolactone) (PCL) core-shell fibers. The influence of shell concentration and core feed/flow rate (ml/h) on the physical, chemical, mechanical and release properties of drug incorporated coaxial fibers were evaluated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy, universal testing machine (UTM) and highperformance liquid chromatography (HPLC). SEM results revealed the influence of feed/flow rate on pore size (in the range 586–1036 nm) and fiber diameter (i.e. 621–1650 nm) of the coaxial fibers. TEM analysis confirmed the presence of core-shell morphology. DSC results conferred that drugs were in an amorphous form within core-shell fibers. The FT-IR spectra established the drug encapsulation by the electrospinning process. Swelling studies demonstrate that increasing the shell (PCL) concentration i.e. 4–10% w/v decreases the swelling ratio (295–140%). The drugs release kinetics satisfactorily described by first-order (R2>0.95) model and Korsmeyer-Peppas model (R2≥0.95) for all the prepared core-shell formulations. These formulations were found to follow anomalous non-Fickian transport, which suggests that the drug release is controlled by both diffusion and erosion of polymer matrix. These results clearly demonstrate that it is possible to control the release rate for the two hydrophobic (contraceptive) drugs through coaxial electrospinning process for the first time to the best of our knowledge.