Preparation, characterization and properties of partially hydrolyzed ethylene vinyl acetate copolymer films for controlled drug release

In this study, partially hydrolyzed ethylene vinyl acetate (EVA) copolymers with three hydrolysis degrees (12.2%, 32.6% and 46.9%) were obtained by alkaline hydrolysis of EVA copolymer, characterized by Fourier-transform infrared spectroscopy (FTIR), 1H NMR and gel permeation chromatography (GPC). Paclitaxel-loaded and drug-free films based on the partially hydrolyzed EVA copolymers were fabricated. The swelling behaviors, crystallinities, mechanical properties of the fabricated films were investigated, and the effects of hydrolysis degree, film thickness and drug loading dose on in vitro drug release from the films were also investigated. In vitro swelling study showed that the swelling of partially hydrolyzed EVA films was greater than the EVA film and the film with higher hydrolysis degree swelled more intensively. X-ray diffraction (XRD) results exhibited that the crystallinity of the polymer increased with increasing hydrolysis degree. In paclitaxel-loaded EVA film, a part of paclitaxel was in crystalline form; while in paclitaxel-loaded partially hydrolyzed EVA films, paclitaxel was distributed in amorphous form or molecularly dispersed. In the in vitro drug release test, the film with higher hydrolysis degree and smaller thickness released paclitaxel more quickly. With higher drug loading dose, the drug release rate was larger. The partially hydrolyzed EVA films were applied for drug delivery systems for the first time, and demonstrated to have great capability of controlling drug release thanks to the adjustable hydrolysis degree.