Preparation,characterization And In Vitro Drug Release Behavior Of Paclitaxel-loaded Polymer Films And Their Covered Stents

The non-vascular malignant tumors cause serious occlusion or stenosis of physiological tubular structures.Stent implantation technique provides relatively simple,safe and effective treatment.Since simple bare metal stent does not have a fundamental role in the treatment of tumors,it’s important to investigate drug controlled delivery systems of non-vascular stent.Ethylene-vinyl acetate copolymer(EVA)has good biocompatibility and a certain degree of viscoelasticity.Research on EVA as coating materials has achieved better results,however,the EVA style used was single and drug released slowly from the films.In this study,we designed different ways to improve drug controlled delivery systems of non-vascular stents.Firstly,we employed EVA with different VA content(EVA42/60,EVA32/43,EVA 30/10)as coating materials.EVA42/60、EVA32/43、EVA30/10 respectively,PTX were mixed and pressed into films by melting method.Simultaneously,we made the films by stretching orientation.The thickness,drug doses,mechanical properties,diffusion,drug release behavior and surface morphologies of the films were studied.We found that the preparation method was relatively simple and feasible.The mechanical tests showed that the higher content of VA led to the decrease of the modulus of elasticity and maximum tensile strength,and the increase of the maximum elongation.Orientation led to the decrease of the maximum elongation and modulus of elasticity,and the increase of the maximum tensile strength.In the experiment,we selected the EVA30/10 film(100μ m)as the backing layer.At the beginning of the ten days,the drug released fast.In the next stage,the drug release rate slowed down gradually,maintaining nearly constant release.The release profiles of coatings could be affected by the EVA materials and orientation.With higher VA content of EVA as coating materials,the drug release quantity was higher.The drug release quantity of orientation film was a little lower than that not.Also,we fabricated numerous PTX/PLGA stents with PLGA75/25 as the drug carrier and EVA30/10 as the drug-free backing layer using a dipping process.In this work,we explored the effects of preparation formulations of the PLGA stents on the mechanical performance and deliverability.Thisdemonstrated that the mechanical performance and deliverability could be modified by altering infiltration solvent,invasion times,invasion time and the concentration of liquid infiltration.We assessed the quality and drug release behaviors of the PTX/PLGA stents in vitro.With the increase of invasion times,invasion time and the ratio of PTX in the coating solution,drug loading could be increased.Compared to the PTX/EVA stents,the PTX/PLGA stents achieved sustained and rapid release of PTX.The drug release behaviors of the PTX/PLGA stents could be affected by the total drug loading.The PLGA stent coverd with drug-loaded films could be an potential drug delivery system.