| Clinically,polyvinyl chloride(PVC)containing DEHP is widely used in intravenous infusion medical devices.Because of the direct contact between PVC and liquid medicine in the infusion process,resulting in the leaching of polymer additives or drug adsorption,which affects the rehabilitation treatment of patients,the development of infusion materials that can replace PVC has become a trend in the medical field.In recent years,styrene thermoplastic elastomer(TPEs)without ester plasticizer has appeared in the medical equipment market to replace PVC.In order to explore the infusion potential of TPEs,the rheological behavior of PVC and TPEs was studied by dynamic frequency scanning to select a reasonable temperature range in the extrusion process.Based on the temperature range of rheological experiments,PVC and TPEs standard samples and tubes were prepared,the mechanical properties,crystallinity and hydrophilicity of the samples were analyzed,the micro morphology and biocompatibility of the tube were analyzed,and the residual styrene content in TPEs tube was tested.Finally,the adsorption performance of PVC and TPEs tube for nine drugs in 0 to 8h was explored.The adsorption isotherm experiment and adsorption kinetics analysis of drugs and materials with adsorption rate greater than10 % were carried out.The experiments showed that in the range of 0.1～100 rad/s shear rate,with the increase of temperature gradient,the molecular weight distribution of PVC and TPEs melts narrowed,the weight average molecular weight decreased,the loss peak value increased,and the curvature radius of Cole-Cole curve decreased.Both materials showed the behavior of shear thinning non-Newtonian fluid.The results showed that the drug delivery tube of TPEs had good application potential.Compared with PVC,TPEs had good elasticity and similar hydrophilicity.The crystallinity of TPEs is higher,and the inner wall of TPEs tube is smoother.In addition,PVC and TPEs had excellent biocompatibility within 1 to 7 days,and the residual amount of TPEs styrene monomer after extrusion did not affect human health.Drug adsorption experiments showed that TPEs had more advantages for some drug infusion.For furosemide,cyclosporine A,chlorpromazine hydrochloride and nimodipine,the losses after flowing through the PVC tube after 8h were 13 %,98 %,24% and 82 %respectively,and the losses in TPEs were 2 %,44 %,3 % and 7 % separately.The loss of cyclosporin A and nimodipine in PVC tube within 2h was more than 80%.The loss of amiodarone hydrochloride in PVC and TPEs tubes within 2h was more than50 %.For vitamin C,vitamin B6 and ranitidine,the adsorption of TPEs tube and PVC tube was less than 7% after 8h.It was mainly controlled by chemical action,including PVC contact with furosemide,cyclosporine A,amiodarone hydrochloride,chlorpromazine hydrochloride and nimodipine,and TPEs contact with nimodipine.TPEs contact with cyclosporine A was mainly controlled by physical action.Except that PVC contact furosemide was monolayer adsorption,the other adsorption methods were multi-molecular layer adsorption,in which the drug diffusion behavior was involved in the adsorption process,but the adsorption rate was not only controlled by diffusion. |
