Coating preparation and drug delayed release of dexamethasone-eluting intravascular stents in vitro and in vivo

To prepare the dexamethasone-eluting intravascular stents by dip coating and then to observe the character of drug delayed release in vitro and in vivo in the stents. Methods Stents were prepared by dip coating. High performance liquid chromatography (HPLC) was used to detect the drug loading of the stents. The weight of bare stents and drug eluting stents was determined in order to know the weight percentage of drugs in the coating. Thermal analyzer was used to analyse the melting point of dexamethasone. The drug slow-release rate in vitro was detected with the flow chamber. The buffer solution was taken out at the scheduled time. The dexamethasoneeluting intravascular stents were implanted into the rabbit abdominal aorta. The tissues of the vessel wall and liver were employed for the detection of the drug slow-release properties in vivo. The data collected were analyzed by using SPSS 12.0. Results The drug loading level increased in a time-dependent manner and peaked 93.15 µg at 4 d. The level of the loaded drug in the coating was (13.70±0.84)%. Differential scanning calorimetry (DSC) indicated that the melting point was 259.3°C, accordant with the related literatures. Drugs were released slowly and the release rate reached 84% at 15 d. The drug concentration was detected after stent implantation. Conclusion Drugs remained 16% of the total loaded drug at 15 d and the drug concentration in the vessel wall and liver tissues was detected after stent implantation, suggesting that the prepared stents may be helpful for the slow-release of dexamethasone.