DSIMS characterization of a drug-containing polymer-coated cardiovascular stent

Dynamic Secondary Ion Mass Spectrometry (DSIMS) was used to study the release behavior of cytochalasin D, an actin polymerase inhibitor effective in the reduction of smooth muscle cell (SMC) proliferation, from a polymer-coated cardiovascular stent. High-performance liquid chromatography (HPLC) was used to determine the percentage of drug released as a function of time and showed the typical behavior of a drug-releasing system that is comprised of a core drug-polymer dispersion surrounded by a drug-free polymeric membrane: an initial burst of the drug followed by a gradual elution over time. DSIMS profiles, as a function of release time, indicated that depletion of the drug initially occurred only in the outer layers of the coating. As release progressed the DSIMS profile showed a gradual decrease of cytochalasin D with increasing depth. This study shows that DSIMS is a powerful tool for the determination of drug distributions in, and the release behavior from, thin polymer layers.