A transferable non-destructive method for the quantification of coronary stent coating components using Raman spectroscopy

Drug content of coronary stents is destructively evaluated using high pressure liquid chromatography. The method involves the dissolution of the coating from the stent into a solution and the analysis and quantification of the solvents' drug content. Quantification of the components of drug by Raman has been demonstrated with most recent methods using multivariate techniques. However, the calibration models generated as part of these methods are not easily transferable because they are developed using defined mixtures. In this work, we demonstrate a transferable non-destructive Raman method for the evaluation and quantification of the drug coating components by developing a model from the pure samples of the coating constituents. Using the designed experiment, the transferable Raman method is equivalence tested with the standard high pressure liquid chromatography approach and compares favorably as a non-destructive viable alternative. A method of dealing with the microheterogeneity of stent coatings is presented by spectral sample collection through the rotation of the stent. Knowledge of the coating formation and substrates is required in order to correctly interpret the results.