Multivariate analysis applied to the study of spatial distributions found in drug-eluting stent coatings by confocal Raman microscopy.
Multivariate data analysis was applied to confocal Raman measurements on stents coated with the polymers and drug used in the CYPHER Sirolimus-eluting Coronary Stents. Partial least-squares (PLS) regression was used to establish three independent calibration curves for the coating constituents: sirolimus, poly(n-butyl methacrylate) [PBMA], and poly(ethylene-co-vinyl acetate) [PEVA]. The PLS calibrations were based on average spectra generated from each spatial location profiled. The PLS models were tested on six unknown stent samples to assess accuracy and precision. The wt % difference between PLS predictions and laboratory assay values for sirolimus was less than 1 wt % for the composite of the six unknowns, while the polymer models were estimated to be less than 0.5 wt % difference for the combined samples. The linearity and specificity of the three PLS models were also demonstrated with the three PLS models. In contrast to earlier univariate models, the PLS models achieved mass balance with better accuracy. This analysis was extended to evaluate the spatial distribution of the three constituents. Quantitative bitmap images of drug-eluting stent coatings are presented for the first time to assess the local distribution of components.
Cordis Corporation, a Johnson & Johnson Company, Welsh and McKean Roads, Spring House, Pennsylvania 19477, USA. kbalss@crdus.jnj.com
Karin M
KM
Balss
Frederick H
FH
Long
Vladimir
V
Veselov
Argjenta
A
Orana
Eugena
E
Akerman-Revis
George
G
Papandreou
Cynthia A
CA
Maryanoff
D002138:Calibration; D054855:Drug-Eluting Stents; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008689:Methacrylates / Q000032:analysis*; D018613:Microscopy, Confocal / Q000379:methods*; D015233:Models, Statistical; D015999:Multivariate Analysis; D011145:Polyvinyls / Q000032:analysis*; D012044:Regression Analysis; D020123:Sirolimus / Q000032:analysis*; D013059:Spectrum Analysis, Raman / Q000379:methods*
D008689:Methacrylates; D011145:Polyvinyls; C116863:poly(butyl methacrylate); C016438:ethylenevinylacetate copolymer; D020123:Sirolimus