Quantitative spatial distribution of sirolimus and polymers in drug-eluting stents using confocal Raman microscopy.
Raman spectroscopy was used to differentiate each component found in the CYPHER Sirolimus-eluting Coronary Stent. The unique spectral features identified for each component were then used to develop three separate calibration curves to describe the solid phase distribution found on drug-polymer coated stents. The calibration curves were obtained by analyzing confocal Raman spectral depth profiles from a set of 16 unique formulations of drug-polymer coatings sprayed onto stents and planar substrates. The sirolimus model was linear from 0 to 100 wt % of drug. The individual polymer calibration curves for poly(ethylene-co-vinyl acetate) [PEVA] and poly(n-butyl methacrylate) [PBMA] were also linear from 0 to 100 wt %. The calibration curves were tested on three independent drug-polymer coated stents. The sirolimus calibration predicted the drug content within 1 wt % of the laboratory assay value. The polymer calibrations predicted the content within 7 wt % of the formulation solution content. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra from five formulations confirmed a linear response to changes in sirolimus and polymer content.
Balss
K M
KM
Cordis Corporation, a Johnson & Johnson Company, Welsh and McKean Roads, Spring House, Pennsylvania 19477, USA. kbalss@crdus.jnj.com
Llanos
G
G
Papandreou
G
G
Maryanoff
C A
CA
D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000737:chemistry; D054855:Drug-Eluting Stents; D018613:Microscopy, Confocal; D004364:Pharmaceutical Preparations / Q000008:administration & dosage* / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D020123:Sirolimus / Q000008:administration & dosage* / Q000737:chemistry; D013059:Spectrum Analysis, Raman
D000900:Anti-Bacterial Agents; D004364:Pharmaceutical Preparations; D011108:Polymers; D020123:Sirolimus