title: Drug-eluting bioabsorbable stents - an in vitro study.
abstract: The aim of this study was to investigate the drug elution properties of novel drug-eluting bioabsorbable stents in vitro with four different drugs: dexamethasone, indomethacin, simvastatin and ciprofloxacin. Braided stents of poly-lactic acid (96l/4d) fibers were coated with a solution containing the appropriate bioabsorbable polymer and drug, with acetone as the solvent. Two different drug concentrations for both non-sterile and gamma sterilized stents were used for dexamethasone and indomethacin. For ciprofloxacin and simvastatin, only one drug dose was used. The stents were placed in sodium-phosphate-buffered saline in a shaking incubator (pH 7.4, +37 degrees C) and the eluted drug was measured periodically using an ultraviolet spectrometer. The drugs were hydrophobic to different degrees, as demonstrated by their various speeds of elution. In general, the higher the drug load in the stent, the faster the drug elution and the more hydrophilic the elution profile. In the cases of dexamethasone, indomethacin and ciprofloxacin, the sterilization decreased the drug elution rate slightly and the elution started earlier. However, in the case of ciprofloxacin, the gamma sterilization increased the drug elution rate slightly. Sustained elution was achieved for all four drugs. It was also evident that both the concentration and the hydrophility of the drug had a great influence on the drug elution profile. Gamma sterilization modified the drug elution profiles of dexamethasone, indomethacin and simvastatin, but had little effect on the drug elution profile of ciprofloxacin compared to three other drugs.
authors.affiliation: Institute of Biomaterials, Tampere University of Technology, Tampere 33101, Finland. joonas.mikkonen@bioretec.com
authors.forename: J
authors.initials: J
authors.lastname: Mikkonen
authors.forename: I
authors.initials: I
authors.lastname: Uurto
authors.forename: T
authors.initials: T
authors.lastname: Isotalo
authors.forename: A
authors.initials: A
authors.lastname: Kotsar
authors.forename: T L J
authors.initials: TL
authors.lastname: Tammela
authors.forename: M
authors.initials: M
authors.lastname: Talja
authors.forename: J-P
authors.initials: JP
authors.lastname: Salenius
authors.forename: P
authors.initials: P
authors.lastname: Törmälä
authors.forename: M
authors.initials: M
authors.lastname: Kellomäki
mesh_terms: D020341:Absorbable Implants; D000042:Absorption; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage* / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry*; D004058:Diffusion; D054855:Drug-Eluting Stents; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008422:Materials Testing
chemical_list: D000893:Anti-Inflammatory Agents; D001672:Biocompatible Materials