title: The application of electrostatic dry powder deposition technology to coat drug-eluting stents.
abstract: OBJECTIVE
  A novel methodology has been introduced to effectively coat intravascular stents with sirolimus-loaded polymeric microparticles.
  
  
  METHODS
  Dry powders of the microparticulate formulation, consisting of non-erodible polymers, were produced by a supercritical, aerosol, solvent extraction system (ASES). A design of experiment (DOE) approach was conducted on the independent variables, such as organic/CO(2) phase volume ratio, polymer weight and stirring-rate, while regression analysis was utilized to interpret the influence of all operational parameters on the dependent variable of particle size. The dry powders, so formed, entered an electric field created by corona charging and were sprayed on the earthed metal stent. Furthermore, the thermal stability of sirolimus was investigated to define the optimum conditions for fusion to the metal surfaces.
  
  
  RESULTS
  The electrostatic dry powder deposition technology (EDPDT) was used on the metal strut followed by fusion to produce uniform, reproducible and accurate coatings. The coated stents exhibited sustained release profiles over 25 days, similar to commercial products. EDPDT-coated stents displayed significant reduced platelet adhesion.
  
  
  CONCLUSIONS
  EDPDT appeared to be a robust accurate and reproducible technology to coat eluting stents.
authors.affiliation: University of Greenwich, School of Science, Medway Campus, Central Avenue, Chatham Maritime, Kent, ME4 4 TB, UK.
authors.forename: Ravi Kumar
authors.initials: RK
authors.lastname: Nukala
authors.forename: Harikrishna
authors.initials: H
authors.lastname: Boyapally
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Slipper
authors.forename: Andy P
authors.initials: AP
authors.lastname: Mendham
authors.forename: Dennis
authors.initials: D
authors.lastname: Douroumis
mesh_terms: D025924:Chromatography, Supercritical Fluid / Q000379:methods; D054855:Drug-Eluting Stents; D006801:Humans; D008956:Models, Chemical; D010316:Particle Size; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000493:pharmacokinetics / Q000494:pharmacology; D011108:Polymers / Q000737:chemistry; D011208:Powders / Q000138:chemical synthesis / Q000737:chemistry*; D020123:Sirolimus / Q000493:pharmacokinetics / Q000494:pharmacology; D055672:Static Electricity; D013499:Surface Properties; D013678:Technology, Pharmaceutical / Q000379:methods*
chemical_list: D010975:Platelet Aggregation Inhibitors; D011108:Polymers; D011208:Powders; D020123:Sirolimus