Phosphorylcholine-based polymer coatings for stent drug delivery

Phosphorylcholine-based polymers have been used commercially to improve the biocompatibility of coronary stents. In this study, one particular polymer is assessed for its suitability as a drug delivery vehicle. Membranes of t he material are characterized in terms of water content and molecular weigh t cut-off, and the presence of hydrophilic and hydrophobic domains investig ated by use of the hydrophobic probe pyrene. The in vitro loading and eluti on of a variety of drugs was assessed using stents coated with the polymer. The rate of a drug's release was shown not to be simply a function of its water solubility, but rather more closely related to the drug oil/water par tition coefficient. This finding was explained in terms of the more hydroph obic drugs partitioning into, and interacting with, the hydrophobic domains of the polymer coating. The suitability of the coated stent as a drug deli very vehicle was assessed in vivo using a radiolabeled analog of one of the more rapidly eluting drugs, angiopeptin. Autoradiography showed that the d rug was released locally to the wall of the stented artery, and could be de tected up to 28 days after implantation. (C) 2001 Kluwer Academic Publisher s.