ABSTRACT
Implant surfaces are coated with drugs for several reasons. These agents can be permanently bonded to an implant (e.g. covalent like heparin or temporary like rapamycin for coronary stents). However, covalent fixed coatings only allow the action of biological processes very close to the implant surface, and a drug carrier from the implant surface to specific cell sites is frequently required. In order to fulfill the need for optimal drug delivery, several important issues need to be considered.
