ABSTRACT
Background Drug delivery systems that can precisely control drug release rates or target drugs to a specific body site have had an enormous medical and economic impact (1). The controlledrelease drug delivery market is expanding rapidly, paralleled by active and aggressive research in the field (2). Conceptually, the ideal controlled drug delivery (CDD) system should fulfill two prerequisites: First, to deliver the drug at a rate dictated by the needs of the body over a period of treatment and second, to achieve spatial targeting to specific sites (3). A number of technological advancements with regard to regulating the rate of drug delivery, sustaining the duration of therapeutic action, and/or targeting the drug to a specific site or tissue have been made over recent years. The ability of CDD systems to release the drug in an amount sufficient to maintain the therapeutic levels over an extended time period provides significant improvements over traditional pharmaceutical formulations, such as tablets, capsules, or intravenous injections (4,5), as shown in Figure 1. The use of drug-eluting stents (DES)—now hailed as the pioneering technology in the interventional cardiology community-was the first successful application of CDD principles for the localized delivery of pharmacologic agents in the management of coronary artery disease.
