Dexamethasone eluting biodegradable polymeric matrix coated stent for intravascular drug delivery

Targeted drug delivery systems are used to minimize the adverse effects of the pharmaceutical agents while maintaining the high local drug concentrations. To minimize post-angioplasty complications like tissue hyperplasia and related restenotic events, cardiovascular stents coated with anti-inflammatory, anti-proliferative agents have been proposed. The efficacy and toxicity of local therapeutics depends upon drug release kinetics which will further decide drug deposition, distribution, and retention at the target site. Drug eluting stents (DES) presently possesses clinical importance as an alternative to coronary artery bypass grafting due to ease of procedure and comparable safety and efficacy. This paper focuses on preparation and evaluation of controlled drug release biodegradable systems for stent base drug delivery providing insight of the drug elution mechanism which ultimately governs release kinetics. Multiple layers of dexamethasone-biodegradable polymers were successfully spray coated on Co–Cr alloy L605 metallic stents by modified air brush technique. In vitro drug elution data acquired by high performance liquid chromatography (HPLC) revealed that release of dexamethasone can be modulated up to 3 weeks by optimized use of blends of biodegradable poly-l-lactide-co-caprolactone and polyvinyl pyrrolidone. Surface investigation by scanning electron microscopy (SEM) represented smooth surface finish without any irregularities suggesting the efficacy of utilization of optimal coating parameters for multiple layer coating.