Polymer-free paclitaxel-coated zilver PTX stentsevaluation of pharmacokinetics and comparative safety in porcine arteries

Purpose: To evaluate the pharmacokinetics and safety of the Zilver PTX Drug-Eluting Stent (Cook Medical, Bloomington, Indiana) in a normal porcine artery model. Materials and Methods: Pharmacokinetic analyses were performed using 18 pigs, each implanted with four paclitaxel-coated stents. Paclitaxel remaining on the stents, delivered locally (to artery wall), regionally (to adjacent and downstream muscle), and systemically (to plasma), was determined at various times through 56 days. For safety evaluation, local, regional, and systemic responses were grossly and histologically assessed at 1 month, 3 months, and 6 months in 21 additional pigs and compared with the responses to bare metal stents in 21 separate pigs. Results: Stents delivered approximately 95% of the total paclitaxel within 24 hours after deployment. Nonetheless, there were sustained paclitaxel levels in the artery wall through 56 days, maintained at approximately 20% of the peak level through 14 days. Very little paclitaxel was distributed regionally or systemically, becoming undetectable in plasma at 10 hours. Complete necropsy, hematology, and serum chemistry revealed no adverse effects associated with the paclitaxel-coated stents. Within 3 months, vessels with both paclitaxel-coated and bare metal stents showed comparable, complete healing. Conclusions: The Zilver PTX stent appears to be safe, achieves sustained paclitaxel levels in the artery wall, and shows complete vessel healing comparable to bare metal stents within 3 months.