New frontiers in cardiology: drug-eluting stents: Part II.

Abstract

In this second part of the article, we will complete the review of drug-eluting stent technologies (Table 1) and discuss methodological and technical aspects of drug-eluting stents. View this table: TABLE 1. Drug-Eluting Stent Platforms Under Investigation ### Biological Agents (Continued) #### (1) Stents Eluting Antiproliferative Agents A number of antineoplastic medications have been considered for the prevention of restenosis. Paclitaxel and its derivatives have been the most investigated compounds of this group. ##### (a) Paclitaxel-Eluting Stents Paclitaxel (Taxol; Bristol-Myers Squibb) is a microtubule-stabilizing agent with potent antitumor activity.1 Many different platforms that use polymer coating or surface modifications to adhere paclitaxel onto the stents have been utilized over the past 2 years. ###### Preclinical Data Unlike other antimitotic agents, paclitaxel shifts the cytoskeleton equilibrium toward assembly, leading to reduced vascular cell proliferation, migration, and signal transduction.2 Paclitaxel is highly lipophilic, resulting in a rapid cellular uptake and a long-lasting effect in the cell.3 NIR stents (Boston Scientific Corp) coated with poly(lactide-co-Σ-caprolactone) copolymer and paclitaxel (200 μg/stent) were placed in porcine coronary arteries. Paclitaxel-eluting stents showed a marked reduction in neointimal and medial cell proliferation at all time points (7, 28, 56, and 180 days).4 However, arteries treated with paclitaxel showed incomplete healing, late persistence of a large number of macrophages, and fibrin deposition. Similar findings were observed with a stent platform coated with cross-linked biodegradable polymer (chondroitin sulfate and gelatin) and 42.0, 20.2, 8.6, or 1.5 μg of paclitaxel in rabbit iliac arteries.5 These studies indicate the need for a more controlled drug release of paclitaxel due to the narrow toxic-therapeutic window and high hydrophobic character of this compound. ###### Clinical Data: De Novo Lesions The QuaDS drug-eluting stent (Quanam Medical Corp) was the first drug-eluting stent implanted in human coronary arteries. This slotted tube stent has 50% of its surface area covered by multiple nonbiodegradable polyacrylate sleeves that release 7-hexanoyltaxol (called QP2 or taxane). Approximately 800 μg of the …