Combined drug release from biodegradable bilayer coating for endovascular stents.

Abstract

In this work, the characterization of a biodegradable bilayer system, used as controlled and combined drug delivery platform, is reported. For this aim, a bilayer system, composed of poly(lactic-co-glycolic acid) and poly(3-hydroxybutyric-co-3-hydroxyvaleric acid), was investigated under physicochemical and functional aspects by evaluating polymer/polymer and polymer/stent material interactions, the kinetic of in vitro degradation, and drug release properties, comparing results with the monolayer reference systems. Obtained results showed that the bilayer system allowed increasing the total amount of eluted Tacrolimus and Paclitaxel drugs with respect to the monolayer systems in the considered testing period and conditions. This evidence was associated to a faster degradation of the tested copolymers in the bilayered configuration, excluding a synergic effect of two drugs on delivery performance. In addition, a macromolecular relaxation process was identified to govern the PLX release from poly(lactic-co-glycolic acid), whereas a pure Fickian diffusion occurred in the delivery of Tacrolimus from poly(3-hydroxybutyric-co-3-hydroxyvaleric acid).