title: Controlled release of sirolimus from a multilayered PLGA stent matrix.
abstract: The release of sirolimus from a bi-layer biodegradable polymeric film is reported in this study. Approved drug-eluting metal stents use a thin polymer coating to control drug release, but the degree of control is limited. In a fully polymeric stent, the use of multilayers allows a range of release kinetics. A bi-layer system, with PLLA as the supporting layer and PLGA as the drug-eluting layer, was used in this study to simulate release of sirolimus from a stent. The results show that the release of sirolimus is diffusion and degradation-controlled, and that the amount of sirolimus loading does not affect its release kinetics. The release of sirolimus is, however, accelerated by the addition of a plasticizer, such as PEG, as water uptake is increased. An increased water uptake increases polymer degradation, and changes the dominant mode of release to degradation-control. The release of sirolimus can, on the other hand, be retarded by using a coating of a biodegradable polyester with a lauryl ester end group. Therefore, multilayered systems offer many options for controlling sirolimus release over months.
authors.affiliation: School of Materials Science & Engineering, Nanyang Technological University, Singapore, Singapore.
authors.forename: Xintong
authors.initials: X
authors.lastname: Wang
authors.forename: Subbu S
authors.initials: SS
authors.lastname: Venkatraman
authors.forename: Freddy Y C
authors.initials: FY
authors.lastname: Boey
authors.forename: Joachim S C
authors.initials: JS
authors.lastname: Loo
authors.forename: Lay Poh
authors.initials: LP
authors.lastname: Tan
mesh_terms: D003692:Delayed-Action Preparations; D004058:Diffusion; D007700:Kinetics; D019344:Lactic Acid / Q000737:chemistry*; D015394:Molecular Structure; D008970:Molecular Weight; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry*; D020123:Sirolimus / Q000008:administration & dosage / Q000737:chemistry; D015607:Stents
chemical_list: D003692:Delayed-Action Preparations; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D020123:Sirolimus