title: A Mechanistic Model for Acidic Drug Release Using Microspheres Made of PLGA 50:50.
abstract: Polyester microspheres are extensively studied for controlled release drug delivery devices, and many models have been developed to describe drug release from the bulk polymer. However, the interaction between drugs and polymers is ignored in most of the existing mathematical models. This paper presents a mechanistic model which captures the interplay between acidic drugs and bioresorbable polyesters. The model considers the autocatalytic effect on polymer degradation arising from carboxylic acid end groups of oligomers and drug molecules. Hence, the enhancing effect of acidic drug on the rate of degradation was fully considered. On the other hand the drug release from polyester microspheres is controlled by drug diffusion from polymer matrix. The drug diffusion coefficient depends strongly on the level of degradation of the polymer. This effect is also included in the model. It is shown that the model can effectively predict experimental data in the literature for both polymer degradation and drug release. Furthermore, the model is used to design different systems of microspheres which release drugs with either a zero order profile or burst followed by zero order release profile.
authors.affiliation: Department of Engineering, University of Leicester , Leicester LE1 7RH, U.K.
authors.forename: Kevser
authors.initials: K
authors.lastname: Sevim
authors.affiliation: Department of Engineering, University of Leicester , Leicester LE1 7RH, U.K.
authors.forename: Jingzhe
authors.initials: J
authors.lastname: Pan
mesh_terms: D002264:Carboxylic Acids / Q000737:chemistry; D003692:Delayed-Action Preparations; D016503:Drug Delivery Systems; D065546:Drug Liberation; D019344:Lactic Acid / Q000737:chemistry*; D008863:Microspheres; D008962:Models, Theoretical; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry*
chemical_list: D002264:Carboxylic Acids; D003692:Delayed-Action Preparations; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid
keywords: acidic drugs; biodegradable polymers; controlled release; microspheres; modeling; zero-order release