Novel Design of Microreservoir-Dispersed Matrices for Drug Delivery Formulations: Drug Release from Polybutadiene- and Poly (ethylene oxide)-Based Segmented Polyurethanes in Relation to Their Microdomain Structures

Abstract

Drug release from monolithic devices of segmented polyether-poly- (urethane-urea) (PEUU)s based on 1,2-polybutadiene (PBD) and poly(ethylene oxide) (PEO) as their soft segments was examined in relation to their micro domain structures. Physical characterization of these PEUU films was carried out in terms of their thermal properties, dynamic mechanical properties, and water structure in water swollen PEUU films. These results reveal that the ter nary microdomain structures are composed of PBD, PEO, and hard segments. The drug release profiles of these PEUU devices are strongly affected by the physicochemical nature of soft segment matrices in PEUUs. The PEUUs with high PEO content exhibited slow and steady (zero-ordered) release of drug in contrast with those with low PEO content from which drug release was en tirely restricted. This result indicates the importance of a matrix to perform the function not only as a drug reservoir but also a transport channel. The solu bility parameters of both constituent segments and the drug must be realized for regulated drug release from microdomain-structured polymeric devices.