title: Control of vitamin B12 release from poly(ethylene glycol)/poly(butylene terephthalate) multiblock copolymers.
abstract: The release of vitamin B12 (1355 Da) from matrices based on multiblock copolymers was studied. The copolymers were composed of hydrophilic poly(ethylene glycol)-terephthalate (PEGT) blocks and hydrophobic poly(butylene terephthalate) (PBT) blocks. Vitamin B12 loaded films were prepared by using a water-in-oil emulsion method. The copolymer properties, like permeability, could be varied by increasing the PEG-segment length from 300 up to 4,000 g/mol and by changing the wt% of PEGT. From permeation and release experiments. the diffusion coefficient of vitamin B12 through PEGT/PBT films of different compositions was determined. The diffusion coefficient of Vitamin B12 was strongly dependent on the composition of the copolymers. Although an increased wt% of PEGT (at a constant PEG-segment length) resulted in a higher diffusion coefficient, a major effect was observed at increasing PEG-segment length. By varying the copolymer composition, a complete release of vitamin B12 in 1 day up to a constant release for over 12 weeks was obtained. The release rate could be effectively tailored by blending copolymers with different PEG-segment lengths. The swelling and the crystallinity of the matrix could explain the effect of the matrix composition on the release behavior.
authors.affiliation: IsoTis NV, Bilthoven, The Netherlands. riemke.van.dijkhuizen@isotis.com
authors.forename: R
authors.initials: R
authors.lastname: van Dijkhuizen-Radersma
authors.forename: F L A M A
authors.initials: FL
authors.lastname: Péters
authors.forename: N A
authors.initials: NA
authors.lastname: Stienstra
authors.forename: D W
authors.initials: DW
authors.lastname: Grijpma
authors.forename: J
authors.initials: J
authors.lastname: Feijen
authors.forename: K
authors.initials: K
authors.lastname: de Groot
authors.forename: J M
authors.initials: JM
authors.lastname: Bezemer
mesh_terms: D001672:Biocompatible Materials; D009682:Magnetic Resonance Spectroscopy; D008962:Models, Theoretical; D011091:Polyesters / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D013997:Time Factors; D014805:Vitamin B 12 / Q000737:chemistry* / Q000493:pharmacokinetics*
chemical_list: D001672:Biocompatible Materials; D011091:Polyesters; D011108:Polymers; C041733:poly(1,4-butylene terephthalate); D011092:Polyethylene Glycols; D014805:Vitamin B 12