title: Characterization and in vitro degradation of salicylate-derived poly(anhydride-ester microspheres).
abstract: The aim of this study was to investigate how glass transition temperature (Tg) influenced polymer microsphere formation and degradation of three chemically, similar novel salicylatebased poly(anhydride-esters): poly[1,6-bis(o-carboxyphenoxy)hexanoate] (CPH), Tg = 59 degrees C; poly[1,8-bis(o-carboxyphenoxy)octanoate] (CPO), Tg = 30 degrees C; and poly[1,10-bis(ocarboxyphenoxy) decanoate] (CPD), Tg = 27 degrees C. Microspheres of these polymers were prepared using a modified oil-in-water solvent evaporation method and processed by either resuspension or washed by centrifugation. The morphology of the microspheres determined by scanning electron microscopy (SEM) revealed that an extra washing step appears to increase aggregation as the Tg decreases; whereas only limited aggregation occurred in the polymer with the lowest Tg, CPD, in those not washed by centrifugation. Residual polyvinyl alcohol apparently affected the drug release rates from the microspheres by a stabilization process that produced an 8 h lag time and a 5% decrease in the amount of drug released over a 7 day period compared to microspheres washed free of PVA. These results demonstrate that salicylate-based poly(anhydride-esters) with sufficiently high Tgs, can be processed into microspheres that release salicylate over a time period amenable for drug delivery applications.
authors.affiliation: Department of Pharmaceutics, The State University of New Jersey, Piscataway, NJ 08854, USA.
authors.forename: Brian A
authors.initials: BA
authors.lastname: Yeagy
authors.forename: Almudena
authors.initials: A
authors.lastname: Prudencio
authors.forename: Robert C
authors.initials: RC
authors.lastname: Schmeltzer
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Uhrich
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Cook
mesh_terms: D000812:Anhydrides / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry*; D001673:Biodegradation, Environmental; D003692:Delayed-Action Preparations / Q000737:chemistry / Q000493:pharmacokinetics; D004952:Esters / Q000737:chemistry; D005898:Glass / Q000737:chemistry; D066298:In Vitro Techniques; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D015394:Molecular Structure; D008970:Molecular Weight; D010316:Particle Size; D044367:Phase Transition; D011108:Polymers / Q000737:chemistry*; D011142:Polyvinyl Alcohol / Q000737:chemistry; D020156:Salicylic Acid / Q000737:chemistry*; D013997:Time Factors; D044366:Transition Temperature; D014867:Water / Q000737:chemistry
chemical_list: D000812:Anhydrides; D001672:Biocompatible Materials; D003692:Delayed-Action Preparations; D004952:Esters; D011108:Polymers; D014867:Water; D011142:Polyvinyl Alcohol; D020156:Salicylic Acid