title: Characterization of the mechanism of interaction in ibuprofen-Eudragit RL100 coevaporates.
abstract: The present study is a preliminary exploration of the affinity between a carboxylic model drug, the nonsteroidal antiinflammatory agent ibuprofen (IBU) and Eudragit RL100 (RL) polymer. Due to the presence of a variable amount of quaternary ammonium groups in this matrix, physical and chemical interaction with the carboxylic drug can occur, which reinforces its scant mechanical dispersion in the polymer network and can ultimately affect its release profile in vitro and in vivo. To study these aspects, IBU was mixed at increasing weight ratios and in different chemical forms (free acid, sodium salt, and n-butyl ester), to investigate further the role of the carboxylic group in the interaction with the RL polymer. Therefore, IBU-RL solid dispersions (coevaporates) were obtained and fully characterized in the solid state through spectroscopic, calorimetric, and x-ray diffractometric analyses. The in vitro release pattern of the drug, in the different chemical states, was studied for the coevaporates, compared with drug-RL physical mixtures, along with drug adsorption profiles from aqueous solutions on the surface of the polymer granules.
authors.affiliation: Dipartimento di Scienze Farmaceutiche, Università degli Studi di Catania, Catania, Italy. r.pignatello@unict.it
authors.forename: Rosario
authors.initials: R
authors.lastname: Pignatello
authors.forename: Daniela
authors.initials: D
authors.lastname: Spadaro
authors.forename: Maria Angela
authors.initials: MA
authors.lastname: Vandelli
authors.forename: Flavio
authors.initials: F
authors.lastname: Forni
authors.forename: Giovanni
authors.initials: G
authors.lastname: Puglisi
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000335:Aerosol Propellants / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D002626:Chemistry, Pharmaceutical; D002627:Chemistry, Physical; D004339:Drug Compounding; D004344:Drug Incompatibility; D005079:Excipients / Q000737:chemistry*; D007052:Ibuprofen / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013997:Time Factors; D014961:X-Ray Diffraction
chemical_list: D000180:Acrylic Resins; D000335:Aerosol Propellants; D005079:Excipients; C050528:Eudragit RS; D007052:Ibuprofen