title: An assessment of the interactions between diclofenac sodium and ammonio methacrylate copolymer using thermal analysis and Raman spectroscopy.
abstract: The objective of the work was to assess the possible interactions between the model drug diclofenac sodium (DS) and the water-insoluble ammonio methacrylate copolymer (AMC). Films with different drug/polymer ratios were therefore prepared by the solvent casting method and investigated as a preformulation study towards sustained release microparticles. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to investigate the dispersed/dissolved state of the DS in the preparation, the thermal stability and the properties of DS-containing AMC films; and Raman spectroscopy was used to confirm the possible interactions between DS and AMC. Thermoanalytical studies confirmed that the DS could behave as a plasticizer, which was indicated by decreasing glass transition temperature (Tg) of the AMC, depending on its dispersity level in the AMC matrix. Partially solid solutions were formed at DS/AMC ratios of 1:12, 1:8 and 1:6. The DS was mainly crystalline at DS/AMC ratio of 1:4, while it remained crystalline at a ratio of 1:2. The Raman spectra confirmed that none of the major structural changes revealed any significant difference, which can indicate a strong ionic interaction between the DS and the AMC. The investigations provided good facilities for the selection of a DS/AMC ratio, in the preformulation study of the microsphere preparation process, in conformity with the therapeutic aim.
authors.affiliation: Department of Pharmaceutical Technology, University of Szeged, Eötvös str. 6, H-6720 Szeged, Hungary.
authors.forename: Péter
authors.initials: P
authors.lastname: Sipos
authors.forename: Mária
authors.initials: M
authors.lastname: Szucs
authors.forename: András
authors.initials: A
authors.lastname: Szabó
authors.forename: István
authors.initials: I
authors.lastname: Eros
authors.forename: Piroska
authors.initials: P
authors.lastname: Szabó-Révész
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D004008:Diclofenac / Q000737:chemistry*; D008689:Methacrylates / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D008689:Methacrylates; D011108:Polymers; D004008:Diclofenac