Drug release modification by interpolymer interaction between countercharged types of Eudragit® RL 30D and FS 30D in double-layer films.

Interpolymer interactions between the countercharged methacrylate copolymers Eudragit(®) RL 30D (polycation) and Eudragit(®) FS 30D (polyanion), were investigated in conditions mimicking the gastrointestinal environment. The formation of inter-macromolecular ionic bonds between Eudragit(®) RL 30D and Eudragit(®) FS 30D was investigated using FT-IR spectroscopy and modulated DSC. The FT-IR spectra of the tested polymeric matrices are characterized by visible changes in the observed IR region indicating the interaction between chains of two oppositely charged copolymers. A new band at 1570 cm(-1) appeared which was assigned to the absorption of the carboxylate groups that form the ionic bonds with the quaternary ammonium groups. Moreover, while increasing the pH values from pH 5.8 to 7.4, a decrease of the intensity of the band at 960 cm(-1) (quaternary ammonium group vibration) was observed. All binary mixtures were characterized by the presence of only one and narrow Tg, pointing to sample homogeneity, because of the compatibility of components. As a result of electrostatic interaction between the copolymer chains during swelling, the resulting Tg is decreased significantly and was dependent on the quantity of copolymers present in the structure of polycomplexes formed. Overall, the interaction between countercharged copolymers during passage in gastrointestinal tract can strongly modify the release profile of the model drug diclofenac sodium.

Structural transformations during swelling of polycomplex matrices based on countercharged (meth)acrylate copolymers (Eudragit EPO/Eudragit L 100-55).

With a view to the application in oral controlled drug delivery systems (DDS), the design of new interpolyelectrolyte complexes (IPECs) between countercharged types of Eudragit EPO (EPO) and Eudragit L 100-55 (L100-55) was investigated. The formation and composition of four new IPECs between EPO and L100-55 were established by elementary analysis. The structure of the synthesized IPEC was investigated using FTIR spectroscopy and modulated-temperature differential scanning calorimetry. The binding ratio of a unit molecule of EPO with L100-55 was found to range between 1:2.75 (Z = 0.36) and 1:0.55 (Z = 1.81) while increasing the pH value from 5.5 to 7.0. As a result of electrostatic interaction between the copolymer chains, the glass transition temperature of the IPEC increased significantly. A large pH-sensitive swelling behavior was observed for different structures of the IPECs. The outcome of swelling and diclofenac sodium release from the polycomplex matrices confirm that they have great potential to be used as a controlled DDS in specified regions of gastrointestinal tract.

Interpolyelectrolyte complexes of Eudragit E PO with sodium alginate as potential carriers for colonic drug delivery: monitoring of structural transformation and composition changes during swellability and release evaluating.

BACKGROUND: With a view to the application in oral colon drug delivery systems, swelling and release behavior of synthesized interpolyelectrolyte complexes (IPEC) between sodium alginate and Eudragit EPO were investigated. METHOD: The microenvironmental changes in IPECs structure as a function of pH during swellability testing were investigated using FT-IR spectroscopy and elementary analysis. RESULTS: All samples of IPECs (Z = 0.66-1.25) during swelling were transformed to a similar structure with approximately the same composition. The release of the model drug diclofenac sodium was significantly delayed from matrices made up of the IPECs and independent from the composition of polycomplexes. CONCLUSION: According to the obtained results, these IPECs can be considered to have potential in colonic drug delivery as combined pH- and time-dependent systems.

Comparative evaluation of interpolyelectrolyte complexes of chitosan with Eudragit L100 and Eudragit L100-55 as potential carriers for oral controlled drug delivery.

With a view to the application in oral controlled drug delivery systems, the formation of interpolyelectrolyte complexes (IPEC) between chitosan (CS) and Eudragit L100 (L100) or Eudragit L100-55 (L100-55) was investigated at pH 6.0, using elementary analysis. The interaction or binding ratio of a unit molecule of CS with Eudragit L copolymers depends on the molecular weight of CS, and changes from 1:0.85 to 1:1.22 (1.17

Physicochemical characterization and drug release properties of Eudragit E PO/Eudragit L 100-55 interpolyelectrolyte complexes.

The formation of interpolyelectrolyte complexes (IPEC) between Eudragit E PO (EE) and Eudragit L 100-55 (EL) was investigated, using turbidimetry, apparent viscosity measurements, elementary analysis and MT-DSC. The structure of the synthesized IPEC was investigated using FT-IR spectroscopy. The binding ratio of a unit molecule of EL with EE was found to be approximately 1:1 at pH 5.5. Based on the results of elementary analysis and FT-IR, the binding ratio of each component in the solid complexes was very close to that observed in turbidity and apparent viscosity measurements and indicate that the synthesized products can be considered as IPEC. As a result of electrostatic interaction between the polymer chains, the glass transition temperature of the IPEC increased significantly. Due to the structure of the IPEC, two maxima were observed in the swelling behavior as a function of pH. The release of the model drug ibuprofen (IBF) was significantly retarded from tablets made up of the IPEC as compared with individual copolymers, its physical mixture and Eudragit RL PO (RL), RS PO (RS).