Interaction between a cationic polymethacrylate (Eudragit E100) and anionic drugs

DANIELA A. QUINTEROS; VERÓNICA RAMIREZ RIGO; ALVARO F. JIMENEZ KAIRUZ; MARÍA E. OLIVERA; RUBEN H. MANZO; DANIEL A. ALLEMANDI

EUROPEAN JOURNAL OF PHARMACEUTICAL SCIENCES

Año: 2008 vol. 1 p. 72 - 72

0928-0987

he interaction between a cationic polymethacrylate (Eudragit® E, EU) and a set of 7 drugshaving acid groups (AH) was studied. Two series of complexes were prepared (EU?AH50 andEU?AH50Cl50), in both 50% of the basic groups of EU were neutralized with AH but in thesecond, the remaining groups were further neutralized with HCl. These products were stablesolid ionic complexes that were characterized through infrared spectroscopy and X-raypower diffraction. All EU?AH50Cl50 at 5?10 mg/ml produced clear optically isotropic aqueousdispersions. This result was in line with the increase of the apparent solubility of the lowsolubility AH assayed. The species distribution, as determined on the complex of diclofenac,showed a degree of counterion condensation as high as 97.9%. The reversibility of the counterioncondensation, as well as the affinity between EU and AH, was evaluated through theproton withdrawing effect produced by the ionic