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

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• 作者：Daniela A. Quinteros ; Veró ; nica Ramirez Rigo ; Alvaro F. Jimenez Kairuz ; Marí ; a E. Olivera ; Ruben H. Manzo ; Daniel A. Allem ; i
• 关键词：Polyelectrolytes ; Complexation ; Diffusion ; Controlled release/delivery
• 刊名：European Journal of Pharmaceutical Sciences
• 出版年：2008
• 出版时间：January 2008
• 年：2008
• 卷：33
• 期：1
• 页码：72-79
• 全文大小：495 K

文摘

The interaction between a cationic polymethacrylate (Eudragit^® E, EU) and a set of 7 drugs having acid groups (AH) was studied. Two series of complexes were prepared (EU–AH₅₀ and EU–AH₅₀Cl₅₀), in both 50 % of the basic groups of EU were neutralized with AH but in the second, the remaining groups were further neutralized with HCl. These products were stable solid ionic complexes that were characterized through infrared spectroscopy and X-ray power diffraction. All EU–AH₅₀Cl₅₀ at 5–10 mg/ml produced clear optically isotropic aqueous dispersions. This result was in line with the increase of the apparent solubility of the low solubility 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 counterion condensation, as well as the affinity between EU and AH, was evaluated through the proton withdrawing effect produced by the ionic exchange generated by titration with NaCl. Besides, drug delivery in bicompartimental Franz cells towards water as receptor medium was very slow. However, it was increased as water was replaced by NaCl solution that upon diffusion generates ionic exchange. Therefore, the EU–AH system behaves as a reservoir of drug able to deliver it in simulated biological fluid.