INTERACTION BETWEEN EUDRAGIT E100 AND DEXAMETHASONE PHOSPHATE

GUZMÁN, MA LAURA; MANZO RUBEN HILARIO; MARIA EUGENIA OLIVERA

Ciudad de Tandil, Buenos Aires

Congreso; Cuadragésima Reunión Anual S. A. F. E. ASOCIACION ARGENTINA DE FARMACOLOGIA EXPERIMENTAL; 2008

ASOCIACION ARGENTINA DE FARMACOLOGIA EXPERIMENTAL

The aim was to study the interaction between the components of a complex formed by a cationic methylmetacrylate polymer (Eudragit E100) and dexamethasone phosphate (DmP). Solid dispersions at various drug-to-polymer weight ratios were prepared by a wet granulation method. Similarly, DmP-loaded hydrogels with the same composition were prepared and characterized. Variable amounts of HCl were used to increase aqueous compatibility. The complexes were studied in solid state (PRXD, DSC, FTIR, solubility) as well as in dispersion (release in Franz cells, NaCl titration) to establish affinity and type of interactions. No residues of crystalline DmP are present in the solids. The phosphate groups of DmP are ionicaly linked to the dimethylamine groups of Eudragit E100, and showed high affinity. The dispersions are clear and allow obtaining concentrations of DmP far above its solubility with final pHs 2-6. They show slow and prolonged release (zero order kinetics) in vitro upon contact with physiologic simulated fluid. The interaction between Eudragit E100 and phosphate groups is stronger than that observed in systems whose acidic moieties were carboxilic acids. From the in vitro studies, the systems are interesting for the design of formulations for topic (ophthalmic, skin, oral mucosa) administration. In particular the 12.5-37.5% (DmP): 25-75% Cl- compositions can be designated for further investigation.