PH-DEPENDENT CELLULOSIC MICROSPHERES CONTAINING CEFUROXIME AXETIL - STABILITY AND IN-VITRO RELEASE BEHAVIOR

Cefuroxime axetil (CA) was encapsulated in pH-dependent cellulosic mic rospheres with the final aim of masking taste while assuring its relea se into the intestinal cavity. The polymers selected were: CAT (cellul ose acetate trimellitate) and two types of hydroxypropylmethylcellulos e phthalate, HPMCP-55 and HPMCP-50. The CA-loaded CAT and HPMCP-55 mic rospheres were obtained by a solvent extraction procedure, whereas the encapsulation of CA into HPMCP-50 microspheres was only achieved by a solvent evaporation technique. All the formulations displayed pH-depe ndent release profiles, releasing their total content in 30 min when e xposed to an aqueous medium of pH 6.0. Analysis of the encapsulated mo lecule by HPLC revealed that a problem of compatibility arises between CA and CAT, lending to the formulation of a high amount of CA impurit ies. By contrast, a minimum amount of impurities was detected upon enc apsulation of CA within HPMCP, this amount being lower for HPMCP-55 th an for HPMCP-50. Finally, the taste-masking test carried out for the f ormulation made of HPMCP-55 evidenced the efficacy of the polymer coat ing in preventing the release of CA in an acidic medium and thus maski ng its taste.