pH-dependent cellulosic microspheres containing cefuroxime axetil: Stability and in vitro release behavior

Cefuroxime axetil (CA) was encapsulated in pH-dependent cellulosic microspheres with the final aim of masking taste while assuring its release into the intestinal cavity. The polymers selected were: CAT (cellulose acetate trimellitate) and two types of hydroxypropylmethylcellulose phthalate, HPMCP-55 and HPMCP-50. The CA-loaded CAT and HPMCP-55 microspheres 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-dependent release profiles, releasing their total content in 30 min when exposed to an aqueous medium of pH 6.0. Analysis of the encapsulated molecule by HPLC revealed that a problem of compatibility arises between CA and CAT, lending to the formulation of a high amount of CA impurities. By contrast, a minimum amount of impurities was detected upon encapsulation of CA within HPMCP, this amount being lower for HPMCP-55 than for HPMCP-50. Finally, the taste-masking test carried out for the formulation made of HPMCP-55 evidenced the efficacy of the polymer coating in preventing the release of CA in an acidic medium and thus masking its taste.