Development of a microencapsulated form of cefuroxime axetil using pH-sensitive acrylic polymers

Cefuroxime axetil (CA) was encapsulated in pH-sensitive acrylic microspheres in order to formulate a suspension dosage form. Using this microencapsulated form it was expected to prevent leaching of the drug from the microspheres into the suspension medium and to assure the release of the drug in the first part of the intestine, thus avoiding changes to its bioavailability. For this purpose, CA was microencapsulated within several types of acrylic polymers by the solvent evaporation and the solvent extraction techniques. The acrylic polymers selected were: Eudragit E (positively charged and soluble at pH 5), Eudragit L-55 (negatively charged and soluble at pH > 5.5) and Eudragit RL (neutral, insoluble, but readily permeable). The influence of the polymer electrical charge on the stability and in vitro release of CA was investigated. Though Eudragit E microspheres presented good morphological characteristics and dissolution behaviour, the analysis of the stability of CA in the presence of Eudragit E by HPLC, indicated a negative interaction between both compounds. However, formulations made of Eudragit L-55 and RL in the ratios 100:0 and 90:10 were adequate in terms of the stability of the encapsulated CA. The dissolution studies showed a critical pH between 5.2 and 6.0, which allowed the complete release of CA in a short period. Furthermore, these polymer microspheres were shown to be efficient in masking the taste of CA.