Study On Preparation And Performance Of Ultra-Fined Cephalsporins

As the first generation cephalosporin, both cefalexin and cephradine belong to quick result anti-bacterial drugs and widely used in clinic. The two kinds of drugs have the similar structure, physical and chemical properties, and are poorly water soluble. In order to improve their bioavailabilities, one of the effective methods is to prepare ultra-fined drugs, thereby increasing the BET surface area and the dissolution rate.Based on our previous research work of ultra-fined cephrdine, ultra-fined powder of cefalexin was produced by combining reactive precipitation and liquid anti-solvent precipitation. The results showed that the silk-like particles with a size of about200nm in a short diameter and a length of5μm could be obtained in a water-acetone system. The optimal condition was as followed: the volume ratio of water to acetone=1:4, concentration of cefalexin solution of0.1g/ml, temperature of50℃, stirring time of10min, stirring rate of1000pm, and drying in rotary evaporator.Furthermore, the performances of ultrafine cefalexin and cephradine were investigated. The contents of ultra-fined cefalexin and cephradine were examined by HPLC. The stability, dissolution rate and antibacterial activities of drug were also studied. The results indicated that the ultra-fined cefalexin and cephradine particles showed good stability in the environment of extreme humidity test and at60℃and40℃, respectively. The contents of cefalexin and cephradine declined to different extents after accelerated test. In addition, the dissolution rates of ultra-fined cefalexin and cephradine slightly increased when compared to those of the crude drugs. Their antibacterial activities did not decrease after micronization process.Finally, ultra-fined cefalexin for oral suspension was also studied. And the prescription dose was determined. The rheology test showed that this suspension was pseudoplastic fluid and had a good fluidity.