Compound erythromycin sustained release preparation and its in vitro release

Using the weight-average molecular weight 50 000 polylactic acid (PLA) as a carrier, and a certain proportion of erythromycin (EM) and prednisone acetate (PNA) to mixed prepare the compound erythromycin sustained release preparation (sustained-release tablets).  Using ultraviolet spectrophotometry and high performance liquid chromatography (HPLC) to detect separately the release amount of EM and PNA in vitro medium.  The sustained-release tablets release for about 21 days, the average content of EM is 99.7 mg/table, RSD = 0.82%; and the average content of PNA is 10.03 mg/table, RSD = 0.93%.  Within 21 days, the cumulative releases of EM and PNA are 86.1% and 78.3%, respectively.  The drug release is steady and slow after 5 days, the burst release phenomenon in early stage is more significant.  The results showed that the sustained-release tablet preparation method is feasible, the release performance is good and the clinical efficacy is significant.