BACKGROUND:Erythromycin spreads widely in the body with a short period of effective concentrations and has a lot of adverse effects.Therefore,it is necessary to make erythromycin as targeted medicine.OBJECTIVE:To optimize the preparation conditions of erythromycin gelatin microspheres.DESIGN,TIME AND SETTING:An orthogonal controlled test was performed in the Department of Pharmacy,Guangdong Pharmaceutical University from June to December in 2005.MATERIALS:Erythromycin and gelatin.METHODS:According to the emulsion principle,erythromycin dispersed in the gelatin solution.In the process of preparing microspheres,the gelatin solution and oil should form W/O emulsion and then it turned into spheres by solidification.The formation and quality of microspheres were influenced by four factors,namely the concentration of gelatin,dosage of emulsifier,the solidification time and the speed of mixing.The arithmetic mean diameter of microspheres,the drug loading efficiency and the encapsulation efficiency were targets for the survey in this study on the basis of pretests.The best preparation conditions were optimized in accordance with the results of L9 (34) orthogonal tests.The optimized preparation conditions were obtained according to the results of orthogonal tests.MAIN OUTCOME MEASURES:The mean diameter of microspheres,the drug loading efficiency,the encapsulation efficiency,and the orthogonal tests were examined.RESULTS:The optimized preparation conditions of erythromycin gelatin microspheres included 15% gelatin,3.0 mL emulsifier,0.5 hour solidification and mixing at 1 000 r/rain.The erythromycin gelatin microspheres were regular in their morphology.Drug was enveloped in microspheres.The average particle size was (14.15±0.20) μm;the drug loading efficiency and the encapsulation efficiency were (5.83±0.38)% and (65.70±0.56)%,respectively.Over 90.16% of the microspheres was in the range of 7-25 μm;The reappearance of pharmaceutical technology was good.CONCLUSION:The optimized preparation conditions of erythromycin gelatin microspheres are obtained using L9 (34)orthogonal tests.The microspheres prepared meet the requirement of the size for lung targeting.