RESUMEN
Objective To establish a microbial limit test for levofloxacin hydrochloride gel. Methods Ca2+ was added to neutralize the antibacterial activity of quinolone,and to form the insoluble precipitate by binding with carbomer, therefore destroying the stability of macromolecules in the gel. The microbial limit test for levofloxacin hydrochloride gel was confirmed combining with membrane filtration and plate methods. Results The normal plate counting was used in detecting the mold and yeast colony in the gel, the recovery was more than 70%.Simultaneously neutralization centrifugation and membrane filtration were used in bacterial count,with recovery less than 70%,and controlling bacteria test. Conclusion The method is accurate and practical for microbial limit test of levofloxacin hydrochloride gel, but is risky for bacterial counting and needs further risk assessment.