OBJECTIVE:To evaluate the stability of 12 kinds of submicro emulsion in market,and screen the test method for the stability. METHODS:12 kinds of submicro emulsion in market were selected,high pressure sterilization (121 ℃,30 min), high speed centrifugation(4000 r/min,15 min),accelerated test [placing 6 months under temperature of(40±2)℃,relative hu-midity of (75 ± 5)%] were conducted to investigate the pH,particle size and other indexes,and SPSS 22.0 was used to analyze the distribution variance and chi-square test,and investigate the correlation of 3 evaluation methods. RESULTS:In terms of stabili-ty investigation,the pH value of 12 kinds of submicro emulsion decreased to some extent after accelerated test,average particle size of 6 kinds of submicro emulsion samples were greater than 300 nm,the variance of the particle size distribution of 9 kinds ap-peared in 0.05-0.15,the chi-square test results of 8 kinds distributed below 1. The average particle size of 4 kinds of submicro emul-sions changed more than 10 nm after accelerated test. In terms of stability test method,Pearson chi-square progressive significance of high pressure sterilization and accelerated test was 0.665,which was higher than 0.05,indicating there was no correlation (no significance),the stability results of high pressure sterilization can not represent the results of accelerated test;that of high speed centrifugation and accelerated test was 0.004,which was lower than 0.05,indicating stability results between high speed centrifuga-tion and accelerated test results were significantly correlated. CONCLUSIONS:The submicro emulsion in market can meet the re-quirements of stability. To a certain extent,high speed centrifugation can replace the acceleration test.

Efficient mucosal delivery remains a major challenge for the reason of the respiratory tract mucus act as a formidable barrier to nanocarriers by trapping and clearing foreign particulates. The surface property of nanoparticles determines their retention and penetration ability within the respiratory tract mucus. However, the interaction between nanoparticles and mucus, and how these interactions impact distribution has not been extensively investigated. In this study, polymeric nanoparticles loaded with a baicalein-phospholipid complex were modified with two kinds of polymers, mucoadhesive and mucus-penetrative polymer. Systematic investigations on the physicochemical property, mucus penetration, transepithelial transport, and tissue distribution were performed to evaluate the interaction of nanoparticles with the respiratory tract. Both nanoparticles had a similar particle size and good biocompatibility, exhibited a sustained-release profile, but showed a considerable difference in zeta potential. Interestingly, mucus-penetrative nanoparticles exhibited a higher diffusion rate in mucus, deeper penetration across the mucus layer, enhanced cellular uptake, increased drug distribution in airways, and superior local distribution and bioavailability as compared to mucoadhesive nanoparticles. These results indicate the potential of mucus-penetrative nanoparticles in design of a rational delivery system to improve the efficiency of inhaled therapy by promoting mucus penetration and increasing local distribution and bioavailability.