RESUMEN
Objective:To study the effect of molecular weight and degree of substitution (DS) of chitosan-poly-arginine (CS-R9) on transdermal penetration enhancement in vitro. Methods:Low molecular CS, medium molecular CS or high molecular CS was respectively used to synthesize CS-R9 with different molecular weight (LCS-R9-1, MCS-R9 and HCS-R9). Low molecular CS was used to synthesize CS-R9 with various degree of substitution by changing the mole ratio between R9 and CS (LCS-R9-1, LCS-R9-2 and LCS-R9-3). The in vitro transdermal penetration enhancement of the different CS-R9 on tinidazole ( TNZ) was studied using Franz diffusion cells. Results:According to the results of FTIR and 1 H-NMR, a series of target CS-R9 were synthesized including LCS-R9-1 with the DS of 2. 30, MCS-R9 with the DS of 2. 17, HCS-R9 with the DS of 2. 20, LCS-R9-2 with the DS of 8. 05 and LCS-R9-3 with the DS of 15. 87. Compared with the blank control group, Azone group, LCS group, R9 group and LCS+R9 group, LCS-R9-1 could enhance the in vitro transdermal penetration of TNZ significantly (P0. 05). When the molecular weight of CS was unchanged, the effect was increased with the rise of DS in the first 21h, however, after that, the effect was decreased with the rise of DS. Conclusion:Molecular weight and DS both have significant effect on the in vitro transdermal penetration enhancement of CS-R9, and it is valuable to further study the in vivo transdermal penetration enhancement of CS-R9 and underlying mechanisms.