Abstract
A drug delivery system was specifically designed for the treatment of rheumatoid arthritis (RA) by local percutaneous administration and the nano-controlled release of methotrexate (MTX). The release behavior of MTX from the synthesized MTX-mSiO(2)@PDA system was investigated in vitro and in vivo. The obtained results show that after 48 h, twice as much MTX (cumulative amount) is released at pH 5.5 than at pH 7.4. This suggests that the MTX-mSiO(2)@PDA system exhibits a good pH sensitivity. In vitro local percutaneous administration experiments revealed that the cumulative amount of MTX transferred from MTX-mSiO(2)@PDA to pH 5.0 receptor fluid through the whole skin was approximately three times greater than the amount transferred to pH 7.4 receptor fluid after 24 h. Moreover, in vivo experiments conducted on a complete induced arthritis (CIA) model in DBA/1 mice demonstrated that the thickness of a mouse's toes decreases to nearly 65% of the initial level after 27 days of local percutaneous MTX-mSiO(2)@PDA administration. Compared to the mice directly injected with MTX, those administered with MTX-mSiO(2)@PDA by local percutaneous application exhibit much lower toe thickness deviation, which indicates that the latter group experiences a better cure stability. Overall, these results demonstrate that the local percutaneous administration of MTX delivery systems characterized by nano-controlled release may play an important role in RA therapy.