Microparticle systems based on polymer-drug interaction for ocular delivery of ciprofloxacin II. Precorneal residence times

Ionic interaction between ciprofloxacin (CPX) and chondroitin sulphate (CS) results in a microparticulate controlled release system (CPX/CS) from which the drug is released after being displaced by the medium’s ions. The objective of this research was to evaluate the mucoadhesion and precorneal residence time of CPX/CS both alone and when coadministered with 0.25 and 0.5% w/v solutions of well-known mucoadhesive polymers such as carbomer, hydroxypropylcellulose and hyaluronic acid. Low and high molecular weight chitosan was also coadministered using a low polymer concentration (0.05% w/v) and then and cross-linked with glutaraldheyde. The results indicate an improvement of ex vivo mucoadhesion with all of the tested formulations. CPX profiles in rabbit tear fluid seemed to depend on mucoadhesion, as well as cohesion and sample spreading. The highest values of elimination half life (14.46 min) and mean residence time (19.94 min) were obtained with carbomer 0.5% w/v. In spite of low polymer concentration, good ex vivo mucoadhesion and in vivo precorneal residence time results were also obtained with chitosan coadministration, which may be due to the polymer’s strong interaction with the CPX/CS microparticles.