Albumin microspheres for intra-articular drug delivery: investigation of their retention in normal and arthritic knee joints of rabbits.

The retention of 131I-labelled albumin microspheres and microsphere-entrapped [131I]rose bengal was investigated in normal and experimentally arthritic knee joints of rabbits. Albumin microspheres were cleared slowly from the joint cavity and no significant difference was observed between normal and inflamed joints. Entrapment of rose bengal within albumin microspheres was found to delay the clearance of the drug from the joint when compared with a solution of rose bengal. In addition, the retention time for entrapped rose bengal was dependent on the degree of inflammation present.