In vitro and in vivo evaluation of diclofenac sodium loaded albumin microspheres

The use of polymeric carriers in formulations of therapeutic drug delivery systems has gained widespread application, due to their advantage of being biodegradable and biocompatible. Among the microparticulate systems, micros pheres have a special importance since it is possible to target drugs and p rovide controlled release. Diclofenac sodium (DS), is a potent drug in the NSAID group having non-steroidal, anti-inflammatory properties, and is wide ly used in the treatment of rheumatoid arthritis, osteoarthritis and ankylo sing spondylitis. In this present study, it was aimed to prepare microspher e formulations of DS using a natural biodegradable polymer as a carrier for intraarticular administration to extend the duration period of the dosage form in the knee joint. Microsphere formulations of DS which were prepared were evaluated in vitro for particle size, yield value, encapsulation effic iency, surface morphology, and in vitro drug release. Two appropriate formu lations were selected for in vivo trials. For the in vivo studies, Techneti um-99m labelled polyclonal human immunogammaglobulin (Tc-99m-HIG) was used as the radiopharmaceutical to demonstrate arthritic lesions by gamma scinti graphy. After the induction of arthritis in knee joints of rabbits, the rad io-labelled microspheres loaded with DS were injected directly into the art icular cavity and at specific time points gamma scintigrams were obtained t o find the residence time of the microspheres in knee joints in order to de termine the most suitable formulation.