In vitro and in vivo characterization of scleral implants of indomethacin.

Scleral implants of indomethacin with sodium alginate as carrier were fabricated and evaluated for various physico-chemical properties such as uniformity of thickness, weight, drug content, surface pH, percent dissolution and water up-take capacity (swelling index). The effect of drug particle size, polymer concentration, drug loading, plasticizer concentration, and effects of physical reinforcement (freeze-thawing for 3 and 6 cycles) and chemical cross-linking with calcium chloride, on the in vitro drug release characteristics were evaluated. Selected batches of the implants were subjected to pharmacodynamic studies, after scleral placement, in uveitis induced (intravitreal injection of Bovine Serum Albumin (BSA)-50 micrograms/ml) rabbit eyes. The release of indomethacin from the prepared implants followed predominantly matrix diffusion kinetics. Swelling and moisture absorption/loss studies correlated well with the in vitro release studies. The pharmacodynamic studies showed a marked improvement in the various clinical parameters (congestion, keratitis, flare, clot, aqueous cells and synechias), in the implanted eye when compared to the control eye in the rabbits.