Gamma sterilization of diclofenac sodium loaded- N-trimethyl chitosan nanoparticles for ophthalmic use.

This study was conducted to investigate the effect of gamma irradiation on physicochemical properties of N-trimethyl chitosan (TMC), diclofenac sodium (DC) and diclofenac sodium loaded N-trimethylchitosan nanoparticles (DC-TMCNs), and to determine suitable doses of gamma rays for sterilization of DC-TMCNs. Physicochemical properties of TMC, DC and DC-TMCNs before and after exposure to gamma rays at various doses were investigated. It was found that gamma irradiation at doses of 5-25kGy did not cause any significant changes in physical and chemical properties of TMC, DC and DC-TMCNs. The bioburden of DC-TMCNs was 1.5×106 CFU/vial. The initial contaminating bacteria were radiosensitive bacteria. A number of microorganisms was reduced to 10-6 after exposure to 9.9kGy of gamma rays. Therefore, DC-TMCNs could be sterilized by gamma irradiation at a dose of 10kGy, which did not alter their physicochemical properties and did not produce any substances toxic to the eye.