European Journal of Biomedical and Pharmaceutical Sciences

STABILIZATION OF PREDNISOLONE IN OPHTHALMIC GELS DURING STERILIZATION BY GAMMA RADIATION

Ahmed A. Bosela*, Kholoud K. Salamah, Ibrahim M. El-Bagory

ABSTRACT

The effect of different types of gel forming polymers, namely Methyl cellulose (MC), Hydroxypropyl methyl cellulose (HPMC), Polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP), on Prednisolone sensitivity to gamma radiation was investigated. At low polymer concentration, irradiation up to 20 KGY resulted in slight protection of the drug. At gel forming concentrations, the drug degradation by radiation was nearly the same as in low polymer so. Moreover, the gel viscosity was considerably decreased by radiation to fluid state in cases of MC and HPMC, while increased in cases of PVA and PVP. The effect of polymer cross-linking on drug stability to radiation was also studied. It was found that 41-49% of initial drug concentration was protected after exposure to 20 KGy of radiation. Also, the maximum polymer concentration which produced the highest cross-linking ratio, while maintaining the gel consistency, was found to be 5%, 4%, 2% and 2% w/w for MC, HPMC, PVA and PVP respectively. Above such concentrations, phase transition to rigid mass was observed. The study also revealed that at high concentration of tween 80 (35%w/w), up to 8%w/w of MC or HPMC and 5%w/w of PVA or PVP could be incorporated in the gels and a significant protective effect was achieved by the four types of polymers. However the highest protective effect was afforded by HPMC.(95%) followed by PVA (93%), MC (90%) and PVP (62%). It can be concluded that the protective effect of the cross-linked polymers was determined by the net result of three factors: the cross-linking ratio; the polymer concentration and the hydrophobicity of the matrix.

Keywords: Prednisolone; gamma radiation; polymeric gels; stability; crosslinking.