Drug-eluting silicone hydrogel for therapeutic contact lenses: Impact of sterilization methods on the system...

Although contact lenses are promising platforms for ocular drug delivery and have been extensively studied for that purpose, the influence of sterilization methods on these systems remains barely investigated. In this work, a silicone-based hydrogel was produced and loaded with different ophthalmic drugs: levofloxacin, chlorhexidine, diclofenac and timolol. The drug release profiles, along with several material properties, were evaluated before and after sterilization by three different methods steam heat, γ-irradiation and ozone gas. Independently of the sterilization method used, the results of the swelling and mechanical properties tests strongly indicate the occurrence of specific drug-polymer interactions promoted by the sterilization. In general, these interactions led to a decrease on the amount of drug released. It is shown that γ-irradiation and ozone led to significant degradation of all of the drugs used in this study. Thus, it was concluded that steam heat is the sterilization method with less impact on the devices. More importantly, the present work shows that the development of efficient and functional drug delivery devices for ophthalmic purposes cannot be done independently of a careful analysis of the influence of the sterilization procedures and methods on the degradation of these polymeric systems as a whole.