Free radicals that are formed during gamma sterilization can initiate chemical modification of the materials used in polymeric matrix of implants. It was reported that POE III polymer degradation was induced by gamma irradiation [46]. The choice of a sterilization method should be done carefully to preserve the integrity of the implants as well as attain satisfactory sterility

assurance level. 3.3. Level of Surgical Procedure Required for Implantation A major challenge in ocular drug delivery to the posterior segment is the multiple layers of protective blood-ocular barriers that Inhibitors,research,lifescience,medical limit drug access to intraocular tissues [76]. As most vision impairing diseases are associated with the posterior eye segment, the administration of drug is becoming even more challenging [30]. The difficulty in obtaining effective therapeutic concentration of drugs using conventional methods has led to the exploration of numerous sustained-release glaucoma drug delivery systems. Some of these systems are still in the investigational phase, Inhibitors,research,lifescience,medical being tested in Go 6983 price preclinical models and Inhibitors,research,lifescience,medical others are approaching clinical study.

The level of surgical procedure involved in securing the implant at the intended site will play an important role in defining the safety and acceptability of the device. Intraocular methods such as intravitreal administration involving direct injection through the pars plana is the direct delivery route to posterior eye segment because it provides high drug concentrations at the vitreous

and minimizes adverse systemic effects [57]. Due to the Inhibitors,research,lifescience,medical invasive nature of administration, it is important to develop implants using drug reservoir to provide extended drug delivery over long duration to minimize frequent dosage. Further, repeated administration via this route could lead to ocular complications such as retinal detachment, vitreous hemorrhage, irritation, and infection Inhibitors,research,lifescience,medical at the implantation site [9, 77]. Hence, even though intravitreal implants are effective for targeted therapy with increased ocular bioavailability, the invasive procedures that are required to secure the implants at the target site and the subsequent surgery to retrieve the device in the event of any complications Oxygenase will create major liabilities in clinical settings. The primary criterion of all is getting patients to tolerate the mode of administration of implantable delivery. Thus there is a growing need to investigate patient friendly delivery routes to eliminate discomfort and side effects resulting from the method of delivery to overcome the fundamental problem of patient adherence. More recently periocular pathways such as subconjunctival, peribulbar, retrobulbar, and subtenon routes are being considered for drug administration to the vitreous cavity by crossing the sclera, choroid, and RPE barriers [76, 78].