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Ocular Drug Delivery Nanosystems: Recent Developments and Future Challenges
Published in Costas Demetzos, Stergios Pispas, Natassa Pippa, Drug Delivery Nanosystems, 2019
Elena A. Mourelatou, Yiannis Sarigiannis, Christos C. Petrou
Regarding the treatment of anterior segment diseases (keratitis, conjunctivitis, dry eye syndrome [DES], etc.), topical administration is the most commonly used route (Fig. 4.1), where formulations such as solutions, suspensions, ointments, and hydrogels are applied [4]. Although this route is characterized by high patient compliance (no pain), low production cost, and easy formulation and production processes, it suffers from low bioavailability, with less than 5% of the administered dose being able to overcome the ocular barriers and reach the target site. This creates the need for repeated administration in order to achieve a therapeutic effect, which leads to poor patient compliance and side effects caused by systemic absorption of the administered drug [5, 6]. On the other hand, the treatment of posterior segment diseases (glaucoma, age-related macular degeneration [AMD], uveitis, diabetic retinopathy [DR], endophthalmitis, diabetic macular edema, etc.) requires more invasive approaches, such as intravitreal, subconjunctival, subtenon, and posterior juxtascleral routes (Fig. 4.1), with the most prevalent being intravitreal injection [5]. The latter, especially when repeated at regular intervals for maintaining the desired drug’s concentration (e.g., for glaucoma treatment), is associated with significant patient discomfort and nonconformance, as well as sight-threatening complications, including a risk of infections, endophthalmitis, retinal tear or detachment, lens damage, and cataract [2, 7]. Reaching the posterior segment through systemic administration (oral and intravenous) is impractical, since the volume of the eye is extremely small compared to the whole body and the presence of blood retinal barriers limits its accessibility [3].
Design of a navigational catheter system for the targeted delivery of therapeutics within the suprachoroidal space
Published in Journal of Medical Engineering & Technology, 2020
Anthony E. Felder, Yannek I. Leiderman, Matthew Tomback, Aaron Chicano, Manuela Burek, Xenon Arendovich, Kimberlee Wilkens, Charles Frisbie, Cristian Luciano, Levi N. Kanu, Peter Pfanner
Diseases of the posterior segment may result in blindness, and the delivery of novel therapeutics through intravitreal injection is often precluded. The SCS is an alternative route to deliver therapeutics to the posterior segment, however, to the best of our knowledge, there are no navigational catheter systems for the delivery of large payloads designed specifically for use in the SCS. Therefore, we designed a system that met the following criteria: 1) the catheter tip must minimise stress applied to SCS-defining tissues, 2) the catheter tip must be controllably articulated to permit navigation, and 3) the catheter must facilitate the targeted delivery of large payloads.